Heat
Treating
Processes
and Related
Technology
Introduction
Heat treating is defined as heating and cooling a solid metal or alloy in
such a way as to obtain desired conditions or properties.
Reasons for heat treating include the following:
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Remove stresses. such as those developed in processing a part
Refine the gram structure of the steel used in a part
Add wear resistance to the surface of a part by increasing its hardness,
and, at the same time. increase its resistance to impacts by mamtaining
a soft, ductile core
Iron-carbon equilibrium
diagram
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Beef up the properties of &an economical
grade of steel, making it
possible to replace a more expensive steel and reduce material costs in a
given application
Increase toughness by providing a combination of high tensile strength
and good ductility to enhance impact strength
Improve the cutting properties of tool steels
ltpgrade electrical properties
Change or modify magnetic properties
The focus in this chapter is on heat treatments
associated with getting the desired result.
and the technology
2 / Heat Treater’s Guide
Fist, key components
abstracts on:
of the heat treating
process are summarized
Second, practical, how-to information
in
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. Normalizing
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hneding
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Stress relieving
Surface hardening
Quenching/quenchants
Tempering
Cold/cryogenic
treatments
Furnace atmospheres
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Heat
Treating
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by overview
atticles on:
Causes of distortion and cracking in quenching
Stress relief heat treating
Furnace atmospheres
Cold and cryogenic treatments of steel
Representative applications of heat treating furnaces
Statistical process control of heat treating operations
Practical applications of the computer in heat treating
Processes
tion in resistance to brittle fracture. Lf a steel, such as austenitic stainless
steel, is not prone to brittle fracture, residual stresses can cause stress-corrosion cracking (SCC). Warping is the common problem.
Normalizing
The term normalize does not characterize the nature of this process. More
accurately, it is a homogenizing
or grain refining treatment, with the aim
being unifotmity
in composition
throughout a part. In the thermal sense,
normalizing is an austenitizing heating cycle followed by cooling in still or
slightly agitated air. Typically, work is heated to a temperature of approximately 55 “C (100 “F) above the upper critical line of the iron-iron carbide
phase diagram, and the heating portion of the process must produce a
homogeneous austenitic phase. The actual temperature used depends upon
the composition
of the steel; but the usual temperature is around 870 “C
(1600 “F). Because of characteristics
inherent in cast steel, normalizing
is
commonly applied to ingots prior to working, and to steel castings and
forgings, prior to hardening. Air hardening steels are not classified as
normalized steels because they do not have the normal pearlitic microstructure typical of normalized steels.
Surface
A generic term denoting a treatment consisting of heating to and holding
at a suitable temperature,
followed
by cooling at a suitable rate; used
primarily to soften metals and to simultaneously
produce desired changes
in other properties or in microstructures.
Reasons for annealing include
improvement of machinability,
facilitation
of cold work, improvement
in
mechanical or electrical properties, and to increase dimensional stability.
In ferrous alloys. annealing usually is done above the upper critical temperature, but time-temperature
cycles vary widely in maximum temperature and in cooling rate, depending on composition of the steel, condition
of the steel, and results desired. When the term is used without qualiftcation. full annealing is implied. When the only purpose is relief of stresses,
the process is called stress relieving or stress relief annealing.
In full annealing steel is heated 90 to I80 “C ( I60 to 325 “F”) above the
A3 for hypoeutectoid steels and above the At for hypereutectoid
steels, and
slow cooled, making the material easier to cut and to bend. In full annealing, the rate of cooling must be very slow, to allow the formation of coarse
pearlite. ln process annealing, slow cooling is not essential because any
cooling rate from temperatures below At results in the same microstructure
and hardness.
Hardening
These treatments, numbering more than a dozen, impart a hard, wear
resistant surface to parts, while maintaining
softer, tough interior which
gives resistance to breakage due to impacts. Hardness is obtained through
quenching, which provides rapid cooling above a steel’s transformation
temperature.
Parts in this condition
can crack if dropped. Ductility
is
obtained via tempering. The hardened surface of the part is referred to as
the case, and its softer interior is known as the core.
Gas carburizing
is one of the most widely used surface. hardening
processes. Carbon is added to the surface of low-carbon steels at temperatures ranging from 850 to 950 “C ( I560 to 1740 “F). At these temperatures
austenite has high solubility for carbon. In quenching, austenite is replaced
by martensite. The result is a high-carbon,
mattensitic case. Carburizing
steels for case hardening usually have carbon contents of approximately
0.2%. Carbon content of a carburized case is usually controlled between
0.8 to I% carbon. Other methods of case hardening low-carbon
steels
include cyaniding, ferritic nitrocarburizing,
and carbonitriding.
Annealing
Stress
is provided
Quenching/Quenchants
Steel parts are rapidly cooled from the austenhizing or solution treating
temperature, typically
from within the range of 815 to 870 “C (1500 to
1600 “F). Stainless and high-alloy steels may be quenched to minimize the
presence of gram boundary carbides or to improve the ferrite distribution,
but most steels, including carbon. low-alloy, and tool steels, are quenched
to produce controlled amounts of martensite in the microstructure.
Objectives are to obtain a required microstructure,
hardness, strength, or toughness, while minimizing residual stresses, distortion, and the possibility of
cracking. The ability of a quenchant to harden steel depends upon the
cooling characteristics of the quenching medium. Quenching effectiveness
is dependent upon steel composition,
type of quenchant, or quenchant use
conditions. The design of a quenching system and its maintenance are also
keys to success.
Relieving
Residual stresses can be created in a number of ways, ranging from ingot
processing in the mill to the manufacture of the finished product. Sources
include rolling, casting, forging, bending, quenching, grinding, and welding. In the stress relief process, steel is heated to around 595 “C (I IO5 “F),
ensuring that the entire part is heated uniformly, then cooled slowly back
to room temperature. Procedure is called stress relief annealing, or simply
stress relieving. Care must be taken to ensure uniform cooling, especially
when a part has varying section sizes. If the cooling rate is not constant and
uniform, new residual stresses, equal to or greater than existing originally,
can be the result. Residual stresses in ferritic steel cause significant reduc-
Quenching
Media
Selection here depends on the hardenability
of the steel, the section
thickness and shape involved,
and the cooling rates needed to get the
desired microstructure.
Typically, quenchants are liquids or gases.
Common liquid quenchants are:
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Oil that may contain a variety of additives
Water
Aqueous polymer solutions
Water that may contain salt or caustic additives
Heat Treating Processes and Related Technology / 3
Most common gaseous quenchants are inert gases, including helium,
argon, and nitrogen. They are sometimes used after austenitizing
in a
vacuum.
A number of other quenching media and methods are available, including fogs, sprays, quenching in dry dies and fluidized beds. Ln addition,
some processes, such as electron-beam hardening and high frequency pulse
hardening are self-quenching.
Very high temperatures are reached in the
fraction of a second, and metal adjoining the small. localized heating area
acts as a heat sink, resulting in ultrarapid cooling.
Tempering
In this process, a previously
hardened or normalized steel is usually
heated to a temperature below the lower critical temperature and cooled at
a suitable rate, primarily
to increase ductility and toughness, but also to
increase gram size of the matrix. Steels are tempered by reheating after
hardening to obtain specific values of mechanical properties and to relieve
quenching stresses and ensure dimensional
stability. Tempering usually
foUows quenching From above the upper critical temperature.
Most steels are heated to a temperature of 205 to 595 “C (-NO to I I OS “F)
and held at that temperature for an hour or more. Higher temperatures
increase toughness and resistance to shock, but reductions in hardness and
strength are tradeoffs. Hardened steels have a fully martensitic structure.
which is produced in quenching. A steel containing 100% martensite is in
its strongest possible condition, but freshly quenched martensite is brittle.
The microstructure
of quenched and tempered steel is referred to as tempered martensite.
Martempering of Steel. The term describes an interrupted quench
from the austenitizing temperature of certain alloy, cast, tool, and stainless
steels. The concept is to delay cooling just above martensitic transformation for a period of time to equalize the temperature throughout the piece.
Minimizing
distortion, cracking, and residual stress is the payoff. The term
is not descriptive of the process and is better described as marquenching.
The microstructure
after martempering
is essentially primary martensite
that is untempered and brittle.
Austempering of Steel. Ferrous alloys are isothermally transformed
at a temperature below that for pearlite formation
and above that of
martensite formation. Steel is heated to a temperature within the austenitiz-
Causes
of Distortion
and Cracking
This problem usually is the result of an imbalance in internal residual
stresses that can lead to cracking, ranging from microcracking
to bulk
failure of a part, Ref I.
Factors, singly or in combination, that can influence the nature and extent
of shape distortion during quenching include:
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Steel composition and hardenability
Geometry of part
Mechanical handling
Type of quenching fluid
Temperature of quenchant
Condition of quenchant
Circulation (agitation) of quenchant
Composition
The quenchant
ing range, usually 790 to 9 I5 “C ( I455 to 1680 “F); then quenched in a bath
maintained at a constant temperature, usually in the range of 260 to 400 “C
(500 to 750 “F); allowed to transform isothermally
to bainite in this bath;
then cooled to room temperature. Benefits of the process are increased
ductility, toughness, and strength at a given hardness; plus reduced distortion that lessens subsequent machining time, stock removal, sorting, inspection. and scrap. Austempering
also provides the shortest possible
overall time cycle to through harden within the hardness range of 35 to 55
HRC. Savings in energy and capital investment are realized.
Maraging Steels. These highly alloyed, low-carbon,
iron-nickel
martensites have an excellent combination of strength and toughness that
is superior to that of most carbon hardened steels, and are alternatives to
hardened carbon steels in critical applications
where high strength and
good toughness and ductility are required. Hardened carbon steels derive
their strength from transformation
hardening mechanisms, such as martensite and bainite formation, and the subsequent precipitation
of carbides
during tempering. Maraging steels, by contrast, get their strength from the
formation of a very low-carbon, tough, and ductile iron-nickel
martensite,
which can be further strengthened by subsequent precipitation of intermetaUic compounds during age hardening. The term marage was suggested by
the age hardening of the martensitic structure.
Cold and Cryogenic
Treatment
of Steel
Cold treatment can be used to enhance the transformation
of austenite to
martensite in case hardening and to improve the stress relief of castings and
machined parts. Practice identities -84 “C (-120 “F) as the optimum cold
treatment temperature. By comparison, cryogenic treatment at a temperature of around -190 “C (-3 IO “F), improves certain properties beyond the
capability of cold treatment.
Furnace Atmospheres. Atmospheres serve a variety of functions:
acting as carriers for elements used in some heat treating processes, cleaning surfaces of parts being treated in other processes, and providing
a
protective environment
to guard against adverse effects of air when parts
are exposed to elevated temperatures. Principal gases and vapors are air.
oxygen, nitrogen. carbon dioxide and carbon monoxide, hydrogen, hydrocarbons (i.e., methane, propane, and butane), and inert gases, such as argon
and helium.
during
Quenching
Part Geometry
Two considerations
here:
I. Quenching at the slowest possible speed as dictated by thickest section
of the part
2. Or resorting to hot oil quenching techniques (more later)
Mechanical
Handling
Care is advised because steel in the austenitic condition is only one-tenth
as strong as it is at room temperature. Avoid dropping parts into the bottom
of a quench tank; and when continuous furnaces are used, quench chute
design can cause damage when thin section parts strike pick-up slots in
conveyor systems (see Figure).
and Hardenability
Type of Quenching
selected should:
I. Just exceed the critical cooling rate of the steel used
2. Provide a low cooling rate in the Ms to Mr transformation
Compromises
in cooling rate often are necessary
range of steels with a range of cooling rate.
range
to accommodate
a
Fluid
The importance of the characteristics
of a quenchant during the three
stages of cooling (vapor phase, boiling phase, and convection phase) is
illustrated by an example involving precision auto transmission gears (see
Figure). During oil quenching, vapor retention in tooth roots, combined
with the onset of boiling on flanks can cause “‘unwinding”
of thin section
gears. Use of accelerated oils with special additives that reduce the stability
4 / Heat Treater’s
Guide
Schematic continuous
heat treatment installation.
Ref 1
Example: Because PAG (a polymer quenchant) has higher cooling
rates than oils in the convection
phase, parts are more susceptible to
distortion. Use of PAG requires careful consideration to steel hardenability,
part section size(s), and surface finishes. By comparison, other polymer
quenchants (ACR. PVP, PEO) have cooling rates similar to those of oils,
which means they can be applied in treating critical alloy steel parts outside
the scope of PAG quenchants. which are suitable in quenching plain
carbon, low-alloy, carburized steels, or higher alloy steel parts with thick
section sizes.
Quenchant
Vapor retention in gear tooth roots during oil quenching. Ref 1
Temperature
In conventional quenching, the surface and thinner sections of a part cool
to the his temperature and are beginning to transform while center and
thicker sections are still in the soft, austenitic condition. This means that
when soft sections begin to transform, their changes in volume are restricted by the hard. brittle martensite previously
formed on surfaces and
thin sections, creating stresses that can lead to distortion or to quench
cracking.
Hot oil quenching, a two-step process, is one remedy. Parts are Fu-st
quenched in specially formulated oils, usually at temperatures within the
range of I20 to 300 ‘C (250 to 390 “F). depending on part complexity and
tendency to distort. Holding time at the temperature chosen is based on the
time required to obtain a uniform temperature throughout a part. In the next
step, parts are removed from the oil and cooled slowly in a furnace
containing an atmosphere (see Figure).
Hot oil quenching techniques to reduce distortion.
of the vapor phase and promote boiling
in cooling is the payoff.
Convection
is one remedy. Greater uniformity
An alternative is marquenching in hot oil ( I50 to 200 “C, or 300 to 390 “F’).
The hlS temperature of typical engineering steels is in the 250 to 350 “C
range (480 to 660 “F).
Phase Characteristics
A temperature of 300 “C (570 “F) generally is accepted as the nom1 for
cooling in this phase because it is within the M&t
temperature range of a
number of different engineering steels, and therefore a critical consideration in controlling distortion.
Typical values for several types of quenchants are as follows:
Quencbant
Normal sped oil
Acceleratal oil
Polymers
PAG (polyalk\ylene glycol)
ACR (sodium polyacrylate)
PVP(polyvinyl pyrrolidene)
PEO(polyethyl oxazolrne)
Ref 1
Cooling rate at 300 ‘C (570 OF) “C/s
s-15
IO-15
Condition
Regular monitoring
of the quenching fluid is preferred practice. The
minimum: testing for acidity and water content of quenching oil and
checking the concentration
of polymer quenchants. An added control:
periodic evaluation of quenching characteristics.
Increases in quenching speeds, especially in the convection phase, are a
common problem. Possible causes include:
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30-80
I o-25
I o-25
I O-30
of Quenchant
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Contamination
of quenching oils with water. As little as 0.05% water can
have a dramatic effect on the maximum cooling rate and on the convection phase cooling rate.
Oxidation of mineral oils reduces the stability of the vapor phase and
accelerates maximum cooling rates.
Heat Treating Processes and Related Technology / 5
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Contamination
or thermal degradation of polymer quenchants increases
the cooling rate in the convection phase. Higher polymer concentrations
are a parIial solution.
Circulation of quenchant is important in maintaining a uniform bath
temperature and in assisting the breakdown of the vapor phase. The degree
of agitation has a significant influence on the cooling rates of both quenching oils and polymer quenchants.
With increases in the agitation of oil, three things happen:
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Duration of the vapor phase is shortened
Maximum cooling rate rises
Cooling rate in the convection phase also goes up
The last named effect adds to the risk of cracking, meaning that excessive
agitation of oils should be avoided.
Agitation of polymer quenchants has a pronounced effect on the vapor
phase and maximum cooling rate, but little effect on the cooling rate in the
convection phase. Vigorous agitation of polymer quenchants normally is
recommended to ensure uniform quenching characteristics,
a practice that
does not enhance the risk of cracking.
Stress
Relief
Heat
Treating
Finally, the direction
influence on distortion.
provide relief.
of quenchant flow over the workpiece can have an
Reversing the direction of flow, for example, can
Reference
I. R.T. van Bergen, conference paper, ‘The Effects of Quenchant Media
Selection
and Control
of Distortion
of Engineered
Steel Parts.”
Houghton Vaughan plc. Birmingham.
England, ASM Conference Proceedings, “Quenching and Distortion Control,”
1992
Other References
Quenching Principles and Practice, Houghton Vaughan plc, UK
G.E. Hollox and R.T. von Bergen, Heat Treatment of Metals, 1978.2
hlEl Course 6. Heat Processing Technology, ASM International,
1977
R.T. von Bergen, Heat Treatment of Metals, 1991.2
of Steel
Residual stresses are built up in a part during the course of a manufacturing sequence. Technically, a part is stressed beyond its elastic limit and
plastic flow occurs.
long distance or highly localized. Postweld heat treating has two objectives: relief of residual stresses and the development of a specilic metallurgical structure of properties (Ref 4.5).
Causes
Relieving
Bending, quenching, grinding, and welding are among the major causes
of the problem (see adjoining Figure).
Bending a bar during fabrication at a temperature where recovery cannot
occur (as in cold forming) can cause a buildup on residual tensile stresses
in one location, and a second location, 180” from the Fust location, will
contain residual compressive stresses (Ref I).
Quenching of thick sections results in high residual compressive stresses
on the surface of a part. They are balanced by residual tensile stresses in
the interior of the part (Ref 2).
Residurtl stresses caused by grinding can be compressive or tensile in
nature. depending on the grinding operation. Such stresses tend to be
shallow in depth, but they can cause warping of thin parts (Ref 3).
In welding, residual stresses are associated with steep thermal gradients
inherent in the process. Stresses may be on a macro-scale over a relatively
Relief is a time-temperature
related phenomenon
rically correlated by the Larson-hliller
equation:
Examples of the causes of residual stresses: (a) Thermal
due to welding.
(c) Residual
stresses
due to grinding
distortion
Residual
Stresses
(see Figure), paramet-
where T is the temperature (Rankin) and I is time in hours. Example: holding
a part at 595 “C (I I05 “F) for 6 h provides the same result as heating at 650 “C
( 1200 “F) for I h.
Other Factors. Creep resistant materials such as chromium bearing,
low-alloy steel and chromium rich, high-alloy steel normally require higher
stress relief temperatures than con\ entional low-alloy steels. Typical treatment temperatures for low-alloys
are between 595 and 675 “C (I I05 and
1245 “Fj. Temperatures
required for the treatment of high alloys, by
comparison. range from 900 to 1065 “C ( 1650 to 1950 “F).
in a structure
due to heating
by solar radiation.
(b) Residual
stresses
6 / Heat Treater’s Guide
Relationship between time and temperature in the relief of residual stresses in steel
925 “C (895 to 1695 “F). However,
at the higher end of this range
stress-corrosion
cracking can occur (Ref 6). Solution annealing temperatures of approximately
1065 “C (1950 “F) are frequently used to reduce
residual stresses in these aBoys to acceptably low levels.
References
I. GE. Dieter, Mechanical Merallurgy, 2nd ed, McGraw-Hill,
1976
2. J.O. Almen and RH. Black, Residual Stresses and Fatigue in Merals,
McGraw-Hill,
1963
3. Machining, Vol 3, 8th ed, Merals Handbook, American Society for
Metals, 1967, p 260
4. N. Bailey, The Metallurgical
Effects of Residual Stresses, in Residual
Stresses, The Welding Institute, I98 I, p 28-33
5. C.E. Jackson et al., Metallurgy and Weldabili& of Sleek, Welding
Research Council, 1978
High alloys such as austenitic stainless steels are sometimes treated at
temperatures as low as 400 “C (750 “F). But in this instance stress reduction
is modest. Better results are obtained at temperatures ranging from 480 to
Furnace
6. Properties and Selecrion: Stainless Sleels, Tool Materials and Special
Putpose Metals, Vol 3.9th ed, Metals Handbook, American Society for
Metals,
1980, p 4738
Atmospheres
Properties of common gases and vapors are listed in Table I. They
include air, oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen,
water vapor, hydrocarbons,
and inert gases. Ref I.
Air provides atmospheres in furnaces in which protective atmospheres
are not used. Air is also the major constituent in many prepared amiospheres. The composition
of air is approximately
79% nitrogen and 2 I %
oxygen, with trace elements of carbon dioxide. As an atmosphere, air
behaves like oxygen, the most reactive constituent in air.
Oxygen reacts with most metals to form oxides. It also reacts with
carbon dissolved in steel, lowering surface carbon content.
Nitrogen in its molecular state is passive to ferrite and can be used as
an atmosphere in annealing low-carbon steels; as a protective atmosphere
in heat treating high-carbon
steels, nitrogen must be completely
drysmall amounts of water vapor in nitrogen cause decarburization.
Molecular
nitrogen is reactive with many stainless steels and can’t be used to heat treat
them. Atomic nitrogen, which is created at normal heat treating temperatures, is not a protective gas-it combines with iron, forming finely divided
nitrides that reduce surface hardness.
Carbon dioxide and carbon monoxide are used in steel processing atmospheres. At austenitizing temperatures, carbon dioxide reacts with
surface carbon to produce carbon monoxide, a reaction that continues until
the supply of carbon dioxide is exhausted and the steel surface is free of
carbon.
Hydrogen reduces iron oxide to iron. Under certain conditions, hydrogen can decarburize steel, an effect that depends on furnace temperature,
moisture content (of gas and furnace), time at temperature, and carbon
content of the steel.
Water vapor is oxidizing to iron and combines with carbon in steel to
form carbon monoxide and hydrogen. It is reactive with steel surfaces at
very low temperatures and partial pressures. It is also the principal cause
of bluing during cooling cycles.
Carbon hydrocarbons are methane (Cb). ethane (C2H6). propane
(C$-Js), and butane (CtHtu). They impart a carburizing tendency to furnace
atmospheres.
Inert gases are especially useful as protective atmospheres in the thermal processing of metals and alloys that can’t tolerate the usual constitu-
Table 1 Properties of Common Gases and Vapors
Gas
Chemical
symbol
Air
Approximate
molecular
weight
k&m3
lb/d’
I.293
0.760
0.178
I.965
0.0807
0.047-l
0.0111
0.1228
0.0780
0.0112
0.0056
0.0447
0.0780
0.0892
0.1229
0. I785
Density(a)
AINllOllitl
NH3
Argon
Carbon dioxide
Carbon monoxide
Helium
Hydrogen
Methane
Nitrogen
Oxygen
Pv=
SulFurdioxide
Ar
CO?
28.97(c)
17.03
39.95
44.02
CO
28.01
I.250
He
H?
CH-I
N?
02
4.00
2.02
16.04
28.01
32.00
0.179
0.090
0.716
I.250
I.429
I.968
2.860
C3Hx
SO?
44.09
64.06
(a) Standard temperature and pressure: 0 “C (32 “F) and 760 mm Hg. (b) Relative
is the average molecular weight of its constituents.
density compared
SpCifiC
to air. (c) Because air IS a mixture,
gravity(b)
l.ooo
0.588
I.380
1.520
0.967
0.138
0.070
0.552
0.968
I.105
I.522
2.212
it does not have a true molecular
weight. This
Heat Treating Processes and Related Technology / 7
Table 2 Classification
Dfscription
Cla5.S
101
102
201
202
301
302
402
501
so2
601
621
622
and Application
Lean exothemic
Rich exothermic
Lean prepared nitrogen
Rich prepared nitrogen
L.eaoendothemic
Rich endothermic
Charcd
Leanexothemric-endothermic
Rich enothennic-endothermic
Dissociated ammonia
Lean cornbusted ammonia
Rich cornbusted ammonia
of Principal Furnace Atmospheres
Common application
NZ
Oxide coating of steel
Bright annealing; copper brazing; sintering
Neutral heating
Annealing, brazing stainless steel
Clean hardening
Gas carburizing
Carburizing
Clean hardening
Gas carburizing
Brazing. sintering
Neutral heating
Sintering stainless powders
86.8
71.5
97. I
75.3
45.1
39.8
64. I
63.0
60.0
25.0
99.0
80.0
reactive
metals and their alloys. Argon costs about half
as much as helium, and is frequently favored; air contains approximately
0.93% argon by volume, and is recovered by liquefying
air, followed by
the fractionation of liquid air: helium is recovered from natural g,as deposits
by cryogenic methods.
ents in protective
Classifications
The American
tions:
of Prepared
Gas Association
Atmospheres
is the source of the following
classitica-
Class 100, exothermic
base: formed by the combustion
of a gas/air
mixture; water vapor in the gas can be removed to get the required dew
point
Class 200, prepared nitrogen base: carbon dioxide and water vapor have
been removed
Class 300. endothermic base: formed by the reaction of a fuel gas/air
mixture in a heated, catalyst tiller chamber
Class 400, charcoal base: air is passed through a bed of incandescent
charcoal
Class 500, exothermic-endothermic
base: formed by the combustion of
a mixture of fuel gas and air; water vapor is removed and carbon dioxide
is reformed to carbon monoxide by reaction with fuel gas in a heated,
catalyst tilled chamber
Class 600. ammonia base: can consist of raw ammonia. dissociated
ammonia, or combusted dissociated ammonia with a regulated dew
point
Subclassifications
supplement the six basic classitications
for prepared
atmospheres-the
two zeros in the latter are replaced by the two-digit
numbers that follow. These atmospheres are prepared by special techniques.
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01: prepared from a lean air and gas mixture
02: prepared 6om a rich air and gas mixture
03 and 04: preparation is completed within the furnace itself without the
use of a special machine or generator
05 and 06: original base gas is subsequently passed through incandescent charcoal before admission to work chamber
07 and 08: raw hydrocarbon
fuel gas is added to base gas before
admission to work chamber
09 and IO: raw hydrocarbon
fuel gas and rah dry anhydrous ammonia
are added to base gas before admission to work chamber
I I and 12: combustible mixture of chlorine, hydrocarbon
fuel gas and
air is added to base gas before admission to work chamber
I3 and 14: all sulfur or all sulfur and odors are removed from gas before
admission to work chamber
IS, 16, I7 and 18: lithium vapor is added to base gas before admission
to work chamber
I9 and 20: gas preparation is completed inside the furnace chamber bith
the addition of lithium vapor
co
Nominal composition, ~01%
co2
I.5
IO.5
1.7
II.0
19.6
20.7
31.7
17.0
19.0
IO.5
5.0
82
CB,
1.2
12.5
I.2
13.2
34.6
38.7
I.2
20.0
2 I .o
75.0
I.0
20.0
0.4
OS
0.5
0.3
0.8
...
.
Table 3 Potential Hazards and Functions of Heat
Treating Atmosphere-Constituent
Gases
Potential hazard
Stole
Gas
Flammable
Nitrogen
Hydrogen
Carbon monoxide
Toxic
Yes
Yes
Yes
Yes
Yes
Carbon dioxide
Yes
Natural gas
Yes
Ammonia
Methanol
Yes
Yes
Yes
Yes
Yes
Yes
Table 4 Physiological
Atmosohere
a5phyknt
..
fUll&Oll
tnell
Strongly reducing
Carburizing and mildly
reducing
Oxidizing and
decarburizing
Strongly carburizing and
deoxidizing
Strongly niniding
Carbon monoxide and
hydrogen generating
Effects of Ammonia
Conceotrstion,
Physiological
mm
30
First perceptible odor
Slight eye irritation in a few individuals
Noticeable irritation of eyes and nasal passages after a few
minutesofexposure
Were irritation of the duoat, nasal passages. and upper
respiratory tract
Severe e)e irritation; no permanent effect if the exposure is limited
to less than r/z h
Serious coughing, bronchial spasms; less than ‘/z h of exposure
may be fatal
Serious edema strangulation, asphyxia; almosl immediately fatal
-lo
I00
m
700
1700
moo
l
l
l
effects
21 and 22: base gas is given an additional
special treatment before
admission to work chamber
23 and 24: steam and air ‘are added and in conjunction with a catalyst in
a generator convert carbon monoxide to carbon dioxide, which is then
removed
25 and 26: steam is added to a generator containing a catalyst, converting
CHJ to Hz and CO?, which is then removed
Few
cially
of the atmospheres
important.
Principal
in the subclassification
furnace
atmospheres
category
and their
are commer-
common
appli-
cations are listed in Table 2. Potential hazards in the use of constituents in
heat treating atmospheres and their functions are listed in Table 3. Physiological effects of ammonia are listed in Table 4, and physiological
effects
of carbon monoxide are given in Table 5.
8 / Heat Treater’s Guide
Exploswe
ranges of typical
atmosphere
constituents
are:
their use as intentional
ture operations.
Concentration
Constituent
in Air Q
Hbdrogcn
-I o-74
Carbon mono\idc
hlrtic
Ammonia
hkthm0l
12.5-71
5.3-13
15.0-28
Endothermic-Based
agents or in special, low tempera-
Atmospheres
These atmospheres are suitable for practically
all furnace processes
requiring strong reducing conditions. Their most common applications are
as carrier gases in gas carburizing
and carbonitriding
operations. Other
applications include bright hardening of steel. carbon restoration in forg-
6 7-36
Exothermic-Based
surface oxidizing
Atmospheres
Class 100 atmospheres of this type are \\idelj
used as lo\rer cost
alternatives to other atmospheres. The) are available in two classes: rich
(class 102) and lean (class 101). The rich types have moderate reducing
capabilities of IO to 2 I% combined carbon monoxide and hydrogen. The
lean types. usually with I to 1 Q combined carbon monoxide and hydrogen.
have minimal reducing qualities.
Rich exothermic atmospheres are used mainlj in the tempering of steel
and sintering of powder meval compacts.
Heat treating applications of lean exothermic atmospheres are generally
limited, particularI)
in the treatment of ferrous metals. Exceptions include
Table 5 Physiological
Effects of Carbon Monoxide
Concentralion,
PPm
Physiological effects
Allo\\sble for an exposure of several hours
Can be inhaled for I h without appreciable effect
Causes a barely appreciable effect tier I h of exposure
Causes unpleasant symptoms. hut not dangerous aher I h
100
400
6ofl
IO00
I ml
Dangerous for exposure of I h
Fall for exposure of less than I h
4000
Table 8 Comparison of Generated Atmosphere Systems Versus Commercial Nitrogen-Based
Generated
ppe of
atmosphere
Designation
Application
Protacti\e
Annealing
Reacti\c
Brazing
Siniering
Carbon controlled
Hardening
Carburizing
Decarburizing
Table 7 Compositions
Exolhermi~
Dissociated ammonia
Exothermic
Dissociated arnmon~a
Endothemlic
Dissociated ;unmonia
Endothemlic
Endothemlic
Erolhermic
atmosphere
Nominal composition,
N2
HZ
70-100
O-16
25
70-80
75
40
2s
10
10
85
7s
IO- I6
75
-IO
75
40
10
5
%
CO
O-II
8-11
70
20
20
3
Designation
Systems
Nitrogen-based
atmosphere
Nominal composition,
N?
co
82
Niuwgen-hydrogen
Nitrogen-methanol
Nitrogen-hydrogen
Niaogen-hydrogen
9% IO0
91-100
60-90
95
O-IO
O-h
IO-40
5
o-3
,..
Nitrogen-hbdrogcn
Nitrogen-merhanol
Nitrogen-mehane
Nitrogen-tnclhanol
Nitrogen-hydrogen
95
85
97
40
90
5
IO
I
JO
IO
5
I
30
of Protective Generated Atmosphere and Commercial Nitrogen-Based
Furnace
atmosphere
analysis,
Carbon steel sheet. rube. wrc
Carbon steel rod
Copper n ire. rod
.Alunlinurn
Skinless
sheet
steel sheet. wire
Srainless sleel tube
hlalleahle
Nick-uon
iron anneal
laminaoons
atmosphere
Exolhermic-purified
N:-S5 Hz
E\othetis-puritird
Exothermic-cndolhemtiii
N,- I!“1 C,H,
N,-55, H>-3=c CH,
N;-3% Ct? <OH
Exolhrnnis-lean
N,-IC H,
Ekorhermls-lean
N,
D&&alrd
ammonia
H,
NkOQ. H 7
Dknziated
anunon~a
H,
N,-2%
H,
Exothetic-puritird
N,-II.C,H,
Dissociated ammonia
N,-ISQ H,
N:
blend
I30
95
IO0
75
97
90
91
86
99
86
100
3
db
25
7s
98
97
25
85
HZ
co
CH,
8
I5
1
7
6
8
I
7
7
;
I
;
I
15
I00
-10
7s
100
25
I
75
IS
2
1
I
CH,
:::
I
Atmosphere Systems
%
‘Itace
Input
Application
%
impurities
HZ0
Co2
0.01
0.00 I
0.01
0.01
0001
0.001
0001
3
0.001
3
0.001
O.GOl
0.0005
0.000.5
0.001
O.ooOS
0.005
0.01
0.001
0.001
0001
0.5
0.5
0.5
0.01
0.0 I
0.0 I
II
II
0.5
0.2
Heat Treating Processes and Related Technology / 9
Table 8 Compositions
of Reactive Atmospheres for Brazing and Sintering Applications
Furnace atmosphere analysis, %
Input atmosphere
Application
Copper bmze carbon sleel
Silver braze stainless steel
hledlize ceramics
Glass-to-metal seal
Carbon steel sintering (6.4 to 6.8 g/cm’. or
0.23 1025 Ib/ii.~density. cO.4%Cc)
Carbon steel sintering (6.8 to 7.2 g/cm’, or
0.25 to0.261b/in.3densirq.>0.4QC)
Brass. bronze simering
Stainless steel sintering
Tungsten carhide
Sintering and brazing
Sintering
Presinrering
Nickel sintering
ings and bar stock, and the sintering
requiring a reducing atmosphere.
Prepared
Nitrogen-Based
NZ
82
Exothetic-rich
Endothermic
N,-55% H,
N;-3% CH,OH
Dissociated ammonia
N2-25’% H,
Dissociatei ammonia t Hz0
N,-10% H--?-B H,O
E~othermi~
N,- 10%.H,-L?q, H,O
Endother&
70
40
95
91
1s
75
2s
90
75
88
40
I-l
39
5
6
7s
25
75
IO
9
I0
39
N2-S% H,
Endothermic
N2-endothermic
9.5
-lo
87
5
39
8
N+? CH,OH
N,-8% H1-2Q CH
Dissociated ammoha
Endothermic
NvIO% H,
Dissociates ammonia
HZ
76
90
2s
-lo
90
25
I6
8
75
39
10
75
100
Dissociated ammonia
H,
N;-20Q H,
Dissociated ammonia
N,-IO% H,
2s
7s
100
20
75
IO
of powder
metallurgy
80
25
90
compacts
Atmospheres
Applications
in this instance extend to almost all heat treatments that do
not require highly reducing atmospheres. They are not decarburizing
and
can be used in annealing. normalizing,
and hardening of medium- and
high-carbon steels: the low carbon monoxide content of lean gases makes
them suitable for heat treating lou-carbon
steels. Because of their low dew
point and virtual absence of carbon dioxide, these atmospheres (in the
absence of oxygen-bearing
contaminants introduced in furnace operations)
are neither oxidizing or decarburizing,
in contrast with exothermic-based
atmospheres. In addition, they are lower in cost than all but one type of
protective atmosphere: the exothermics.
Nitrogen-based
atmospheres enriched with methane or other hydrocarbons are used occasionally
as carrier gases in annealing. gas carburizing.
and carbon restoration; but endothermic and other protective atmospheres
are generally preferred for their high carbon potentials and greater ease of
control.
Lean. nitrogen-based
atmospheres are also used in large. seni-continuous and continuous annealing furnaces. Their rich counterparts can be used
in the sintering of iron powder compacts.
Generated atmosphere systems and commercial. nitrogen-based systems
are compared in Table 6.
Commercial
Nitrogen-Based
Atmospheres
These products fall into three major categories. based on function:
protective atmospheres, reactive atmospheres, and carbon-controlled
atmospheres.
co
CE4
II
I9
I
2
3
7
I9
2
I9
-I
7
;
7
I
I
I
I9
2
‘Itace impurities
820
Co2
0.0s
0.05
0.001
0.001
0.001
0.001
3
2
3
2
0.05
0.001
0.0s
0.01
0.005
0.005
0.00 I
0.05
0.00 I
0.001
0.001
4
0.1
0.01
6
0. I
0.2
0.05
0.05
0.01
0.3
0.001
0.001
0.001
0.001
0.001
Protective atmospheres prevent oxidation or decarburization during heat treatment. Typical applications
include batch and continuous
annealing of most ferrous metals.
Reactive atmospheres have concentrations
of reactive gases greater than
S%--to reduce metal oxides or to transfer small amounts of carbon to
ferrous surfaces. Hydrogen and carbon monoxide are usual reactive components. Typical applications:
brazing. sintering powder metal compacts,
and powder metal reduction.
Carbon-Controlled Atmospheres. Their main function is to react
I{ ith steel in a controlled manner so that significant amounts of carbon can
be added to or removed from the surface of a steel. Typical atmosphere
components can include up to SO8 hydrogen, 5 to 20% carbon monoxide,
and traces (up to 3%) of carbon dioxide and water vapor.
Most common apptications are carburizing and carbonitriding
machined
parts. neutral hardening. decarburization
of electrical laminations, sintering of powder metals, and carbon restoration of hot worked or forged
materials.
Advantages
of commercial.
nitrogen-based
atmospheres include the
technical viability of substituting them for generated ahnospheres in most
heat treating operations.
Compositions
of protecti\ e generated atmospheres and commercial,
nitrogen-based
systems are listed in Table 7. Compositions
of reactive
atmospheres for brazing and sintering are given in Table 8. Compositions
of carbon-controlled
atmospheres for selected applications are summarized
in Table 9.
Dissociated,
Ammonia-Based
Atmospheres
Applications
include: bright heat treating of some nickel alloys and
carbon steels; bright annealing of electrical components. and use as a
carrier mixed gas for certain nitriding processes, including the Floe nitriding system. a method of controlling
the formation of white layer.
10 / Heat Treater’s Guide
Table g Compositions
of Carbon-Controlled
Atmospheres for Selected Applications
Furnace
Input
Neutral harden
Carburize
Carbonitride
Lamination decarburize
atmosphere
NZ
82
Endothermic + CH,
N,-2% CH,. or 1% C,H,
39
97
8-l
37
37
70
55
36
36
68
53
75
83
79
40
I
IO
Xl
40
I6
28
xl
40
I8
30
9
IO
IO
N,-5% CH,OH-I% CH,
Endothetic + CH,
N?-20% CH,OH + CH,
N--17% CH,-4% CO,
N;-20%. CH,-5% Hz6
Endothermic + CH, + NH,
N,-20% CH,OH + CH, + NH,
NJ- 17% CH,-4% CO, + NH,
N,-20% CH,-5% H,O t NH,
Exothermic + H,O
N?- 10% H,-4% H,O
Nz-5%. CH,OH-4C Hz0
Table 10 Physiological Effects of Contamination
by Ammonia in Various Concentrations
Ammonia
concentration
in air, ppm
53
100
30@5cKl
408
698
17’0
2s00-4500
5ooo- lO.ooo
Physiological
of Air
effect
Smallest concentration at which odor can he detected
Maximum concenaation allowable for prolonged
exposure
Maximum concenuation allowable for short exposure
(‘/?-I h)
Least amount causing immediare irritation to the throat
Least amount causing immediate irritation to the eye
Least amount causing coughing
Dangerous for short exposure (‘12 h)
Rapidly fatal for short expsure
atmosphere
analysis,
co
Hydrogen
Atmospheres
T’he commercially
available product is 98 to 99.98 pure. All cylinder
hydrogen contains traces of water vapor and oxygen. Methane.
nitrogen,
carbon monoxide,
and carbon dioxide may be present in very small
amounts as impurities.
Hydrogen is a powerful
deoxidizer,
and its deoxidizing
potential is
limited by moisture content only. Its thermal conductivity
is about seken
times that of air. Its main disadvantage is that it is readily absorbed by most
common metals, either by occlusion or by chemical composition
at elevated temperature. Absorption can result in serious embrittlement.
especially in high-carbon steels. It may also reduce oxide inclusions in steel to
form water, which builds sufftcient pressure at elevated temperatures to
cause intergranular
fracture of steel. Dry hydrogen will decarburize highcarbon steels at elevated temperature by reacting with carbon to form
methane.
lhwe
HZ0
C&
I9
I
5
I8
I8
7
IO
I8
I8
7
IO
7
I
2
0.05
2
I
I
5
5
7
7
5
5
7
7
0.001
O.OOS
0.0s
0.05
O.OOS
0.0 I
0.05
0.05
0.005
0.01
3
3
3
impurities
CO2
0.1
0.01
0.01
0.1
0.1
0.05
0.05
0. I
0.1
0.05
0.05
6
3
6
Table 11 Equipment Requirements for Sintering
Stainless Steel Powder Metallurgy Parts in Hydrogen
Production
requirements
Load weight. kg (lb)
Heating cycle, min
Output per hour, kg (Ih)
Equipment
9(30)
40
l4(3OJ
requirements
Bumoff furnace
Size ofhearth. mm (in.)
Length of cooling chamber. m (ft)
Power, hp (kW)
*rating
temperature, “C (“F)
Atmosphere. m’/h tft3/h)
High-heat furnace
Size ofhearth, mm (in.)
This atmosphere (class 601) is a medium cost product which provides a
dry, carbon-free source of reducing gas. Typical composition:
75% hydrogen, 2YZ nitrogen, less than 300 ppm residual ammonia. Dew point is less
than -SO “C (- 60 “F).
High hydrogen content provides a strong deoxidizing
potential, an advantage in removing surface oxides or preventing oxide formation during
high temperature heat treatment. Care is advised in selecting heat processing applications that might result in unwanted hydrogen embrittlement
or
surface nitriding reactions.
Physiological
effects of the contamination
of air with ammonia in different concentrations
are set forth in Table IO.
5%
Lengthofcoolingchamber.mm(li~
Power. hp (kW)
Operating temperature. “C (“F)
Pusher. electrically heated; forced circulation
25Sby lSOby915(lOby6by36)
I .8 (6)
17 (‘0)
43 (800)
Dissociated ammonia, 4.2 ( 150)
OPen chamber, electrically heated; front
push rear pull
255by610(10by24)(preheating)
255 by 9lS(lOby 36)(high heating)
U(8)
17(35)
I275 (2325)
Hydrogen best suited for metallurgical purposes is made by the electrolysis of distilled water. In most heat treating procedures requiring hydrogen,
hater vapor and oxygen are objectionable,
and hydrogen must be puritied
before it can be used.
Applications
for dry hydrogen include the annealing of stainless steels,
low-carbon
steels, electrical steels, some tool steels. nickel brazing of
stainless steel and heat resisting alloys, the annealing of metal powders, and
the sintering of powder metal compacts.
Equipment requirements for sintering stainless steel powder metallurgy
parts in hydrogen are found in Table I I.
Steam Atmospheres
Scale-free tempering and stress relieving of ferrous metals in the temperature range of 3-U to 650 “C (655 to I200 “F) are among the applications here. Steam causes a thin, hard, and tenacious blue-black oxide to
form on a metal surface. The film, approximately
0.00127 to 0.008 mm
(0.00005 to 0.0003 in.) thick, improves properties of various metal parts.
Steam treating decreases the porosity of sintered iron compacts and
provides increased compressive strength and resistance to wear and corrosion. Steam penetrates the pores of compacts and forms the oxide internally
as well as on the surface. The oxide seals pores and partially fills voids.
Heat Treating Processes and Related Technology / 11
Exothermic and Endothermic Furnace Atmospheres.
Source:
Cast iron and steel parts, treated at 345 “C (655 “F) or higher, have
increased resistance to wear and corrosion.
Before parts are processed their surfaces must be clean and oxide-free,
to permit the formation of a unique coating. To prevent condensation and
rusting, steam should not be admitted until workpiece surfaces are above
100 “C (210 “F). Air must be purged from the furnace before the temperature exceeds 425 “C (795 “F), to prevent the formation of a brown coating
instead of the desired blue-black coating
Charcoal-Based
Atmospheres
These atmospheres (AGA classes 402 and 42 I ) are on the day to
becoming obsolete. Their main use currently is by small manufacturing
Electric
Furnace
Co.
plants wanting a generator low in initial cost and for intermittent
use.
Principal uses today are in the manufacture of malleable iron castings and
as atmospheres in small toolroom, heat treating furnaces.
Exothermic-Endothermic-Based
Atmospheres
These atmospheres (classes 501 and 502) are m-formed exothermicbased types and are less reducing than conventional
endothermic-based
atmospheres. Potentially. they can be substituted for exothermic, endothermic, and nitrogen-based atmospheres in virtually all applications for which
any one of the three amlospheres is recommended. Also, they are used as
carrier gas in carburizing and carbonitriding.
12 / Heat Treater’s Guide
Equipment requirements for hardening small parts made of 1070 steel in
cxothermic-endothermic
atmospheres are provided in Table I?.
Atmospheres
for Backfilling
Quenching
in Vacuum
and
Production
Backfilling
with a cooling gas in a vacuum furnace speeds up the cooling
rate. Other uses of backfilling
include: suppressing the vaporization of oil
in integral quench vacuum furnaces and providing
an atmosphere for
carburizing and nitriding.
Inert gases, nitrogen, and hydrogen (rarely) are used for cooling; contaminants in cooling gases must be held to a minimum to maintain the
surface intefity
of workpieces and to avoid damage to furnace parts.
Backfilling
and forced circulation increase cooling rates. aid in hardening, and in some instances are used to anneal metal alloys. Cooling gas is
usually introduced into a vacuum chamber at the end of the high temperature soaking period.
Vacuum furnaces can be used for carburizing by the injection of any one
of several atmospheres that induce carburizing at appropriate temperatures.
Nitrogen enriched with a hydrocarbon gas is most frequently used.
Carburizing is normally carried out in the range of 870 to 980 YI t 1600
to 1795 “F). ln the carburizing
and diffusion
process, surface carbon
content of 1% or more is formed initially. The high-carbon case is then
diffused in vacuum to the desired surface content and case depth.
Ion Carburizing
Atmospheres
A hydrocarbon gas that is ionized by a high voltage system in a vacuum
is a suitable atmosphere for this process. Methane is frequently used. The
process is faster than conventional
atmosphere carburizing.
and surface
carbon content approaches saturation. For carbon control, other diluting
gases are added.
An AISI 1018 steel can be ion carburized to a depth of I .O mm (0.040
in.) with a IO min cycle in an atmosphere of methane at I .3 to 2.7 kPa ( IO
to 30 torr) and a temperature of 1050 “C (1920 “F). Carburizing is followed
by a 30 min diffusion cycle in vacuum at the same temperature. About 100
V is needed to produce the plasma.
Cold and Cryogenic
Table 12 Equipment Requirements for Hardening
Small Parts Made of 1070 Steel in an ExothermicEndothermic Atmosphere
Treatment
Common practice for cold treatment is regarded to be -84 “C (-120 “F).
In cryogenic treating. parts are chilled to approximately
- 190 “C (-3 IO “F).
Ref I.
Benefits from cold treatment range from enhancing transfomiation
from
austenite to martensite to improving the stress relief of castings and machined parts. In each case, even greater gains are realized \ ia cryogenic
treatment.
Cold Treating
As a rule. I h for each inch of cross section is adequate. All hardened
steels treated in this manner have less tendency to develop grinding cracks
and grind easier after retained austenite and untempered martensite are
eliminated-100%
transformation
to martensite in hardening is rare.
Cold Treating vs. Tempering. The best opportunity for maximum
transformation
to martensite is to cold treat parts immediately
after hardening (and before tempering) when parts cool down to room temperature,
or at a temperature within the range for quenching. A caveat is attached to
this procedure: cracking could result. For this reason, it is important to
ensure that the grade of steel and product design will tolerate immediate
cold treating. rather than immediate tempering. Some steels must be trans-
requirements
Number of parts per load
Weigh1 of each part. kg I lb)
AIa.\imum nel wright of load. kg(lh)
Production rale. kg I lb)
Equipment
2625
00069~0.015)
18(-K))
7.5 loads ( 135. or 300) per h
requirements
Hardening furnace
Size of hearth, m (ti)
Heat input. H’/h I Btu/h)
Operating Iempzrature. “C c”F)
Capacir) of generator. nil/h (ft-l/hJ
T> pe of atmosphere
Capacih’ofoil-quench tank. Ltgal)
lJprofoil,“C(“F)
Tmmperarure ofoil. “C IOF)
Oil agilation
Ion Nitriding
Gas-tired radiant-tube single-row pushertype
\virh automatic quench
0.9 (3) wide by 2.9 (9%) long
2.2 x I oi HhKs (7.5 x 105)
900 i 1650)
68 (1400)
Class so1
1250(330,
Fas& I80 (360) flash point
70 ( 160) (controlled)
~ldhll
Atmospheres
The process is similar to that of ion carburizing. except that the atmosphere gas generates nitrogen ions. and the process is carried out at lower
temperatures. Suitable sources for nitrogen ions are ammonia or mixtures
of hydrogen and nitrogen. A typical cycle of 8 h at 5 IO “C (950 “F) with a
mixture of 75% hydrogen and 2% njtrogen at a pressure of0.9 kPa (7 torr)
and a current density of 0.8 mA/cm- will produce a nitrided case of 0.30
mm (0.012 in.) in AISI 4140 steel. About 400 V is needed to generate the
plasma.
Reference
I. XX
hler~~ls Hmdbook. Vol4.
10th ed. ASM International
of Steel
ferred to a tempering furnace when they are still warm to the touch to
minimize chances of cracking. Design features such as sharp comers and
abrupt changes in section create stress concentrations
and promote cracking.
In most instances, cold treating does not precede tempering. Ln several
applications,
tempering is followed
by deep freezing and retempering
uithout delay. Such parts as gages and pistons are treated in this manner
for dimensional
stability. In critical applications,
multiple freeze-temper
cycles are used.
In addition, in cases where retained austenite could result in excessive
wear. the wear resistance for several different materials is improved, ie.,
tool steels; high-carbon. martensitic stainless steels, and carburized alloy
steels (see adjoining table).
Process
Limitations
In some applications, explicit amounts of retained austenite are considered beneficial, and treatment could be detrimental. Also, multiple tempering, rather than alternate freeze-temper cycles, is generally more practical
in transforming
retained austenitc in high speed and high-carbon/highchromium steels.
Heat Treating Processes and Related Technology
Hardness Testing. Lower than expected HRC values may indicate
excessive
following
retained austenite. Significant
increases in hardness readings
cold treatment indicate conversions from austenite to martensite.
Precipitation-Hardening
Steels. Specifications for these steels may
include a mandatory deep freeze after solution treatment and prior to aging.
Shrink Fits. This result can be obtained by cooling the inner member
of a complex part. Care is advised to avoid brittle cracking when the inner
member is made of heat treated steel containing large amounts of retained
austenite, which converts to martensite in subzero cooling.
Stress Relief. Cold treating is beneficial in stress relieving castings
and machined parts of even or nonuniform
cross section. Features of the
treatment include:
l
l
l
l
l
l
l
Transformation
of all layers is accomplished when the material reaches
-84 “C (-I 20 “F)
The increase in volume of the outer martensite is somewhat counteracted
by the initial contraction due to chilling
Rewarm time is more easily controlled
than cooling time, allowing
equipment flexibility
The expansion of the inner core due to transformation
is somewhat
balanced by the expansion of the outer shell
The chilled parts are more easily handled
The surface is unaffected by low temperature
Parts that contain various alloying elements and that are of different sizes
and weights can be chilled simultaneousI)
Advantages
/ 13
Wear Resistance as a Function of Cryogenic Soak
Temperature for Five High-Carbon Steels
Wear
reistance,
&(a)
SOaked
Alloy
Untreated
52100
25.2
D2
22-l
A2
hl2
01
85.6
1961
237
-tLaT(-12oT)
19.3
308
174.9
2308
382
-l!mT(-31oT)
135
878
565
3993
996
(a) R, = R’AVH,.
where Fis the normal force in newtons. N. pressing the surfaces together; \‘isthesliding
velocib inmm/s; \\‘is theaearrate
in mm’/s;and Hv is the Vickers hardness in MPa. R, is dimensionless.
Source: Ref 3
Plot of temperature vs. time for the cryogenic
treatment proc_ ess. Sour&
Ref 2
of Cold Treating
Success depends only on reaching the minimum low temperature, and
there is no penalty for a lower temperature. As long as -80 “C t,- I IS “F) is
reached transformation
takes place. Reversal is not caused by additional
chilling. Also. materials with different compositions and different configurations can be chilled at the same time. even though each may have a
different high temperature transformation
point.
Cryogenic
Treatment
A typical treatment consists of a slow cool-down
rate (25 “C/min
equivalent to 3.5 “F/min) from ambient temperature to the temperature of
liquid nitrogen. When the material reaches approximately
80 K (-3 IS “F).
it is soaked for an appropriate
time (generally 24 h). Then the part is
removed from the liquid nitrogen and allowed to warm to room temperature in ambient air. The temperature-time
plot for this treatment is shown
in the adjoining Figure. By using gaseous nitrogen in the cool-down cycle.
temperatures can be controlled accurately. to avoid thermal shock.
Single cycle tempering usually is the next step-to
improve impact
resistance, although double or triple tempering cycles are sometimes used
for the same reason.
Kinetics
of Cryogenic
Treatment
According to one theory with this treatment, transformation
of retained
austenite is nearly complete-a
conclusion that has been verilied by x-m>
diffraction
measurements.
Another theorq is based on strengthening
a
Representative
Applications
Pit Furnaces
Normalizing
Stress relieving
References
I. ,&SM &m/s
Hmdhook. Heat Treating, Vol 3. 10th ed., ASM Lntemational
2. R.F. Barron and R.H. Thompson, Effect of Cryogenic Treatment on
Corrosion Resistance, in Adwnces in C~ogenic Engineering, Vol 36,
Plenum Press. 1990. p I375 I379
3. R.F. Barron, “How Cryogenic Treatment Controls Wear,” 2lst InterPlant Tool and Gage Conference. Western Electric Company, Shreveport, LA, 1982
of Heat
Representative
applications
of 36 different types of heat treating furnaces, reported by suppliers of equipment. are listed in this section. Ref I
Soaking
material via the precipitation
of submicroscopic
carbides. An added benefit
is said to be a reduction in internal stresses in the martensite developed
during carbide precipitation.
Lo\\er interior stresses may also reduce tendencies to microcrack.
Treating
Furnaces
Reheating
Batch or In-and-Out
Normalizing
Annealing
Aging
Furnaces
14 / Heat Treater’s Guide
Carburizing (diffusion
Stress relieving
Normalizing
Carburizing
Nitrocarburizing
Carbonitriding
AMeding
Carbon restoration
Stress relieving
Austenitizing
phase)
Box Furnaces
Annealing
Tempering
Hardening
Normalizing
Stress relieving
Aging
Carburizing
Malleabilizing
Solution heat treating
Carbon
Bottom
Tip-Up
Annealing, i.e., wire, long bars, rods, pipe
Hardening
Spheroidizing
Normalizing
Malleabilizing
Tempering
Stress relieving
Furnaces
Annealing, i.e., coatings
Hardening
Normalizing
Malleabilizing
Stress relieving
Carburizing
Tempering
Spheroidiiing
Homogenizing
Wraparound
Vertical
Annealing, including long cycle annealing
Hardening
Tempering
Normalizing
Stress relieving
Steam treating
Homogenizing
Carburizing
Carbonitrid’mg
Carbon restoration
Bluing
Nitriding
Solution heat treating
Bell and Hood Furnaces
Hardening
Nitriding
Aging
Bluing
Tempering
Stress relieving
Solution heat treating
Hearth
Quench
Case hardening
Neutral hardening
Clean hardening
of ferrous parts
Furnaces
Continuous
Slab and Billet
Solution heat treating
Homogenizing
Carbunzing
Walking
Beam Furnaces
Hardening
Annealing
Tempering
Stress relieving
Normalizing
Sintering stainless steel compacts
Hearth
Furnaces
Hardening
Annealing
Carburizing
Carbonitriding
Carbon restoration
Malleabilizing
Tempering
Austempering
Pusher
Furnaces
Furnaces
Annealing
Hardening
Normalizing
Malleabilizing
Tempering
Stress relieving
Austempering
Carburizing
Rotary
Solution heat treating
Hardening
Aging
Malleabilizing
Tempering
Annealing
Stress relieving
Lab work
Integral
and Split Furnaces
Annealing
Stress relieving
Pit Furnaces
Elevating
Furnaces
Furnaces
Annealing
Carbonitriding
Carburizing
Hardening
Normalizing
Clean hardening
Heating
Furnaces
Heat Treating Processes and Related Technology
Screw Conveyor
Ferritic nitrocarburizing
Malleabiliziig
Solution heat treating
Tempering
Stress relieving
Carbon restoration
Spheroidizing
Furnaces
Hardening
Tempering
Annealing
Stress relieving
Slotted Roof, Monorail
Roller Hearth Furnaces
Nitriding. i.e.. extrusions
Carburizing steel parts
Hearth Furnaces
cover gas
Rotary Hearth Furnaces
Small ferrous parts
Process and production testing
Small volume production
Hardening
Tempering
Austempering
Anneahg
Carburizing
Carbon restoration
Carbonitriding
chains. and other long and
Furnaces
and D? tool steels
Annealing. i.e.. bright annealing
Hardening
Tempering
Stress relieving
Cnrburizing
Carbonitriding
Depassinp
Carbon deposition
Bed Furnaces
Nitrocarburizing
Nitriding
Carbonitriding
Steam oxidizing
Carburizing
Hardening. bright type
Tempering
Salt Bath Pot Furnaces
Shaker Hearth Furnaces
Hardening, i.e.. neutral hardening
Carburizinp
Carbonittiding
Stress relieving
Normalizing
Anneding
Tempering
Austempering
Furnaces
Vacuum Furnaces
Fluidized
Furnaces
Applications
requiring hydrogen
Heat treating stainless steel
Annealing
Stress relieving
Carburizing
Hardening
crankshafts.
Ion NitridingKarburizing
Tempering
Hardening, i.e.. clean hardening
Carbon restoration
Annealing, i.e.. bright annealing
Carbonitriding
Austempering
Carburizing
Spheroidizing
Homogenizing
Humpback
Conveyor
Annealing. i.e.. large castings,
unusually shaped parts
Hardening
Tempering
Annealing
Normalizing
Stress relieving
Solution heat treating
Stress relieving
Bluing
Spheroidizing
Tempering
Nomutlizing
Malleabilizing
Hardening, i.e., clean hardening
Tempering
Carburizinp
Carbonitriding
Carbon restoration
Conveyor
/ 15
carbon steel and light case hardenmg
Austempering
Martempering
Hardemng
Tempering
Carburizing
Cyaniding
Salt Bath Furnaces:
Austempering.
i.e.. ductile
Carburizing
Carbonitriding
Nitrocarburizinp
Nomtalizing
Neutral hardening
Salt Bath Furnaces:
Austemper
Batch Austemper
iron. steel
Mesh Belt
System
Austempering.
i.e.. ductile
Carboaustempenng
steel
iron. steel
System
16 / Heat Treater’s Guide
Neutral
Salt Based Furnaces
Quartz Tube Furnaces
Austempering
Martempering
Hardening
Cyanide
Sintering
Heat treating
Rotating
Based Salt Type Furnaces
Furnaces
Heat treating, continuous long lengths of pipe, turbine, bars, rods, billets
Included in quench and temper lines for high grades ofoil country tubing
Cloverleaf
Induction
Furnaces
primarily.
Treating
hardenable
Heating
types
Systems
Aging
Stress relieving
Hardening
Annealing. i.e., bright annealing
Carbonitriding
Normalizing
Equipment
i.e., martensitically
Systems
i.e.. surface and localized
Resistance
Beam Surface
Surface hardening
metals
Heat Treating
Hardening,
Tempering
Hardening
Normalizing
Tempering
Carburizing
Annealing
Carbonitriding
Carbon restoration
Electron
Furnaces
Hardening
Normalizing
Tempering
Annealing
Stress relieving
Carburizing
Case Hardening
Barrel
Finger
ferrous
Reference
Laser Heat Treating
Furnaces
I. Joseph H. Cireenberg, lndrtstrial Tirenml Processing Equipment Handbook, ASM International, 199-I
Annealing
Statistical
Process
Control
of Heat
Statistical process control (SPC) is being applied to advantage in heat
treating shops with continuous, hatch, and single part operations. (A case
history of how one shop has integrated this technology into its operations
is reported in a sidebar feature to this article. In many instances. as in this
one, teaming SPC with the computer is the next step). Ref I.
Continuous equipment, such as rotary retorts, pusher carburizers,
and belt furnaces, offer the most straightforuard
approach to applying both
statistical quality control (SQC) and SPC techniques to improle process
performance. The high volume of work handled by continuous equipment
provides many opportunities
for sampling key product characteristics.
Treating
Operations
Problems can be predicted and corrective action taken in a timely manner.
Also, special causes of prohlems are often more identifiable
because
process variables are steadier in continuous processes than they are in batch
operations.
Batch operations alloh a significant amount of sampling and analysis within a load. However, the only net payoff is a degree of confidence in
treating an entire load. Process vmables must be monitored and analyzed
to ensure that the process is under control, and that there is load-to-load and
day-to-day repeatabilit~-especiall~
when each load is different in terms
of part geometry. matenal. and/or specification.
Contribution of Selected Parameters to Variations in Effective Case Depth for Required 0.85 to 1.OO%Surface Carbon
Level at 870 “C (1600 “F) Processing Temperature
Variation
Case depth
mm
in.
OS1
I .O?
I .52
2.03
0.020
0.040
0.060
0.080
Temperature
variation
28 T
11°C
(2OW
6
6
7
9
(AT)
56 =‘C
(50OF) (1~W
I-l
16
17
19
33
34
35
36
in case depth for selected parameters,
Timevariation
Smin
10 min
3
1
>I
>I
7
‘)
;
>I
(A I )
30 min
30
5
2
I
0.10%
a
a
a
a
Atmosphere
0.15%
13
13
13
13
%(a)
Carbon
0.25%
27
27
17
27
tariatioo
(AC )
Quench uniformity(b)
0.05%
0.10%
0.20%
I1
II
II
II
23
23
23
23
45
45
45
45
(a) Total process variation = dA2+ B’ + C’ + D’
+ Z-‘, where r\. B. C, D, and Zare ‘7%variations attributed 10AT. .I 1.aunosphere X. quench uniformity AC, and additional vtiahles. respectively (b) Variation in case c&on level u hen quenched to SOHRC
Heat Treater’s
Guide: Practices
and Procedures
for Irons and Steels
Copyright@ ASM International@ 1995
Heat Treating Processes and Related Technology / 17
Final hardness
Identification
distribution
of heat-treating
analysis
for a typical
variables
quench
for the neutral
and temper
hardening
operation
process
18 / Heat Treater’s
Guide
Variation in natural gas composition
monitored in the Canton, OH, area over nearly a 2l&year period
Plot of furnace temperature versus elapsed time to show that
heat input equilibrium lags behind attaining of setpoint temperature after furnace loading
Plot of furnace temperature versus elapsed time to show effect of load size on heat balance equilibrium
Single part treatment, as with induction or flame treating, does not
lend itself to using part evaluation techniques to predict negative results.
The focus must be shifted to SPC and to the identification,
monitoring, and
control of process variables to ensure repeatability
of results. Some variables that need to be considered are electrical power, flame temperature,
scan speed, coil dimension, part positioning,
and quenchant temperature.
Trending of process variables can be utilized to determine special causes.
Process deterioration
is another factor that must also be taken into
account in all types of heat treating operations. The challenge is to counter
wear and tear on equipment with corrective action before out-of-specification parts are produced.
Key process variables fall into three categories: those which ;LTecontrollable, those which aren’t, and those which are secondary.
Controllable variables include temperature, atmosphere carbon potential. and quenchant temperature.
Uncontrollable variables include quench transfer time, temperature
recovery time, and quench temperature rise. However, suitable courses of
action are available. Examples follow:
l
l
l
With most furnace systems. control of quench transfer time is not
possible, but is often a critical parameter in producing good parts. A
possible course of action is to monitor and analyze transfer time to get
an early warning of trouble.
One automatic control system compares maximum allowable transfer
time needed to get the desired result with actual transfer times; an alarm
is triggered when the maximum is exceeded, indicating a mechanical
failure or deterioration
in the system.
Temperature recovery time can be determined, for instance, by measuring and analyzing the time taken by a batch furnace (with a standard load
weight or empty) to reach set temperature. In this manner, trends, plotted
Heat Treating Processes and Related Technology / 19
Calculated CCT diagram from actual part composition
to form during
l
heating.
Ac3: temperature
at which
with modeled part cooling rates. AC,: temperature
transformation
of ferrite
on an WC chart, may indicate a loss in furnace performance which, via
investigation, could be traceable to damaged insulation, poor door seals,
or heating system malfunction,
for example.
Knowing how quench temperature cycles from quench to quench can be
important. Findings may trigger an investigation
of the entire quenching
system, which may suggest problems with quench agitation or quench
cooling, for example. Furnace overloading
is another possibility.
Secondary process variables, such as fuel consumption and additive atmosphere gas, are caused by deterioration
in control loops. By
monitoring gas or electrical consumption for a standardized furnace cycle
and loading (or the furnace could be empty), diminished performance in
the heating system can be detected.
By monitoring
and trending the amount of natural gas or propane
addition required to control a given carbon potential setpoint, deterioration
of furnace atmosphere integrity can be detected.
Examples of parameters with an influence on effective case depth are
given in an adjoining Table.
A variable distribution
analysis of hardness of a job is shown in an
adjoining Figure.
Heat treating variables involved in neutral hardening are given in an
adjoining Figure.
Changes in natural gas composition over an extended period are plotted
in an adjoining Figure.
How heat input equilibrium
lags setpoint temperature after a furnace is
loaded is shown in an adjoining Figure.
to austenite
is completed
during
at which
heating
Effect of load size on heat balance equilibrium
ing Figure.
Integrating
austenite
is indicated
begins
in an adjoin-
SPC and SQC
Potentials for real time process improvement can be realized by combining the disciplines of SPC. which focus on process variables, and SQC.
which focus on product quality. The computer is needed to statistically
analyze data in a way that allows timely adjustment of process.
As a product characteristic
(as-quenched
hardness, for example) is
shown to be trending away from average, a special cause, such as quench
temperature. may be identified quickly. Ability to compare process variable
trend charts to the product characteristic
trend chart, for the same time
period, offers a valuable tool for continuing improvement.
Information
can be valuable even if no special cause can be. identified
among monitored process variables to correlate with a change in product
quality. Such knowledge could lead the heat treater to an uncontrollable
variable, such as material, more quickly than he could otherwise.
An example of hou the computer is being utilized is shown in an
adjoining Figure.
Reference
I. Memls Hmcfbook. IO ed. Vol3.
Heat Treating,
ASM International
20 / Heat Treater’s
Guide
How a Commercial
Heat l’kater
This shop decided in 1989 to look into statistical processcontrol
(SPC) as a way to track down sources of persistent processing
problems. At the time. rework jobs (in carburizing and nitriding)
were running at a rate of 25 to 30 per quarter. Ref 1.
Consultants were hired to train the plant’s thirty-plus employees
in the application of WC lo heat treating. how to recognize out-ofcontrol conditions. and how lo react correctly lo them.
Training was thorough. but stopped short of teaching how-to-be
statisticians. The program consisted of I2 h in the classroom(three
4 h sessions),plus followups on the shop floor lo answer questions
as WC was being installed.
The key to making SPC work, it was stressedcontinuously, is
accuracy of data. At the same time. employees were assuredthat
these data would be used as spotlight opportunities for impmvemen&not to point the finger of blame at anyone.
The First Step
The program was started by gathering data from carburizing
furnaces.using simple SPC charts.Operatorsuseda shim shock test
9n early control chart shows large variations, with a low
Drocess capability
caused by poor understanding
of
Jariables
Uses SPC and the Computer
to compare actual carbon in the working zone compared with the
level set on the furnace controller and measuredwith an oxygen
pl-0bl.L
Resultsfell short of expectations-a typical chart from that period
is shown in an adjoining Figure. Note the largediscrepancybetween
oxygen probe and shim shock data. A seriesof meetings followed.
which included the quality manager,production manager,and all
shop employees.In addition. furnace operators.maintenancepeople, and all other employeeswere encouraged to submit suggestions
for improvements.
Ultimately. a decision was made to do capability studies of all
carburizing and nitriding furnaces in the shop. covering, for instance,natural gas flow, air flow, nitrogen/methanol flow, load size,
time in furnace. carbon control instrument settings,methodsoperators used lo run furnacesand to correct out-of-control conditions.
Much of the inconsistency in performance, it was learned. was
accountedfor by differences in practice from operator lo operator.
To improve control here,procedureswere written, basedon proven
strategiesfor correcting out-of-control conditions.
The same furnace, eight months later, remains within
control limits of kO.O7% C
Heat Treating
With time, operators managedto keep data points closer to the
target mean (for carbon potential setpoint), and control limits were
set at ?0.07%. Improvement in the performance(seeprevious Figure) over a period of eight months is shown in the secondFigurenote that control limits were maintained within 0.07%.
By 1992, reworks were down by a factor of four (see Figure).
Reasonsfor rework, along with percentagesattrihutahle for each
cause, are shown in the next Figure. Shallow case depth was the
most common causefor rework, with a 23.3% rating. CauseNo. 2
was operator error, accounting for 20% of all rework. For each
rework. the company evaluates findings, investigates, and corrects
any areasof concern.
Statistical
Methods
The company now tracks performanceby processcapability values, C, and Cpk (see Figure for definitions of theseand other SPC
terms). Information collected by operatorsis loadedinto a statistical
program, which producesall values neededfor review by management.
Tighter
Shallow
control
and more-predictable
case depth and operator
process
results
and Related Technology
A processcapability study of furnace number 37 for one month is
shown in an adjoining Figure. The Cpk is I.41 and the process
capability index (C,) is I S2, showing that the natural variation in
the process is less than the maximum acceptable range for the
product. One year earlier, this furnace had a Cpkvalue of 0.55 and a
C, value of 0.63.
The company performs a Paretoanalysis (seeprevious Figure for
definition) for all rework. Reasonsfor rework, the furnace. and the
operatorsare recorded.
The Next Step
The company has computerized all carburizers and oil hardening
furnaces with atmosphereand temperaturecontrollers. With these
controllers, furnace operation and tinal results are much more consistent than before.
Controllers are also programmable. Operators simply input the
correct program number to control all parametersrelated IO the
carburizing cycle, ensuring that all temperatureand carbonpotential
have reduced
error were the most common
Processes
the number of reworks
reasons
for
reWOrk
in
1992
required
(30
reWOrkS
by a factor of four
total)
/ 21
22 / Heat Treater’s
Guide
SPC Terminology
Mean, x: The central value in the range of processvariables,
also known as the average.It is calculated by adding all readings
and dividing by the total number of readings.
Standarddeviation, O: A measureof the spreadof data values
that is, the how far the data varies from the mean. It is calculated
by the formula
whereXi is the valueof datapoint numberi. Zis the mean,andn is the
total numberof datapoints.
Control limits: Upper and lower control limits are defined as
three times the standarddeviation (30) from the mean (X ) of a
processvariahle.Statistically.99% ofreadingsshouldfallwithin
thesecontrollimits.unlessthereisachangeintheprocess.
Control chart: A graph used to record the readings of process
variables. Each point in an x chart is typically an averageof four
or more readings. Each point in an R chart is the difference
betweenthe highest and lowest readings(range).Trendsin control
chart data can be signs of trouble. Examples include a point
outside the control limits. sevenconsecutivepoints drifting in the
samedirection, or fewer than two-thirds of the points within the
middle third of the chart.
Natural variation: Processvariable fluctuations that are beyond the control of the operator. The only way to reduce the
amount of natural variation is to improve the process.
Pareto analysis: A process used to identify what J.M. Juran
talk the “vital few projects” for which quality improvement is
justified; that is. those which contain the bulk of the opportunity
for improvement. Named for Italian economist Vilfredo Pareto
(1848-1923).
Process capability index, C,,: The product specification or
tolerance range divided by six times the standarddeviation. Cp
indicates whether the process is able to meet the customer’s
requirements.A value lessthan one indicates that natural variation
will produce results that are out of spec.
Actual Process Capability Index, Cpk: A stricter index than
C, Cpk measurescentering as well as the amount of natural
variation. It is defined asthe difference betweenthe processmean
and its closest specification limit, divided by 30.
Heat Treating
Practical
Applications
of the Computer
A quick overview of available simulation software for on-line programs
that control processes and those that assist in decision-making and process
analysis is provided by the adjoining Table, which also lists and describes
available databases developed by computers.
Software programs can be subdivided as follows:
l
l
l
l
l
Property prediction programs
Process planning programs
Material selection programs and their databases
Programs for special technical and economic programs related to heattreating, such as energy consumption for a given process or calculating
the expense of a heat treatment
Finite element analysis for modeling the effecti of quench severity or
distortion and dimensional control of parts
Simulation modeling with the computer can be subdivided thusly:
l
Static models based on empirical formulas
l
l
Processes
in Heat
and Related Technology
/ 23
Treating
Dynamic models based on differential equations or differential equation
systems
Programs with both static and dynamic models
Static models are based on simple empirical formulas that can be
derived by physical principles and observation or from statistical methods.
Generally, regression analysis is used in statistical modeling.
Example: Formulation or prediction of Jominy hardenability from
austenitic grain size and chemical composition (Ref l-3).
Dynamic models are based on the solution of differential equations,
differential equation systems, or finite element analysis.
Examples of the differential equation approach: predicting carbon and
nitrogen profiles (Ref 4-6) phenomenological models that describe the
transformation of austenite under nonisothermal conditions (Ref 7-l I).
Finite element analysis is used, for example, to predict residual stress and
distortion (Ref 12-14) and in determining suitable quenchants (gas, oil, or
water) for a given alloy (Ref 12).
24 / Heat Treater’s Guide
Examples of Available Computer Programs and Databases Pertaining to Steel Selection, Microstructure,
and Heat-Treatment Technologies
Computerized
hlat.DB
Features
Availability
Name of the sofhvare
materials
properties
storage, retrieval,
AShl lntemational. U.S.A.
and use
Database Steelhiaster
PERlTUS
A LlETA
SACfTSteel
Advisory Centre for Industrial
Technologies, Hungary
KOR
SACfTSteel
Ad\ isory Cenue for Jndustrtal
Tu-hnologies. Hungary
Computer
programs
Materials data base management program containing the designations, chemical compositions, forms
(sheet bar and so forth), and properties t up to -MI properties). It is designed to select alJoys on the
basis of many characteristics
Contains the chemical compositions. meshanicaJ properties, application fields, and the international
comparison tequiv alent steels) of 6500 standard steels from I8 countries
Contains compositions, mechanical properties. heat-treatment parameters, CCTdiagrams.
tempering
charts for commonly used German structural and tool steels The heat-neaanent technologies
designed by the user of the softwate can be stored and retrieved
This data hase pro\ ides engineers uith up-to-date information about materials ranging from traditional
met& to new polvmers. The range of information: mechanical and physical properties,
environmental
r&istance. material forms. processing methods, trade names, and standan%
This data base of individual measured steel properties contains data collected from laboratories of
industry quality control departments. The range ofdata: steel designation, heat number, dimensions
of the machine part. composition, heat treatment of the part, results of tensile tests, impact test results,
measured Jominy curve of the heat, and other tests. The system makes statistical analysis of the data
KOR is a corrosion information system. which contains a data base of 3OOcorrosive media, more than
IS 000 individual corrosion dataset I50 metallic structural materials. and 200 isocorrosion
diagrams. Structural material selection is possible according to prescribed mechanicrd. physical,
technological properties. or it is possible to find a suitable resisting material fora corrosive medium
withgtven temperatureandconcentratJon.The
system #ill alsoaccept the user’sowndata
SACIT Ste4 Advisory Cenae for Industrial
Technologies, Hungary
Dr. F?Sommer
Wkrkstoftiechnik
GmbH. Germany
hlatsel Systems Ltd., Great Britain
EQUJST 2.0
for calculation
of processes
occurring
in steels during
PRJZDIC & TECH
SACIT Steel Ad\ isory Centte for industrial
Technologies. Hungary
AC3
Marathon
CETfM-SICLOP
PREVERT
Cenue Technique des Industries Mechaniques
PROGETfM.
France
Comline Engineering Software, Great Britain
and ASM International
Creusot-Loire
Industries. France
CHAT
lntemational
hlfNlTECH
hlinitech
PRJZDCARB
SACfTSteel
Advisory Centm for Industrial
Twhnologies.
Hungary
SINULAN
Lammar.
Ensam Bordeaux.
C4RBCALC
Marathon
hlonitors
CARBODIFF
Process Electronic.
Carbo-O-Proof
lpsen Industries Ltd.. U.S.A.
SYSM’ELD
Framasoft.
SteCal
Examples
of programs
Monitors
Limited.
Company.
Calculates the micmsmtcture
and mechanical properties ofquenched and tempered low-alloy steels
from composition and heat-treating parameters
CHAT is a two-part system for selecting the optimum steel composition to be used where heat treating
is perfomted to develop required engineering pmperties
The hlinitech Alloy Steel Information System consists of tvvelve computer programs which generate a
series of hardenability-related
properties of steels. such as Jominy curves. hardenahility bands,
mechanical properties of hot rolled products. hardness distributions for quenched and tempered and
carburized products
This computer program detemunes the gas carburizing technology and calculates the carbon profile
and hardness distribution in the case and core on the basis of chemical composition, dimensions of
the workpiece. cooling intensity of the quenchant, prescribed characteristics of the case
Simulates the gas carburization and inductton hardenmg process. and calculates the carbon and the
hardness profile
Smtulates the carburirmg reactions between a steel and surrounding atmosphere. It calculates the
carbon profile
hlonitoring of carbon protile dunng carburizing and prediction of hardness distribution after
quenching ofcase-hardened
steels
This software is able to optimize the carburizing process, calculates continuously the carbon profile,
and regulates the process in accordance \v ith program target values
This system is based on finite-element technique and simulates the transformation
processes in steel
during heat treatment or welding. The program calculates the temperaturedistribution.
microsnucture,
hardness. and stresses
U.S..\.
Canada
France
Ltd.. Great Britain
Gemtatty
Great Britain
based on finite
element
analysis
heat treatment
Stmulates the cooling. transfomtation of austenite in cylindrical. plate-shaped workpieces, Jominy
specimens made of case-hardenable and quenched and temprrcd low-alloy steels and calculates the
microstructure and mechanical properties in any location of the LTOSSsection of the workpiece taking
into account the actual chemical composition, dimensions. austenitizing temperature, duntions,
cooling intensity of quenchant, tempering temperature. and time. The same program worksas
technology plannmg program if the prescribed mechanical properties and composition are given
Hardenability
model designed to predict the response to quenching of through-hardening
and
carburized loa -ahoy steels in terms of microstructure and hardness distribution
Contains a steel data base for the selection of structural and tool steels and calculates the mechanical
properties along the cross section of \5 orkpieces
Calculates the heat-treatment response and properties of lo\\-alloy steels from composition
Ltd.. Great Britain
Harvester
include:
tinuous
cooling
H ith the results
l
CONTA
program-for
l
TOPAZ
2D program-for
calculating
l
NIKE
2D program-for
surface
calculating
cttkulating
heat fluxes
temperatures
stresses
overviews
of the subject
Database systems
metal alloys
them include
are being
chemical
containing
marketed.
composition,
are found
(Ref
(Ref
(Ref
State of the Art Uses of Computer
General
Properties,
13)
I-%)
ISj
Simulation
in Ref
I6 and
17.
the main
characteristics
of several
lnfomtation
that can be retrieved
front
mechanical
characteristics.
and con-
transformation
(CCT)
of user process
planning.
curves.
Databases
can
be loaded
Example: Research Ltorkers at hlinitech Ltd (Canada) designed a soliware package to estimate such properties as weldability.
phase diagrams,
and hardenability
of low-. medium-, and high-carbon steels (Ref 16).
Example: Chrysler Corporation developed an interactive system that
makes it possible for designers and technologists to get material information on their own local computer terminals (Ref 16).
Example: Utilization of databases of measured steel properties is discussed in Ref 18.
The CETIM Institute (France) has developed a program for the planning
of heat rrcatment technology
and for steel selection.
An essential part of the
Heat Treating Processes and Related Technology
software is a database containing chemical composition,
mechanical properties, and Jominy curves of the most often used quenched and tempered
and case hardened steels as a function of section size (Ref 19).
Hardenability prediction has been of longstanding theoretical and
practical interest (Ref 20-24).
In applying a static model, Murry et al. (Ref 25) developed a computing
method for predicting the hardness of cylindrical
workpieces along their
cross section after quenching.
Input data are: chemical composition.
austenite grain size, geometrical characteristics,
and cooling time from 700
to 400 “C ( 1290 to 750 “F).
Creusot-Loire
(Ref I6 and 26) used nonlinear multiple regression analysis to derive a series of formulas for the estimation of critical cooling rates
from 700 “C ( I290 “F). The steelmaker aJso published equations to calculate as-quenched and tempered hardness from chemical composition
and
cooling rate from 700 “C ( 1290 “F).
Starting from a thermodynamic
basis, researchers at McMaster Llnivershy (Hamilton,
Ontario, Canada) developed methods for the computeraided determination
of equilibrium
diagrams of multicomponent
steel
alloys and for the calculation
of starting curves (incubation
time) of
isothemtal transformation
diagrams as well (Ref 17. 23, 37). They also
investigated the tempering process and developed usable computer programs for the prediction of hardenability
and its application in steelmaking.
Programs for material selection and/or analysis of heat treatment processes usually contain a system for property or hardenabilit!
prediction.
Liscic and Ftletin (Ref 21. 22). for example, published a
computerized
process designing
a system for the heat treatment of
quenched and tempered steels. The system is suitable for the determination
of technological
parameters (austenitization
and tempering temperatures),
knowing the steel type and required properties.
More sophisticated models based on finite element analysis are being
investigated as a way of modeling distortion
and analyzing quenching
methods (Ref 12).
Analysis of residual stresses and distortion generally in\ elves
finite element anaJysis of internal stresses developed during transformation
sequences. Typical examples are given in Ref I?, 28-30.
A method of calculating transformation
sequences in quenched steels is
found in Ref41.
A software package has been developed for the prediction of residual
stresses in case hardened steels by tracing the transformation
of the case
and core of the workpiece (Ref 32 and 43).
Simulation of Case Hardening. New type models predict carbon
and nitrogen profiles during and after gas carburizing and nitriding t Ref 5.
6.28-31). In this field, calculation methods can be used to model case depth
and hardness proftles (Ref 30, 35. 36). lngham and Clarke developed a
computerized method of predicting the microstructure
and hardness profile
of case hardened parts. Methods of microstructure
prediction are described
in Ref 8 and 37.
A description of how a commercial heat treater is using SQC. SPC. and
Process Control in Heat
the computer is found in the article. “Statistical
Treating Operations,” preceding this one.
This article is based on article, “Computerized
Properties Prediction and
Technology Planning in Heat Treatment of Steel,” AShl hietals Handbook,
Heat Treating, Vol 4. IO ed.. Hear Treatirrg Handbook. ASM International.
References
I. C.A. Siebert, D.V. Doane. and D.H. Breen. The Hurdetu~biliy of.Sireels-
Cor~cep~s.Memlhrrgical Itljluences and Indrrsrrial Applicarions, American
Society for Metals. I977
2. E. Just, Formeln der Hartbarkeit, Hiin.-Tech. Min., Vol23 (No. 2). 1968. p
85-99
3. E. Just, New Formulas for Calculating Hardenability Curves, Mer. Prog..
NW 1969, p 87-88
4. J. Slycke. T. Ericsson, and P Sjoblom. Calculation ofcarbon and Nitrogen
Profues in Carburizing and Carbonitriding.
Corrzpwers iu Marerials Technology, Proceedings of the International Conference. Linkoping Llnivershy. 4-S June 1980. T. Ericsson. ed.. Pergamon Press. p 69-79
/ 25
5. EA. StiU and H.C. Child, Predicting Carburizing Data. Hear. Treat. Met..
No. 3, 1978. p 67-72
Carburizing Process, Mefull.
6. CA. Stickcls, Analytical Models for the GZLS
Trans. B., Vol30B, Aug 1989. p 535-546
7. T. R&i. G. Bobok, and M. Gergely, “Computing Method for Nonisothernlal Heat Treatments.” Paper presented at Heat Treatment ‘8 I, The Metals
Society, 1983, p 91-96
8. E. Ftiredi and M. Gergely, A Phenomenological
Description of the
Austenite-Martensite
Transformation
in Case-Hardened Steels, Pmceedings of lhe 3rh Ituernarional Congwss on Hear Treamwtrr of Materials, Vol
I, 3-7 June 1985. p 291-301
9. T. R&i. hl. Gergely. and P. Tardy, hlathematical Treatment of Non-isothermal Transformations. Aluclrer:Sci. Technol.. Vol 3, May 1987, p 365-371
IO. E.B. Hawbolt. B. Chau. and J.K. Brimacombc, Kineticof Austenite-Pearlitc Transformations
in a 1025 Carbon Steel, Melall. Trans. A, Vol l6A.
April 1985. p 568-578
I I S. Denis. S. Sjosuiim. and A. Simon. Coupled Temperature, Stress, Phase
Transformation Calculation Model: Numerical Jllustration of the Internal
Stresses Evolution during Cooling of a Eutectoid Carbon Steel Cylinder,
h~lemll. Trans. A, VOI l8A, July 1987, p I203- I2 I2
I2 R.A. Wallis et al., Application of Process hlodeling to Heat Treatment of
Superalloys. /rid. Hear.. Vol 55 (No. I). Jan 1988, p 30-33
13. J.V. Beck. “Users Manual for CONTA: Program for Calculating Surface
Heat Fluxes from Transient
Temperatures
inside Solids.”
Report
SAND83-7 131. Sandia National Laboratories, Dee 1983
I-2. A.B. Shapiro. ‘TQPAZZD:
A Tvvo-Dimensional
Finite Element Code for
Heat Transfer Analysis. Electrostatic and Magnetostatic Problems,” Report
LJCJD-20824. Lawrence Livemtore National Laboratory, July 1986
IS. J.O. Hallquist. “NlKE2D:
A Vectorized, Implicit, Finite Dcfomtation.
Finite Element Code for Analyzing the Static and Dynamic Response of
2-D Solids.” Report LJCJD- 19677. rev. I, Lawrence Livermore National
Laboratory, Dee I986
16. D.V. Deane and J.S. Kirkaldy, ed.. Hardenabiliry Concepts with Applications ro Sled. Symposium proceedings, 24-26 Ott 1977, American Society
for hletals. p 493-606
17. T. Ericsson, Ed.. Conrpurers in Materials Technolog?: Proceedings of the
International Conference. 4-S June 1980, Linkoping University, Pergamon
Press, p 3-68
18. hl. Gergely, T. Reti. G. Bobok. and S. Somogy i. “Lltihzation of Databases
of Measured Steel Properties and of Heat Treatment Technologies in
Practice,” Paper presented at hlatcrials ‘87, The Metals Society, I l-14 May
1987
19. C. Lebreton and C. Tout-trier. CETlM-SICLOP:
Un nouvel outil logiciel
pour le tmitment themtique. Traif. 77rrrrn.. No. 308.1987. p l-8 (in French)
20. hl.E. Dakins. C.E. Bates, and G.E. Totten. Calculation of the Grossmann
Hardenability Factor from Quenchant Cooling Curves, Memlhtrgic~, Furnace supplement. Dee 1989. p 7
2 I. B. Liscic and T. Fiietin, Computer-Aided
Evaluation of Quenching Jntensity and Prediction of Hardness Distribution. J. Hear Trear.. Vol 5 (No. 2).
1988. p 115-124
32. B. List+ ,and T. Fiietin, Computer-Aided
Determination of the Process
Parameters for Hardening and Tempering Structural Steels. Hear Treur.
hder.. No. 3. 1987. p 62-66
23. J.S. Kirkaldy, G.O. Pazionis. and SE. Feldman, “An Accurate Predictor
for the Jominy Hardenability of Low-AUoy Hypoeutectoid Steels,” Paper
presented at Heat Treatment ‘76. The hletals Society. 1976
2-t. hl. Umemoto, N. Komatsubara, and I. Tamura Prediction of Hardenability
Effects from lsothemtlll Transfomtation Kinetics, ./. Hear Trrrrr,
Vol I (No.
3). 1980. p 57-6-l
25. G. blurry. hl&hode Quantitative d’ Appreciation de la Trempabihte des
Aciers: Esemples d’ Application. R~I: Mc~~ull..Vol 12. 197-l. p 873-895 (in
French)
26. l? hlaynier.
Le Pretert: hlodcl dr: Prevision des Charncteristiques
hlechaniques des Aciers, Ir,,ri/. Tltentt.. Vol223. 1988. p 55-62 (in French)
27. J.S. Kirkaldv and R.C. Sharma. A New Phenomenology for Steel IT and
CCT Cun es. Scr: MeraIl.. \;bl 16. 1982. p I I93- I 198
26 / Heat Treater’s Guide
28. M. Gergely
29.
30.
3 I.
32.
33.
34.
35.
36.
and T R&i. Application
of a Computerized
Information
System for the Selection of Steels and Their Heat Treatment Technologies,
J. Hear Tmat., Vol5 (No. 2). 1988.~ 125-140
T. R&i, M. RCger, and M. Gergely, Computer Prediction of Process
Parameters of Two-Stage Gas Carburizing, J. Hear Treat., Vol8, 1990, p
55-61
U. Wyss, Kohlenstoff und Hglrteverlauf in der Einsatzb&tungsschicht-verschiedenen legierter Einsatzhlihle, Htirr. -7kh. Mirt.. Vol43 (No. I ), 1988,
p 27-35 (in German)
T. R&i and M. Cseh. Vereinfachtes mathematisches Model fiir awistugige
Autlcohlungsverfahren.
H&f.-Tech. Min., Vol42 (No. 3). 1987, p 139-146
(in German)
J. Wiinning, Schichtwachstum bei S~ttigungs- und Gleichgewichtsaulkohlung-sverfahren,
H&.-Tech. Mu.. Vol 39 (No. 2). 1984, p 50-54 (in
-)
B. Edenhofer and H. ffau. Self-Adaptive Carbon Pmfik Regulation in
Carburizing, Proceedings of the 6th International Congress on Heat Treatment of Materials, 28-30 Sept 1988. p 85-88
D.W. lngham and PC. Clarke, Carburize Case Hardening: Computer
Prediction ofStructure and Hardness Distribution, Hear Treat. Met., Vol IO
(No. 4). 1983, p 91-98
N.F. Smith Computer Prediction of Carbtuized Case Depth: Some New
Factors lnlluencing Accuracy of Practical Results, Heat Treat. Met., No. I,
1983. p 27-29
D. Roempler and K.H. Weissohn. Kohlenstoff und Hglrteverlauf in der
Eiiaehslrtungsschicht-Zusatzmodul
fk Dilkionsrechner,
Hiin.-Tech.
Min. Vol44,1989, p 360-365 (in German)
37. M. Gergely, T. R&i, P Tardy, and G. Buzz. “Prediction of Transformation
Chamctaistics and Microstructure of Case Hardened Engineering Components,” Paper presented at Heat Treatment ‘84. 24 May 1984. The
Institute of Metals
38. S. Kamamoto et al., Analysis of Residual Stress and Distortion Resulting
loom Quenching in Large Low-Alloy
Steel Shafts, Mare,: Sci. TechnoL.Vol
1,Oct 1985, p 798-804
39. P. Jeanmart and J. Bouvaist, Finite Element Calculation and Measurement
ofThermal Stresses in Quenched Plates of High-Strength 7075 Aluminum
Alloy, Mater: Sri. Technol., Vol I, Ott 1985, p 765-769
40. A.J. Fletcher and A.B. Soomro, Effects of Transformation
Temperature
Range on Generation of Thermal Stress and Stress during Quenching,
Mater: Sci. Technol., No. 2, July 1986, p 7 14-7 19
41. M. Gergely, S. Somogyi, and G. Buza, Calculation of Transformation
Sequences in Quenched Steel Components to Help Predict lntemal Stress
Distribution, Mates Sci. Tech&., Vol I, Ott 1985. p 893-898
42. B. Hildenwall and T. Ericsson, Prediction of Residual Stresses in CaseHardening Steels, in Hardenability
Concepts with Applications to Steel,
Symposium proceedings, 24-26 Ott 1977, D.V. Doane and J.S. Kirkaldy.
ed, American Society for Metals, p 579-606
43. B. Hikienwall and T. Ericsson, How, why, and When Wii the Computed
Quench Simulation be Useful for Steel Heat Treaters, in Compufers in
Materials Technolog?: Proceedings of the Lntemational Conference,
Linkiiping University, 4-S June 1980, T. Ericsson, ed.. Pergamon Press, p
45-53
Guidelines
for the Heat Treatment
of Steel
introduction
Articles
in this chapter address the hands-on aspects of:
l
Normalizing
l
Annealing
l
Surface hardening
The Normalizing
l
l
Quenching/quenchants
other processes)
Tempering (including
(articles
on eight conventional
articles on martempering
processes and 17
and austempering)
Process
This process is often considered from both thermal and microstructural
standpoints.
In the thermal sense, normalizing
is an austenitizing
heating cycle,
followed by cooling in still or agitated air. qpical
normalizing
temperatures for many standard steels are given in an accompanying Table.
ln terms of microstructure,
areas that contain about 0.8% C are pearlitic.
Those low in carbon are ferritic.
Range of Applications
AU standard, low-carbon,
medium-carbon,
and high-carbon
wrought
steels can be normalized, as well as many steel castings. Many weldments
are normalized to refine the structure within the weld-affected
zone, and
maraging steels either can’t be normalized or are not usually normalized.
Tool steels are generally annealed by the supplier.
Reasons for normalizing are diverse: for example, to increase or decrease
strength and hardness, depending on the thermal and mechanical history of
the product.
Comparison
of time-temperature
cycles for normalizing
and
full annealing. The slower cooling of annealing results in higher
temperature transformation to ferrite and pearlite and coarser microstructures than does normalizing. Source: Ref 1
In addition, normalizing functions may overlap with or be confused with
annealing, hardening, and stress relieving.
Normalizing
is applied, for
example, to improve the machinability
of a pact. or to refine its grain
structure, or to homogenize its grain structure or to reduce residual stresses.
Tie-temperature
cycles for normalizing
and full annealing are compared
in an adjoining Figure.
Castings are homogenized
by normalizing
to break up or refine their
dendritic structure and fo facilitate a more even response to subsequent
hardening.
Wrought products may be normalized,
for example, to help reduce
banded grain structure due fo hot rolling and small grain size due to forging.
Details ofthree applications are given in an adjoining Table. including
mechanical properties in the normalized and tempered condition.
Normalizing
and tempering can be substituted for conventional
hardening when parts are complex in shape or have sharp changes in section.
Otherwise. in conventional
hardening such parts would be susceptible to
cracking, distortion, or excessive dimensional changes in quenching.
Rate of cooling in normalizing generally is not critical. However, when
parts have great variations
in section size. thermal stresses can cause
distortion.
Tie
at temperature is critical only in that it must be sufficient to cause
homogenization.
Generally, a time that is sufticient to complete austenitization is all that is required. One hour at temperature, after a furnace has
recovered, per inch of part thickness, is standard.
Rate of cooling is significantly
influenced by amount of pearlite. i& size,
and spacing of pearlite IameUae. At higher cooling rates more pearlite
forms and lamellae are finer and more closely spaced. Both the increase in
pearlite and its greater fineness result in higher strength and hardness.
Lower cooling rates mean softer parts. Cooling rates can be enhanced with
fans to increase the strength and hardness of parts, or to reduce the time
required, FoUowing the furnace operation, for sufficient cooling to allow
workpieces to be handled.
After parts cool uniformly through their cross section to black heat below
Arl, they may be water or oil quenched to reduce total cooling time.
Cooling center material in heavy sections to black heat can take considerable time.
Carbon
Steels
Steels containing 0.20% C or less usually are not treated beyond normalizing. By comparison, medium- and high-carbon steels are often tempered
28 / Heat Treater’s
Typical
Normalizing
Guide
Temperatures
Temperature(a)
OF
OC
Grade
Plain carbon steels
1015
915
1020
915
10’1
91s
IO3
900
1030
900
IO35
88.5
lo40
860
104s
860
ioso
860
I060
830
IO80
830
1090
830
109s
8.45
III7
900
II37
885
II-II
860
II44
860
Standard alloy steels
I330
900
1335
870
13-m
870
313s
870
31-m
870
3310
92s
(a) Based on Production
should be cooled in still
Typical
Grade
of Normalizing
Steel
Cast50mm(?-in.)~akhcdy.
191025
mm C3/,to I in.) in section thickness
Ni-Cr-hlo
41.37
forging
Temperature(a)
T
OF
1IUl
and Tempering
Temperature(a)
T
OF
Grade
of Steel Components
Beat treatment
Full annealed at 955 “C (I 750 “FI.
notmtizedat 870°C (1600°F).
tempered at 665 “C ( 1275 “F)
Nomtized at 870 “C ( l6lXl ‘F).
tempered at S70 “C ( 1060 “F)
Normalized at 870 “C ( 1600 “Rand
tempered
after normalizing,
i.e., to get speciftc properties such as lower
prior to straightening. cold working. or machining.
Alloy
Temperature(a)
oc
OF
Grade
I675
I675
1675
I650
Part
\‘d\r-honnet
Carbon and Alloy Steels
Standard alloy steels (continued)
Standard alloy steels (continued)
Standard alloy steels (continued)
4027
900
16.50
1700
8645
870
1600
1817
92s
4028
900
1650
1700
8650
870
1600
-1820
925
403’
900
1650
870
1600
8655
870
1600
SO%
4037
870
1600
1700
8660
870
1600
5120
925
1650
4042
870
1600
5130
900
8720
92s
1700
1650
8740
92s
1700
I615
‘m-17
870
1600
5132
900
870
1600
8742
870
1600
4063
870
1600
513s
I575
4118
925
1700
870
1600
8822
925
1700
IS75
5140
870
I600
9255
900
16.50
IS75
4130
900
1650
51-E
413s
870
1600
870
1600
9260
900
1650
1525
5147
9262
900
1650
Jl37
870
1600
870
1600
IS?5
SISO
9310
925
1700
‘II40
870
1600
870
1600
1515
5155
I.550
4142
870
1600
870
1600
9840
870
1600
5160
41-15
870
I600
1700
98SO
870
1600
6118
925
1650
41.47
870
I600
1700
SOB40
870
1600
I63
6120
9’5
1650
4150
870
1600
6150
900
SOB-M
870
1600
I575
4320
925
1700
1700
5OB-l.6
870
1600
157s
8617
925
4337
a70
1600
1700
508.50
870
1600
8620
91s
43-u)
870
I600
1700
60860
870
1600
8622
935
I650
4520
92s
I700
1650
81835
870
1600
862.5
900
1600
86845
870
1600
4620
925
1700
1650
8627
900
I600
1650
4621
925
1700
8630
900
91BlS
925
1700
1600
870
1600
91Bl7
925
1700
4718
92s
1700
8637
I600
4720
925
1700
870
1600
91830
900
16.50
86-m
1700
4815
925
1700
870
1600
94B-U)
900
l6SO
8642
experience, normalizing trmpenture may \ary from as much a 28 “C (50 “F) helow. to as much as 55 “C (100 “FJ above. indicated temperature. The steel
air from indicated tstitperature.
Applications
Forged flange
for Standard
hardness
Steels
Forgings, roUed products. and alloy steel castings are often normalized
as a conditioning
treatment before tinal heat treatment. Normalizing
also
reftnes grain structures in forgings. rolled products. and castings that have
been cooled nonuniformly
from high temperatures.
Some alloys require more care in heating to prevent cracking from
thermal shock. They also require long soaking times because of louer
austenitizing
and solution rates for c,arbon. Cooling rates in air to room
temperature for many alloys must be carefully controlled. Some alloys are
forced air cooled from the normalizing
temperature to develop specific
mechanical properties.
Forgings
When forgings are normalized prior to carburizing or before hardening
and tempering, the upper range of normalizing
temperatures is used. But
Properties after treatment
Reason for
qormaRiing
To meet mechanical-property
Tensile strength. 620 MPa (90 ksi);
0.X yield strength. -I IS hlPa (60 I&): requirements
elongation in SOmm. or 1 in.. 20%;
reduction in area. 40%
To reline gmin size and obtain required
Hardness. XXI to 23 HE
hardness
Hardness. 220 to 210 HB
To obtain uniform structure, improved
machinability, and required hardness
when normalizing
is the tinal heat treatment, the lower temperature range
is used. Small forgings are typicall> normalized as-received from the forge
shop.
Large. open die forgings are usually normalized in batch furnaces pyrometrically
controlled to a narrow temperature range.
Low-carbon
steel forgings containing 0.2% C or less are seldom normalized.
Multiple Treatments. Carbon and low alloy steel forgings with large
dimensions are double normalized
when forging temperatures are extremelj high (Ref 2) to obtain. for example, a uniform fine grain structure
to pet specific properties such as impact strength to subzero temperatures.
Bar and Tubular
Products
Nomlalizing
is not necessary and may be inadvisable when properties of
these products obtained in the finishing stages of hot mill operation are
close to those produced in normalizing.
But reasons for normalizing
bar
and tube are generally the same as those that apply lo other steel products.
Guidelines
Castings
In industrial practice, castings may be normalized in car bottom, box. pit,
and continuous furnaces. Heal treatment principles are standard for all
these furnaces.
When higher alloy castings, such as C5, C I?, and WC9, are loaded,
furnace temperatures should be controlled
to avoid thermal shock that
could cause metal failure. A safe loading temperature in this instance is in
the range of 315 to 425 “C (600 to 795 “F). Lower alloy grades tolerate
furnace temperatures as high as 650 “C (I200 “F). Carbon and low-alloy
steel castings can be charged at normalizing
temperatures.
After charging, furnace temperatures are increased at a rate of approximately 225 “C (400 “F) per h, until the normalizing temperature is reached.
Depending on steel composition and casting configuration,
the heating rate
Annealing
Cycles
Cycles fall into three categories,
cooling methods (see accompanying
l
l
l
of Steel / 29
may be reduced to approximatelq
28 IO 55 “C (SO to 100 “F) per h, to avoid
cracking. Extremely large castings may be heated more slowly to prevent
the development of extreme temperature gradients.
After normalizing
temperature is reached. castings are soaked for a
period that ensures complete austenitization
and carbide solution.
After soaking, parts are unloaded and allowed to cool in still air. Use of
fans, air blasts. or other means of speeding up the cooling process should
be avoided.
References
I. G. Ksauss, Sleels: Heor Treurrnerrr cm1 Processing Principles,
International.
Metals Park, OH, 1990
2. A.K. Sinha. Ferrars Pi~~sical Memll~r~~, Butterworths,
1989
ASM
of Steel
Ln this process, steels are heated to a specific temperature, held at Ihat
temperature for a specific time, then cooled at a specific rate.
Generally, in treating plain carbon steels, a ferrite-pearlite
microstructure
is produced (see adjoining Figure). Softening is the primreason for
annealing. Other important applications
are to facilitate cold work or
machining, IO improve mechanical or electrical properties, or LO promote
dimensional stability.
Annealing
for the Heat Treatment
based on heating
table):
temperatures
and
Subcritical annealing-the
maximum temperature may be below the
lower critical temperature, A 1
Inlercritical
annealing--the
maximum temperature is above Al, but
below the upper critical temperature, A3, for hypoeutectic steels. or AC,,,
for hypereutectic steels
Full annealing-the
maximum temperature is above A3
Austenite is present at temperatures above Al, so cooling practice (see
Table) through transformation
is a critical factor in getting the desired
microstructure
and properties. Steels heated above A 1 are subjected LO
slow, continuous cooling, or to isothermal treatment at a temperature below
A fully annealed 1040 steel showing a ferrite-pearlite
structure. Etched in 4% picral plus 2% nital. 500x
micro-
Al, at which transformation
to the microstructure
wanted can occur in a
reasonable time. In some applications,
two or more annealing cycles are
combined or used in succession to get a specilied result.
Subcritical
Annealing
Austenite is not formed in this type of treatment. The prior condition of
a steel is modified by such processes as recovery, recrystallization,
grain
growth. and agglomeration
of carbides. The prior history of a steel is
important in subcritical annealing.
In treating as-rolled or forged hypoeutectoid
steels containing ferrite and
pearlite, the hardnesses of both constituents can be adjusted. But if substantial softening is the objective, times at temperature can be excessively long.
Subcritical annealing is most effective on hardened or cold worked steels,
which recrystallize readily LOform new ferrite grains. The rate of softening
increases rapidlq as the temperature approaches Al. A more detailed discussion of subcritical annealing is found in Ref I.
Intercritical
Annealing
Austenite begins to form when the temperature of the steel exceeds Al.
Carbon solubility
rises abruptly (nearly 1%) near the Al temperature. In
hypocutectoid
steels. the equilibrium
structure in the intercritical
range
between Al and A3 consists of ferrite and auslenite, and above Aj. the
smcture becomes totally austenitic. But the equilibrium
mixture of ferrite
and austenite is not obtained immediately. For example. Ihe rate of solution
for a typical eutectoid steel is shown in an accompanying
Figure.
In hypereutectoid
steels. carbide and austenite coexist in the intercritical
range betn een A I and A,-,,,. The most homogeneous structure developed at
h&her austenitizing temperatures tends to promote lamellar carbide struclures on cooling. while lower austenitizing
temperatures result in less
homopenous nustenite. which promotes the formation of spheroidal carbides.
Temperature-time
plots shoiving the progress of austenite formation
under isothermal (IT) or continuous transformation
(CT) conditions for
many steels have been published (Ref 2,3).
Cooling After Full Transformation. After complere transformation
to austenite. little else of metallurgical
consequence can occur during
cooling to room temperature. Extremely
slow cooling can cause some
agglomeration
of carbides, and, consequently. some slight additional softening of the steel: but in this case. such slow cooling is less effective than
high-temperature
transformation.
This means there is no reason for slow
cooling after transformation
is completed and cooling from the uansformation temperature may be as rapid as is feasible to minimize the time needed
for the operation.
30 / Heat Treater’s
Approximate
Steel
1010
I020
1030
IO40
1050
loa
1070
1080
1340
3140
4027
4042
4130
4140
4150
4340
4615
5046
5120
51-U)
5160
52100
6150
8115
8620
8640
9260
Austenitizing
Guide
Critical
Temperatures
Critical temperaACI
T
OF
725
725
725
725
725
725
725
730
715
735
725
725
760
730
745
725
725
715
765
740
710
725
750
720
730
730
745
1335
I335
1340
I340
1340
1340
1340
1345
1320
1355
1340
1340
I395
1350
1370
1335
1340
I320
1410
1360
1310
1340
1380
1300
1350
I350
1370
for Selected
Carbon and Low-alloy
on heating at 28 “C/h (SOOF/h)
AC,
T
OF
875
845
815
795
770
745
730
735
775
765
805
795
810
805
765
775
810
770
840
790
765
770
790
840
830
780
815
1610
1555
I495
1460
1415
I375
I350
I355
1430
I-110
1485
1460
1490
I480
I410
1325
1490
I-120
I540
I450
1410
I415
l-150
I540
I525
1135
1500
Steels
Critical temperatures on cooling at 28 “c/b (50 OF/h)
An
An
OF
T
T
OF
850
815
790
755
740
725
710
700
720
720
760
730
755
745
730
710
760
730
800
725
715
715
745
790
770
725
750
1560
1500
I450
I395
I365
1340
1310
1290
1330
1330
1100
I350
I390
1370
1335
1310
I400
1350
1470
1340
I320
I320
I370
1450
141.5
1340
1380
680
680
675
670
680
685
690
695
620
660
670
655
695
680
670
655
650
680
700
695
675
690
695
670
660
665
715
1260
I250
I240
1260
1265
I275
1280
II50
1220
I240
1210
1280
1255
I240
1210
1260
1290
1280
1250
1270
1280
1240
I220
1230
1315
rate-temperature curves for comnmercial plain carbon eutectoid steel. Prior treatment was normalizing from 675 “C
(1605 OF); initial structure, fine peariite. First curve at left shows beginning of disappearance of pearlite; second curve, final disappearance
of pearlite; third curve, final disappearance of carbide; fourth curve, final disappearance of carbon concentration gradients.
Guidelines
for the Heat Treatment
of Steel / 31
The iron-carbon binary phase diagram showing region of temperatures for full annealing (Ref 4)
Recommended
Temperatures
and Cooling
Cycles for Full Annealing
Data are for forgin s up to 75 mm (3 in. in section thickness. Time at temperature
thick; l/2 h is adde 8 for each additional 3 5 mm (1 in.) of thickness.
of Small Carbon Steel Forgings
usually is a minimum of 1 h for sections up to 25 mm (1 in.)
Cooling cycle(a)
Annealing
temperahwe
T
OF
Steel
T
OF
From
To
From
1018
IO.20
85WOO
lo22
85WOO
855~900
1575-1650
1575-1650
lS75-1650
1575-1650
ISSO-1625
ISSO-162s
1350-I600
IJSO-1600
IdSO-1600
1450-1550
1450-1550
1150-1550
1450-1525
1450-1525
855
855
855
855
8-U
845
790
790
790
790
790
790
790
790
705
700
700
700
650
650
650
650
650
650
6.50
650
650
655
1575
1575
1575
1575
1550
1550
1150
I-150
1150
1150
1450
l-150
l-i50
I-WI
1025
1030
1035
1040
1045
IO50
1060
1070
1080
1090
IO95
(a)
ass-900
845-885
845-885
790-870
790-870
790.870
790-845
790-845
79o-a-is
790-830
790-830
Furnacecooling at 28 “C/h (SO”F/h)
To
Eardness
range, FIB
Ill-149
Ill-149
Ill-14cf
Ill-187
126-197
137-207
137-207
156-217
156-217
156-217
167-229
167-229
167-229
167-229
32 / Heat Treater’s Guide
Recommended Annealing Temperatures for Alloy Steels
(Furnace Cooling)
AISI/SAE
Steel
1330
1339
13-m
I345
31-m
4037
-Ku2
40.47
4063
1130
-II35
4137
-1140
314S
1147
1150
1161
3337
-t34O
SOB40
SOB-U
SO46
SOB-t.6
SOB60
5130
Sl32
513s
51-m
5145
Sl47
5150
515s
5160
SIB60
so100
51100
VI00
6150
81815
8627
X630
8637
8640
8643
86-E
86B4S
x61650
86SS
8660
8740
874'
9360
94B30
94B10
9840
Supercritical
Annealing temperature
T
OF
&Is-900
849-900
84S-900
81.5-900
815.870
8 I S-855
815.8SS
790.845
790-815
790-815
790-849
790-815
790-a-15
790-845
790-845
790-845
79c-8-n
790.845
790-845
815-870
815-870
8 I S-870
8 I S-870
815-870
8 I S-870
790-815
790-845
815-870
815-870
8 I S-870
815-870
X15-870
815-870
8 I S-870
81%870
730-790
730-790
730-790
845900
845-900
815-870
790-845
8 I S-870
8 I S-870
8 I S-870
815-870
815-870
815870
815-870
815870
t-415-870
8 I S-870
815.870
790-x15
790-84.5
790-845
ISSO- I650
ISSO-1650
ISSO-I650
ISSO-I650
I SOO- I600
1500-1575
1500-157.5
I -Iso- I 550
I GO- I sso
I4SO- ISSO
1450-1550
I -so- I SSO
l-150- ISSO
1450-1550
14.50-1550
l-150. ISSO
l1SO- ISSO
l-150- ISSO
I-m- I SSO
1500-1600
1500-1600
1500-1600
1500-1600
ISOO-I600
ISO@
I-ISO- ISSO
1450-1550
ISOO-I600
ISO@
ISO@
1500-1600
1500-1600
1500-1600
1500-1600
1500-1600
I3SO- I450
I3SO- I -is0
1350. IJSO
1550-1650
I SSO- I650
1500-1600
l1SO- I sso
1500-1600
1500-1600
1500-1600
1500-1600
ISOO-I600
ISCO-1600
1.500.1600
1500-1600
1500-1600
1500-1600
lSOWl600
11.50-1550
I-150- IS50
I -Iso- I sso
Spheroidized microstructure of 1040 steel after 21 h at 700°C
(1290 oF). 4% picral etch. 1000x
HWdlll?SS
@au), RB
179
I87
I92
I87
I83
I92
201
233
I74
192
197
'07
212
223
I87
197
I92
I92
201
217
I70
170
17-I
I87
I97
197
201
717
2'3
223
I97
197
207
201
I92
I74
179
I92
197
201
207
207
212
"3
--.
'29
203
229
I74
192
207
or Full Annealing
Full annealing, a common practice, is obtained by heating hypoeutectoid
steels above the uppercritical
temperacure, Aj. Ln treating these steels (they
are less than 0.77% in carbon content). full annealing takes place in the
austenite region at the annealing temperature. However.
in hypereutectoid
steels (they are above 0.77%, in carbon content), annealing takes place
above the At temperacure. which is the dual phase austenite region. In an
adjoining Figure. the annealing
superimposed on an iron-carbon,
temperature range for full annealing is
binary phase diagram.
Austenitizing Time and Dead Soft Steel. Hypereutectoid
steels
can be made extremely soft by holding for long periods at austenitizing
temperatures: there is little effect on hardness, i.e., at a change from 241 to
X9 HB, the effect on machining or cold forming properties may be
substantial.
Annealing
Temperatures
In specifying many annealing operations, it isn’t necessary to go beyond
stating that the steel should be cooled in the furnace from a designated
austenitizing
temperature. Temperatures
and associated hardnesses for
simple annealing of carbon steels are given in an adjoining Table: requirements for alloy steels are in another Table.
Heating cycles in the upper austenitizing
temperature ranges shown in
the Table for alloy steels should result in pearlitic structures. At lower
temperarures.
structllres
should be predominately
spheroidized.
Most
steels can be annealed by heating to the austenitizing
temperature then
cooling in the furnace at a controlled rate, or cooling rapidly to, and holding
at, a lower temperature for isothemutl transformation.
With either procedure, hardnesses are vir~ally
the same. However, isothermal transformation takes considerably
less time.
Spheroidizing
This treatment is usually chosen to improve cold formability.
Other
applications include improving the machinability
of hypereutectoid
steels
and tool steels. This miCroStruCture
is used in cold forming because it
lowers the flow stress of the materials. Flow stress is determined by the
proportion and distribution of ferrite and carbides. Ferrite strength depends
on its grain size and rate of cooling. The formability
of steel is signiticantly
affected by whether carbides are in the lamellae or spheroid condition.
Steels may be heated and cooled to produce globular carbides in a ferritic
matrix. An adjoining Figure shows IO-IO steel in the fully spheroidized
condition. Spheroidization
can take place by using the FoUowing methods:
l
Prolonged holding at a temperature just belo- the Act
l
Heating and cooling alternately between temperatures that are just above
Act and just below Art
l
Heating to a temperature just above Act, and then either cooling very
slowly in the furnace. or holding at a temperature just above Art
l
Cooling at a suitable rate from the minimum temperature at which all
carbide is dissolved to prevent the reformation of carbide networks, then
reheating in accordance with the fist or second methods described
Guidelines for the Heat Treatment of Steel / 33
The iron-carbon binary phase diagram showing region of temperatures for spheroidizing
Effect of prior microstructure
[as-quenched).
on spheroidizing
(b) Starting from a ferrite-pearlite
(Fief 4)
a 1040 steel at 700 “C (1290 OF) for 21 h. (a) Starting from a martensitic microstructure
microstructure
(fully annealed).
Etched in 4% picral plus 2% nital. 1000x
34 / Heat Treater’s Guide
previously
work)
The extent of spheroidization at 700 “C (1290 OF)for 200 h for
the 1040 steel starting from a ferrite-pearlite microstructure
etched in 4% picral. 1000x
(applicable
to hypereutectoid
steel containing
a carbide net-
The range of temperatures for spheroidizing
hypoeutectoid and hypereutectoid steels is shown in an adjoining
Figure. Rates of spheroidizing
depend somewhat on prior microstructures,
and are the greatest for
quenched structures in which the carbide phase is fine and dispersed (see
Figures). Prior cold work also increases the rate of the spheroidizing
reaction in a subcritical spheroidizing
treatment.
For full spheroidization,
temperatures either slightly above Act or about
midway between Act and ACJ are used. Low-carbon
steels are seldom
spheroidized for machining because in this condition they are excessively
soft and gummy, and produce long, tough chips in cutting. Generally,
spheroidized low-carbon steel can be severely deformed.
Hardness after spheroidization
depends on carbon and alloy content.
Increasing carbon or alloy content, or both, results in an increase in
as-spheroidized
hardness, which generally ranges from I63 to 212 HB (see
adjoining Table).
Process
Annealing
As a steel’s hardness goes up during cold working, ductility drops and
further cold reduction becomes so difficult
that the material must be
annealed to restore its ductility. The practice is referred to as in-process
Recommended Temperatures and Time Cycles for Annealing of Alloy Steels
Conventional
Steel
temperature
OF
T
To obtain a predominantly
I340
a30
2340
800
2345
800
312qd)
88s
31-m
a30
3150
a30
33low
a70
4042
a30
w7
a30
4062
a30
4130
ass
4l4O
83s
41.50
a30
432qd)
a85
a30
4340
4620(d)
885
4640
a30
3820(d)
5045
a30
Sl2qd)
88s
5132
a45
SIUI
a30
5150
a3o
S2loom
6150
a30
a62qd)
88s
a630
a45
a640
a30
8650
a30
a660
a30
8720(d)
a85
8710
a30
8750
a30
9260
860
93 IO(e)
a70
98-m
a30
9aso
a30
cooliog(a)
Ikmperahu-e
Austenitixhg
T
From
pearlitic structure(c)
IS25
735
1475
655
1475
655
1625
1525
735
IS25
705
I600
74s
1515
I525
735
IS25
695
I575
765
I550
755
IS25
745
1625
1525
705
1625
1525
715
OF
Cooling rate
OClh
OFlh
Tie,
h
To
From
To
610
555
550
I350
1210
I210
II30
1030
1020
IO
as
as
20
I5
IS
II
I2
12.7
650
64s
1350
I300
I200
ll9o
IO
IO
20
20
7.5
5.5
640
630
630
665
665
670
1370
I350
1280
1310
I390
1370
ii80
II70
1170
1230
1230
I240
IO
IO
a.5
20
I5
a.5
20
20
I5
3s
25
IS
9.5
9
7.3
5
6.4
8.6
565
13cil
1050
a.5
IS
16.5
600
I320
Ill0
7.6
1-I
IS
IS25
I635
I550
IS25
152s
755
66s
I390
I230
IO
20
a
755
7-m
705
670
670
650
I390
I360
I300
l2Ul
1240
I200
IO
IO
IO
20
10
20
7.5
6
5
I525
16’5
I550
IS’5
IS25
1525
I625
I525
1525
IS75
16cQ
IS25
I525
760
675
I-NO
I250
as
I5
735
725
710
700
6-m
640
650
655
I350
l34o
1310
I290
ii80
ii80
1200
I210
IO
IO
a.5
a.5
20
20
IS
IS
as
a
7.2
a
725
720
760
645
630
705
13-w
1330
I-too
II9o
II70
I300
IO
a.5
a.5
20
I5
IS
7.5
10.7
6.7
695
700
640
645
I 280
1290
ilao
II9O
a.5
a.5
IS
I5
6.6
6.7
IO
Isothermal method(b)
Cool to
OF
Eold,h
T
Elardness
(PpProX),
EJ3
620
595
595
650
660
660
595
660
660
660
675
675
675
660
650
650
620
605
660
690
675
675
675
II50
Iloo
Iloo
1200
I225
I225
Iloo
I225
1225
I225
1250
I250
1250
1225
IXO
1200
II50
II25
I225
I275
I250
1250
I250
4.5
6
6
4
6
6
I4
4.5
5
6
4
5
6
6
a
6
a
4
4.5
4
6
6
6
la3
201
201
179
la7
201
la7
197
207
223
174
197
212
197
223
la7
197
I92
I92
179
la3
la7
201
675
660
660
660
650
650
660
660
660
660
595
650
650
1250
1225
1225
I225
I200
1200
1225
I225
I235
1225
llccl
IZOO
I200
6
4
6
6
a
a
4
7
7
6
I4
6
a
201
la7
I92
197
212
229
la7
201
217
229
ia7
207
223
Guidelines for the Heat Treatment of Steel / 35
Recommended Temperatures and Time Cycles for Annealing of Alloy Steels (continued)
Attstenitizii
Steel
temperature
T
OF
T
From
Conventional cooling(a)
Temperature
OF
Cooling rate
To
To
From
“CP
Wl
Tie,
h
Isothermal method(b)
Cool to
T
OF
Hold, h
Eardness
(apF)v
To obtaio a predominantly ferritic and spheroidized carbide structure
1320(d)
1340
23-U)
2345
3 120(d)
3140
3150
9840
9850
805
750
715
71s
790
745
750
745
745
1180
1380
I320
1320
1450
1370
1380
1370
I370
..
735
655
655
.‘.
610
555
550
...
1350
1’10
I210
1130
“’
1030
IO20
5
5
5
IO
IO
IO
22“’
18
I9
735
705
695
700
650
64s
640
64s
1350
1300
I280
I290
I200
...
I190
I I80
II90
5
5
5
5
IO
IO
IO
IO
ii
II
II
II
650
640
605
605
650
660
660
6SO
650
I200
II80
II25
II25
1200
1225
1225
I200
I200
8
8
IO
IO
8
IO
IO
IO
I2
170
174
I92
I92
163
I74
I87
I92
207
(a) The steel is cooled in the furnace at the indicated rate through the temperature range shown. (b) The steel is cooled rapidly to the temperature indicated and is held at that temperature for the time specified. (c) ln isothermal annealing to obtain pearlitic StrucNre. steels may be austenitized at temperaNreS up to 70 “C ( I25 “F) higher than temperatures
listed. (d) Seldom annealed. !hIKNreS
of better machinability
are developed by normalizing or by transforming
isothermally after rolling or forging. (e) Annealing is imptactical
by the conventional
process of continuous slo\c cooling. The louer transformation
temperature IS markedly depressed, and excessively long cooling cycles ate required to obtain
are seldom desired in this steel.
transformation
to pearlite. (I) Predominantly
pearlitic struc~res
The iron-carbon binary phase diagram showing region of temperature for process annealing (Ref 4)
36 / Heat Treater’s Guide
annealing or simply process annealing. ln most cases, a SubcriIical treatment is adequate and the least costly procedure. The term process annealing, without further qualification.
refers to the subcritical treatment. The
range of temperatures normally used are shown in an adjoining Figure.
It is often necessary to call for process annealing when parts are cold
formed by stamping, heading, or extrusion. Hot worked, high-carbon and
alloy steels are also process annealed to prevent them from cracking and to
soften them for shearing, turning. and straightening. The process usualI>
consists of heating to a temperature below AC,. soaking for an appropriate
time. then cooling-usually
in air. Generally, heating to a temperature
between IO and 22 “C (20 and 10 “F) below AC] produces the best
combination of microstructure,
hardness, and mechanical properties. Temperature controls are necessary only to prevent heating above Act. which
would defeat the purpose of annealing.
When Ihe sole purpose is to soften for such operations as cold sawing
and cold shearing, temperatures are usually well below Act. and close
control isn’t necessary.
Annealed
Structures
for Machining
Different combinations of microstructure
and hardness are important for
machining. Optimum microstructures
for machining steels with different
carbon contents are usually as follows:
Carbon, W
0.c60.20
0.20-0.30
0.30-0.40
0.00-0.60
0.6@1.00
Optimum microslructure
As-rolled (,mosteconomical)
Under75 mm (3 in.)diameter,normaliz.ed: 75 mm diameterando\er.
as-rolled
Annealed to produce coarse pearlite. minimum ferrite
Coarse Iamellar pearlite to coarse spheroidized carbides
100%.spheroidizrd carbides. coarse to fine
qpe of machining operation must also be taken into consideration,
i.e.,
in machining 5160 steel tubing in a dual operation (automatic
screw
machines. plus broaching of cross slots), screw machine operations were
the easiest with thoroughly spheroidized material. H hilt a pearlite smcture
was more suitable for broaching. A senispheroidized
structure proved to
be a satisfactory compromise-a
structure that can be obtained by austenitizing at lower temperatures, and sometimes at higher cooling rates, than
those used to get pearlitic structures. In the last example, the 5 160 tubing
was heated to 790 “C ( I455 “F) and cooled to 650 “C ( I200 “F), at 28 “C
(50 “F) per h. When this grade of steel is austenitized at about 775 “C (I125
“F), results are more spheroidization
and less pearlite.
Medium-carbon
steels are harder to carburize than high-carbon steels,
such as IO95 and 52 100. In the absence of excess carbides to nucleate and
Surface
Hardening
promote the spheroidization
reaction, it is more difficult to get complete
freedom from pearlite in practical heat-treating operations.
At lower carbon levels, structures consisting of coarse pearlite in a ferrite
matrix are the most machinable. With some alloy steels, the best way of
getting this type of structure is to heat well above Ac3 to establish coarse
austenite gram size, then holding below Art to allow coarse, lamellar
pearlite to form. The process is sometimes referred to as cycle annealing or
lamellar annealing.
Annealing
Annealing
Significant
tonnages of these products are subjected to treatments that
lower hardness and prepare the steels for subsequent cold working and/or
machining. Short time, subcritical annealing is often enough to prepare
low-carbon steels (up to 0.204; C) for cold working. Steels higher in carbon
and alloy content require spheroidization
to get maximum ductility.
Annealing
of Plate
These products are occasionally
annealed to facilitate forming or machining operations. Plate is usually annealed at subcritical temperatures,
and long annealing times are generally avoided. Maintaining
flatness of
large plate can be a significant problem.
Annealing
of Tubular
Products
Mechanical
tubing is frequently
machined or formed. Annealing is a
common treatment. In most instances, subcritical temperatures and short
annealing times are used to lower hardness. High-carbon
grades such as
52100 generally are spheroidized
prior to machining. Tubular products
made in pipe mills rarely are annealed. and are used in the as-rolled, the
normalized, or quenched and tempered conditions.
References
B.R. Banerjee, Annealing
Heat Treatments,
Met. frog..
Nov 1980, p 59
Atlas of Isorhent~al Transfomtariot~ and Cooling Transformation Diagratns. American Society for Metals, 1977
hl. Atkins, Ailas for Cotlriturous Cooling Transfomtarion Diagramsfor
Engineering Steels, American Society for Metals, in cooperation with
British Steel Corporation.
G. Krauss, Sleek:
International.
processes
l
l
l
Induction hardening
l
Flame hardening
l
Gas carbutizing
l
Pack carbutizing
l
Liquid carburizing and cyaniding
l
Vacuum carburizing
l
Plasma (ion) carburizing
. Carbonitriding
Bar, Rod, Wire
1980
Hear Treammenr and Processing Principles, ASM
1989
Treatments
In the articles that follow, overvie\% s of I6 surface hardening
are presented. They include. in the order that follows:
l
of Forgings
Forgings are most often annealed to facilitate subsequent operationsusually machining or cold forming. The method of annealing is determined
by the kind and amount of machining or cold fomting to be done, as well
as type of material being processed.
l
l
l
l
l
Gas nitriding
Liquid nitriding
Plasma (ion) nitriding
Gaseous and plasma nitrocarburizinp
Fluidized bed hardening
Boriding
Laser surface hardening
Electron beam surface hardening
For more detailed
information
and hundreds of references, see the ASM
IO ed., ASM International,
1991.
Metals Handbook. Hear Treating. Vol1.
Guidelines
Induction
h4any problems associated with furnace processes are avoided. Rate of
heating is limited only by the power rating of the alternating current supply.
Surface problems such as scaling and decarburization
and the need for
protective atmospheres often can be bypassed because heating is so fast.
Heating is also energy efficient-as
high as 80 percent. In gas fued
furnaces. by comparison, a fairly substantial amount of consumed energy
in hot gases is lost as they exit the furnace.
HoNever, the process seldom competes with gas or oil-based processes
in terms of energy costs alone. SaGngs emanate from other sources:
Characteristics
In designing treabnents, consideration
must be given to the workpiece
materials, their starting condition, the effect of rapid heating on the ACT or
Accm temperatures, property requirements, and equipment used.
and Production
Material
Rounds
13
19
‘5
29
49
4130
IO35 mod
IMI
1041
13B3SH
‘/z
Flats
16
I9
22
25
29
5/g
34
‘4%
I
I ‘/8
lrregularshapes
17.5-33 “/16-15/lb
17.529 ‘Vlh-lt/~
Data for Progressive
FIX?quencyb),
Ez
Section size
mm
in.
%
I
I ‘/8
I ‘V,6
of Steel / 37
Hardening
Steels are surface hardened and through-hardened,
tempered, and stress
relieved by using electromagnetic
induction as a source of heat. Heating
times are unusually rapid-typically
a matter of seconds, Ref I.
Operating
for the Heat Treatment
1038
1038
1043
1043
lo-13
t037mod
t037mod
9600
9600
9600
180
Induction
Tempering
Power(a),
kW
Total
heating
time,s
II
12.7
18.7
20.6
23
17
30.6
d-I.2
51
196
0.39
0.71
I .01
1.18
2.76
I
1.8
2.6
3.0
7.0
SO
SO
so
SO
50
120
I20
I20
I20
I20
56s
510
565
565
56.5
1050
9.50
IOSO
1050
IOSO
I23
I64
312
25-l
328
0.59
0.79
I so
1.22
I .57
I.5
2.0
3.8
3I
1.0
40
40
-lo
10
40
loo
100
100
loo
loo
‘90
31s
290
290
290
550
600
950
550
550
0.9-l
0.67
2.1
I.7
65
65
IS0
IS0
550
125
IO70
800
60
60
60
60
60
88
too
98
85
90
9600
9600
I92
IS-I
64.8
46
Sean time
s/cm
sjm.
Work temperature
Leabing coil
Entering coil
OF
T
T
OF
Production
rate
ki#
lblb
Inductor
illput
kW/cmz kWlm.2
0.064
0.050
92
II3
I11
IS3
I95
202
‘SO
311
338
429
0.054
0.053
0.031
0.4 I
0.32
0.35
0.34
0.20
I449
1576
1609
1365
1483
319-t
3171
3548
3009
3269
0.01-l
0.013
0.008
0.01 I
0.009
0.089
0.08 I
0.0.50
0.068
0.060
2211 3875
2276 5019
0.043
0.040
0.28
0.26
(a) Power tmnsmitted by the inductor at the operating frequency indicated. For con! erted frequencies. this po\\er is approximately ?S@kless than the power input to the machine,
because of losses within the machine. (b) At the operating frequency of the inductor
Examples
of quench
rings for continuous
hardening
and quenching
of tubular
members.
Courtesy
of Ajax Magnethermic
Corp.
38 / Heat Treater’s
Guide
Power Densities
Required
Frequency,
KEZ
Depth of hardening(a)
in.
mm
500
for Surface
0.381-1.143
1.143-2.286
1.524-2.286
2.286-3.048
3.0483.064
2.286-3.048
3.048-4.064
4.064-5.080
5.080-7. I I2
7.112-8.890
IO
3
I
Hardening
Of Steel
~PMJ)W
Optimum(e)
kW/cmz
kWrm.2
Low(d)
kW/cmz
kW[m.’
I .08
0.46
I .24
0.78
0.78
I s5
0.78
0.78
0.78
0.78
7
3
8
5
5
IO
5
5
5
5
0.015-0.045
0.045-0.090
0.060-0.090
0.090-0. I20
O.I20-0.160
0.090-0. I20
0.120-O. I60
0.160-0.200
0.200-0.280
0.280-0.350
I.55
0.78
I .ss
I ss
I .55
2.33
2.17
I .55
I .55
I.55
em
kW/cm
10
5
IO
IO
IO
I5
I4
10
IO
IO
kWtin.2
I2
8
I6
I5
I4
I7
I6
I4
I2
I2
I.86
I .24
2.48
2.33
2.17
2.64
2.48
2.17
1.86
I.86
(a) For greater depths of hardening, lower kilowatt inputs are used. (b) These values are based on use of proper frequency and normal overall operating efficiency of equipment.
These values may be used for both static and progressive methods of heating; however, for some apptications. higher inputs can be used for progressive hardening. (c) Kilowattage
is read as maximum during heat cycle. (d) Low kilowatt input may be used when generator capacity is limited. These kilowatt values may be used to catculate largest part hardened
(single-shot method) with a given generator. (e) For best metatturgical results. (f) For higher production when generator capacity is available
Approximate
Operations
Power Densities
Required
for Through-Heating
of Steel for Hardening,
Tempering,
or Forming
Input(b)
150-425T
(30Mtoo°F)
kW/cm’
kWrm.2
~uency(a),
62
60
I80
1009
3000
10000
0.009
0.008
0.006
0.00s
0.003
421760 T
(soo-1400°F)
kW/cmz
kWlin.2
0.06
0.05
0.04
0.03
0.02
0.023
0.022
0.019
0.016
0.012
76M80 T
(1400-BOOoF)
kW/cmz
kwp.*
0.15
0.14
0.12
0.10
0.08
(c)
w
0.08
0.06
0.05
980-lo!zOc
(1&300-2ooooF)
k W/cm2
kW/in.”
Cc)
(c)
0.155
0.085
0.070
0.5
0.4
0.3
1095-l205oc
(2tmo-2200 OF)
kW/ii2
kW/cml
w
w
0.22
0.11
0.085
I .o
0.55
OX?
(c)
w
1.4
0.7
0.55
(a) The values in this table are based on use of proper frequency and normal overall operating efficiency ofequipment. (b) In general, these power densities are for section sizes of
I3 to SOmm ( ‘/? to 2 in.). Higher inputs can be used for smaller section sizes, and lower inputs may be required for larger section sizes. (c) Not recommended for these temperatures
Typical
Operating
section size
mm
in.
Rounds
I3
‘/z
Conditions
for Progressive
Through-Hardening
of Steel Parts by Induction
Material
Frequency(a),
El2
Power(b),
kW
Total
beating
time,s
4130
I80
20
21
28.5
20.6
33
19.5
36
19.1
35
32
38
I7
68.4
28.8
98.8
44.2
II4
fit
260
II9
0.39
0.39
0.7 I
0.71
I .02
1.02
I.18
I.18
2.76
2.76
I
I8
I.8
2.6
2.6
3.0
3.0
7.0
7.0
75
sto
75
620
70
620
75
620
75
635
I65
950
I65
II50
I60
II50
I65
II50
I65
II75
510
925
620
955
6’0
955
630
95s
635
95.5
950
1700
IISO
I750
II50
1750
IISO
I750
II75
1750
92
92
II3
II3
I41
I31
IS3
I53
19.5
I95
202
202
250
250
311
311
338
338
429
429
0.067
0.122
0.062
0.085
0.054
0.057
0.053
0.050
0.029
0.048
0.43
0.79
0.40
0.55
0.35
0.37
0.34
0.32
0.19
0.31
I80
9600
I80
9600
I80
9600
I80
9600
scao time
s/cm
Sri.
I
Work temperature
Entering coil
Leaving coil
‘=C
OF
T
“F
Production rate
lblh
k%h
Inductor
input(c)
kW/cml kW/in.l
I9
34
1035 mod
25
I
1041
29
I ‘/*
IO41
19
I ‘V, 6
I4B3SH
%
3/a
‘4
I
I ‘/8
1038
1038
1043
IO36
1036
3000
3000
3000
3000
3000
300
332
336
30-I
34-l
II.3
I5
38.5
26.3
36.0
0.59
0.79
I so
I .38
I.89
I.5
2.0
3.8
3.5
4.8
20
‘0
20
20
‘0
70
70
70
70
70
870
870
870
870
870
1600
1600
1600
1600
1600
1449
1576
1609
IS95
I678
3193
347-l
3548
3517
3701
0.361
0.319
0.206
0.225
0.208
2.33
2.06
I .33
I .45
I.34
t037mod
3ooo
580
25-t
0.94
2.4
20
70
885
1625
2211
4875
0.040
0.26
Flats
I6
I9
22
25
‘9
Irregular shapes
17.5-33 t’/te-15/ts
(a) Note use of dual frequencies for round sections. (b) Power transmitted by the inductor at the operating frequency indicated. This poaer is approximately 25% less than the power
input to the machine, because of losses within the machine. (c) At the operating frequency of the inductor
Guidelines
Eleven basic arrangements for quenching induction-hardened
shortened processing times, reduced labor, and the ability to heat treat in a
production line or in automated systems, for example. Surface hardening
and selective hardening can be energy competitive
because only a small
part of the metal is heated.
[n addition, with induction heating it often is possible to substitute a plain
carbon steel for a more expensive alloy steel. Short heating times make it
possible to use higher austenitizing
temperatures than those in conventional heat-treating practice.
Less distortion is another consideration.
This advantage is due to the
support given by the rigid, unheated core metal and uniform, individual
handling during heating and quenching cycles.
Operating
Information
Power densities for surface hardening are given in an adjoining Table.
Approximate
power densities needed for through-heating
of steel for
hardening and tempering are given in an adjoining Table.
Typical operating conditions
for progressive
through-hardening
are
given in an adjoining Table.
for the Heat Treatment
of Steel / 39
parts. See text for details.
Operating and production data for progressike induction tempering are
given in an adjoining Table.
Frequency and power selection influence case depth. A shallow, fully
hardened case ranging in depth from 0.25 mm to I .5 mm (0.010 to 0.060
in.) provides good resistance to wear for light to moderately loaded parts.
At this level, depth of austenitizing can be controlled by using frequencies
on theprder of IO KHz,to 2 MHz, power densities to the coil of 800 to 8000
W/cm’ (5 to 50 kW/i.-)
and heating times of not more than a few seconds.
For parts subjected to heavy loads, especially cyclic bending, torsion, or
brinneling. case depths must be thicker. i.e.. 1.5 IO 6.4 mm (0.060 to 0.250
in.j. To get this result. frequencies range from 10 KHz down to I KHz;
power densities are on the order of 80 to 1550 W/cm2 (l/2 to IO kW/in.2).
and heating times are several seconds.
Selective hardening is possible, as is in volume surfacing hardening, in
which parts are austenitized and quenched to greater than usual depths.
Depth of hardness up to 25 mm (I in.) measuring over 600 HB has been
obtained with a I percent carbon. I .3 to I .6 percent chromium steel that has
been water quenched. Frequencies range from 60 Hz to 1 KHz. Power
40 / Heat Treater’s
Guide
Power Input for Static Hardening. Slope of graph indicates
that 35 to 40 kW-seciin.’ (5 to 6 kW-secicm’) is correct
power input for static hardening most steels. Source:
Park-Ohio Industries
Straight-line Relationships Between Depth of Hardnessand
Rate of Travelfor Surface Hardening by Induction of long
Bars Progressively. Source: Park-Oh10 lndustrles
Effect of Varying Power Density on Progressive
Hardening. Power density at 10 000 cycles.
Case, 0.100 in. (2.54 mm) deep.
Park-Ohio Industries
Source:
Guidelines
for the Heat Treatment
of Steel / 41
Minimum Power Density VersusStock Diameter for Static Hardening and VersusRate of Travel for Progressive Hardening. Source:
Park-Oh10 Industries
Influence of Prior Structure on Power Requirements
for Surface Hardening. Prior structure consists of fine
microconstituents.
Source: Park-Ohio Industries
42 / Heat Treater’s
Guide
Effect of Varying Power Density on Progressive
Hardening. Power density at 500 000 cycles.
Case, 0.050 In. (1.27 mm) deep. Source:
Park-Ohio Industries
densities are expressed in a fraction of kW/in.‘. Heating times run from
about 20 to 140 s.
Through-hardening
is obtained in the medium frequencies (180 Hz to IO
KHz). In some instances, two hequencies may be used, a lower one to
preheat the steel to a subcritical temperature, followed by a higher ti-equency to obtain the full austenitizing temperature.
Tempering with induction heating is highly efficient. The two most
common types of quenching systems are spray quench rings (see Figure)
and immersion techniques. Eleven other systems are shown in an adjoining
Figure.
Water and oil are the most frequently used quenching media. Oil typically is used for high hardenability
parts or for those subject to distortion
and cracking. Polyvinyl
alcohol solutions and compressed air also are
commonly used, i.e., the former where parts have borderline hardenability.
where oil does not cool fast enough, and where water causes distortion or
cracking. Compressed air quenching is used for high hardenability,
surface
hardened steels from which little heat needs to be removed.
Flame
Applications
The process is applied mostly to hardenable grades of steel; some
carburizing and slow cooled parts often are reheated in selected areas by
induction heating.
Typical applications include:
l
l
l
Medium-carbon
steels, such as 1030 and 1045, for parts such as auto
driveshafts and gears
High-carbon steels, such as 1070, for parts such as drill and rock bits and
hand tools
Alloy steels for such parts as bearings, valves, and machine tool parts
Reference
I. ASM Metals Handbook. Heat Treating, Vol 4. 10th ed., ASM lntemational.
1991, p 164
Hardening
In this process, a thin surface shell of a steel part is heated rapidly to a
temperature above the critical point of the steel. After the structure of the
shell becomes austenitic, the part is quenched quickly, transforming
the
austenite to martensite. The quench must be fast enough to bypass the
pearlite and bainite phases. In some applications, self-quenching
and selftempering are possible, Ref I. (See articles on other self-quenching
processes-electron
beam, laser, and high frequency, pulse hardening-elsewhere in this chapter.)
Characteristics
Hardening is obtained by direct impingement
of a high-temperature
flame or by high-velocity
combustion product gases. The flame is produced by the combustion of a mixture of fuel gas and oxygen or oil. The
mixture is burned in flame heads: depth of hardness ranges from approximately 0.8 to 6.4 mm (0.03 125 to 0.25 in.), depending on the fuels used,
design of the flame head, duration of heating, hardenability
of the workpiece, the quenching medium, and quenching method.
Flame hardening differs from true case hardening in that hardness is
obtained by localized heating.
The process generally is selected for wear resistance provided by high
levels of hardness. Other available gains include improvements in bending
properties, torsional strength, and fatigue life.
Comparative benefits of flame hardening, induction hardening, nitriding,
carbonitriding.
and carburizing are summarized in an adjoining Table.
Operating
Information
Methods of flame hardening include these types: spot (or stationary),
progressive,
spinning, and combination
progressive-spinning.
Spot and
progressive
spinning are depicted in a Figure, spinning methods in a
second Figure.
Guidelines
for the Heat Treatment
of Steel / 43
Fuel Gases Used for Flame Hardening
usual
Beatingvalue
Gas
Acetylene
City gas
Natural gas
(methane)
Propane
MAPP
MJ/m’
Bhr/ft’
53.4
1433
I I .2-33.5 300900
37.3
loo0
93.9
90
2520
2406
Ftarne temperature
With oxygen
With air
OF
OC
OC
OF
nltioof
oxygen to
fuel gas
Beating value of
oxy-fuel gas
mixture
hfJjtn’
Bhr/ftJ
Notmal
velocity of
buruiug
mm/s
i0.p
Combustion
intensity(a)
mm/sx
tn./s x
I\lJ/m’
Btu/ftJ
USUd
ratio of
airI0
fuel gas
3105
2540
2705
5620
4600
4900
2325
1985
1875
4215
3605
3405
I.0
(b)
I .75
26.1
(hi
13.6
716
(b)
364
535
(b)
280
II
(b)
II
I4 284
(b)
3808
15 036
(W
4004
12
W
9.0
2635
2927
477s
5301
192s
1760
3495
3200
4.0
3.5
18.8
20.0
504
53s
30s
381
I2
I5
5 734
7 620
6oJ8
8025
25.0
22
(a) Product of normal velocity of burning multiplied by heating value of oxy-fuel gas mixture. (b) Varies with heating value and composition
Procedure
for Spin Flame Hardening
the Small Converter
Preliminary operation
Turn on water, air, oxygen, power, and propane. Line pressures: water, 220 kPa (32
psi); air. 550 kPa (80 psi); oxygen, 825 kPa ( 120 psi); propane. 20.5kPa (30 psi). Ignite pilots.
Loading and positioning
Mount hub on spindle. Hub is held in position by magnets. Flame head pm\ iously centered in hub within 0.4 mm (‘1~ in.). Distance front flame head to inside diameter of
gear teeth, approximately 7.9 mm &te in.)
Cycle start
Spindle with hub advances over flame head and starts to rotate. Spindle speed. I-10 rpm
Beating cycle
Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of
propane and oxygen ignited at flame head by pilots. Check propane and oxygen
gages for proper pressure. Adjust flame by regulating propane. Heating cycle controlled by timer. Tune ptedetemtined to obtain specified hardening depth
Shallow hardness patterns of less than 3.2 mm (0.125 in.) deep can be
obtained only with oxy-gas fuels. When specified hardnesses are deeper,
oxy-fuels or air-gas fuels may be used. Time-temperature
depth relationships for various fuel gases used in the spot (stationary),
spinning, and
progressive methods are shown in an adjoining Figure.
Burners and Related Equipment. Burners vary in design, depending on whether oxy-fuel or air-fuel gas mixtures are used. Flame temperatures of the air-fuel mixtures are considerably
lower than those of oxy-fuel
mixtures (see Table).
Flame heads for oxy-fuel gas are illustrated in an adjoining Figure, while
those for air-fuel gas are shown in a second Figure.
Operating Procedures and Control. The success of many applications depends largely on the skill of the operator.
Procedures for two applications are summarized in adjoining tables.
Preheating. Difficulties
in getting the required surface hardness and
hardness penetration in treating parts large in cross section often can be
overcome by preheating. When available power or heat input is limited,
depth of hardness can also be increased by preheating. Results in one
application are shown in an adjoining Figure.
Quenching Methods and Equipment.
Method and type of quenchant vary with the flame hardening method used. hnrnersion quenching
generally is the choice in spot hardening, but spray quenching is an
alternative. In quenching after progressive heating, the spray used is integrated into the flame head. However, for steels high in hardenability,
a
separate spray-quench
sometimes is used. Parts heated by the spinning
method are quenched several ways. In one, for example, the heated part is
Gear Hub
Beating cycle (continued)
Propane and oxygen solenoid valves close (propane flow delayed slightly). Spindle
stops rotating and retracts. Hub stripped from spindle by ejector plate. Machine ready
for recycling
Propane regulated pressure, I25 kPa ( I8 psi ); oxygen regulated pressure, 550 kPa (80
psi); oxygen upstream pressure, ux) kPa (58 psi); oxygen downstream pressure, I40
kPa (20 psi). flame velocity (ap roximate), I35 m/s (450 ft/s). Gas consum tions
(approximate); propane, 0.02 rn.7 (0.6 fts) per piece: oxygen, 0.05 m3 ( I .9 ft ) per
piece. Total heating time, 95 s
Flame pan design: I2 ports per segment; IO segments; port size, No. 69 (0.74 mm. or
0.0292in.).withNo.56(1.2mm,orO.O46Sin.)counterbore
f
Quench cycle
Hubdrops into quench oil, is removed from tank by conveyor. Oil temperatute. S4f
5.6 “C (130-t IO “F); time in oil (approximate), 30s
Eardoess and pattern aim
Hardness, 52 HRC minimum to a depth of 0.9 mm (0.035 in.) maximum above toot of
gear teeth
Relative
Benefits
carburizing
Carbonitriding
Nitriding
induction hardening
Flame hardening
of Five Hardening
Processes
Hard. highly wear-resistant surface (medium case depths);
excellent capacity for contact load; good bending fatigue
strength; good resistance to seizure; excellent freedom from
quench cracking; low-to-medium-cost steels required; high
capital investment required
Hard, highly wear-resistant surface (shallow case depths):
fair capacity for contact load; good bending fatigue
strength: good resistance to seizure; good dimensional
control possible; excellent freedom Fromquench cracking;
low-cost steels usually satisfactory; medium capital
investment required
Hard. highly we=-resistant surface (shallow case depths);
fair capacity for contact load; good bending fatigue
strength;excellent resistance toseizure; excellent
dimensional control possible; good 6eedom Fromquench
cracking (during pretreatment): medium-to-high-cost steels
requited; medium capital investment required
Hard. highly wear-resistant surface (deepcase depths); good
capacity for contact load; good bending fatigue strength;
fair resistance to seizure; fair dimensional control possible:
fair freedom from quench cracking; low-cost steels usually
satisfactory; medium capita) investment required
Hard, highly wear-resistant surface (deepcase depths); good
capaci3 for contact load; good bending fatigue strength;
fair reststance to seizure; fair dimensional control possible;
fair freedom from quench c73cking; low-cost steels usually
satisfactory; low capital investment requited
44 / Heat Treater’s
Guide
Spot (stationary) and progressive
methods of flame hardening. (a) Spot (stationary)
internal lobes of a cam; quench not shown. (b) Progressive hardening method
Spinning methods
Quench not shown
Response
of flame hardening.
In methods shown at left and at center, the part rotates. In method at right, the flame head rotates.
of Steels and Cast Irons to Flame Hardening
hlaterial
Plain carbon steels
1025-1035
I043 IO.50
10.55-1075
1080-1095
11’5-1137
ll38-114-l
114&1151
Qpical hardness, EIRC, as affected by quenchant
Air(a)
Oil(b)
Water(b)
SO-60
55-62
92-58
58-62
S8-62
15-55
SO-55
52-57(C)
s5-60
33-50
55-60
60-63
62-65
AS-55
55-62
58-61
58-62
60-63
62-65
62-65
52-57(C)
55-60
58-62
61-63
SO-55
52-56
58-62
53-57
56-60
52-56
S-62
60-6-I
63-65
63-65
55-60
55-60
62-65
60-63
62-6s
60-63
Carburized grades of plain carbon steels(d)
SO-60
1010-1020
50-60
1108-1120
Alloy steels
13-u)-1335
3110-3115
3350
4063
4130-413s
4l40-4I-15
11-17~1150
13374340
4347
-I640
method of flame hardening a rocker arm and the
35-55
50-60
55-60
55-60
52-56
M-62
53-57
56-60
52-56
‘l)pical hardness, EIRC, as affected by quenchant
Air(a)
Water(b)
oil(b)
hiaterial
Allo] steels (continued)
52100
6150
8630-8640
86x-8660
M-60
48-53
55-63
Carburized
3310
461.54620
86 I S-8620
grades of alloy steels(d)
55-60
58-62
hlsrtensitic
-llO.-tl6
-II-l1131
120
UOttvpical)
.
stainless steels
55-60
5260
52-57
55-63
62-64
Xi-60
58-62
62-64
58-62
62-65
58-6’
63-65
64-66
62-65
-11-l-I
G-47
-t9-56
55-59
41-U
12-47
49-56
55-59
Cast irons (ASThI classes)
Class 30
class 40
Class-!5010
s0007.53004.6lmJ3
Class 80002
52-56
class &l-45- IS
43-48
-18-52
3543
52-56
56-59
43-18
38-52
35-45
55-60
X1-61
35-45
ta)Toobtainthe hardnessresultsindicated. thoseareasnotdirectly heatedmust be kept relativelycoolduring
the heatingprocess.~b)Thinxctionsaresusceptible~ocracking
when
quenched with oil or water. (c) Hardness is slightly lo\rer for material heated by spinning orcombination progressive-spinning methods than it is for material heated by progressive
or stationary methods, td) Hardness values of carburized cases containing 0.90 IO I. 10% C
Guidelines
Calculated time-temperature-depth
ness given in millimeters
relationships
Typical
gas. (a) Radiant type. (b) High-velocity
burners
for use with air-fuel
for spot (stationary),
spinning,
for the Heat Treatment
and progressive
convection
flame hardening.
type (not water cooled)
of Steel
/ 45
Depth of hard-
46 / Heat Treater’s
Guide
Flame heads for use with oxy-fuel gas
Effect of preheating on hardness gradient in a ring gear
Progressive
Flame Hardening
of Ring Gear Teeth
Workpkxe
Bevel ring gear made of 87-12 steel with 90 teeth. Diametral
mm (8 in.); outside diameter, I.53 m (60.112 in.)
pitch, 1.5; face width. 200
hlouoting
Gear mounted on holding fixture to within 0.25 mm (0.010 in.) total indicator runout
Flame beads
ILvo IO hole. double-row. air-cooled flame heads. one on each side of tooth. Flame
heads set 3.2 mm (‘/s in.) 6om tooth
Operating
removed
tank.
from the heating area and quenched
by immersion
conditions
Go.sp~ssurps. Acetylene, 69 kPa ( IO psi); oxygen. 97 kPa ( I4 psi)
Speed. I .9 mm/s (4.5 in./min). Complete qcle (hardening pass, overtravel at each end,
index rime. preheat return stroke on next tooth), 2.75 min
hdering. Index every other tooth. index four times before immening in coolant.
Coolanr. Mixture of soluble oil and hater. at I3 “C (55 “Fj
Hardnessaim.
53 to 55 HRC
in a separate
Quenching Media. Water, dilute polymer solutions, and brine solutions are used. Oils are not: they should not be allowed to come into contact
with oxygen, or to contaminate equipment.
In many types of flame hardening (excluding through hardening) selfquenching speeds up cooling. The mass of cold metal underneath the
heated layer withdraws heat, so cooling rates are high compared with those
in conventional
quenching. During progressive
hardening of gear teeth
made of medium-carbon
steels, such as 4140, 4150. 4340, and 4610, for
instance, the combination
of rapid heating and the temperature gradient
between the surface and interior of a gear results in a selfquench.
Results
are similar to those obtained with oil.
Tempering. Flame hardened parts usually are tempered, with parts
responding as they do when they are hardened by other methods. Standard
procedures, equipment, and temperatures may be used. If parts are too large
to be treated in a furnace. they can be Hame tempered. Also, large parts
hardened to depths of about 6.4 mm (0.25 in.) can be self-tempered
by
residual heat in the part: hardening stresses are relieved
separate operation may not be necessary.
and tempering
in a
Applications
flame hardened plain carbon steels, carburized grades of plain carbon
steels, alloy steels, martensitic stainless steels, and cast irons that are flame
hardened are listed in an adjoining Table.
Reference
I. ASM Merals Handbook
tional, 1991, p 368
Hear Treating, Vol 4. 10th ed., ASM lntema-
Gas Carburizing
In this process, carbon
temperatures required to
carbon steels. Austenite
quenching and tempering,
is dissolved in the surface layers of parts at the
produced an austenitic microstructure
in lowis subsequently
converted
to martensite by
Ref I.
Characteristics
This is the most important carburizing process commercially.
The gradient in carbon content below the surface of a part produced in the process
causes a gradient in hardness; resulting surface layers are strong and
resistant to wear. The source ofcarbon is a carbon-rich furnace atmosphere,
including gaseous hydrocarbons, such as methane, propane, and butane, or
vaporized hydrocarbon liquids. Lou-carbon
steels exposed to these atmospheres carburize at temperatures of 850 “C (I 560 “F) and above.
Operating
Information
In present practice,
for two reasons:
l
carbon content in furnace atmospheres
To hold tinal carbon concentration
solubility limit in austenite
is controlled
at the surface of parts below
the
Guidelines
Plot of total case depth versus
l
To minimize
carburizing
time at four selected
071 ‘C IMOO ‘FI
.899T116M’F1
l
927 ‘C 11700 ‘FI
in.
mm
in.
“Ill
in.
mm
in.
I
,
;
0.46
0.64
0.89
0.018
0.035
0.03
0.53
0.76
1.07
0.02 I
0.0-P
0.030
0.6-I
0.89
I.27
O.OY
0 050
0.035
0.‘4
I.04
I.30
0.029
0.051 I
0.04
8
I?
I6
.?4
30
I.27
I.55
1.80
2.18
2.46
0.050
0.061
0.071
0.086
0.097
I.52
18.5
2.13
2.62
2.95
0.060
0.073
oon4
0.103
0.116
I.80
2.21
?..(-I
3.10
3 -In
0.07 I
0.087
0.100
0.1’2
O.li?
2.11
2 59
2.9:
3.M
4.09
0.083
O.lO!
0.117
Residual stresses put into parts prior to heat treating
Shape changes caused by heating too rapidly
/ 47
951 ‘C 11750 “FI
mm
sooting of the furnace atmosphere
of Steel
Graph based on data in table
Time.
h
Endothermic gas, the usual carrier, plays a dual role: it acts as a diluent
and accelerates the carbutizing reaction at the surface of parts.
Parts, trays, and fixtures should be thoroughly cleaned before they are
charged into the furnace-often
in hot alkaline solutions. In some shops,
these furnace components are heated to 400 “C (750 “F) before carburizing
to remove traces of organic contaminants.
Key process variahles are temperature, time, and composition
of the
atmosphere. Other variables are degree of atmosphere circulation and the
alloy content of parts.
Temperature.
The rate of diffusion of carbon in austenite determines
the maximum rate at which carbon can be added to steel. The rate increases
significantly
with increasing temperature. The rate of carbon addition at
925 “C (1695 “F) is about 40 percent higher than it is at 870 “C (1600 “F).
At this temperature, the carburizing rate is reasonahly rapid and the deterioration of furnace components, especially alloy trays and futtures, is not
excessive. When deep cases are specified, temperatures as high as 966 “C
(1770 “F) sometimes are used to shorten carburizing times.
For consistent results, temperatures must be uniform throughout
the
workload. The desired result can be obtained, for example, with continuous
furnaces with separate preheat chambers.
Time. The combined effect of time and temperature on total case depth
is shown in an adjoining Figure. The relationship of carburizing tune and
increasing carburizing temperature is shown in a second Figure.
Dimensional
Control. To keep heat-treating times as short as possible, parts should be as close to final dimensions as possible. A number of
other factors also have an influence on distortion, including:
l
temperatures.
for the Heat Treatment
0.I.t.l
0 Ihl
Reducing effect of increased
process temperature
on carburizing time for 8620 steel. Case depth: 1.5 mm (0.060 in.)
Properties
of Air-Combustible
Gas Mixtures
Autoignition
temperahwe
Flammable limits in
Gas
OC
OF
Methane
Propane
Hydrogen
Carbon mono.tiurde
Methaool
S-IO
466
-mo
100s
5.1IS
870
750
1130
72s
2.19,s
4.0-7s
12.5-74
6.7-36
609
385
air, vol %
48 / Heat Treater’s
Guide
Plot of stress relief versus tempering temperatures held for 1
h for two carbon concentrations in austenite
A high-productivity
l
l
The manner in which
quenching
Severity of quenching
A pit batch carburizing furnace. Dashed lines outline location of
workload.
gas-fired integral quench furnace
parts are stacked or fixturcd
in carburizing
and
Quenchants include brine or caustic solutions, aqueous polymers,
oils, and molten salt.
In some industries, parts are carburized at 917 “C (I 700 “F) or above,
cooled slowly to ambient temperature. then reheated at 843 “C (I 550 “F),
then quenched. Benefits include refinement in microstructure
and limiting
the amount of retained austenite in the case.
Tempering. Density changes during tempering affect the relief of residual stresses produced in carburizing.
An adjoining Figure shows the
effect of tempering for I h at various temperatures on stress relief. Stress
relief occurs at lower tempering temperatures as the amount of carbon
dissolved in austenite is increased.
Selective Carburizing. Some gears, for example, are carburized only
on teeth, splines, and bearing surfaces. Stopoffs include copper plating and
ceramic coatings.
Safety Precautions. The atmospheres used are highly toxic and
highly inflammable.
When combined with air, explosive gas mixtures are
Guidelines
Relation Between Dew Point and Moisture Content of
Gases. Hydrogen can be purified by a room-temperature catalytic reaction that combines oxygen with hydrogen, forming water.
Then, all water vapor is removed by drying to a dew point of -60
“F (-51 “C).
Composition
Steel
of Carburizing
C
Mn
for the Heat Treatment
of Steel / 49
Iron Oxides from CO, or H,O. Data point 1: an atmosphere consisting of 75 H, and 25 H,O will reduce scale on iron (Fe0 or
Fe,O,) at 1400 “F (760 “C). Data point 2: same atmosphere will
scale metal at 900 “F (480 “C)
Steels
Composition, Q
Ni
Cr
MO
Other
Carbon steels
1010
1019
1018
0.08-0.13 0.30-0.60
0.15-0.20 0.70-1.00
0.60-0.90
.
...
.. .
.
..
.. .
i”? IZ
$ ;;;
1020
1021
0.18-0.23
0.30-0.60
0.60-0.90
..
. ..
. ..
$1: y;
1022
1524
1527
0.18-0.23
0.19-0.25
0.22-0.29
0.70-1.00
1.35-1.65
1.20-1.50
...
.
...
..
.
..
(:I: (b)
(4, (b)
Resulfurized steels
1117
0.14-0.20
1.00-1.30
..
.. .
..
0.08-O. 13 S
Alloy steels
3310
0.08-0.13
4023
0.20-0.25
4027
0.25-0.30
4118
0.18-0.23
4320
0.17-0.22
4620
0.17-0.22
4815
0.13-0.18
4820
0.18-0.23
5120
0.17-0.22
5130
0.28-0.33
8617
0.15-0.20
8620
0.18-0.23
8720
0.18-0.23
8822
0.20-0.25
9310
0.08-0.13
0.45-0.60
0.70-0.90
0.70-0.90
0.70-0.90
0.45-0.65
0.45-0.65
0.40-0.60
0.50-0.70
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.75-1.00
0.45-0.65
3.25-3.75 1.40-1.75
...
.
.
.
0.40-0.60
1.65-2.00 0.40-0.60
1.65-2.00
3.25-3.75
3.25-3.75
0.70-0.90
0.80-1.10
0.40-0.70 0.40-0.60
0.40-0.70 0.40-0.60
0.40-0.70 0.40-0.60
0.40-0.70 0.40-0.60
3.00-3.50 1.00-1.40
0.40-0.70
0.40-0.60
2.75-3.25
0.35
2.00
Special alloys
CBS-600 0.16-0.22
CBS0.10-0.16
1OOOM
Alloy 53
0.10
(a)0.004Pmax,0.05
Smax.(b)0.15-0.35Si.
...
0.15-0.25
0.15-0.25
0.20-0.30
0.30-0.40
0.08-0.15
1.25-1.65 0.90-1.10
0.90-1.20 4.00-5.00
1.00
(b)> Cc)
(b). Cc)
(b), Cc)
(b). Cc)
(b)> Cc)
(b). Cc)
(b). (cl
(b), (cl
(b). Cc)
(b), (c)
(b). Cc)
(b)> Cc)
(b), Cc)
(b)> Cc)
(b), Cc)
0.20-0.30
0.20-0.30
0.08-0.15
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
3.25
0.90-1.25 Si
0.40-0.6OSi
0.15-0.25 V
1.OOSi, 2.00
cu,o.1ov
(c)O.035 Pmax,O.O4Smax
Available Carbon (the Weight of Carbon Obtained for Carburizing from a Given Gas at a Given Temperature). Charcoal
gas analyzes 20 CO, 80 N,. Natural gas is principally methane.
Data point 1: at 1700 “F (925 “C), the available carbon in charcoal
gas is 0.0000272 lb/k3 (0.004357 kg/m3). Data point 2: in natural
gas, there is 1200 times as much or 0.0337 IbW (0.5398 kg/ma)
50 / Heat Treater’s
formed. Properties
ing Table.
Guide
of air-combustible
gas mixtures
are given in an adjoin-
Water Gas Reaction, CO + H,O CJ CO, + H,. Variation of equilibrium constant K with temperature. K is independent of pressure,
since there is no volume change in this reaction.
Carburizing
Equipment.
Both batch and continuous
furnaces are
used. Among batch types, pit and horizontal furnaces are the most common
in service. A pit furnace is illustrated in an adjoining Figure. Adisadvantage
of the pit type is that when parts are direct quenched, they must be moved
in air to the quenching equipment. The adherent black scale developed on
parts with this practice may have to be removed by shot blasting or acid
pickling. Horizontal batch furnaces with integral quenching facilities are
an alternative (see Figure).
Continuous
furnaces used in carburizing
include mesh belt, shaker
hearth. rotary retort, rotary hearth, roller hearth, and pusher types.
Compositions
Carbon steel, resulfurized
In an adjoining Table.
steel, and alloy steel compositions
are listed
Reference
I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed., ASM Intemational,
Pack
1991, p 312
Carburizing
Operating
Information
In this process, carbon monoxide derived from a solid compound decomposes at the metal surface into nascent carbon and carbon dioxide. Carbon
is absorbed into the metal; carbon dioxide immediately reacts with carbonaceous material in the solid carburizing
compound to produce fresh
carbon monoxide. Carbon monoxide formation is enhanced by energizers
or catalysts such as barium carbonate, calcium carbonate, potassium carbonate, and sodium carbonate present in the carburizing compound. Energizers facilitate the reduction ofcarbon dioxide with carbon to form carbon
monoxide, Ref I
The common commercial carburizing compounds are reusable and contain IO to 20 percent alkali or alkaline earth metal carbonates bound to
hardwood charcoal, or to coke by oil, tar, or molasses. Barium carbonate is
the chief energizer, usually accounting for 50 to 70 percent of total carbonate content.
Process Control. Two parameters are unique to the process:
Characteristics
l
Both gas carburizing and liquid carburizing
have labor cost advantages
over this process. This disadvantage may be offset in jobs requiring additional steps, such as cleaning and the application of protective coatings in
carburizing stopoff operations.
Other considerations
favor pack carburizing:
A wide variety of furnaces may be used because the process produces its
own contained environment
l
It is ideally suited for slow cooling from the carburizing temperature
l
It offers a wider selection of stopoff techniques than gas carburizing for
selective carburizing techniques
On the other side of the ledger, pack carburizing
is less clean and less
convenient to use than the other carburizing processes. In addition:
l
Case depth may vary within a given furnace due to dissimilar thermal
histories within the carburizing containers
Distortion
of parts during carburizing
may be reduced because compound can be used to support workpieces
Carbon potential of the atmosphere generated by the compound, as well
as the carbon content obtained at the surface of the work, increase directly
with an increase in the ratio of carbon monoxide to carbon dioxide.
l
l
l
l
l
It isn’t well suited for shallow case depths where depth tolerances are
strict
It is labor intensive
It takes more processing time than gas or liquid carburizing because of
the heating time and cooling time required by the extra thermal mass
associated with the solid carburizing compound and the metal container
used
It isn’t suited for direct quenching or quenching in dies
Effect of time on case depth at 925 “C (1700 “F)
Guidelines
Typical Applications
for the Heat Treatment
of Steel / 51
of Pack Carburizing
CprbUIiZiIlg
Dimensions(a)
OD
Pall
Mine-loader bevel gear
flying-shear timing gear
Crane-cable drum
HigIl-misaligNnent coupting gear
Continuous-miner drive pinion
Heavy-duty ir~Iustrial gear
Motor-brake wheel
l-Qll-performance crane wheel
Calender bull gear
Kiln-uunnion roller
Leveler roll
Blooming-mill screw
Heavyduty rotting-mill gear
Prccessor pinch roU
OA
mm
in.
102
216
603
305
I27
618
457
660
2159
762
95
381
914
229
4.0
8.5
23.7
12.0
5.0
24.3
18.0
26.0
85.0
30.0
3.7
IS.0
36.0
9.0
mm
Weight
in.
76
92
2565
152
I27
I02
215
3.0
3.6
101.0
6.0
5.0
4.0
8.9
6.0
24.0
16.0
31.3
131.0
159.0
212.0
I.52
610
406
794
3327
4038
5385
kg
I.4
23.6
1792
38.5
5.4
IS0
IO4
335
5885
1035
36.7
2950
II 800
1700
lb
3.1
52.0
3950
84.9
II.9
331
229
739
I2975
2’80
80.9
6505
26015
3750
Steel
2317
2317
I020
46617
2317
I022
10’0
103s
1025
1030
3115
311s
2325
8620
Case depth to 50
ERC
mm
in.
0.6
0.9
I.2
I.2
I.8
I.8
3.0
3.8
4.0
4.0
4.0
5.0
5.6
6.9
0.02-I
0.036
0.048
0.048
0.072
0.072
0.120
0.150
0.160
0.160
0.160
0.200
0.220
0.270
Temperahue
OF
T
925
1700
I650
I750
I700
1700
I725
1700
1725
I750
I725
1700
1700
1750
I925
900
955
925
925
940
925
940
955
940
925
925
955
1050
(a) OD, outside diameter; OA, overall (axial) dimension
Operating temperatures normally run from 815 to 955 “C ( 1500 10
1750 “F). However, temperatures as high as 1095 “C (2005 “F) are used.
The rate of change in case. depth at a given temperature is proportional
to the square root of time. This means the rate of carburization
is highest at
the beginning of the cycle and gradually diminishes as the cycle continues.
Case Depth. Even with good process control, it is difficult to hold case
depth variation below 0.25 mm (0.010 in.) from maximum to minimum in
a given furnace load, assuming a carburizing temperature of 925 “C (1695
“F). The effect of time on case depth is shown in an adjoining Figure.
Furnaces are commonly of the box, car bottom, and pit types. Temperature uniformity must be controllable
within &5 “C (+99 “F).
Containers normally are made of carbon steel, aluminum coated carbon
steel, or iron-nickel-chromium,
heat-resisting alloys.
Liquid
Carburizing
and Properties
and workpiece
is not
provides good support
Applications
Reference
I. ASM Metals Hundbook. Hear Treating, Vol 4, 10th ed.. ASM Intemational, 1991, p 325
and Cyaniding
Both are salt bath processes. In liquid carburizing. cyanide or noncyanide
salt baths are used. Cyaniding is a liquid carbonitriding
process. 11differs
horn liquid carburizing because it requires a higher percentage of cyanide
and the composition of the case produced is different. Cases produced in
the carburizing process are lower in nitrogen and higher in carbon than
cases produced in cyaniding. Cyanide cases are seldom deeper than 0.25
mm (0.010 in.); carburizing cases can be as deep as 6.35 mm (0.250 in.).
For very thin cases, low-temperature
liquid carburizing baths may be used
in place of cyaniding, Ref I.
Compositions
Packing. Intimate contact between compound
necessary, but with proper packing the compound
for workpieces.
of Sodium
Cyanide
Liquid carburizing. Parts are held at a temperature above Act in a
molten salt that introduces carbon and nitrogen, or carbon, into the metal
being treated. Diffusion of the carbon from the surface toward the interior
produces a case that can be hardened, usually by fast quenching, from the
bath.
Cyaniding. In this process, steel is heated above Act in a bath containing alkali cyanides and cyanates, and its surfaces absorb both carbon and
nitrogen from the molten bath.
Mixtures
specificgravity
ktktwegrade
designation
NaCN
%98(a)
75(b)
45(b)
30(b)
97
75
45.3
30.0
Composition,w(%
NaCOJ
Melting point
NaCl
OC
OF
2.3
3.5
37.0
40.0
Trace
‘I.5
17.7
30.0
560
590
570
625
ICUI
1095
1060
115s
25oc
(75W
I.50
I .60
I.80
2.09
I.10
I .25
I.40
I.54
(a) Appearance: white crystalline solid. This grade contains 0.5%, sodium cyanate (NaNCO) and 0.X. sodium hydroxide (NaOH); sodium sulfide (Na,S) content. nil. (b) Appearance: white granular mixture
52 / Heat Treater’s
Typical Applications
Guide
of Liquid
Carburizing
Weight
Part
In Cyanide
Baths
Depth of case
mm
in.
Temperature
OC
OF
Steel
Disk
Flange
Gage rings, knurled
Hold-down block
hen. tapered
Lcwr
Link
Plate
Plug
Plug gage
Radius-cutout toll
Torsion-barcap
0.9
0.5
0.7
3.5
I.1
I.1
0.03
0.09
0.9
4.75
0.05
0.007
0.007
0.7
O.-IS
7.7
0.05
2
I.1
I5
7.7
2.5
3
0.06
0.2
2
IO.5
0.12
0.015
0.015
1.6
I
I7
0. I
CR
1020
CR
1020
CR
I020
1020
1020
CR
1020
1020
1018
IO10
CR
10’0
CR
IO’2
I.0
IS
I.5
1.3
1.3
I.3
0.4-0.5
I5
I.0
1.3
0.13-0.2s
0 13-0.2s
0 ‘S-O.-l
I.5
I .s
I .s
0.02-0.05
0.040
0.060
0.060
0.050
0 050
0.050
0.0 I s-0.020
0.060
0.040
0.050
0.005-0.010
0005-0010
0.010-0.015
0.060
0.060
0.060
0.001-0.002
940
9-10
9-lO
9-h)
940
9-10
815
9-10
9-10
9-to
a-15
8-15
8-e
9.40
9-10
910
900
I720
I720
I720
I720
I720
I720
I550
I720
I720
I720
1550
1550
1550
I720
I720
I720
I650
4
6.5
6.5
5
5
5
-I
6.5
4
5
I
I
2
6.5
6.5
6.5
0.12
AC
AC
AC
AC
AC
(h)
Oil
AC
AC
AC
Oil
AC
Oil
AC
AC
AC
Caustic
(a)
(a)
(a)
(a)
(a)
(b)
(C)
(a)
Resulfurized steel
Bushing
Dash sleeve
Disk
Drive shah
Guide bushing
Nut
Pm
0.01
3.6
0.0009
3.6
0.1
0.0-I
0.003
0.09
8
0.002
8
OS
0.09
0.007
III8
III7
III8
III7
III7
III3
III9
0.25-0.-l
I.1
0.13-0.2s
I.1
0.75
0.13-0.2s
0.13-0.25
0.010-0015
0.015
00050.010
0.045
0.030
0.005-0.010
0.009-0.010
815
915
81s
91.5
915
84.5
8-15
I550
I675
1550
1679
1675
IS50
1550
7
7
I
7
5
I
I
Plug
Rack
Roller
screw
Shah
Spring seat
slop collar
Stud
Valve bushing
Valve retainer
Washer
0.007
0.31
0.0 I
0.003
0.08
0.009
0.9
0.007
0.02
0.15
0.007
0.015
0.75
0.03
0.007
0.18
0.02
2
0.015
0.05
I
0.015
III3
III3
1118
III3
III8
III8
1117
1118
III7
1117
III8
0.075-o. I3
0.13-0.2s
0.25-0.1
0.0750. I3
0.25-0.-l
0.2.5-0.4
I.1
0.13-0.2s
1.3
I.1
0.25-0.-l
0.003-0.005
0.0050.010
0.0 I o-0.0 IS
0 003-0.00.5
0.0 I o-0.0 I s
0.010-0.015
0.045
0.0050.0I0
0.050
0.045
0.0 I O-O.0IS
815
U-15
845
x-15
845
81s
925
x-l.5
915
915
a-15
I sso
I550
IS50
1550
I550
I.550
1700
1550
1675
1675
ISSO
0.9-36
0.20
0.03
0.9
0.31
0.03
O.-IS
4.586
0.20
0.15-82
2.3-23
0.0009
0.45-5-I
0.20
S.-l
I.8
0.0 I
0.20
0.45-3.6
2-80
0.5
0.06
2
0.75
0.06
I
IO-190
0.5
l-180
S-50
0.002
I-120
0.5
I’
-I
0.03
0.5
l-8
8620
8620
8620
8620
8620
8620
8620
8620
8620
8620
8620
9317
86’0
8620
86’0
8620
8620
8620
8620
2.3
2.3
0.25-0.4
I .o
I .o
0.075cl. I3
0.75
I .5
1.3
I.3
I.1
0. I-O.2
I.3
I.1
‘3
I .s
0.1-03
I.1
I3
0.090
0.090
0.0 I o-0.0 IS
0.040
0.040
0.003-0.005
0.030
0.060
0.050
0.050
0.045
0 00-l-0.008
0.050
0.045
0.090
0.060
0.01 s-o.020
0.045
0.050
9’5
925
8-15
915
915
8-15
915
9’9
915
91s
91.5
81s
925
915
925
915
84s
915
915
I700
I700
I.550
I675
I675
1550
I675
1700
I675
1675
1675
I s50
1700
I675
I 700
I675
IS50
I675
I675
Carbon steel
Adaprcr
Arbor. tapered
BWJliflg
Die block
Alloy steel
Beating races
Bearing rollers
Couplmg
Crankshaft
Gear
Idler shah
Pintle
Piston
Plunger
Ram
Retainer
Spool
Thrust cup
Thrust plate
Universal socket
Valte
valve seat
Wear plate
Tie,
h
Quench
Subsequent
treatment
lb
kg
Eardnes.,
ERC
(a)
(a)
(c)
62-63
62-63
62-63
62-63
59-61
56-57
55 mitt(d)
62-63
62-63
62-63
W
(C)
(a)
(a)
(a)
(0
(e)
62-63
62-63
62-63
45-47
Oil
AC
Brine
AC
(j)
Oil
Oil
(d
(iit)
Cc)
(h)
Cd
58-63
(e)
58-63
58-63
W
(e)
0.5
I
7
OS
2
2
6.5
I
8
7
2
Oil
Oil
Oil
Oil
Oil
Oil
AC
Oil
AC
ci)
Oil
(CJ
w
(C)
(C)
Cc)
(C)
(I?)
(c)
(8)
II
II
2
6.5
6
0.5
5
I’
AC
AC
Oil
AC
AC
Oil
(i)
tit
AC
(ii
(ij
Oil
ti)
tit
AC
AC
Oil
AC
AC
(is)
(I3
8
8
7
0.33
7
7
I-l
IO
-I
7
7
w
(C)
(c)
IL;
w
(c)
(8
ti)
(P)
$
(ia
(8)
1:;
l:;
W
(e)
60-63
k)
58-63
58-63
(e)
61-64
61-64
(e)
60-63
60-63
(e)
58-63
58-63
60-63
58-63
58-63
(a
58-63
58-63
60-6-I
58-63
60 mm(d)
60-63
60-63
(a) Reheatedat79O”C( 1150”F),quenched incaustic. temperedat 150”C(30O”F~. tb~Transferrrd~o neutralsalt at 79O’C( 1450°F).qurnchedincaustic,
temperedat I75 “C(350
“F). (c)Tempered at I65 “C (325 “Ft. (d) Or equivalent. te) File-hard. (0 Tempered at 205 “C (400 “F). tg) Reheated at 8-U OC( I SSO“FJ. quenched in salt al I75 “C (350 “F). (h)
Reheatedat775”C( 1325”F).quenched insaltat 19S”Ct380°Ft.(i)Quencheddirectl~
insaltar 17S”Ct3SO”Ft.tj)Temprredat
16s 0C~3250F)andtreatedat-850C(-1300Ft
Guidelines
Liquid
Operating
Carburizing
Characteristics
The case produced is comparable to one obtained in gas carburizing in
an atmosphere containing
some ammonia. In addition, cycle times are
shorter because heat up is faster, due to the excellent heat transfer characteristics of the salt bath solution.
Operating
Information
Most of these baths contain cyanide. Both nitrogen and carbon are
introduced into the case. A noncyanide process uses a special grade of
carbon, rather than cyanide, as the source of carbon. These cases contain
only carbon as the hardening agent.
Low-temperature
(for fight cases) and high-temperature
(for deep cases),
cyanide-containing
carburizing baths are available. In addition to operating
temperatures, cycle times can also be different.
Low-Temperature
Baths. Typical
operating
temperatures
range
from 845 to 900 “C (1555 to 1650 “F). Baths generally are of the accelerated cyanogen type. Operating compositions of liquid carburizing baths are
listed in an adjoining Table. Baths usually are operated with a protective
carbon cover. Cases that are 0. I3 to 0.25 mm (0.005 to 0.010 in,) deep
contain substantial amounts of nitrogen.
High-Temperature
Baths. Operating temperatures usually are in the
range of 900 to 955 “C (1650 to 1750 “F). Rapid carbon penetration may
be obtained at operating temperatures between 980 and 1040 “C ( I795 to
1905 “F). Cases range from 0.5 to 3.0 mm (0.020 to 0. I20 in.) deep. The
most important application of this process is for the rapid development of
cases I to 2 mm (0.040 to 0.080 in.) deep. These baths contain cyanide and
a major amount of barium chloride (see Tablej.
Applications
Typical applications
an adjoining Table.
of liquid carburizing
Noncyanide
Liquid
in cyanide
baths are listed in
Carburizing
A specirll grade of carbon is used in place of cyanide as the source for
carbon. Carbon particles are dispersed in the molten salt by mechanical
agitation with one or more simple propeller stirrers. The chemical reaction
is thought to be adsorption of carbon monoxide on carbon particles. Carbon
monoxide is generated by a reaction between carbon and carbonates in the
salt bath. Carbon monoxide is presumed to react with steel surfaces in a
manner similar to that in pack carburizing.
Operating
Information
Operating temperatures usually are higher than those for cyanide-type
baths. The common range is about 900 to 955 “C ( I650 to I750 “F). Case
depths and carbon gradients are in the same range as those for hightemperature, cyanide-type
salts. Carbon content is slightly lower than that
of standard carburizing baths containing cyanide.
Cyaniding
Operating
(Liquid
Constituent
for the Heat Treatment
Compositions
of Liquid
of Steel / 53
Carburizing
Baths
Composition ofbath, %
Light case, Deep case,
low temperature
high temperature
8.l~900°C (1550-16SO“F)
9oo-95S°C (16-W175oT)
IO-23
Sodiumcyanide
6-16
Barium chloride
30-55(a)
Salts ofother alkaline
O-IO
O-IO
earth met&t h)
Potassium chloride
O-25
O-20
Sodium chlonde
‘O-40
O-20
30 max
Sodium carbonate
30 max
Accelerators other than
O-5
o-2
those in\olvingcompounds of alkaline
earth metals(c)
0.5 milx
Sodium cyanate
I .Oniax
Den.@ of molten salt I .76 g/crdat 900 “C tO.0636 2.00 gkm’at 92s “C (0.0723
Ih/in.‘at 1650°F)
Ib/in.‘at 1700°F)
(a) Proprietary barium chloride-free deep-case baths are available. (b) Calcium and
strontium chlorides ha\e hecn employed. Calcium chloride is more effective, but its
hyqoscopic nature has limited its use.(c) Among theseacceleratorsare manganesedioxtde. boron oxide, sodium fluoride, and sodium pyrophosphate.
Effect of Sodium Cyanide
in 1020 Steel Bars
Concentration
on Case Depth
Samples are 25.4 mm diam (1 .O in. diam) bars that were cyanided
minat815”C(1500”F).
NaCN in
bath, 96
mm
ill.
9-l.3
76.0
SO8
-13.0
30.2
20.8
15.1
10.8
52
0 IS
0.18
0.15
0.15
0.15
0.14
0.13
0.10
0.05
0.0060
0.0070
0.0060
0.0060
0.0060
0.0055
0.0050
0.0040
0.0020
30
Deptb of case
Faster carbon penetration is obtained by using operating temperatures
above 950 “C (I 730 “Ft. Nancy anide baths are not adversely affected at
this temperature because no cyanide is present to break down and cause
carbon scum or frothing.
Parts quenched after treatment contain less
retained austenite than those quenched following cyanide carburization.
Carbonitriding)
Information
In this instance, sodium cyanide is used instead of the more espensive
potassium cyanide. The active hardening agents (carbon monoxide and
nitrogen) are produced directly from sodium cyanide.
A sodium cyanide mixture such as grade 30 (containing
30 percent
NaCN, -IO percent Na2C.03. and 30 percent NaCI) generally is the choice
for production applications (see Table shorn ing compositionsj.
A 30 percent cyanide bath operating at 8 IS to 850 “C ( IS00 to IS60 “F) produces a
0. I3 mm (0.005 in.) case containing 0.65 percent carbon at the surface in
54 / Heat Treater’s
Guide
45 min. Similar
case depths can be obtained with sodium cyanide in
treating 1020 steel. The effect of sodium cyanide on case depth in treating
the steel is in an adjoining Table.
brine. The case contains less carbon and more nitrogen
oped in liquid carburizing.
Applications
Reference
A fde hard, wear-resistant surface is produced on ferrous parts. The hard
case is produced in quenching in mineral oil, paraffin-base oils, water, or
I. ASM Metals Handbook, Heat Treating, Vol4.
tional. 1991, p 329
Vacuum
in a
then
Characteristics
Benefits of the process include:
l
l
Excellent uniformity
and repeatability
due to the degree of process
control inherent in the process
Improved mechanical properties due to a lack of intergranular oxidation
Reduced cycle times due to higher processing temperatures
A continuous
10th ed., ASM Intema-
Carburizing
In this process, steel is austenitized in a rough vacuum, carburized
partial pressure of hydrocarbon
gas, diffused in a rough vacuum,
quenched in oil or gas, Ref I.
l
than those devel-
ceramic
vacuum-carburizing
furnace
Operating
Information
A continuous vacuum carburizing
furnace is pictured in an adjoining
Figure. Furnaces usually are designed for vacuum carburizing.
with or
without vacuum quenching capability. Controls and plumbing are modified
to accommodate the process.
Heat and Soak Step. Steel is fust heated to the desired carburizing
temperature (typically
in the range of 845 to 1040 “C (1555 to 1905 “F).
Soaking follows at that temperature, but only long enough to get temperature uniformity
throughout the part.
In this step, surface oxidation must be prevented, and any surface oxides
present must be reduced. In a graphite-lined
heating chamber with graphite
Guidelines
for the Heat Treatment
Comparison of Time Required to Obtain a 0.9 mm (0.035 in.) and 1.3 mm (0.050 in.) Effective
8820 Steel at Carburizing
Temperatures
of 900 “C (1850 “F) and 1040 “C (1900 “F)
Carburizing
temperature
Effective depth
mm
in.
0.9
0.035
1.3
0.050
T
900
I040
900
1040
OF
lkatiog to
carburizing
temperature
1650
1900
1650
1900
78
90
78
90
smkiog
prior to
carburizing
Boost
45
30
45
30
Time, mio
Gas quench
toHoT
Diffusion
(ItWOoF)
101
1s
206
31
83
23
169
46
of Steel / 55
Case Depth in an AISI
Reheat to
845 oc
(1550°F)
soak at
845T
(155OV)
oil
quench
Total
(a)
22
(a)
22
(a)
60
(a)
60
1s
1s
15
I5
>322
275
>s13
314
(3)
20
(Jo
20
(a) Not available
heating elements, for example, a rough vacuum in the range of 13 to 40 Pa
(0. I to 0.3 torr) usually is satisfactory.
Boost Step. The result here is carbon absorption by the austenite to the
limit of carbon solubility in austenite at the processing temperature for the
steel being treated. The operation in this instance is backfilling
the vacuum
chamber to a partial pressure with either a pure hydrocarbon gas, such as
methane or propane, or a mixture of hydrocarbon gases.
A minimum partial pressure of the gas is needed to ensure rapid carburizing of the austenite. Minimum
partial pressure varies with carburizing
temperature, gas composition,
and furnace construction.
‘Qpical partial
pressures vary between I .3 and 6.6 kPa ( IO to 50 torr) in furnaces of
graphite construction
and I3 to 25 kPa ( 100 to 200 [err) in furnaces of
ceramic construction.
Diffusion Step. In this instance, carbon is diffused inward from the
carburized surface, resulting in a lower surface carbon content (relative to
the limit of carbon solubility
in austenite at the carburizing temperature)
and a more gradual case/core transition.
Diffusion
usually is in a rough
vacuum of 67 to I35 Pa (0.5 to I .O torr) at the carburizing
temperature.
Oil Quenching Step. Steel is directly quenched in oil, usually under
a partial pressure of nitrogen.
When temperatures are higher than those in conventional
atmosphere
carburizing. requirements usually call for cooling to a lower temperature
and stabilizing at that temperature prior to quenching.
If a reheating step is needed for grain refinement,
the steel is gas
quenched from the diffusion
temperature to room temperature, usually
under partial pressure of nitrogen. Reheating usually consists of austenitizing in the range of 790 to 845 “C (1455 to 1555 “F), followed by oil
quenching.
Plasma
(Ion)
Characteristics
The process has several advantages
ing:
l
l
l
l
l
l
Gas Circulation.
For uniform
case depths the chief re-
are:
Temperature uniformity
of +8 “C (fl4 “F) or better
Uniform circulation of carburizing gas
High-Temperature
Vacuum
Carburizing
Typical atmosphere furnace construction generally limits maximum carburizing temperatures to about 955 “C (1750 “F). Vacuum furnaces permit
higher carburizing
temperatures,
14ith correspondingly
reduced cycle
times.
The process can significantly
reduce overall cycle times required to get
effective case depths in excess of 0.9 to I .O mm (0.030 to 0.040 in.). There
is no advantage for lower case depths. In an adjoining Table, the times
needed to get 0.9 to I .O mm (0.030 to 0.040 in.) case depths with vacuum
carburizing at 900 “C (I650 “F) and 1040 “C (1905 “F) for an AISI 8620
steel are compared.
Applications
The process is well suited to process the more highly alloyed, highperformance
grades of carburizing
steels and the moderately
alloyed
grades being used. Gas pressure quenching in vacuum opens up opportunities for treating high-performance,
low distortion gearing.
Reference
I. ASM Metals Handbook, Hear Treating, Vol 4, 10th ed.. ASM
tional, 1991. p 3-18
Intema-
Carburizing
This is basically a vacuum process utilizing glow discharge technology
to introduce carbon bearing ions to steel surfaces for subsequent diffusion
below the surfaces, Ref I.
l
Carburizing
quirements
Higher carburizing rates
Higher operating temperatures
Improved case uniformity
Blind hole penetration
Insensitivity
lo steel composition
over gas and atmosphere
carburiz-
Carburizing
rates are higher because the process involves several steps
in the dissociation process that produce active soluble carbon. With methane, for example, active carbon can be formed due to the ionizing effect of
the plasma. Carburizing
rates of plasma and atmosphere carburizing
are
compared in an adjoining Figure. Note that the results obtained in atrnosphere carburizing for 240 min at 900 “C (1650 “F) were obtained with the
plasma process in half the time.
In some applications,
higher temperatures are permissible because the
process takes place in an oxygen-free
vacuum.
Improvements
in unifomlity
of case depth in gear tooth profiles are
shown in an adjoining Figure. Results obtained with the plasma process at
980 “C (I795 “F) and those obtained \sith atmosphere carburizing at the
same temperature are compared.
56 / Heat Treater’s
Guide
Carbon concentration profiles in AISI 1020 steel after ion carburizing for 10,20,30,60, and 120 min at 900 “C (1650 “F).
Carbon profile after atmosphere carburizing
(1650 “F) shown for comparison
Production installation
for 240 min at 900 “C
Comparing uniformity of case depth over gear-tooth profiles.
(a) Ion carbunked at 980 “C (1800
in a 980 “C (1800 “F) boost-diffuse
its more consistency, particularly
Courtesy of Surface Combustion,
“F). (b) Atmosphere carburized
cycle. Case depth in (a) exhibin the root of the gear profile.
Inc.
of two dual-chamber ion carburizing furnaces. Courtesy of Surface Combustion,
Inc.
Guidelines
Racked array of universal-joint
Courtesy
components ready for ion carburizing. Two stacked
fixtures
for the Heat Treatment
constitute
one furnace
of Steel / 57
load of 1500 parts.
of Dana Corporation
Carbon concentration profiles in three carburizing steels after ion carburizing illustrating insensitivity to steel composition. Data are based on a boost-diffuse
cycle of ion catburizing
at
1040 “C (1900 “F) for 10 min followed
1000°C (1830°F).
by diffusion
for 30 min at
1
The ion carburizing
rate for a given steel is quite insensitive to alloy
composition, as shown in an adjoining Figure. The process is also insensitive to the hydrocarbon gas used as a source of carbon.
A two-chamber ion carburizing furnace is shown in an adjoining Figure.
As in other carburizing processes, time and temperature are the parameters that determine surface carbon and case depth. Temperature, and indirectly time, dcterrnine grain size and mechanical properties. Higher operation temperatures are used to speed up diffusion rates.
After a time/temperature
cycle is established, operating pressure is chosen, which can be any value. provided the plasma covers the parts and no
hollow cathode effect is evident; a low pressure usually is chosen, in the
range of 130 to 670 Pa (I to 5 torr). Optimum uniformity
in carburizing is
obtained in this range.
The gas may be any hydrocarbon. The simplest and most commonly used
is CHJ (methane). Propane (C3Hs) is also used.
To be successhtl in plasma carburizing,
the plasma envelope must
surround the parts, meaning that parts must be finned.
or positioned so
that they do not touch each other (see Figure). In the figure universal joint
components
are stacked in layers separated by a woven wire screen
between layers.
Applications
The range of applications
includes
1020, 1521, and 8620 steels.
Reference
I. ASM Metals Handbook,
tional, 1991. p 353
Heat Treating,
Vol 4. 10th ed., ASM
Intema-
58 / Heat Treater’s
Guide
Carbonitriding
This is a modified form ofgas carburizing. rather than a form of nitriding.
The modification:
ammonia is combined with the gas carburizing atmosphere to add nitrogen to the carbutized case as it is being produced. Nascent
nitrogen is at the work surfaces. Ammonia dissociates in the furnace
atmosphere: nitrogen diffuses into the steel simultaneously
with carbon.
Ref I.
Characteristics
Carbonitriding
is similar to liquid cyaniding in terms of its effects on
steel. The process is often substituted for liquid cyaniding
because of
problems in the disposal of cyanide-bearing
water. Case characteristics
of
carburized and nitrided parts are also different; carburized cases normally
Effect of Material/Variables
Formation in Carbonitrided
hlaterial/processing
variables(a)
Tempenture increase
Longer cycles
Highercase nitrogen levels
Higher case carbon levels
Alumintu~-killed steel
tncrcased alloy content of steel
Severe prior cold working of material
Ammonia addition during heat-up cycle
on the Possibility
Cases
of Void
do not contain nitrogen, and nitrided cases are primarily
nitrogen, while
carbonitrided cases contain both carbon and nitrogen.
Ability to produce hard, wear-resistant cases, which are generally in the
range of 0.075 to 0.75 mm (0.003 to 0.030 in.), is the typical reason for
selecting this process. Cases have better hardenability
than carburized
types (nitrogen increases the hardenability
of steel); nitrogen is also an
austenite stabilizer. and high nitrogen levels can result in retained austenite.
particularly
in alloy steels.
Economies can be realized with carbonitriding
and quenching in the
production of hard cases within a specific case depth range and for either
carbon or low-alloy
steel. With oil quenching, full hardness with less
distortion can be obtained, or in some cases, with gas quenching, using a
protective atmosphere as the quenching medium.
Another plus: carburizing and carbonitriding
often are combined to get
deeper case depths and better performance in service than are possible with
carbonitriding
alone.
Operating
Possibility
of void
formation
Increased
Increased
Increased
increased
Increased
DeWXsed
Increased
Increased
Information
Industrial practice for time and temperature is indicated in an adjoining
Figure. which shows the effects of time and temperature on effective depth
(as opposed to total case depth).
Effects of total furnace time on the case depth of 1020 steel is shown in
adjoining Figure (a). Specimens were heated to 705.760,815.
and 870 “C
Results of a survey of industrial practice regarding effects of
time and temperature
on effective case depth of carbonitrided cases
(a) All other variables heldconstant
Effects of temperature and of duration of carbonitriding
on
effective case depth. Both sets of data were obtained
in the
same plant. Note that upper graph (for 1020 steel) is in terms of total furnace time, whereas
bottom graph (for 1112 steel) is for 15
min at temperature.
End-quench
hardenability
curve for 1020 steel carbonitrided
at 900 “C (1650 OF) compared with curve for the same steel
carburized
at 925 “C (1700 “F). Hardness was measured along
the surface of the as-quenched
hardenability
specimen.
Ammonia and methane contents
of the inlet carbonitriding
atmosphere
were 5%; balance, carrier gas.
Guidelines
Typical
Applications
and Production
Cycles
for the Heat Treatment
of Steel / 59
For Carbonitriding
Part
Steel
Case depth
mm
0.001 in.
Furnace temperature
T
OF
Carhoo steels
Adjusting yoke, 25 hy 9.5 mm ( I by 0.37 in. j
Bearing block,64 by 32 by 3.2 mm (2.5 by I.3 by 0.13 in.)
Cam. 2.3 by 57 by 64 mm (0. I bj 2.25 hy 2.5 in.)
cup. I3 g (0.4602)
Distributordriveshaft. I25 mmOD by 127 mm (5 by 5 in.)
Gear,-U.Smmdiamby3.2mm(l.75by0.l2Sio.)
Hex nut. 60.3 hy 9.5 mm (2.4 b] 0.37 in.)
Hood-latch bracket, 6.1 mm diam (0.25 in.)
Link 2 hy 38 by 38 mm (0.079 hy I .S b> I.5 in.)
hlandrel, 40 g ( I .AI 02)
Paper-cutting tool, 4 IO mm long
Segment 2.3 hy 44.5 hy 44.5 mm (0.09 by I.75 by I .7S tn.)
Shaft. 1.7 mm diam hy IS9 mm (0. I9 bj 6.25 in.)
shiftcollar,s9g(2.loz)
Slidingspurgear,66.7mmOD(2.625
in.)
Spring pin, 14.3 mmOD by I l4mm(O.S6 by-l.5 in.j
Spur pinion shaft. II .3 mm OD (I ,625 in.)
Transmission shift fork. I27 hy 76 mm (5 by 3 in.)
1020
1010
1010
101s
1015
1213(h)
1030
1015
1022
III7
1117
1010
1213(b,
III8
1018
1030
1018
1040
0.05-O. IS
0.05-O. I5
0.38-0.45
0.08-o. I3
0. IS-O.25
0.30-0.38
0. IS-O.25
0.05-0.1.5
0.30-0.38
0.20-0.30
-0.7s
0.28-0.45
0.30-0.38
0.30-0.36
0.38-0.50
0 25-0.50
0.38-0.50
0.25-0.50
2-6
2-b
IS-18
3-s
6-10
12-15
6-10
2-6
11-15
8-l’
-30
15-18
12-15
12-l-l
15-20
IO-20
IS-20
I O-20
775 and 715
775 and 7-lj
855
790
8lSand7-15
855
815and745
775 and 745
855
845
1125and 1375
1125 and I375
IS75
I150
I SO0and I375
I575
IS00 and I375
I-I?i and I375
IS15
IS50
855
815
77s
870
815and7-15
870
815and7-15
I S75
I.500
I-130
1600
IS00 and I375
I600
I500 and I375
Alloy steels
Helical gear, 82 mm OD (3.23 in.)
Input sti
I.2 kg (2.6 lb)
Pinion gear. 0.2 kg (O.-U lb)
Ring gear, 0.9 kg (2 lb)
Segment I .4 hy 83 mm (0.OS.Tby 3 17 in.j
Spur pinion shaft. 63.5 mm OD by 203 mm (2.S by 8 in.)
Stationary gear plate, 0.32 kg (0.7 Ihj
Transmission main shaft sleeve, 38 mm OD by 25 mm (I .S by 2 in.)
Transmission main shaft washer, 57 mm OD b! 6.4 mm (2.25 b> 0.25 in.)
8617H
5140
4017
1047
8617
5 I40H
5110
8622
8620
0.50-0.7s
0.30-0.3s
0.30-0.3s
0.20-0.30
0. IX-0.2s
0.0.5-0.20
0.30-O 35
0. I s-0.25
0.25-0.50
20-30
12-14
12-11
8-10
7-10
2-8
12-l-l
6-10
IO-20
845
775
77s
760
815
845
775
8I5and715
8lSand715
IS50
I430
l-130
l-m0
1500
1550
I430
I SO0and I375
15OOand 1375
Total time
in Furnace
Quench
64min
@mitt
2’/?.h
‘/? h
108min
I v4 h
64min
&min
I ‘/? h
I ‘/z h
Oil
Oil
Oil
Oil
Gas(a)
Oil(c)
Oil
Oil
Oil
Oil
2h:fj
I44min
2 h(lI
I62 min
Oil
Gas(a)(d)
Oil(e)
Oil(g)
Oil
Oil(h)
GW)
6h(f)
Oil(g)
51/?h
5 ‘/2 h
9h
I 1/Zh
I MD
51/, h
108min
I62 min
Oil(e)
Oil(e)
Oil(i)
Ga.sW
Oil(j)
Oil(e)
Gt3.W
(a) Modifiedcarboniuidingatmosphere.
(b) Leaded. rc) Tempered at 190°C (375 “F). td)Temperedal 150°C (300 “FJ. (c)Tempered ;II 16.5“C (325 “F). (f Tiieat
(g)Oilatl50”C(300”F):temperedatlS0”C(300”~forIh.(h)oilatl50”C(,300”F)temper~dat76O”C(500”F)forIh.(i)Temprredatl75”C(350oF).(i)OilatISO”C(300
“F); tempered at 230 “C (150 “F) for 2 h. OD, outside diameter
Effect of ammonia additions on nitrogen content and formation
‘C(1695 “F) 0.13%
(c) 950 “C (1720 “F) 0.10% CO,
co,.
of subsurface
Gas(a)
temperature,
voids in foils. (a) 850 “C (1580 “F) 0.29% CO,. (b) 925
60 / Heat Treater’s Guide
(1300,1400,1500, and 1600 “F). An adjoining Figure(b) shows total case
depthsobtained with 1112steelheld at 15 min at temperaturesbetween750
and 900 “C (1380 and 1650 “F).
Depth of Case.
l
l
l
l
l
Casedepthsof 0.025 to 0.075 mm (0.001 to 0.003 in.) commonly areput
on thin parts requiring wear resistanceunder light loads.
Casedepthsup to 0.75 mm (0.030 in.) are applied to parts such ascams
for resistanceto high compressiveloads.
Casedepthsof 0.63 to 0.75 mm (0.025 to 0.030 in.) are applied to shafts
and gears subjectedto high tensile or compressive stresses,or contact
loads.
Medium-carbon steel with hardnessesof 40 to 45 HRC normally require
less casedepth than steelswith core hardnessesof 20 HRC or below.
Low-alloy steelswith medium-carbon content, i.e., those used in transmission gears for autos, often have minimum case depths of 0.2 mm
(0.008 in.).
Hardenability of Case. Case hardenability is significantly greater
when nitrogen is addedby carbonitriding than when the samesteel is only
carburized (seeFigure). This opensup the use of steelsthat could not have
uniform hardnessif they were only carburized and quenched.
When core properties are not important, carbon&riding permits the use
of low-carbon steelsthat cost less and may provide better machinability or
formability.
Because of the hardenability effect of nitrogen, the process makes it
possible to oil quench such steels as 1010, 1020, and 1113 to obtain
martensitic casestructures.
Void Formation. Casestructuresmay contain subsurfacevoids or porosity if processing conditions are not adjustedproperly (seeFigure). The
problem is related to excessiveammonia additions. Factorsthat contribute
to the problem are summarizedin an adjoining Table.
Furnaces. Almost any furnace suitable for gas carburizing can be
adaptedfor carbonitriding.
Atmospheresgenerally are a mixture of carrier gas, enriching gas, and
ammonia. Basically, the required atmospherecan be obtained by adding 2
to 12 percent ammonia to a standardgas-carburizing atmosphere.
Quenching. Whether parts are quenched in water, oil, or gas depends
on allowable distortion, metallurgical requirements,caseor core hardness,
and type of furnace used.
Tempering. Many shallow caseparts are used without tempering. Nitrogen in the caseincreasesresistanceto softening-the degreedepending
on the amount of nitrogen in the case.
Applications
Applications are more restricted than those for carburizing. The process
is largely limited to case depths of approximately 0.75 mm (0.03 in.).
Typical applications and production cycles for a number of steelsare listed
in an adjoining Table.
On the plus side, resistanceto softening during tempering is markedly
superior to that of a carburized surface. Other benefits include residual
stresspatterns,metallurgical structure, fatigue and impact strength at specific hardnesslevels, and the effects of alloy composition on caseand core
hardness characteristics. In many applications, properties equivalent to
those obtained in carburizing alloy steelscan be obtained with less expensive gradesof steel.
On the minus side, a carbonitrided caseusually contains more retained
austenite than a carburized caseof the samecarbon content. However, the
amount of retained austenite can be significantly reduced by cooling
quenchedparts to -40 to -100 “C (-40 to -150 “F).
P/M Applications. The processis widely usedin treating ferrous powder parts. Partsmay or may not be copper infiltrated prior to carbonitriding.
The processis effective in casehardening compactsmadeof electrolytic
powders which are difficult to harden by carburizing. To avoid such
problems,parts are treatedat 790 to 8 15 “C (1455 to 1500 “F). Lower rates
of diffusion at these temperaturespermit control of casedepth and allow
the buildup of adequate carbon in the case. The presence of nitrogen
provides sufficient hardenability to allow oil quenching.
File hard cases(with microhardness equivalent to 60 HRC) with predominately martensitic structurescan be consistently obtained.
Partsusually are temperedeven though there is little danger of cracking
untemperedpieces. However, there is a reasonfor tempering: it facilitates
tumbling and deburring operations.
Reference
1. ASM Metals Handbook, Heat Treating, Vo14, 10th ed., ASM Intemational, 1991,p 376
Gas Nitriding
In this process,nitrogen is introduced into the surface of a solid ferrous
alloy at a temperaturebelow AC] in contact with a nitrogen gas, usually
ammonia, Ref 1.
Nitriding downgradesthe corrosion resistanceof stainlesssteel because
of its chromium content. On the upside, surface hardnessis increasedand
resistanceto abrasion is improved.
Characteristics
Operating
A hard case is produced without quenching. Benefits of the process
include:
The nitriding temperaturefor all steelsis 495 to 565 “C (925 to 1050OF).
All hardenablesteelsmust be hardenedand temperedprior to nitriding.
The minimum tempering temperature usually is at least 30 “C (55 “F)
above the maximum nitriding temperature.
Either a single- or double-stageprocess may be used in nitriding with
anhydrous ammonia.
The operating temperatureof the single-stageprocessis in the range of
about 495 to 525 ‘C (925 to 975 “F). A brittle, nitrogen-rich layer, called
the white layer, is produced on the surfaceof the case.
Reducing white layer thicknessesis a benefit of the double-stageprocess-also called the Floe process.Nitriding applications for both processes
are listed in an adjoining Table. White layers produced in the single- and
double-stageprocessesare comparedin an adjoining Figure. Examples of
where nitriding eliminates production or service problems with parts case
hardenedby other methodsare found in an adjoining Table.
l
l
l
l
High surfacehardness
Improved resistanceto wear and galling
Improved fatigue life
Improved corrosion resistance(stainless steel is an exception)
In addition, distortion and deformation are less than they are in carburizing and other conventional hardening processes.Best results are obtained
with steels containing one or more of the nitride-forming alloying elements-aluminum, chromium, vanadium, tungsten, and molybdenum.
Other alloying elements such as nickel, copper, silicon, and manganese
have little, if any, effect on nitridmg characteristics.Alloys containing 0.85
to 1.50 percent aluminum yield the best results (seeTable).
Information
Guidelines
Hardness gradients and case depth relations for single-stage nitrided aluminum-containing
for the Heat Treatment
SAE 7140 steel
of Steel / 61
62 / Heat Treater’s
Nitriding
Guide
Applications
and Procedures
Part
Dimensions or weight of part
Single-stage nitriding
Hydraulic barrel
Trigger for pneumatic h-er
Governor push button
Tachometer shaft
Helical timing gear
Gear
Generator shaft
Rotor and pinion for pneumatic drill
Sleeve for pneumatic tool clutch
hlarine helical transmission gear
Oil-pump gear
Loom shuttle
Double-stage nitriding
Ring gear for helicopter main transmission
Aircraft cylinder barrel
Bushing
Cutter spindle
Plunger
CtXtlkShilft
Piston ring
Clutch
Double helical gear
Feed screw
Pumper plunger
Seal ring
Stop pin
Thrust collar
Wear ring
Clamp
Die
Gib
Spindle
Torque gear
Wedge
Pumper plunger
SOmtn(2in.jOD.
19mm(3/~in.jfD.
Steel
ISOmm(6in.jlong
Nitriding
time, h
6mm(‘/Iin.)diam
380mm(l5in.)long
205mm(8in.)OD(-t.Sk
or IOlb)
9 Ltin.)thick
50mm(2in.)OD.6mm(
25 mm (I in.) OD. 355 mm (14 in.) long
22 mm (7/8in.)diam
38 mm ( I ‘/J in.) diam
635 mm (3-Sin.) OD (227 kg or 500 lb)
SOmm(2in)OD. 180mmt7in.)long
I SOmm by 25 mm by 25 mm (6 in. by I in. by I in.)
AMS 6170
A hf.5 6-470
AMS 6-!70
AhlS 6-47s
-1140
-II-IO
-II-t0
-II-IO
4l-u)
-II42
1330
4lOstainless
230
380mm(lSin.)OD.3S0mm(l3.8in.)a),~mm(3.Sin.)long
180mnt(7in.)DD,305mmt,12in.)long
lOkg(23Ibj
3 kg(7 lb)
7Smm(3in.jOD.l52Smnt16Oin.)long
205 mm (8 in.) OD (journals). -I m (I3 ft) long
lSOmm(6in.)OD.4.2Sm(I-lti)long
I kg(2 lb)
50kg(l08lb)
4 kg (9 lb)
0.5 kg t I lb)
9.S kg (2 I Ihj
3 kg (7 lb)
3.6 kg(8 lb)
40kg(87lh)
7kg(l5Ib)
21 kg(A7lbj
IO kg(23 Ibj
I22 kg(270lb)
62Skg(l38Ib)
I8kg(Ilb)
I.lkg(3lb)
AhlS 6-170(a)
A MS 6470
AhlS 6170
AhlS 6470
AMS 6-t7s
-1130
3130
-II40
-II-l0
-11-M)
4l-tO
-1130
41-u)
11-M
-II40
1150
43u)
-t3Jtl
1330
J3-u)
-I340
-120stainless
60(b)
2
24
24
9
9
32
25
8
35(c)
90
4s
72
65
65
2
45
I27
90
2
90
2
2
90
42
127
Note: OD,outerdiameter; ID, innerdiameter. (a) Vacuum melted. (h)9 hat 525 “C (975 “F). 5 I hat S-t5 to SSO”C( 1015 to 1025 “F). (c)6 hat S’S “C(975 “Fj, 29hat S65 “C( 1050°F)
Examples of Parts for Which Nitriding
Requirements
Part
Proved Superior
to Other Case-hardening
Requirement
Gear
High-speed pinion (on gear motor)
Bushings (for conveyor rollers handling ahrasive alkaline material)
Spur gears (in train of power geats; IO-pitch.
tip modified)
Good wear surface and fatigue properties
Provide teeth with minimum (equivalent)
hardness of SOHRC
High surface hardness for abrasion
resistance; resistance to alkaline corrosion
Sustain continuous Hertz stress of 1035
klPa ( I50 ksi) (overload of I MO hlPa, or
275 ksi). continuous Lewis stress of 275
hlPa(40 ksijto\erloadof725
hlPa or
IO5 bij(c)
Processes
for Meeting
Material and process originally
used
Carhurized 33 IO steel 0.4 to 0.6 mm (0.017 to 0.02.5 in.) case
X620 steel gas carburized at 900 “C ( I650 OF)to 0.5 mm (0.02 in.) case, direct
quenched fmnt 815 “C ( 1550 “F), and tempered at 205 “C (300°F)
Carburized bushings
Carbutired AhlS 6260
Resultant problem
Gear
Good wear surface and fatigue properties
High-speed pinion (on gear motor)
Pro\ ide teeth with mintmunt (equivalent)
hardness of SOHRC
Difficulty in obtaining satisfactory
case to meet a reliability requirement
Distortion in teeth and bore caused
high rejection rate
Bushings (for comevorrollers
site alkaltne material)
handbngahra-
High surface hardness for abrasion
resistance; resistance to alkaline corrosion
Sen ice life of bushings was short
because of scoring
Spurgears(in trainof powergeats; IO-pitch,
tip modified)
Sustain continuous Hertz stress of 1035
hiPa t 150 ksij (overload of IS50 hIPa. or
235 ksi ). continuous Lea is stress of 275
hlPa (-IO hi) (overload of 72s hlPs or
IO.5ksij(c)
Gears failed because of inadequate
scuffreststartce. also suffered
property losses at high operating
temperatures
Solution
Ah1.86170substituted for33lOand
double-stage nitrided for 25 h
ll4Osteel. substituted for 8620, was
heat treated to 255 HB; parts were
rough machined tinish machined.
niuided(a)
Substitution of Nitralloy I35 type G
(resulfurired) heat treated to 269 HB
and nitrided(hj
Substitution of material of H I I type,
hardened and multiple tempered (3 h
+ 3 h) to 18 to 52 HRC, then doublestage nitrided(d)
(a) Single-stage nitrided at5 IO’C (950°F) for 38 h. Cost increased 55,. but rejection rate dropped to zero. (b) Single-stage ninidedat S 10°C (950°F) for 38 h. Casedepth wasO.-l6
mm (0.018 in.), and hardness was 94 HR IS-N: parts had three times the senice life of carburized parts tc) hlust withstand operating temperatures to 290°C (550 “Fj. (d) IS hat
5 IS “C (%O “F) ( IS to 25% dissociation); then 525 ‘C (980 “F) (80 to 83% dissociation). Effective case depth (IO 60 HRC). 0.29 to O.-l mm (0.010 to 0.015 in.): case hardness, 67
to 72 HRC (converted from Rockwell IS-N scale)
Guidelines
The fust stage of the double-stage process is the same as that for the
single-stage process, except for time (see Table). The operating tcmperature in the second stage may nc the same as that in the first stage, or it ma!
be increased from 550 to 565 “C ( IO20 to IO50 “F). The higher temperature
increases case depth.
Prior to nitriding. parts should be thoroughly
cleaned ttypicall>
mrith
vapor degreasing) after they are hardened and tempered.
Furnace Purging. After loading and sealing the furnace at the start of
the nitriding cycle. air must be purged from the retort before the furnace is
heated above IS0 ‘C (300 “F). Purging pre\.ents osidation of workpieces
and furnace components. When ammonia is the purging atmosphere, pur_ging avotds the production of a potentially
explosi\.c mixture. Nitrogen IS
the preferred quenching medium.
Under no circumstances should ammonia be introduced into a furnace
containing air at 330 ‘C (6X “F) because of the explosion hazard. Furnaces
should also be purged at the conclusion of the nitriding cycle. during the
cool-down
period. At this time. it is common practice to remobe an)
ammonia in the retort with nitrogen.
Emergency Purging. If the ammonia suppI is cut off during the
nitriding cycle or a suppI! line hreaks. air can be sucked into the fumncethe greatest danger is dunng the cooling cycle. The common safety measure is an emergency purging system that pumps dry rutrogen or an oxygenfree. generated gas and maintains a safe pressure.
Case Depth Control. Case depth and case hardness VW \\r;th the
duration of the nitriding cycle and other process conditions.
Hardness
Nominal Composition
Gas Nitrided
SAE
7140
Steel
AMS
6470
6475
Nitralloy
and Preliminary
C
hln
Si
G
135hI
0.35
0.42
0.55
0.55
N
EZ
0.2-l
0.35
0.55
0.80
0.30
0.30
0.30
0.30
(a) Sections up IO SO mm (2. in.) in diameter.
Microstructure
Heat-Treating
3.5
of Steel / 63
gradients and case depths obtained in treating SAE 7l-lO (AhlS 6470) as a
function of cycle time and nitriding conditions are indicated in an adjoining
Figure.
Equipment. Several designs are in common use, including the vertical
retort furnace (see Figure). bell bpe movable furnace, box furnace. and
tuhe retorts. hlost furnaces ‘are of the batch type.
Furnace fixtures are similar in design to those used in gas carburizing.
Ammonia and dissociated products can react chemically
with material in
retorts. fans. work baskets. and fixtures. Alloys containing a high percentage of nickel and chromium normally are used in furnace parts and fixtures
(see Table).
Ammonia Supply. Anhjdrous
liquid ammonia (refrigerator
grade.
99.98 percent NH? hy lbeight) is used.
Applications
The list of applications
l
l
l
l
l
includes:
Aluminum containing. low-alloy
steels (see Table)
Medium-carbon.
chromium-containing,
low-alloy
steels of the 4100.
-l300. 5 100.6 100, 8600. 8700. and 9800 series
Hot-work die steels containing 5 percent chromium. such as HI I. HI?.
and HI?
Lo)<-carbon. chromium-containing.
low-alloy steels of the 3300. 8600.
and 9300 series
Air-hardening
tool steels. such as A-2. A-6. D-2. D-3. and S-7
Cycles for Aluminum-Containing
Composition, W
Cr
Ni
1.2
1.6
1.15
I.15
for the Heat Treatment
hln
Al
0 20
0 38
O.?i
0.X
I .o
I.0
I .o
I .o
se
.:.
0.i)
Low-Alloy
Steels Commonly
Austenitizing
temperature(a)
T
OF
955
95s
900
9SS
I750
I7SO
1650
1750
Tempering
temperature(a)
T
OF
56570s
10.50-1300
56.5-70s
650-675
565-705
1050-1300
I X0- I250
IOSO-1300
quenched in oil: larger sections ma! bc mater quenched
of quenched and tempered 4140 steel after (a) gas nitriding for 24 h at 525 “C (975 “F) with 20 to 30% dissociation and
(b) gas nitriding for 5 h at 525 “C (975 “F) with 20 to 30% dissociation followed by a second stage of 20 h at 565 “C (1050 “F) with 75 to 80%
dissociation. Both specimens were oil quenched from 845 “C (1550 “F), tempered for 2 h at 620 “C (1150 “F), and surface activated with
manganese phosphate before nitriding. (a) Structure after single-stage nitriding 0.005 to 0.0075 mm (0.0002 to 0.0003 in.) white surface
layer (Fe,N), iron nitride, and tempered martensite. (b) The high second-stage dissociation caused absence of white layer, and the final
structure had a diffused nitride layer on a matrix of tempered martensite. Both 2% nital, 400x
64 / Heat Treater’s
Guide
Recommended
Materials
Nitriding Furnaces
for Parts and Fixtures
Materials are recommended on the basis of maximum
temperature of 565 “C (1050 “F).
in
operating
Vertical retort nitriding furnace. 1, gasket; 2, oil seal; 3, work
basket; 4, heating elements; 5, circulating fan; 6, thermocouple;
and 7, cooling assembly. At end of cycle, a valve is opened and
fan (not shown) incorporated in the external cooler circulates atmosphere through the water-jacketed cooling manifold.
Material
Wnwght
Part
Retorts(a)
FarIS
Tmys. baskets. fixtures
Thermocouple protection tube
l)ye 330; tnconel600
lype 330; lnconel6oo
Types 310.330; tnconel600
l)pe 330; Inconel600
cast
Not usually cast
3S- IS orequivalenl
3S- 1.Sorequivalent
Not usually cast
(a) Periodic inspection of austenitic stainless steel retorts is mandatory because ofembrittlement after long exposures to nitriding. Retorts of 18-8 stainless steel lined nith
high-temperature glass habe been used successfully.
l
l
l
l
l
High-speed steels, such as M-2 and M-4
Nitronic stainless steels, such as 30.40,50.
and 60
Ferritic and martensitic stainless steels of the 400 and SO0 series
Austenitic stainless steels in the 200 and 300 series
PH stainless steels, such as 13-8 PH. 15-5 PH. 17-7 PH. A-286, AM 350,
and AM 355
As stated previously, gas nitriding reduces the corrosion resistance of
stainless steels. However, all of these steels can be nitrided to some degree.
Prior to nitriding. some surface preparations unique to stainless steel are
necessary. Primarily,
the chromium oxide film that provides corrosion
protection must be removed by such processes as dry honing, wet blasting,
and pickling. The treatment must precede placing workpieces
into the
furnace. In addition, all parts must be perfectly clean and free of embedded
foreign particles.
Special nitriding processes include pressure nitriding, bright nitriding, pack nitriding, ion (plasma) nitriding, and vacuum nitrocarburizing.
Liquid
Reference
I. ASM Metals Handbook, Heat Treating, Vol 4. 10th ed.. ASM
tional. 1991, p 387
Intema-
Nitriding
Processing takes place in a molten salt bath at the gas nitriding operating
temperature-5
IO to 580 “C (950 to 1075 “F). The case hardening medium
is a molten, nitrogen-bearing,
fused-salt bath containing either cyanides or
cyanates. Ref I.
salts. Cyanide-free
salt compositions
are available. They have gained wide
acceptance within the heat-treating industry because they contribute substantially to the alleviation of a potential source of pollution.
Characteristics
Bath compositions
are similar to those in liquid carburizing
and cyaniding. However, liquid cyaniding has an operating temperature lower
than the critical transformation
temperature. This means it is possible to
treat finished parts because dimensional
stability can be maintained in
liquid carburizing.
The process also improves surface hear resistance and the endurance
limit in fatigue. Also, the corrosion resistance of many steels is improved.
Generally, the process is not suitable where applications require deep cases
and hardened cores.
Gas nitriding and liquid nitriding have common applications. Gas nitriding may have the edge where heavier case depths and dependable stopoffs
are specified. Four examples of conversions from other processes to liquid
nitriding are summarized in an adjoining Table.
The process has become the generic term for a number of different fusedsalt bath processes, all of which are carried out at the subcritical transformation temperature. The basic processes are identified
in an adjoining
Table. A typical commercial
bath is a mixture of sodium and potassium
Results of liquid pressure nitriding on type 410 stainless steel
$c;xxition.
O.l2C-0.45Mn-0.41
Ni-11.900;
core hardness,
24
Guidelines
Automotive Parts for Which Liquid
Service Requirements
Component
Nitriding
Requirement
Proved Superior
Materialand
pmcess originally
to Other Case-Hardening
used
Processes
Wthstand thrust load without
galling and deformation
Bronze, carbonitrided
shafl
Resist wear on splines and bearing
area
Induction
Seat bracket
Resist wear on surface
1020 steel, cyanide treated
Distortion; high loss in
straightening(b)
Rocker arm shaft
Resist water on surface; maintain
w-try
SAE 1045 steel, rough ground,
induction hardened straightened,
finish ground, phosphate coated
Costly operations
1010 steel
Bronze galled, deformed;
Warped
harden through areas
Required costly inspection
increase incost. (b)Also.
Nitrogen gradients in 1015 steal as a function of time of nitriding at 565 “C (1050 “F), using the aerated bath process
steel
brittleness.
and material
(c) Resulted in lessdistortionand
of Steel / 65
for Meeting
Solution
Resultant problem
Thrust washer
(a)Resultedin
improved product performanceandextended
life, withno
loss.(d) Eliminated finish grinding. phosphatizing. and straightening
for the Heat Treatment
101Osteelnitrided9Ominin
cyanide-cyanate
bath at 570 “C
( 1060 OF) and water quenched(a)
Nitride for 90 min in cyanidecyanate salt bath at 570 “C ( 1060
“F)
1020 nitrided 90 min in cyanidecyanate salt bath and water
quenched(c)
SAE I01 0 steel liquid-nibided
90
min in low-cyanide fused salt at
570to580”C(
106Oto 1075 “F)(d)
briflleness.andeliminationofsc7ap
Depth of case for several chromium-containing
low-alloy
steels, aluminum-containing
steels, and tool steels after liquid nitriding in a conventional salt bath at 525 “C (975 “F) for
upto70h
Nitrided case and diffusion zone produced by cyanide-cyanate liquid nitriding. The characteristic
needle structure
is
seen only after a 300 “C (570 “F) aging treatment.
Liquid nittiding processes include liquid pressure nitriding. aerated bath
nitriding, and aerated, low-cyanide
nitriding.
Results in liquid pressure nitriding type 410 stainless steel are found in
an adjoining
Figure.
Results in aerated salt bath nittiding a 1015 steel part are shown in an
adjoining Figure.
A nitrided case and diffusion zone obtained in cyanide-cyanate
liquid
nittiding are shown in an adjoining Figure.
Operating
Important
l
l
Information
procedures
include:
Initial preparation and heating of the salt bath
Aging of molten salts, when required
66 / Heat Treater’s
l
Analysis
Guide
and maintenance
of baths
practically all steels must be quenched and tempered for core properties
before nitrided or stress relieved for distortion.
Prior heat treatment requirements are similar to those for gas nitriding.
Parts are hardened prior to nitriding. Tempering temperatures should be no
lower than the nitriding temperature, and preferably, slightly higher.
Liquid
Nitriding
Starting Baths. Baths basically are sodium and potassium cyanides,
or sodium and potassium cyanates. Cyanide, the active ingredient, is
oxidized to cyanate by aging. The commercial
salt mixture of 60 to 70
percent sodium salts and 30 to 40 percent potassium salts is melted at 540
to 595 “C (1000 to I IO5 OF). During melting, a cover should be placed over
the retort to guard against spattering or explosion of the salt, unless
Processes
Suggested
Process ideotilication
Aerated cyanidecyanate
Casing salf
Pressure nitriding
Regenerated cyanate-carInmate
Operating range composition
Sodium cyanide (NaCN), pokssium cyanide (KCN)
and potassium cyanate (KCNO). sodium cyanate
(NaCNO)
Potassium cyanide (KCN) or sodium cyanide (NaCN).
sodium cyanate (NaCNO) or potassium sqana~e
(KCNO). or mixtures
Sodium cyanide (NaCN). sodium cyanate (NsCNO)
potassium
m A: Potassium cyanate (KCNO).
carbonate (K,CO,)
l)pc B: Potassium cyanate (KCNO), potassium
carbonale(K2C0,). I-10ppm,sulFur(S)
Chemical
nature
post
treatment
Operating temperature
T
OF
U.S. patent
number
Strongly reducing
Water or oil quench;
nitrogen cool
570
1060
Strongly reducing
Water or oil quench
s I O-650
95O- I200
Strongly reducing
Mildly oxidizing
Aircool
Water, oil. or salt quench
525.565
580
975-1050
1075
4.019.928
Mildly oxidizing
Water. oil quench, or salt
quench
S-IO-575
Iwo-1070
4006,643
3.208.885
Hardness gradients for several alloy and tool steels nitrided in salt by the liquid pressure process. Rockwell C hardness values are
zonvetted from Knoop hardness measurements made using a 500 g load. Temperatures are nitriding temperatures.
Guidelines
for the Heat Treatment
of Steel / 67
equipment is completely
hooded and vented. Salts must be dry before
placing them in the retort; entrapped moisture can cause eruption when the
salt is heated. Baths are heated internally or externally.
Bath Maintenance. All work placed in the bath should be thoroughly
cleaned and free of surface oxide. Either acid pickling or abrasive cleaning
prior to nitriding is recommended. Finished parts should be preheated prior
to immersion in the bath to rid them of surface moisture.
Safety. Compounds containing sodium cyanide or potassium cyanide
or both can be handled safely with the proper equipment and must be
neutralized by chemical means before discharge. These compounds are
highly toxic. Great care should be taken to avoid taking them internally. or
aUowing them to be absorbed through skin abrasions. Another hazard is
caused by contact between the compounds and mineral acids. Hydrogen
cyanide gas, an extremely toxic producl, is produced. Exposure can be fatal.
Equipment. Salt bath furnaces may be heated by gas. oil, or electricity.
and essentially are similar in design to furnaces used in other processes. Batch
furnaces are the most common, but continuous operations are feasible.
up to 70 h. Effective cyanide content of the bath was 30 to 35 percent and
cyanate content was IS to 20 percent. Before being nitrided. all parts were
tempered to the core hardnesses indicated in the Figure previously cited.
Steels treated included three chromium-containing,
low-alloy steels (4140,
3310, and 6 150); tuo aluminum-containing
nitriding steels (SAE 7 I40 and
6475); and four tool steels (HI I, H 12. h450, and D2).
An adjoining Figure presents data on core hardnesses obtained in liquid
pressure nitriding several alloy and tool steels: SAE 7140. AMS 6475,
4l-tO. 4310; and medium carbon HI I, HIS, and MSO. In this instance, case
depths and hardnesses are comparable to those obtained in single-stage gas
nitriding.
In treating high-speed steel cutting tools with liquid nitriding, cases have
a lower nitrogen content and are more ductile than those produced in gas
nitriding.
Applications
I. .LWt Mcvals Handbook,
tional. 1991, p-110
Reference
Hem Trrmting,
Vol 4, 10th ed., ASM Intema-
Data in an adjoining Figure show depth of case obtained in a number of
steels treated in a conventional
liquid nitriding bath at S2S “C (975 ‘F) for
Plasma
(Ion)
Nitriding
In this vacuum process, nascent (elemental) nitrogen is introduced to the
surfaces of workpieces
for subsequent diffusion
into the metal. High
voltage electrical energy forms a plasma through which nitrogen atoms are
accelerated to impinge on workpieces. Ion bombardment heats workpieces,
cleans surfaces, and provides active nitrogen (Ref I).
Compound layer of y’ (Fe,N) on the ion-nitrided surface of
quenched and tempered 4140 steel. The y ’ compound layer is
supported by a diffused case, which is not observable
crograph. Nital etched. 500x
in this mi-
Characteristics
The process, in comparison with conventional
gas nitriding. provides
more precise control of nitrogen supply at the workpiece surface. Another
advantage: ability to select either an epsilon (E) or gamma (y) monophase
layer, or prevent white layer formation entirely. A compound layer on
quenched and tempered -II30 is shown in an adjoining Figure. The diffusion zone in type 416 stainless steel is shown in another Figure A third
Figure shows typical gas compositions and resulting metallurgical configu-
Observable diffusion zone on the unetched (white) portion of
an ion-nitrided 416 stainless steel. Nital etched. 500x
68 / Heat Treater’s
Guide
rations. The process is replacing carbonitriding
for better dimensional
control and the reduction or elimination
of machining after heat treating.
Operating
Information
A typical ion nitriding vessel is depicted in an adjoining Figure. Operating temperatures are in the range of 375 to 650 ‘C (705 to 1200 “F). At the
lower temperacure, the amount of residual stress relief is minimized.
Because loads are gas cooled. they do not experience distortion
from
temperature gradients or from martensitic formation.
After work is heated to the desired temperature, process gas is admitted
at a flow rate determined by the load surface area. Pressure is regulated in
the I to IO torr range by a control valve just upstre‘am from the vacuum
pump. Process gas is normally
a mixture of nitrogen. hydrogen, and
occasionally, small amounts of methane.
Cooling is by backfilling
with nitrogen or other inert gases, and by
recirculating
the gas from the load to a cold surface, such as a cold wall.
Prior microst.rucNre can influence response to nitriding. For alloy steels,
a quenched and tempered strucNre is believed to get optimum results.
Tempering temperatures should be IS to 25 “C (25 to 45 “F) higher than
the anticipated nitriding temperature to minimize further tempering of the
core during the nitriding process.
Hardness profiles for typical ion nitrided alloys are shown in an adjoining Figure.
Applications
Response to ion nitriding depends heavily on the presence of strong.
nitride-forming
elements. Plain carbon steels can be treated. but cases
aren’t significantly
harder than the cores.
Steels in the Nitralloy series with about I percent aluminum and I to I.5
percent chromium are the premier applications. Other suitable applications
include:
l
Chromium-bearing
alloys,
ie., 4 100, 4300, 5 100, 6100, 8600, X700,
9300, and 9800 series
l
l
l
Most tool and die steels, stainless steels, and PH alloys
P/M parts (due to porosity, cleaning is a critical requirement)
Cast iron wear parts
Typical ion-nitriding
vessel
Gears, crankshafts,
applications.
cylinder
liners. and pistons are regarded as excellent
Reference
I. ASM Merals Handbook, Hear Treating, Vol 4. 10th ed., ASM
tional, 1991, p 120
lntema-
Hardness profile for various ion-nitrided
materials.
1, gray
cast iron; 2, ductile cast iron; 3, AISI 1040; 4, carburizing
steel; 5,
low-alloy
steel; 6, nitriding steel; 7,5% Cr hot-work steel; 8, coldworked die steel; 9, ferritic stainless
steel; 10, AISI 420 stainless
steel; 11, 18-8 stainless steel
Guidelines
Typical gas compositions
Gaseous
and the resulting metallurgical
and Plasma
configurations
(Both Processes)
Improving resistance to scuffing is a common benefit of the compound
layer produced with these processes. In addition, fatigue properties are
Plasma nitrocarburizing
installation
of Steel / 69
steel
Nitrocarburizing
In the gaseous process, carbon and nitrogen are introduced into a steel,
producing a thin layer of iron carbonitride
and nitrides. This is the white
layer. or compound layer, with an underlying
diffusion zone containing
dissolved nitrogen and iron or alloy nitrides. Gas processes include Nitemper, Alnat-N, black nitrocarburizing,
and austenitic nitrocarhurizing.
White
layers formed in gaseous nitrocarburizing
are shown in an adjoining
Figure.
Plasma nitrocarburizing
is a variant ofglow discharge plasma nitriding
(see the article “Plasma (Ion) Nitriding”
in this chapter). The microsttucmre produced in ENlOB steel is shown in an adjoining Figure.
Characteristics
of ion-nitrided
for the Heat Treatment
enhanced when nitrogen is retained
beneath the compound layer.
Gaseous
in solid solution
in the diffusion
zone
Processes
Operating Information. Parts usually are treated at a temperature of
570 “C (1060 “F), which is just below the austenitic range for the Fe-N
system. Treatment times usually run I to 3 h.
To get optimum results, surfaces must be free of contaminants, such as
oxides, scale, oil, and decarburization.
Vapor degreasing is adequate in
most applications.
Preliminary
heat treatments include simple stress relieving and tempering to increase core strength. Both stress relief and tempering should be at
temperatures at least 25 “C (45 “F) above the nitrocarburizing
temperature
to prevent changes in core properties during nitrocarburizing.
for heat treating a load of 3000 automotive seat rails. Source:
Klockner
IONON GmbH
70 / Heat Treater’s
Microstructure
Guide
(a) of a plasma nitrocarburized
EN40B steel sample with (b) the corresponding
Stnztural charactefistics of an austenitic nitrocarburized material.
(a) Micrograph of EN32 steel nitmcarburized for 1 h at 700 “C (1290 “F)
in ammonia/endothermic gas with 15% residual ammonia and oil
quenched. (b) Carbon and nitrogen profiles for EN32 nitrocarbutized for
1 h at 700 “C (1290 “F) in ammonia/endothermic gas with 15% residual
NH,
Production
Austenitic
treatment
x-ray diffraction pattern.
Applications
qitroearburizing
type
of Austenitic
Nitrocarburizing
Applications
Alpha Plus(0.125mm, or 0.005in., Clutch plates,levers, gears,bushes,thin
underlyingcase)
pressings
Alpha Plus(0.25mm, or 0.010in., Gears,levers,pulleys, liners
underlyingcase)
Beta (0.60mm, or 0.025in., under- Machine slideways,guide bars,gears,
lying case)
sprockets,pins, bushes,water-pumpparts,
liners,jigs/fixtures, bearings
Microstructure of a plasma nitrocarburized P/M steel (SINTD35) with a compound layer thickness of 10 pm. Source:
Klockner IONON GmbH
1
Guidelines
Compound layers formed on iron by gaseous nitrocarburizing
at 80x (a, C, d, e, and fetched
in alcoholic
ferric chloride
Fluidized
in various methanol ammonia ratios. Quenched
and hydrochloric
Batch furnaces with integral oil quenches are ideally suited for the
process. The hot chamber temperature should be controllable
to within k5
“C ( f9 “F) at 570 “C (1060 “F). For safety reasons gas leaks in the furnace
and around doors must be minimized.
Nitemper Process. Sealed quench furnaces normally are used. Atmospheres consist of 50 percent ammonia and 50 percent endogas. Treatment temperature is 570 “C (1060 “F). Treatment times usually run between I and 3 h. Parts are oil quenched, or cooled under recirculated
protective gas.
Alnat-N Process. Nitrous oxide in the atmosphere enhances the rate
of compound layer formation through the indirect presence of oxygen.
Another feature is claimed for this patented process: it is possible to
eliminate the addition of a carburizing
gas to the basic ammonia/nitrous
oxide/nitrogen
mixture. Carbon is incorporated into the compound layer by
diffusion from the matrix material.
Black Nitrocarburizing. This process was fist used as a cosmetic
treatment for gaseous nitrocarburized
parts for the hydraulic industry. It has
since been found that the application
of the process can be extended to
improving the fatigue, wear, and corrosion properties of mild steels.
Austenitic Nitrocarburizing. In this process, the treatment temperature makes it possible to get partial transformation
of the matrix to austenite
via enrichment with nitrogen. The reason for this is to get around the main
disadvantage of ferritic nitrocarburizing:
in treating plain carbon steel there
for the Heat Treatment
acid with iodine;
b, etched
samples,
in nital with ferric chloride)
of Steel / 71
all shown
is no significantly
hardened case below the compound layer. This means
resistance of a part to horizontal
(contact) stresses is restricted. In the
process, the subsurface (but not the entire cross section) is transformed to
iron-carbon-nitrogen
austenite, which is subsequently transformed to tempered martensite and bainite, with a hardness in the range of 750 to 900 HV
(see adjoining Figure and Tablej.
Plasma Process
Operating Information. Atmospheres in this instance are mixtures of
hydrogen, nitrogen. and carbon-bearing
gas. Treatment temperature is 570
“C ( 1060 “F). The compound layer measures >5 pm; surface hardness runs
around 350 HV. Parts are cooled under controlled vacuum conditions.
Applications. The plasma equipment shown in an adjoining Figure
has been treating seat slider rails for autos for a number of years without
significant technical or metallurgical
problems. Applications
include lowalloy, chromium-bearing
steels. some plain carbon steels, and, recently,
sintered P/M parts, replacing the salt bath process (see adjoining Figure).
Reference
I. ASM hlnols Handbook.
tional. 199l.pd25
Hem Trmtitlg,
Vol 4. 10th ed., ASM Intema-
Bed Hardening
Steel parts are nitrocarburized,
carburized, and carbonitrided
in fluid bed
hmaces. The process also is used in quenching (see article in this chapter).
In heat-treating applications, a bed of dry, finely divided (80 mesh to I80
pm) particles, typically aluminum oxide, is made to behave like a liquid bj
a moving gas fed upward through a diffuser or distributor into the bed of
the furnace.
Characteristics
Fluidized beds, using atmospheres made up of ammonia. natural gas,
nitrogen, and air or similar combinations,
are capable of doing low-temperature nitrocarburizing.
Results are equivalent to those with conventional
salt bath processes or other atmosphere processes. High-speed steel tools
72 / Heat Treater’s
Fluidized-bed
Guide
furnace
with external
heating
by electrical
resistance
oxynitrided
in a fluidized bed have properties similar to those of tools
treated by the more conventional gas processes. In carburizing and carbonitriding, results can be similar to those obtained with conventional
ammosphere processes. In an adjoining Figure, results in treating SAE 8620 steel
are compared with those obtained in gas carburizing.
An effective case
depth of I mm (0.04 in.) was obtained in I .5 h.
Advantages of the process include:
l
l
l
l
Carbtizing
is rapid because treatment temperatures are high
Temperature uniformity
is ensured
Furnaces are tight; upward pressure of gases minimizes leakage of air
Part finishes are uniform
Operating
Information
The carbon potential of the atmosphere varies with the air-to-gas ratio.
For each hydrocarbon
gas (typically
propane, methane, or vaporized
methanol) a relationship can be established. Furnaces are equipped with
ports and probes to facilitate necessary measurements.
Dense phase furnaces are the most widely used in heat treating. In this
instance. parts are submerged in a bed of fme. solid particles held in
suspension, without any particle entrainment, by a flow of gas. Several
methods of heating are available, including external-resistance-heated
beds
(see Figure); external-combustion-heated
beds, submerged-combustion
elements
Comparison
of hardness profiles obtained by fluidized-bed
and conventional
gas carburizing.
SAE 8620 steel, rehardened
from 820 “C (1510 “F)
Guidelines
Fluidized-bed
applications;
beds, intemalcombustion,
tion. gas-fired beds.
Operational
gas-fired
decision
beds; and two-stage,
into the majority
of Steel
/ 73
model
intemal-combus-
Safety. As with all forms of gas heating, accepted safety
devices are incorporated
for the Heat Treatment
of today’s
furnaces.
Applications
Applications
of fluidized beds and those of competing processes are
listed in an adjoining Figure. Note that the information
includes operating
temperatures.
Reference
I. ASM M~mls Hmcfhok.
tional. I99 I, p 43-I
Hmt Trraring. Vol 1. 10th ed., ASM lntema-
74 / Heat Treater’s
Boriding
Guide
(Boronizing)
Process
This is a thermomechanical
surface hardening process which is applied
to a number of ferrous materials. During boriding, the diffusion
and
subsequent absorption of boron atoms into the metallic lattice on the
surface of workpieces form initial boron compounds, Ref I.
Characteristics
The process has advantages over conventional
case hardened parts. One
is extremely high hardness (between 1450 and 5000 HV) with high melting
points of constituent phases (see Table). Typical surface hardness values
are compared with those of other treatments in an adjoining Table. In
addition, a combination
of high surface hardness and low surface coefftcients of the borided layer helps in combating several types of wear, i.e.,
adhesion, tribe-oxidation,
abrasion, and surface fatigue.
On the negative side, boriding techniques lack flexibility
and are labor
intensive,
making the process less cost effective
than other thermomechanical treatments, such as gas carburizing and plasma &riding.
Alternative
processes include gas boriding. plasma boriding. fluidized
bed boriding. and multicomponent
boriding. A diagram of a lluidized bed
for boriding is shown in an adjoining Figure.
Typical Surface Hardness of Borided Steels Compared
with Other Treatments and Hard Materials
MiCl.Ob~dlless,
Material
Multicomponent
Boriding
1600
1800
1900
900
S-IO-600
630-700
900-910
6SO-1700
650-950
looo-1200
ll60-1820(30kg)
1483 (30 kg)
I738 (30 kg)
lS69(30kg)
2ooo
3500
4ooo
5ooo
>I0000
Information
Welt-cleaned material is heated in the range of 700 to 1000 “C (I290 to
1830 “F) for I to I2 h in contact with a boronaceous solid powder, paste,
liquid, or gaseous medium.
In the multicomponent
process, conventional
boronking
is followed by
applying one or more metallic elements, such as ahuninum, silicon, chro-
Melting Point and Microhardness
Phases Formed During Boriding
Materials
Substrate
Fe
co
co-‘7.5 Cr
Ni
k&mm~orEV
Boride mild steel
Bonded AtSI H I3 die steel
Borided AtSl A2 steel
Quenched steel
Hardened and tempered H I3 die steel
Hardened and tempered A2 die steel
High-speed steel BM42
Niuicted steels
Carburized low-alloy steels
Hard chromium plating
Cemented carbides, WC t Co
AI,O, + ZrO: ceramic
Alz03 t TC t ZrO, cemmic
Sialon ceramic
TIN
-liC
SIC
B,C
Diamond
Constituent
Phases
in tbe boride layer
FeB
Fe?B
COB
CozB
Co3B
COB
CozB
Co,B(‘?)
Ni&3
Ni:B
Ni3B
ho lccl
MO
Ta
MozB
MOB>
Mo:Bs
WzBs
IiB
TIBZ
TiB
TIB:
NbB:
NbB.l
Ta:B
Hf
zr
Re
TaB:
HI-&
ZrB:
ReB
w
Ii
Ti-6AI-4V
Nb
of Different Boride
of Different Substrate
MiCl.0hanlnCS.S
of layer,
EV or kg/mm*
Melting point
OF
OC
1900-2100
1800-2000
I850
1500-1600
700-800
2200 (lOOg)(a)
-l55O(lOOg)(a)
700-800
1600
IS00
900
1700~3-00g)(b)
1660
2330
2400-2700
2600
2500
3370
1390
2535
...
.
.
.
...
.
.
.
2txxl
-2100
2100
2300
-1900
2980
.
“’
3630
-3810
3810
4170
3450
5395
3OOO(lOOgj(a)
2200
3050
5520
“’
2500
2900
2250
2700-2900
32003500
3200
3250
3040
2100
57906330
5790
5880
5500
3810
(a) IOOg load. (bj 2oOg load
Treatments
Multicomponeot
boridhrg technique
Media type
61
62
Boroaluminizing
Boroaluminizing
Electrolytic salt bath
Pack
2
Borochromizing
Pack
2
Borosiliconizing
Pack
2
Borovanadizing
Pack
Reference
Operating
Media
composition(s), wt k
Process steps
investigated(a)
Substrate(s)
treated
S
S
B-AI
AI-B
S
B-Cr
Cr-B
B-Si
Si-B
B-V
Plain carbon steels
Plain carbon steels
900( 1650)
lOSO( 1920)
Plain carbon steels
Borided at 900 ( 1650)
Chromized at loo0 (1830)
3-20% AlzOr in borax
8% B,C t 16% borax
974 ferroaluminum t 3%, NHJZI
5% B.&Z+ 5% KBF, t 905, Sic (Ekabor ffj
78%. ferrochrome + 20% AI?03 + 2C WC1
SB B,C t I% KBF, + 90%. SIC (Ekabor Oj
IOOB Si
5% BJ t 5% KBR + 90% Sic (Ekabor U)
60%, ferrovanadium + 37% Al:01 + 3%, NH,CI
(a) S. simultaneous boriding and metallizing: B-Si. borided and then siliconized; Al-B. aluminized and then bonded
0.44 Steel
I .O%-C steel
Ikmperature,
OC (OF)
900-lOOO(l650-1830)
Borided at 900 ( 1650)
Vanadized at 1000 ( 1830)
Guidelines
Proven Applications
AIS1
for Borided
Substrate material
HSI
I020
10-n
1138
1042
E
C2
HII
HI3
Ferrous
BHI I
...
HI0
I15CrV3
4OCrMnMo7
X38CrMoV5 I
X4OCrMoVS I
X32CrMoV33
D2
.
s”li
-BSI
D2
L4i
BS224
02
-802
XlSSCrVMol21
Xl6SCrVMol2
56NiCrMoV7
X$k4SrY4
Materials
Diagram
of a fluidized
for the Heat Treatment
of Steel / 75
bed for boriding
Application
Bushes, bolts. nozzles. conveyer tubes. base
plates, runners, blades, th&d guides
Gear drives, pump shafts
Pins, guide nngs. gnndmg disks. bolts
Casting inserts, nozzles. handles
Shaft protection sleeves, mandrels
Swirl elements, nozzles (for oil burners).
rollen. t&s. gale plates
Gate plates
Clamping chucks, guide bars
Bushes, press tools, plates. mandrels,
punches, dies
Drawing dies, eje,cton: guides, insen pins
Gate platqs,,ben,dmg*es
~h~i~Z%~~~~$ZZlrL~wer
dies and matrices for hot forming, disks
injection molding dies, fillers. upper and
lower dies and matrices for hot forming
Threaded rollers, shaping and pressing
rollers. pressing dies and matrices
Engraving rollers
Straightening mllerj
Press and drawing matrices. mandrels.
liners, dies, necking rings
Drawing dies. rollers for cold mills
Extrusion dies. holts. casting inserts,
$%;$$;;~~~~d
en&ving
dies
rollers. bushes, drawing dies,
Microstructure
of the case of a borochromtitanized
tion alloy steel
construc-
Es2100
4140
4150
4317
708A42
(EnlW
-708A42
(CDS-15)
.
X5OCrMnNiV229
42CrMd
SOCrMo4
I7CrNihlo6
5115
16MnCrS
6152
5CCrV-l
302
316
302825
(EnSgA)
-3 16s I6
05580
410
420
4lOS21
(En56A)
-42OS45
(En56D)
X I2CrNi I88
exuuder barrels. non-Rturn valves
Nozzle base plates
Bevel gears. screw and wheel gears,
shafts, chain components
Helical gear wheels, guide bars, guiding
collmlns
Thrust plates. clamping devices. valve
sprin&. spring c&t&s
Screw cases, bushes
XSCrNiMo I8 IO Perforated or slotted hole screens. parts for
the textile and tubber industries
GXIOCrNiMol89
Valve plugs, parts forthe textileand
chemical industries
Valve components, fittings
XIOCrl3
XjOCrl3
X3SCrMo I7
Gray and ductile cast iron
Valve components. plunger rods. fittings.
guides, parts for chemical plants
Shafts, spmdles, valves
Parts for textile machinery, mandrels.
molds, sleeves
mium. vanadium, or titanium (see Table). The operating temperature
ranges from 850 to 1050 “C (1560 to 1920 “F). It is a two-step process:
I. Boding by conventional methods, such as pack, paste, and electrolpic
salt bath techniques
2. Dillitsing me.taliic elements through the powder mixture or borax-based
melt into the borided surfaces. With the pack method, sintering of
particles is avoided by passing argon or hydrogen into the reaction
chamber. The mierosttucture of a borocbromtitanized
alloy steel is
shown in an adjoining Figure..
Quenching
and Tempering.
Borided
steels are quenched
in air, oil,
salt baths, and aqueous Polymers.
Applications
Marty ferrous materials can be borided, including structural steels, tool
steels, stainless steels, cast steels, Armco CP iron, gay and ductile irons,
and ferrous P/M materials. Proven applications are shown in an adjoining
Table.
Air-hardening
steels can be simultaneously
hardened and borided; waterhardening steels are not borided because of the susceptibility
of the boride
layer to thermal shock.
Also excluded are resulfurized and leaded steels (because of tendencies
toward case spalling and case cracking), and nitrided steels (due to their
sensitivity to cracking).
Reference
I. ASM Memls Ha&book,
tional. 1991, p 137
Hear Trt~~tir~g. Vol 3, 10th ed., ASM Intema-
76 / Heat Treater’s
Laser
Guide
Surface
Hardening
austenitizing
temperatures without unduly affecting the bulk temperature
of the workpiece.
fn laser surface hardening, as in the electron beam process and high
frequency, pulse hardening methods (see article on these self-quenching
processes in this chapter), a quenching medium is not needed. Self-quenching occurs when the cold interior of the workpiece is a large enough heat
sink to quench the hot surface by heat conduction fast enough to allow the
formation of martensite on the surface.
A laser heats the surface of a part to its austenitic temperature. The laser
beam is a beam of light, is easily controlled, requires no vacuum, and does
not generate combustion products. However, complex optics are required,
and coatings are required on surfaces to be hardened because of the ION
infrared absorption of the steel, Ref I.
Characteristics
Lasers are effective in selective hardening of wear and fatigue prone
areas of irregularly
shaped machine componems such as camshafts and
crankshafts.
Distortion
is low. Lasers are not efficient
from an energy
utilizaGon standpoint. Energy efficiency may be as low as IO percem.
Operating
Applications
More than 50 applications of the process have been reponed. Materials
include plain carbon steels (I 010. 1050, 1070). alloy steels (4340.52 100).
tool steels, and cast irons (gray, ductile, and malleable types). Reported
case depths on steels run from 250 10 750 pm; those on cast irons about
1000 pm.
Information
This surface hardening process is not fundamentally
different
from
conventional
through hardening of ferrous materials. In both instances,
increased hardness and strength are obtained by quenching the material
from the austenite region to form hard martensne. Wilh laser hardening,
however, only a thin surface layer is healed to the austenitizing temperature
prior to quenching, leaving the interior of the workpiece essentially unaffected. Because ferrous materials are fairly good conductors of heat, ir is
necessary IO use very intense heat fluxes to heat the surface layer to
Electron
Beam
Reference
I. ASM hlerals Handbook, Hevat Trtvaring, Vol 4. 10th ed., ASM
tional, 199 I, p 286
Intema-
Hardening
This is a shon surface hardening process for martensitically
hardenable
ferrous malerials. Energy for austenilizing
is provided by electron beams,
Ref I.
(see article on process in this chapter). To accommodate self-quenching,
workpiece thickness should be at least 5 LO IO times the depth of austenitizing.
Characteristics
Applications
Carbon, alloy, and 1001 steel applications
are listed in the adjoining
Table.
Extremely low hardening distortion and relatively low energy consumption give the metallurgist an alternative to conventional
hardening processes In some instances. the technique is competitive with case hardening
and induction hardening processes.
Reference
Operating
I. ASM hl.erals Handbook, Heat Treoring, Vol 4. 10th ed., ASM Intemational. 1991. p 297
Information
Typical hardening depths range from 0. I to I.5 mm (0.004 to 0.006 in.).
Rapid cooling of austenite to martensite occurs mrough self-quenching
Steels Commonly
Material
UNS No.
Used in Electron
Beam Hardening
C
Si
Carbon and low alloy
4140
GA 1400 12 CrMo 1
1340
Cl3400
42MnV7
Exloo
GS2986
IOOCr6
1015
G10150
c IS
1045
GlOjSO
C-IS
I070
Gl0700
Ck 67
SSCrl
SOCrV J
0.38.O.-IS
0.38-0.1s
0.9s- I .os
0.17-0.19
0.42-0.50
0.650.72
0.52-0.60
0.47.0.59
0.17-0.37
0.17-0.37
0.17-0.37
0.17-0.37
0.17-0.37
0 25-0.50
0.17-0.37
0 4 max
I 60-I .90
0.20-0.45
0.35-0.65
0.50-0.80
0.60-0.80
050.8
0.7-1.1
Tool steels
T31502
02
WI
T72301
0.85-0.95
0.95-1.04
0.15-0.35
0.15-0.30
1.80-2.00 0.03Omax 0.030max
0.15-0.25 0.02Omsx 0.020max
AlSl
DWa)
9OMnV8
c IOOWI
(a) Deutsche tndusu-ie-Normen. ihj 0.25 max Cu
Mn
Applications
P
S
Composition, ~1%
hlo
Cr
0.50-0.80 0.035max 0.035 max 0 90-I 20 O.lS-0.25
0.035 mx
0.027 mm
0.040 max
0.040 max
0.035 mar
0.035 max
0.035
0.035 maa
0.020 max
0.040 max
0.040 max
0.035 max
_.
0.03 max
0.30 ma\ O.lOmax
I .30-I .6S
0.50 mas O.lOma
0.50 max O.lOma
0.35 m;Lx
0.2-0s
0.9-l 1
___
0.20max
___
,._
Ni
v
Al
cu
Ti
0.30max
0.30mcu
0.30max
0.30mrtv
0.30maK
0.3Smax
0.3max
0.06max
0.07-0.12
,,.
__.
_..
,,_
___
__.
0.10
max(hj
0.07-0.12
0.25
___
_..
___
0.02-0.05
0.35
0.3 max
0.015
0. I-O.2
.
.
Steel
Quenching
Technology
Introduction
“Quenching
is one of the least understood of the various heat treating
technologies,”
in the words of a world authority on the subject, George E.
Totten of Union Carbide Chemical & Plastics Co., Inc.
Other dimensions of the problem are identified in the follouing
quotes
from other experts:
l
l
l
“Quenching
is critically
important, but often the neglected part of heat
treating.”
“Quenching is the most critical part of the hardening process... [it] must
be designed to extract heat from the hot horkpiece at a rate required to
produce the desired microstructure,
hardness, and residual stresses.”
“Distortion
is perhaps one of the biggest problems in heat treating... little
information on the subject has been published.”
The subject was introduced in the previous chapter by two articles on
the subject: “Causes of Distortion
and Cracking during Quenching”
and
“Stress Relief Heat Treating of Steel.”
In this section, the topic is surveyed in depth in eight articles on conventional quenching processes:
l
l
l
l
l
l
l
l
Air quenching
Water quenching
Oil quenching
Polymer quenching
Molten salt quenching
Brine quenching
Caustic quenching
Gas quenching
l
l
l
l
l
l
l
l
l
l
l
l
l
Austempering
hlartempering
Isothermal quenching
Aus-bay quenching
Spray quenching
Fop quenching
Cold die quenching
Press quenching
Vacuum quenching
fluidized
bed quenching
HIP quenching
CUtrasonic quenching
Quenching in electric and magnetic fields
Quenching flame and induction hardened parts
Self-quenching
processing-electron
beam hardening,
and high frequency pulse hardening
laser hardening,
Process
of Process
Air, a gas high in nitrogen,
cools by extended
vapor phase cooling.
Information
As with other quenchants. heat transfer rates are dependent on flow
rate-in
this instance, flow rate of air past the hot part (see Figure). Cooling
can be speeded up by increasing the velocity of air 110~. but the accelerated
rate is not sufficient to quench harden man) steels. The ability of air to
harden plain carbon steels drops dramatically
with increasing carbon content (see Figure).
Application
l
methods of quenching are discussed in articles:
I. George E. Town. preface to AShl Conference Proceedings, “Quenching and Distortion Control.” ASM International,
‘92
2. Totten et al, “Handbook
of Quenchants and Quenching Technology,”
ASM International.
‘93
Air is the oldest most common. least expensive quenching medium, Ref I.
Operating
l
I7 alternative
References
Air Quenching
Characteristics
In addition.
Range
Air is used in quenching steel and several nonferrous
metals. The
comparative heat transfer coefficients
of different metals as a function of
surface temperature are shoun in an adjoining Figure. To get optimal
hardness, it is often necessary to use a more actike quenching medium.
such as brine or oil.
Reference
I. Totten et al, Handbook oj Qwttclrottts
ASM International.
1993
md Qutwclriny Teclrtrolog~:
Heat transfer coefficients
face temperature
for air cooling as a function of sur-
78 / Heat Treater’s
Guide
Hardness values obtained with different quenching media
Cooling capacities of still and compressed air
Water
Quenching
Process
Like air, water is an old, common, inexpensive quenchant (Ref I). It is
applied in several ways: in straight, immersion quenching; in a special,
double-step, hot water quenching process; and in conjunction with polymer
quenchants and with brine quenchants.
Characteristics
of Process
Water, especially cold water, is one of the most severe
available. Vigorously agitated water produces a cooling
the maximum with liquid quenchants (Ref 2). As water
the vapor phase is prolonged and the maximum rate
sharply (see Figure).
Operating
quenching media
rate approaching
temperature rises,
of cooling drops
Information
l
l
Maintaining
water at a low temperature through cooling
Vigorous agitation to disperse the vapor blanket
Addition of an organic salt (see Brine Quenching)
Double-step, hot water quenching
ing of steel wire. It consists of:
l
l
Range
Water is the choice where a severe quench does not result in excessive
distortion and cracking. Use generally is restricted to quenching simple,
symmetrical parts made of shallow hardening grades of steel. Other applications include austenitic stainless steels and other metals that have been
solution treated at elevated temperatures.
Effect of temperature
Generally, good results are obtained in straight immersion quenching by
maintaining water temperatures in the range of I5 to 25 “C (60 to 75 “F)
and by agitating water to velocities greater than 0.25 m/s (50 ft/min). Water
temperature, agitation of water, and amount of contamination
in the water
must be controlled. The comparative cooling properties of hard water and
distilled water are indicated in an adjoining Figure.
The detrimental
effect of temperature dependence and vapor phase
stability can be minimized (Ref 3) by:
l
Application
is a possible alternative
to lead patent-
Heating wire to 920 to 950 “C ( 1690 to 1710 “F) and immersing
boiling hot water for an appropriate time
Removing wire from water and air cooling (Ref I)
into
Source:
ES. Houghton
&
on quenching
Co.
properties
of water.
Steel Quenching Technology / 79
Cooling curves for hard water and distilled water
References
I. Totten et al., Handbook of Quenchanrs
ASM International,
1993
Oil Quenching
and Quenching
Technology,
Process
AU modem quenching oils are based on mineral oil, usually paraffin
based, and do not contain fatty oils.
Usage of oils opens up a number of options for the heat treater:
l
l
l
l
l
Normal-speed oil for treating steels high in hardenability
Medium-speed oils for medium hardenability
steels
High-speed oils for treating low hardenability
steels and for other applications
Hot oil quenching (also called marquenching or martempering) provides
another option
Water-washable quenching oils: for removing oils on treated parts with
plain water
Characteristics
of Process
Oils are characterized
in various ways, depending upon operating requirements. Quenching speed and operating temperature are among these
considerations.
The importance of quenching speed is that it influences hardness and
depth of hardening. Cooling rate curves for normal-, medium-, and highspeed quenching oils are shown in an adjoining Figure (Ref I). Cooling
curves for different quenchants are given in an adjoining Figure (Ref 7).
Almost all quenching oils produce lower quenching rates than water or
brine solutions, but they remove heat from workpieces
more uniformly
than water normally does, meaning less likelihood of distortion and cracking (Ref 3).
Temperature of operation is important because it influences:
l
l
l
l
2. ASM Metals Handbook, Heat Treating, Vol 4, 10th ed.. ASM lntemational. 1991
3. Houghron on Quenching, E.F. Houghton & Co., Valley Forge, PA
Oil life
Quenching speed
Viscosity of oil
Distortion of workpieces
Effect of temperature on quenching
shown in an adjoining Figure (Ref I).
speed for a hot quenching
oil is
Changes in viscosity can indicate oxidation and thermal degradation, or
the presence of contaminants.
Ln general, viscosity goes up as an oil
degrades and can result in changes in quenching speed.
Flash point, another consideration,
is the lowest temperature at which oil
vapors ignite in the presence of an ignition source; it is important because
Cooling rate curves for quenching oils. Source:
& co.
E.F. Houghton
80 / Heat Treater’s
Guide
Cooling rates for different quenchants
Effect of temperature on quenching speed of hot oil. Source:
Characteristics
of Quenching
Oils
E.F. Houghton&Co.
‘Qpe ofoil
Bath
temperature
“C
“F
FlZL5b
point
OC
OF
Con\rntionaI
Accelerated
hlarquenching
~65
<I20
COO
170
180
300
Use Temperatures
Viscosity
at 40 T
U~W,
SUS
<IS0
<xi0
<-u)o
Qpical
viscosity
at 40 OC
(loooF),
sus
3-m
355
105
94
570
7ocl
for Marquenching
Operating
Data on the
quenching oils
marquenching
Applications
l
l
l
-IO to SO
Information
use temperatures for conventional,
accelerated, and mmare given in an adjoining Table and use temperatures for
oils are given in a second Table (Ref 2).
based on oil speed are as follows:
Normal-speed
oils: used where the hardenability
of a steel is high
enough to provide specified mechanical properties with slow cooling.
Typical applica6ons are highly alloyed steels and tool steels
Medium-speed
oils: typical applica6ons
are medium- Lo high-hardenability steels
High-speed quenching oils: for low hardenability
alloys, carburized and
carbonitrided
parts, and medium hardenability
steel parts large in cross
Elotwire
test,
A
16.0
IO
30
30
39
30
Oils
Use temperature
hlinimum
flash point
OF
T
250-550
“0
700 1500
2000-2800
2.50
290
130
-180
550
Protective
atmosphere
oc
OF
Open air
T
9s-150
120-175
I SO-205
OF
X0-300
250-350
3OsmO
section that require very high rates of cooling
cal properties
it is related to the maximum safe operating temperature-usually
“C (71 to 90 OF) below the open cup flash point for oil.
GM
quench*
meter
(nickel ball)
time, s
95-175
120-205
I SO-230
200-350
250-400
300-450
to get maximum
mechani-
Hot oil quenching: for applications
where it is desirable
tion and cracking to a minimum. It is a two-step operation:
l
l
l
to keep distor-
Operating temperature generally of the oil is 100 to 200 “C (210 lo 390 “F).
Operating temperature is held until the temperature throughout
the
workpiece is uniform.
Workpieces are then air cooled to ambient temperature.
References
I. Houghton on Quenching, E.F. Houghton & Co., Valley Forge, PA
2. Totten et al.. Handbook oj’ Quenchants and Quenching Technology
ASM International,
1993
3. ASAl Metals Handbook, Hem Trearing, Vol -I, 10th ed.. ASM lntemational. 1991
Steel Quenching
Polymer
Technology
/ 81
Quenchants
Around 20 different aqueous polymers,
quenching steels (Ref I). They include:
it’s reported,
have been used in
Effect of PAG concentration
on quenching characteristics
. Polyvinyl alcohol (PVA)
l
Polyalkylene glycol (PAG)
l
Sodium polyacrylate
(ACR)
l
Polyvinyl pyrrolidone
(PVP)
l
Polethyl oxazoline (PEO)
PAG is No. I in usage today
Characteristics
Inverse solubility in water is a key characteristic of a number of polymer
quenchants, including PAG’s, because this phenomenon modifies the conventional, three-stage quenching mechanism, providing flexibility
in cooling rate. These polymers are completely soluble in water at room temperature, but insoluble at elevated temperatures, ranging from 60 Lo 90 “C (l-10
to I95 “F).
When a hot part is fist immersed in a quenchant bath, the quenchant in
the immediate vicinity of the hot metal surfaces becomes insoluble and
deposits itself on the part in the form of a polymer-rich
film.
The tilm acts as an insulator, which slows down cooling to a rate
analogous to that of oil in the vapor phase. ln a number of applications. the
quenching rates of aqueous polymers are intermediate between those of
water and oil (see adjoining Table).
Ln stage 2 of cooling (boiling phase), the film eventually collapses and
the quenchant comes into contact with the hot metal. resulting in nucleate
boiling and high heat extraction rates.
In the final stage, cooling is by conduction andcomection
into the liquid.
When metal surface temperatures fall below the inversion temperature. i.e..
75 s, the polymer redissolves and forms a homogeneous polymer-water
mixture.
Operating
Typical Quench
Media
Oil
Polymer
Water
Brine
on quenching
charac-
Information
Cooling rates can be tailored to requirements by changing the concentration of the solution, quenchant temperature. and degree of agilation of the
bath.
Concentration influences tilm thickness; with increasing concenfration, the maximum rate of cooling and the cooling rate in the comection
phase drop (see Figure). Agitation of the quenchant has little effect during
the film stage.
Wettability of workpiece surfaces is improved with S% solutions of PAG,
which is beneficial to quench uniformity.
At this concentration,
problems
with soft spotting associated with water quenching are avoided.
Concentrations
in the IO to 20% range accelerate cooling rates to the
level of fast quenching oils. These concentrations
are suitable for quenching low hardenability
steels requiring maximum mechanical properties.
Concentrations of 20 to 308 boost cooling rates suitable for a wide range
of through hardening and case hardening steels.
Bath temperature has an influence on the quenching speed of solutions. The effects of three different temperatures on a 2% PAG concentration with vigorous agitation is sho& n in an adjoining Figure. The maximum
cooling rate decreases with increasing temperature. PAG solutions must bs
Quenchant
Effect of PAG-water temperature
teristics
Severities
Achievable
with Various
Grossmann
H factor
03-0.8
o.L?-I.2
0.9-1.0
2.0.5.0
1 Effect of agitation on quenching characteristics
of PAG solu- 1
82 / Heat Treater’s
Sensitivity
Guide
band for quenchant selection
Spray curtain in quenching chute
cooled to prevent them from reaching the inversion temperature. A maximum operating temperature of approximately
55 “C (130 “F) normally is
recommended.
Agitation has an important effect on all polymer quenchants, by ensuring a uniform temperature distribution
within the bath; it also affects
cooling rate (see Figure). As the severity of agitation increases, the duration
of the vapor phase (tilm phase) is shortened and eventually disappears.
During the convection phase, agitation has comparatively
little effect.
PAG’s are used in immersion quenching of steel parts, in induction
hardening, and in spray quenching. Applications
of other polymers include
forgings, open tank quenching of high hardenability
steels, use in integral
quenching furnaces. patenting of high-carbon steel wire and rod, and in
quenching railroad rails.
Guidelines
Considerations
l
l
l
l
l
l
for Selecting
generic to polymer
Polymers
quenchants
include:
Material composition
Section size of workpiece
Type of furnace
Quenching system design
Method of quenching
Distottion control
Material composition and section size play critical roles in quenchant selection (see Figure). Note that this figure provides guidelines for
selecting polymer quenchants based on such considerations
as hardenability of the steel, section size, quench severity factors, and polymer selection
per applications. Alloy content influences hardenability,
which determines
the quenching speed needed to get a specified hardness and other properties.
Section size and complexity affect quenching speed requirements.
Heavy section parts are quenched faster than those with thin sections to get
equivalent results.
Furnaces used in oil quenching may require modification
for polymer
quenching, and certain precautions are observed.
The design of integral quench furnaces, for example, may require modification to minimize the possible effects of water vapor in furnace atmospheres. Changes include ensuring a good inner door seal and the maintenance of positive gas pressure in the hot zone.
Spray curtains are needed in the quenching chutes of continuous furnaces to prevent contamination
of the furnace atmosphere with water vapor
(see Figure).
A precaution: polymer quenching of steel parts previously treated in salt
baths generally is not recommended due to the effects of the carryover of
high-temperature
salt.
Aqueous polymer quenchants are recommended
for parts treated in
induction heating.
Quenching system design can have an influence on quenching
characteristics.
Examples include design features relating to agitation,
method of circulating quenchants. and fluid temperature controls.
Method of quenching can directly affect cooling rates and the results
obtained in quenching.
Direct Quenching. This technique is commonly used in quenching
with aqueous polymers in many different types of furnaces.
Time or Interrupted Quenching. This technique is used to change
the cooling rate during quenching, i.e.. quenching a large forging in water
for a specified time, then transferring
the workpiece to a polymer quenchant to reduce cooling in the convection phase. An alternative practice,
used to reduce quench cracking and distortion,
is to quench first in a
polymer solution, followed by an air quench.
In spray quenching quenchant characteristics are influenced by the
volume and pressure of the quenchant and by spray nozzle design.
Distortion control is needed in quenching thin or complex section
workpieces. Use of a slower quenchant is one of the control techniques.
References
I. Totten et al., Handbook of Quenchotm and Quenching Technology,
ASM International,
1993
2. Horcghron on Qrtenching. E.F. Houghton & Co., Valley Forge, PA
Steel Quenching
Molten
Salt Quenching
Characteristics
Minimum quenching temperatures depend on the melting point of the
salt mixture, which depends on the composition
of the mixture (see Figure); the ratio of the salt mixture may also affect the viscosity of the
medium, which, in turn, affects cooling.
Like all quenchants, the heat extraction capabilities of molten salt depend on the agitation rate of the bath (see Figure). Agitation is applied in
several ways. One approach is shown in an adjoining Figure.
In heat treating it is common for steel to be austenitized in a hightemperature salt bath composed of a binary blend of KNO3/NaNO3,
or a
ternary chloride blend, such as KCVLiCVNaCI.
When austenitization
is
completed, the workpiece
is quenched in a lower temperature, ternary
blend of KNO~/NaN02/NaN03.
Information
Quenching temperatures of the bath range from 140 to 600 “C (285 to
II IO “F), but salt melting points as low as 80 “C (175 “F) can be obtained
with additions of up to 10% water.
Control of bath temperature is critical (see Table). Salt baths are subject
to potential explosive degradation at temperatures above 600 “C (I I IO “F).
Care is also advised in making water additions, because they are accompanied by spattering of the molten salt. In one safety procedure, additions are
made very slowly and bath temperatures are held below 175 “C (3-U “Fj.
An automatic additive device and probe monitoring system (see Figure) is
an alternative. Controlled additions of specific amounts of salt are made in
a temperature range of I80 to 250 “C (355 to 180 “F).
Another consideration:
salt can absorb water from a humid environment
at room temperature when a quenching system is not in use. Before normal
operations are resumed, heating the bath to 95 “C (205 “F) until all water
is removed is a general recommendation.
Effect of Salt Temperature
Salt temperature
T
OF
195
200
230
270
295
350
385
390
450
51s
560
660
(a) A KNO,-NtiO,
/ 83
Process
These salts usually are the medium of choice for high-temperature
quenching. They are either binary or ternary mixtures of potassium nitrate
(KNO3). sodium nitrite (NaNO?). and sodium nitrate (NaNO3). Ref I.
Operating
Technology
on Quench
Freezing points of ternary alkali nitrate-nitrite
in percent
mixtures given
Severity(a)
Grossmann
Center
H factor, hr.-r
0.46
0.45
0.40
0.45
0.4 I
0.43
Surface
0.63
0.65
0.65
0.64
0.57
058
salt with a melting point of I35 “C (275 OF) was used u ith no agi-
tation.
Degussa system for adding water to molten salt
Effect of agitation on quench severity of molten salt
84 / Heat Treater’s
Application
Molten
l
l
l
l
l
Guide
Range
salt quenching
Dual impeller salt bath agitation system
applications
include:
Martempering
and austempering
(see items on both subjects in this
chapter)
Quenching high-alloy steels
Quenching high-speed steel tools, to minimize scaling, distortion. and
cracking
Quenching steels such as spring wire to reduce the risk of cracking
during martensitic formation
Quenching to enhance the formation of high-temperature
transformation
products, such as bainite and ferrite.
Reference
I. Totten et al., Handbook of Quet~chuttts
ASM International,
1993
Brine
Quenching
curd Q~renchitrg
khnolog~~
Process
The term refers to aqueous solutions containing different percentages
salts such as sodium chloride (NaCI) or calcium chloride (CaClj.
of
lently. creating turbulence
high cooling rates.
that destroys
the vapor phase, resulting
in very
Characteristics
Operating
Cooling rates are higher than those of water for the same degree of
agitation, or. alternately, less agitation is needed to get a given cooling rate.
Higher cooling rates reduce the possibility of steam, the cause of soft spots
in quenching, but higher cooling rates generally increase the likelihood of
distortion
and cracking. Use of baffling patterns on quench tanks and
propeller agitation may be needed in quenching very lower hardenability
steels (Ref 2).
In quenching, minute salt crystals are deposited on the surfaces of
workpieces. Localized high temperatures cause crystals to fragment vio-
Brine concentration
is expressed in several ways (see Table). Both
sodium chloride and sodium hydroxide.
the latter a caustic solution, are
covered in the Table.
Brine concentrations
up to 33 percent progressively
reduce the vapor
phase. but such concentrations
generally are considered impractical. A IO
percent solution of NaCl is quite effective in hardening. The relationship
of brine concentration
to hardness is indicated in an adjoining Figure. It is
necessary to monitor brine concentration
to get reproducible
results in
quenching.
Cooling properties are not seriously alTected by small variations in the
operating temperatures. Brines can be used at temperatures near that of
Relation
of Brine Density
salt, ?o
NaCl solutions
-I
6
8
9
IO
I2
to Brine Concentration
Specitk gravity
Direct reading
OBk(a)
hydrometer
(Ref 2)
Relation of hardness to brine concentration when stillquenching, end quench specimens 90 “C (195 “F) brine solution. Number above curves indicate distance from quenched end
Salt concentration
lb/sd
sir.
in UnitS Of ‘/lfj in. (Ref 2).
I .026&J
I.0413
I .0559
I .0633
I .0707
I .0857
3.8
5.8
7.7
8.7
9.6
II.5
11.1
62.4
81.5
95.9
107.1
130.3
0.313
OS2 I
0.705
0.800
0.89-l
I.087
1.0095
I .0207
I.0318
I .04x3
I .OS38
I .-I
2.9
4.5
6.0
7.3
IO.1
20.4
31.0
-11.7
52.7
0.08-E
0. I704
0.2583
0.348 I
0.1397
NaOB solutions
I
2
3
4
5
Information
(a) “Be. Baumb; specific gravity
II is reading on Be scale in “Be
for liquids hea\ ier than Hater is 1154 I15 -n).
where
Steel Quenching
Technology
/ 85
Relation of hardness to distance from quenched end of specimens quenched in water and brine. Cooling power . of brine is greater
than that of water at 80 “C (175 “F) (Ref 2).
boiling water, but their maximum cooling power is at a temperature of
approximately
20 “C (70 “F). Effects of temperature on cooling power are
indicated in an adjoining Figure.
Sludge and scale should be removed from baths periodically.
They can
clog pumps and recirculating
systems and reduce cooling rates. Excess
water reduces solution strength and cooling power.
Caustic
Quenching
I. Totten et al., Handbook of Quenchnnrs and Quenching Technology,
ASM International.
1993
2. ASM Merals Handbook, Hear Treating, Vol 4, 10th ed.. ASM fntemational. 1991
Process
The most common alternative to sodium chloride quenching is aqueous
sodium hydroxide
(a caustic) in concentrations
ranging from 5 to IO
percent (Ref I).
Characteristics
Cooling rates are similar to those of sodium chloride at high surface
temperatures. Slower cooling rates than those available with sodium chloride are obtained in the martensitic transformation
temperatures for many
steels (450 “C. or 660 “F), which would be expected to reduce susceptibility to cracking.
Operating
References
Information
The effect of NaOH concentration on cooling rate, at a bath temperature
of 20 “C (70 “F), is shown in an adjoining Figure. The effects of I to 5
percent concentrations
of NaOH are shoun in an adjoining Table. In
practice, aqueous solutions are in the 5 to IO percent range.
Comparatively,
NaCl solutions are considered to be safer. less costly. and
easier to handle than NaOH solutions. The main shortcoming of the latter
is that its high alkalinity is harmful to human skin (Ref 2).
Relation of Brine Density
and NaOH Solutions
Salt, 9
NaCl solutions
-I
6
8
Y
IO
I2
NaOEl solutions
I
2
3
-I
5
to Brine Concentration
Specific gravilg
Direct reading
“Be(a)
hjdrumeter
of NaCl
Salt concentration
lb/gal
ks
I .0268
I.Wl3
I .055Y
1.0633
I .0707
I .0857
3.8
5.8
7.7
8.7
9.6
I IS
11.1
62.3
84.5
95.9
107.1
130.3
I.OO9.r
I .0207
I.0318
I .@I28
I .0538
I .-I
2.9
4,s
6.0
7.4
10.1
20.4
3 I .o
41.7
52.7
0.343
0.52 I
0.705
0.800
0.893
I.087
0.0842
0.170-t
0.2583
0.318 I
0.1397
(a) “BC. Baumt: specific grak ity for liquids hea\ ier than \\ater is l-IS/( I45 -n). where
II is reading on BP scale in “Be
88 / Heat Treater’s
Guide
Effect of NaOH concentration
on cooling rate
References
I. Totten et al.. Handbook of Quenchants
ASM International,
and Quenching
Technology,
1993
Gas Quenching
Heat Treating,
Vol 4, 10th ed., ASM
Interna-
Process
Atmospheres containing some hydrogen or helium are commonly used.
Nitrogen is among the alternatives. Gases are also used in vacuum quenching.
Characteristics
Cooling rates are faster than those in still air and slower than those
obtained with oil. Austenitized
workpieces
are placed directly
in the
quenching zone and heat is extracted by a fast-moving stream of gas (Ref I).
Operating
2. ASM Metals Handbook.
tional. 1991
Cooling rate is adjusted and controlled by altering the type, pressure, and
velocity of the gas.
In quenching, large volumes of gas are directed through nozzles or vanes
to impinge on the workpiece.
After the gas absorbs heat from the hot
workpiece, it is cooled by being passed through water-cooled or refiigerated coils. Recirculating
fans return gas to the nozzles, through which they
are again directed at the workload.
Quenching units are of the batch or continuous types, and the former are
most commonly used.
Information
The cooling rate of the metal being treated is related to surface area and
mass of a part, as well as the type, pressure, and velocity of the cooling gas.
Cooling curves in quenching
air (normalizing)
4130 steel in gas, oil, and still
Brinnel hardness of forged, 1095 steel disks 100 mm (4 in.
thick) after oil quenching, gas quenching (forced air), and
cooling in still air (normalizing)
Steel Quenching
Application
Range
In some instances quenching in still gas is too slow and oil quenching is
not desirable for such reasons as distortion, cost, handling problems, or
insufficient
ftnaf hardness. Quenching in a fast-moving stream of gas is a
compromise.
The process is used, for example, in hardening aircraft tubing, steels that
are not air hardenable, and tool steels.
Data on quenching 4 I30 aircraft tubing are found in an adjoining Figure.
Data on steel that is not air hardenable (forged 1095 steel in this instance)
are presented in an adjoining Figure.
In the tool steel example, A2 and Tl, in the form of solid blocks 50 by
100 by 100 mm (2 by 4 by 4 in.), were gas quenched with cylinder nitrogen
in a vacuum furnace. Cooled gas was admitted to the chamber at 69 kPa
(IO psig). As indicated in an adjoining Figure, A2 was cooled from 1010 to
345 “C (1850 to 655 “F) in 8 min. and Tl was cooled from 1290 to 345 “C
(2355 to 655 “F) in I3 min. In both instances, cooling rates were suitable
for maximum hardness.
Reference
I. ASM Metals Handbook,
tional. 1991
Heat Treating,
Vol -k 10th ed.. ASM Intema-
Technology
/ 87
Surface cooling curves for blocks made of types Tl and A2
tool steels quenched from austenitizing
temperatures
by
cooled nitrogen in a vacuum furnace
Other
Quenchants/Processes
Introduction
A numher of alternatives
including:
l
l
l
l
l
to standard quenchants/processes
l
frequency.
pulse hardening;
electron
or magnetic
field
Quenching
Characteristics
of Process
Alternative quenches must be used to make vacuum quenching viable.
Other media include oil. aqueous polymers. and pas. Gas is the most
commonly used. In fact. the fastest growing technology in heat treating is
gas quenching in a vacuum furnace (Ref I).
Information,
Quenching
of Heat Transfer
Quenchant
Ga.s.recirculated(
1000mbarN2~
Gzs.o~rrprcsrure.
high \rlocib
Salt bath (5.50 “C or 1070 “FJ
Fluidizedbed
’
Stationq
oil (20-80 “C. or 70. I75 “F)
Recirculated oil (30-80 “C, or 70. I75 “F)
\hhter( 15-25 “C.or60-75
“FJ
Coefficients
of Various
Aeat transfercoefficient(
I@%I50
300400
350-450
-loo-500
100@1500
I8OO-‘100
3OOc3500
W/m?.
Vacuum Quenching
in Oil
With the exception of relatively high pressure (>20 bar) gas quenching,
quench severities with _gas are limited to those up to. but usually not
including. conventional
oil. k’hen lovver hardenahihty
alloys are heat
treated in vacuum furnaces. more quench severity is needed. which is the
niche for oil.
Reference
I. Totten et al., Hmrdbook c$ Q~rtwctrunrs
AS hl International.
I993
with Gas
In this procedure. the furnace is pressurized with gas after the heat
treating step is completed-this
is called backfilling.
The two main factors affecting quench severity are gas velocity and gas
pressure (see adjoining Figures).
Gas quenching usually is done with nitrogen. argon, helium. or hydrogen. Physical properties of quenching gases are listed in an adjoining Table.
Recently developed applications are based on gas mixtures. such as nitrogen/helium. Gas blending is a cost-elTective way of getting heat transfer
rates greater than those available uith helium alone.
High pressure gas quenching (helium at a pressure of 20 bar) can produce
quench severities comparable to those of conventional.
recirculated oil. At
very high pressures (hydrogen at SO bar) heat transfer coefficients
are
greater than those of eater.
Comparison
Media
l
Spray quenching
Fop quenching
Cold die quenching
Quenching in an electric
In addition. some processes are uniquely suited for quenching parts
surface hardened in a specific process. such as quenchants for flame and
induction hardened ~orkpieces.
Parts can he quenched,in
vacuum furnaces, but heat transfer rates are
relatively slob (5.7 W/mK. or 3.6 B&h
“F) in comparison with those
of oil. helium, nitrogen. and air (see adjoining Table and Figure, Ref I).
Operating
l
l
Vacuum quenching
Selfquenching
processes (high
karn process, and laser process)
Fluidized bed quenching
l~ltrasonic quenching
HIP quenching
Vacuum
are availahle.
R
Quench severities of different media
nnd Qtrmchitrg
Technology,
Other QuenchanWProcesses
Physical
Properties
of Quenching
/ 89
Gases
Quenching gas
Nitrogen
Helium
Hydrogen
I. I 70
0.967
28.0
I.o-ll
259 x IO-’
17.74 x lo+
0.167
0. I38
4.0026
5.1931
ISOOX lOA
19.68 x IO4
0.084 I
0.0695
2.0158
I-I.3
1869x IO-’
892 x IO”
Mw
Density,kg/m3at lS”CII bar
Density ratio, v/r. to air
Molar mass. kg/m01
Specific heat(a). k.lkg K
Thermal conducti\ Q(a). \V/m K
Dynamic viscosity(aJ, N s/m?
1.6687
I .3797
39.938
0.5204
177 x IO-’
22.6 x IO”
Ia) Gas conditions. 35 “C. I bar
Effect of chamber pressure at constant volumetric
cooling time
Self-Quenching
rate on
Effect of volumetric
flow rate of gas at constant density on
Processes
In this category are high frequency pulse hardening (Ref I ), electron
beam, and laser processes (Ref 7).
Self-quenching
occurs when the cold interior of a Horkpiece is a sufficiently large heat sink to quench hot surfaces hq heat conduction to the
interior at a rate fast enough to allo\\ martensite to form at the surface.
Heat sources are the laser. electron beam. and inductive electric heating.
In pulse hardening wjth induction heating, for example. power density is
up to about 300 W/mm-. and heat treatment is in the millisecond rangs (Ref
I). With each process, areas treated are small and part size can be a
restriction.
Applications
Lasers. Materials hardened include plain carbon steels ( IO-IO, 1050,
1070). alloy steels (4340. X!lOO,, tool steels, and cast irons (pm!. ductile.
and malleable). Examples include selectike hardening of irregularly shaped
parts like camshafts and crankshafts. which are subject to wear and have
fatigue-prone areas (see adjoining Figure. Ref Zj.
Electron Beam. Commonly used steels are listed in an adjoining Table. Typical parts are shown in an adjoining Figure (Ref I?).
Area treated on ductile iron camshaft is indicated (Ref 2)
90 / Heat Treater’s
Guide
Pulse Hardening. Selectively hardened parts include saws (in an adjoining Figure, Ref I). circular saw blades, and punching tools, plus
precision engineering components for the electrical and textile industries
(see Figure, Ref I). Also, this process produces very fine, acicular structures that add corrosion resistance to a part.
References
I. G. PIBger, “HF Pulse Hardening in the Millisecond
Range,” ASM
Conference Proceedings, Quenching and Dbronion Control, ASM Intemational. I992
2. ASM Memls Hundbook, Hear Treoring. Vol4. 10th ed., ASM Intemational. 1991
Typical components heat treated with electron beam hardening method. (a) Rollerbearing element support. (b) Selected
components used for both linear and rotary motion applications.
Courtesy of Chemnitzer Werkzeugmaschinen
GmbH (Ref 2)
Hardened teeth on band saw blade (Ref 1)
Samples of textile industry parts (Ref 1)
Steels Commonly
AIs1
Material
UNS No.
Used in Electron
Carbon and low alloy
GJl400
12CrMa-l
-II40
1340
ES2100
1015
IO45
I070
Gl34OO
GS2986
G10150
G lO4SO
Gl0700
C
DtN(a)
Beam Hardening
Si
Applications
hln
P
s
Composition, wt %
Cr
hlo
QMnV7
IOOCr6
c I5
c-is
Ck67
55CrI
SOCrV 1
0.X3-0.45
0.38-0.45
0.95-1.05
0.12-0.19
0.12-0.50
0.65-0.72
0.52-0.60
0.37.0.55
0.17-0.37
0.17-0.37
0.17-0.37
0.17-0.37
0.17-0.37
0.15-0.50
0.17-0.37
O.-l max
0.50-0.80
1.60-1.90
0.20-0.15
0.35-0.6.5
O.SO-0.80
0.60-0.80
0.5-0.8
0.7-I. I
0.03Smax
0.03Smax
0.027 max
O.O-lOmax
0.04Omax
0.03Smax
0.03.5 max
0.035
0.035 max
0.035max
0.020max
O.O-K)ma.\
O.O-!Omax
0.035 max
0.03 max
0.90-1.10
0.30max
1.30-1.65
O.SOmax
OSOmax
0.3Smas
0.2-0.5
0.9. I .2
9OMnV8
c IOIIWI
0.8.5-0.9.5
0.95-1.04
0.15-0.35
0.15-0.30
I 80-2.00
0.15-0.25
0.030max
0.02Omax
0.030max
0.020mai
.._
0.20max
O.iS-0.2s
O.lOmax
O.lOmax
O.lOmax
Ni
0.3Omax
0.30max
0.30max
0.3Omax
0.30max
0.35 mar
0.3max
v
(a) Deuwhe
T31.502
T72301
Industrie-Normen.
(bj0.25
max Cu
Ti
0.25
__.
0.02-0.0s
0.07-0.12
0.20maxfb)
Cu
0.06max
0.07-0.12
Tool steels
02
WI
Al
0.35
0.3 max
0.015
0. I-O.2
Other Quenchants/Processes
Fluidized
Bed Quenching
Nitrogen and air are common quenching media. Other quenchants are
argon, carbon dioxide, helium, or hydrogen. Critical variables are rate of
fluidizing gas flow and thermal conductivity
of the gas.
Characteristics
/ 91
of Process
Control over quenching with this process CompXes favorably with that
of other liquid quenchants. The heat transfer mechanism is uniform
throughout the entire temperature range. and is dominated by the properties
of the gas phase. Quench rates are reproducible, do not degrade with time.
and can be adjusted within wide limits and operate over a wide temperature
range (Ref I ).
The quenching or heat treating rate can be adjusted by altering operating
conditions of the fluid bed. Variables include particle size and volume
(aluminum oxide is preferred). rate of fluidizing gas flow, and the thermal
conductivity
of the gas. Nitrogen usually is the choice. Quench seberitics
are between those of still air and slow air.
Comparisons of quenching rates for fluidized beds operating
on nitrogen, and vacuum furnaces operating at 2 bar and 6
bar quench pressures at temperatures up to 575 “C (1065 oF)
In comparison with other heat treating/quenching
processes, the fluid
bed is less sensitike to load densit) and part geometry. Because of the
liquidlike characteristics
of the fluid bed. parts are surrounded by aluminum oxide particles. and the high heat capacity of aluminum oxide does
not require complete gas flow over all surfaces because heat is removed by
conduction.
Operating
Information
In treating H-I I and H- 13 forging dies the following
(Ref I):
Preheat work to 595 “C ( I I05 “Fi
Austenitize at IO-10 “C (I905 “F)
l
Step quench at 595 “C (I IO5 “F)
9 Fluid bed quench at ambient temperature
290 “C (555 “F)
l
Air cool to room temperature
procedure
was used
l
l
for 5 to 7 min at approximately
A second, two-stage process: quenching in helium first, followed by
quenching in nitrogen. Application:
austempering 4340. medium carbon
steel tools. replacing salt processing. i.e., austenitizing at 920 “C (1690 “F)
and quenching into salt at 330 “C (610 “F). then holding for 30 min. For
the two-stage process. the quench temperature was reduced from 330 “C
(625 “F) to 295 “C (565 “F).
Step NO. 1: Short pulse (30 to 60 s) of helium to drive the load past the
nose of the cooling curve. (In treating 4340, the fust IO s of the cooling
curve is critical). Beyond this point allowable time is increased.
Step NO. 2: Gas is switched from helium to nitrogen for the remainder
of the cycle.
In cases u here hardness values in fluidized bed quenching are slightly
lower than those of the other quenchants, higher hardness can be obtained
by slightly decreasing fluidized bed temperatures.
Range
of Applications
Standard and special fluid bed processes are available. Air hardening tool
steels. for example, are within the range of the former, while medium and
low allo) steels are among the applications of the latter.
Standard Process. Performance of this process in treating air hardening tool steels is said to compare favorably with that of high pressure gas
quenching in a vacuum furnace. In this instance. two critical factors are:
the quench rate must be severe enough to effect full metallurgical transformation of thick sections. Chile not causing severe distortion or cracking.
COmpariSOn
of results in quenching and normalizing
normalized.
Specimens
were 12.6 mm (0.50 in.) diameter
with: A, salt solution;
bars.
B, agitated
water;
C, still water;
D, oil; E, fluidized
bed; F,
92 / Heat Treater’s
Guide
Quenching rates for the fluid bed process and those for high pressure gas
quenching in vacuum are compared in an adjoining Figure. The fluid bed
rate is slightly higher than that at 6 bar quench pressures. The material is
M-2 high speed tool steel. Other comparisons are made in a second Figure.
Special Process. The standard fluidized bed has insuffwient heat
transfer characteristics
to be useful in quenching medium to IOU allo]
steels because the critical portion of their cooling cycle is the first IO s.
which precludes the application of a number of these alloys in austempering. marquenching,
and direct hardening. This limitation is bypassed by
modifications
in the standard process. Quenching speeds are significantly
higher.
The special process has t&o phases.
In the first phase, helium replaces nitrogen for cooling in the critical
portion of the cycle (the nose of the isothermal transformation
cycle).
Helium has a gas conductivity
nearly six times that of nitrogen. and the
fluidization
rate is doubled. The helium phase takes 30 to 60 s.
In the second phase, nitrogen replaces helium for the rest of the
cycle.
Example of an Application: nustempering 4310 steel tools. In salt
processing. parts were austenitized at 920 ‘C (1690 “F). and they \ierc
quenched in salt at 315 “C (600 “F). then held at that temperature for 30
min. In processing uith the modified fluid bed process. the austemperinp
quenching temperature was reduced from 3 I5 to 295 “C (600 to 565 “F).
Hardness of these parts was lower than that of those treated ~rith the salt
Ultrasonic
Virtually
of Process
Vapor blanket formation
Figure).
Operating
52 100, bearing races. oil quenched
1340, wood routing bits, austempered at 350 “C (660 “F)
Modified S-3. screw driver bits austempered at 3 I5 “C (600 “F)
O-l, general tooling. marquenched in salt at 210 “C (410 “F)
Ductile iron. crankshaft. oil quenched
86B-lO. forging, oil quenched
5 150, machined parts. oil quenched
Reference
I. A. Dinunsi, “AdLances
Conference Proceedings.
ternational. I992
in Fluidired
Bed Quenching,”
p 71. ASM
Qutvrchittg md Disronion
Conrtd, ASM In-
Other References
l
l
Totten et al., Hmdbook
AShl International
.4W Aie~l~ls Hntdbook.
tional
oj Qrret~chatrrs
Hear Twctrittg.
md
Qwm-hittg
Technology
Vol 4. 10th ed.. ASM
Intema-
Quenching
any liquid quenching medium can be used in ultrasonic quenching.
Characteristics
process. The desired result H;LS obtained by slight reductions in the fluid
bed temperature.
Steel parts treated by this process and prior quenching techniques include
the foIloH ing:
is readil)
interrupted
by ultrasonic
energ! (see
Reference
I. Totten et al.. Hmcibook of Quettchcwts
AShl International.
1993
and Quenching
Technology,
Information
Ultrasonic agitation substantially
increases quench severit) (see Table).
but the cracking and distortion that can be caused b>, oil, Water, or brine
quenchants often are eliminated. Reductions in distortlon and cracking are
often accompanied by an increase in hardness.
Grossmann H Values of Various
without Ultrasonic Energy
Quenchant
Quenchants
with and
Gmssmann H value
Oil
Still quench
Violent agitalion
llltra.sonic agitation
0.2YO.30
0.80/1.10
I .bS
Brine
Still quench
Violenr agitation
Uluasonic agitalion
2.0
s.0
7.5
Hot salt at (400 OF)
Still quench
Violenl agitation
llluasonic agifation
0.30
I.20
1.80
Comparison of vapor blanket phases during oil quenching
and ultrasonic quenching
Other QuenchanWProcesses
/ 93
HIP Quenching
The HIPquencher
is an offshoot of the more familiar hot isostatic press
used to densify metal powders and ceramics and to improve certain properties of castings.
Gas (usually argon) is the only cooling medium in HIPquenching.
Rapid
cooling is obtained with high pressure gas at 800 to 1800 bar. Heated gas
is cooled in a heat exchanger. Gas pressure pushes gas atoms closer
together, increasing the number of atoms that remove heat from steel
surfaces. The heat exchanger is located in the HIP vessel outside the hot
zone.
Characteristics
of Process
The extremely high heat transfer coefficient of gas under high pressure
makes for less variation in temperature in different areas of a part. reducing
the likelihood of distortion. Characteristics
of several different quenching
methods are compared in an adjoining Table. The heat transfer coefficient
of the process is of the same magnitude as that for the fluidized bed and
about three times greater than that for the vacuum furnace (see Figure). Gas
temperature is closely controlled by computer as a function of time.
Applications
Higher hardenability
are in the applications
ment can be combined
steels such as high speed steels and other tool steels
range of the process. Densiftcation
and heat treatin a single operation.
Heat transfer coefficients
Spray
References
I. Bergman and Segerberg. “HIP Quencher for Efftcient and Uniform
Quenching.” and Segerberg. ASM Conference Proceedings, Qumching
and Disioniotr
Cotlrrd. AShl International,
I992
1. A. Traff. M~!nl Powder Repon, 15 (199Oj, 1
3. ltdus~rial
Qutwchitrg
Oils-Dt~rennitlnrion
of Coolitrg
Ctraracreristics-Lahomroy
T&r Mrrhod.
Draft
international
standard
ISO/DIS 9950. International Organization
for Standardization
(submitted 1988).
1. S. Segerberg, n/F‘-mpporr
920-71. n/F, Giiteborg, Sweden
Characteristics
Method of
quenching
Vacuum
Sah halh
Fluidizrd bzd
HIPquencher
of Four Quenching
Temperature of
quenchant, OC
Methods
Gas
60
Nitrogen
230
20
Drlcrrasing from 1000
Nitrogen
Argon
PMSU~,
bar
Refl
of different quenching methods (Ref 1)
Quenching
Process
High pressure streams of quenching fluids arc directed onto areas of a
uorkpiece requiring higher cooling rates. Quenchant droplets formed by
the spray account for the speedup in cooling rate. Lou pressure spraying.
providing a flood-type now, is preferred in quenching with some aqueous
polymers. Spray nozzles are located on a quench rig. Quenching characteristics can be innuenced by volume and pressure of the quenchant. as well
as the design of spray nozzles.
94 / Heat Treater’s
Guide
Fog Quenching
Process
A tine fog or mist of liquid droplets in a gas carrier is the cooling agent.
Cooling rates are lower than those in spray quenching because of the
relatively low liquid content of the stream.
Cold Die Quenching
Llsed for parts such as thin disks and long. slender rods that distort
excessively
when quenched in conventional
liquid media. Quenching is
between various forms of cold, flat, or shaped dies, which usually are in a
press close to austenitizing operations.
Quenching
in an Electric
of Process
In quenching in an electrical field, uniformity
of surface heat transfer is
enhanced by destabilizing
vapor blanket cooling by passing an electrical
current through the workpiece.
Operating
I. ASM Mrrals Haruibook, Hear Treating,
tional. I99 I
or Magnetic
In quenching steels in an electrical field, electrical current is passed
through the part while it is submerged in a liquid such as oil or water.
In quenching in a magnetic field. steel is quenched into an aqueous
suspension of IO nm magnetic particles.
Characteristics
Reference
Information
It has been demonstrated. for example that the hardness of a 0.15 percent
carbon steel can be increased IO to I8 HRC, while quench-induced
microstresses are virtually eliminated (see Figure).
Similar results have been obtained in magnetic field quenching. Cooling
rates throughout the quench can be controlled
by the concentration
of
magnetite particles and the force of the magnetic field (Ref I .4).
References
I. Totten et al., Handbook qf Q~tetrchatm and Qttenctring Techtwlog?;
ASM International,
I993
2. A.A. Skimbov. LA. Kozhukhar. and N.N. Morar. So\: Eng. Ai~p/. Necrrochem, Vol 2, 1989, p 136-138
3. A.A. Skimbov, LA. Kozhukhar. and N.N. Morar. Elekrrontray
Obrab.
MareI. Vol2, 1989. p 87-88
1. S.N. Verkhovskii.
L.I. Mirkin.
and A.Ya. Simonovskii.
Fi:. Khitn.
Obrab. Mares:, Vol2. 1990, p I27- I32
Vol 4. 10th ed., ASM
fntema-
Field
Microstresses on perimeter of 0.45 percent carbon steel
quenched in different media (Ref 1)
Other QuenchanWProcesses
Quenching
Flame
and Induction
Water is the common quenchant for flame and induction hardened
workpieces.
Other media are oil, soluble oil, compressed air. aqueous
polymer solutions. and brine (Ref I).
Characteristics
Parts
Reference
I. ASM Metals Handbook,
tional, 1991
Hear Treating.
Vol 1. 10th ed., ASM Interna-
of Process
Water is the choice unless metallurgical
severe quenching media.
Operating
Hardened
/ 95
considerations
call for less
Information
Open and submerged spray systems generally are used in conjunction
with induction hardening. Spray oriftces for water quenching are relatively
small to maximize cooling rates. Different orifice sizes and spray pressures
are required in quenching with aqueous polymers. High pressure and fine
spray cause premature rupture of polymer films on hot metal surfaces,
which reduces cooling rates. Recommended orifice sizes and fluid pressure
for quenching steels from an austenitizing temperature of 845 “C (I 555 “F)
with polyethylene
glycol (PAG) are listed in an adjoining Table (Ref I).
Recommended
Orifice Sizes and Fluid Pressures
Induction Spray Systems
Orifice
diameter
-m(b)
Tjpe ofsprq
Q-=n
Submerged
(8)
for
kPa
psi
mm
in.
<l-ICI
>ZlS
<X
>-Ml
3.2
6.1
‘4
‘4
(a) All of the cooling c‘urves for the quench factor correlation were determined using
AlSl bpe 30.4 stainless steel prohes. thy Data for LJCON (Union Carbide Chemicals
and Plastics Company. Ins JQuenchant B
Tempering
Conventional
Processes/Technology
Processes
Tempering is a process in which previously hardened or normalized steel
is usually heated to a temperature hclocr the IOU er critical temperature and
cooled al a suilable rate. primarily to increase ductility and toughness. hut
also to increase the grain size of the matrix. Steels are tempered b)
reheating after hardening to obtain specific Lalues of mechanical properties
and also to relieve quenching stresses and to ensure dimensional stahilitj.
Tempering usually follows quenching from above the upper critical temperature; hoNever, tempering is also used to relieve the stresses and reduce
the hardness developed during ueldinp and to relisve stresses induced b)
fomling and machining.
Principal
Variables
Variables that affect the microstructure
a tempered steel include:
l
l
l
Tempering temperature
Time at temperature
Cooling rate from the tempering
Typical
Hardnesses
Grade
Carbon
content,
k
Carbon
1030
I040
1050
lob0
1080
IO??5
11.37
IIJI
1131
Alloy
SO
51
s2
56
57
ss
44
19
55
steels, water
hardening
0.30
0.30
0.30
0.30
0.30
0.30
47
47
47
47
37
47
Alloy
steels, oil hardening
O.-IO
4140
4340
ul-lo
8740
4150
5150
6150
8650
8750
9850
0.40
0.10
O.-IO
0.40
0.50
0.50
OS0
050
o.so
050
260 ‘=C
(500°F)
carbon content, alloy content, and
ln a steel quenched to a microstructure consisting essentially of martensite, the
iron lattice is strained b) the carbon atoms, producing the high hardness of
quenched steels.
Under certain conditions. hardness may remain unaffected hy tempering
or may even be increased as a result of it. For example, tempering a
hardened steel at I eq low tempering temperatures may cause no change in
hardness but may achieve a desired increase in yield strength. Also, those
allo) steels that contain one or more of the carhide-forming
elements
(chromium. molybdenum.
vanadium. and tungsten) are capable of secondq hardening: that is. they ma) become somewhat harder as a result of
tempering.
The tempered hardness \ alues for se\ eral quenched steels are presented
in an adjoining Table. Temperature and time are interdependent variables
in the tempering process. Within limits. lowering temperature and increasing time can usualI! produce the same result as raising temperature and
decreasing time. However, minor temperature changes have a far greater
315T
(6OOT)
37OT
(700°Fj
J25T
temperiag
for 2 hat
48OT
-540 T
595 T
650 T
@OO°F) (9OO’=F)(lOOO°F) (1100°F) (1200°F)
Heat treatment
hardening
1330
2330
3130
1130
Sl30
8h.30
0.10
of
Composition
of the steel. including
residual elements
Carbon and Alloy Steels after Tempering
Hardness, HRC, after
0.30
0.40
0.50
0.60
0.80
0.95
0.30
O.-IO
0.40
1340
properties
temperature
of Various
205 T
(.WO”F)
steels, water
31-U)
and the mechanical
l
57
55
57
55
51
57
56
57
58
ss
56
51
45
13
48
50
ss
55
57
42
46
so
46
16
SO
SO
51
40
13
47
39
42
4-l
42
43
-17
37
II
4s
31
37
40
38
II
43
33
38
39
28
30
37
37
40
-12
30
31
32
9513) Normalized at 900°C (1650°F). waterquenched from
830~X-iS“C(
l525-15SO”F):s~eragedea
point.
94cIJ
72
16”Cl60”F,
Normalized a~885 “C I I625 “F). water quenched From
26
7’
800-81.5 “C (1175.15OO”F):a\rrage dew poim.
;;
7“Ct4S”F)
91ta1 Normali~dur 900 “C Il650”F~. waterquenched from
830-855 “C 1 I SZS- I S7S “F); average dew point.
943)
‘5
‘7
31
3s
39
-II
27
28
29
97w
I6
I6
I6
22
‘2
22
s3
52
s3
5’
ii
53
55
55
57
5-l
55
5.3
50
49
50
46
17
17
4-t
-II
15
II
37
41
38
33
36
35
30
33
so
50
50
53
52
53
s2
5’
ii
17
48
17
51
19
SO
49
51
18
42
45
+I
17
45
46
4s
46
1s
40
41
II
46
39
1’
-II
4-t
II
37
39
38
43
3-I
40
37
39
36
3-l
31
35
39
31
36
32
3-t
33
Data were obtained on 25 null t I in.) bars adequateI) quenched wdc\elop
full hzdnejs. (a~ Hardness. HRB
31
16
19
31
27
37
ii
18
31
28
3’
lo
lB”Cl55”F1
at 900 “C ( 1650°F). water quenched fmm
800-815 “C(I-175-1500”F):a\er~gedew
point,
16”Ct6O”F)
Normalized at 88S “C ( 1625 OF),water quenched from
8004355 “Cl l-l7S-lS7S “F);areragedew point.
Normtired
I6 “C (60 “F)
Normalized at 870 “C t 1600 “F). oil quenched hum
X30-849 “C I ISIS- I550 “F); average dew point.
l6’>C (60°F)
Normalized at 870 “C (1600 “F). oil quenched from
830-845 “C ( 1525. I575 “F): average dew point.
I3 “C (5.5 “F)
Normalizcda1870”C( 1600”F),oiIquenchedfrom
830-870 ‘C t I SZS-I600 “F); aLerage deu point.
13”CtSS’F)
Normalized at 870 “C ( 1600°F). oil quenched from
8 1%845 “C t IYJO- lSSO”F): average dew point.
13”C155”F,
Tempering
effect than minor time changes in typical tempering operations. With few
exceptions, tempering is done at temperatures between 175 and 705 “C
(315 and I300 “F) and for times from 30 min to 1 h.
Structural Changes. Based on x-ray, dilatometric. and microstructural studies, there are three distinct stages of tempering, even though the
temperature ranges overlap (Ref I-4):
l
l
l
Stage I: The formation of transition carbides and lobering of the carbon
content of the martensite to 0.1SQ ( 100 to 250 “C, or 310 to 480 “F)
Stage II: The transformation
of retained austenite 10 ferrite and cementite
(200 to 300 “C. or 390 to 570 “F)
Stage IfI: The replacement of transition carbides and low-temperature
martensite by cementite and ferrite (250 to 350 “C. or 180 to 660 “F)
An additional
stage of tempering (stage IV). precipitation
of fineI>
dispersed alloy carbides, exists for high-alloy steels. It has been found that
stage I of tempering is often preceded by the redistribution
of carbon atoms.
called autotempering or quench tempering, during quenching and/or holding at room temperature (Ref 5). Other structural changes take place
because of carbon atom rearrangement preceding the classical stage I of
tempering (Ref 6,7).
Dimensional
Changes. Martensite transformation is associated with
an increase in volume. During 1empering. martensite decomposes into a
mixture of ferrite and cementite with a resultant decrease in volume as
tempering temperature increases. Because a 100% martensitic structure
after quenching cannot always be assumed, volume may not continuous11
decrease with increasing tempering temperature.
The retained austenite in plain carbon steels and low-alloy
steels transforms to bainite with an increase in volume, in stage II of tempering. When
certain alloy steels are tempered. a precipitation
of finely distributed allo)
carbides occurs. along with an increase in hardness, called secondq
hardness, and an increase in volume. With the precipitation
of allo) carbides. the MS temperature (temperature at which martensite starts to foml
from austenite upon cooling) of the retained austenite will increase and
transform to martensite during cooling from the tempering temperature.
Tempering Temperature.
Several empirical relationships have been
made between the tensile strength and hardness of tempered steels. The
measurement of hardness commonI> is used to evaluate the response of a
steel to tempering. An adjoining Figure shous the effect of tempering
Effect of tempering
temperature
of 1050 steel that was forged
heat: 0.52% C, 0.93% Mn
on room-temperature
to 38 mm (1 SO in.) in diameter,
mechanical
then water
Processes/Technology
/ 97
temperature on hardness, tensile and yield strengths, elongation, and reduction in area of a plain carbon steel (AISI 1050) held at temperature for I h.
It can be seen that both room-temperature
hardness and strength decrease
as the tempering temperature is increased. Ductility at ambient temperatures. measured by either elongation or reduction in area, increases with
tempering temperature.
hlost medium-allo)
steels exhibit a response to tempering similar to that
of carbon steels. The change in mechanical properties with tempering
temperature for 4330 steel is shorn n in an adjoining Figure.
There is no decrease in ductility in the temperature range of tempered
martensite embrittlement.
or ThIE (also known as 160 “C [SO0 “F] embrittlsment or one-step temper embrittlement)
because the tensile tests are
performed on smooth. round specimens at relatively
low strain rates.
Home\sr. in impact loading. catastrophic
failure may result when alloy
steel is tempered in the tempered martensite embrittlement
range (260 to
370 “C. or SO0 to 700 “F).
H’hereas elongation and reduction in area increase continuously
with
tempering temperature. toughness. as measured by a notched-bar impact
test. \ aries uith tempering temperature for most steels, as shown in an
adjoining Figure. Tempering at temperatures from 260 to 320 “C (500 to
610 “F) decreases impact energy to a value below that obtained at about
IS0 “C (300 “F). Above 320 “C (610 “F), impact energy again increases
mith increasing tempering temperature. Both plain carbon and alloy steels
respond IO tempering in this manner. The phenomenon of impact energy
centered around 300 YY (570 ‘Fj is called tempered martensite embrittlement (ThlE) or 160 “C (SO0 “F) embrittlement.
Tempering Time. The difision
of carbon and alloying elements necessarj for the formation of carbides is temperature and time dependent. The
effect of tempering time on the hardness of a 0.828 C steel tempered at
various temperatures is shown in an adjoining Figure. Changes in hardness
are approximateI)
linear over a large portion of the time range when the
time is presented on a logarithmic scale. Rapid changes in room temperature hardness occur at the start of tempering in times less than IO s. Less
rapid. but still large. changes in hardness occur in times from I to IO min.
and smaller changes occur in times from I IO 2 h. For consistency and less
dependency on variations in time. components generally are tempered for
I to 2 h. The levels of hardness produced by very short tempering cycles,
properties
of 1050 steel. Properties
quenched
and tempered
at various
summarized
temperatures.
are for one heat
Composition
of
98 / Heat Treater’s
Guide
Effect of tempering
temperature
on the mechanical
properties of oilquenched
4340 steel bar. Single-heat results: ladle
composition, 0.41% C. 0.67% Mn, 0.023% P, 0.018% S, 0.26% Si,
1.77% Ni, 0.78% Cr, 0.26% MO; grain size, ASTM 6 to 8; critical
pointsAc,, 770°C (1420”F);Ar,, 475°C (890°F); Ar,, 380°C (720
“F); treatment, normalized at 870 “C (1600 “F), reheated to 800 “C
(1475 “F), quenched in agitated oil; cross section, 13.46 mm
(0.530 in.) diam; round treated, 12.83 mm (0.505 in.) diam; round
tested; as-quenched hardness, 601 HB. Source: Ref 8
Notch toughness as a function of tempering temperature
for
4140 (UNS G41400) ultrahigh-strength
steel tempered 1 h
Alloy Content
Carbon Content
The main purpose of adding alloying elements to steel is to increase
hardenability
(capability to form martensite upon quenching from above its
critical temperature). The genera) effect of alloying elements on tempering
is a retardation of the rate of softening, especially at the higher tempering
temperatures. Thus. to reach a given hardness in a given period of time,
alloy steels require higher tempering temperatures than do carbon steels.
Alloying elements can be characterized as carbide forming or non-carbide forming. Elements such as nickel, silicon, aluminum. and manganese,
which have little or no tendency to occur in the carbide phase, remain
essentially
in solution in the ferrite and have only a minor effect on
tempered hardness. The carbide forming elements (chromium, molybdenum. tungsten, vanadium, tantalum. niobium, and titanium) retard the
softening process by the formation of alloy carbides.
Strong carbide-forming
elements such as chromium, molybdenum, and
vanadium are most effective in increasing hardness at higher temperatures
above 205 “C (100 “F). Silicon was found to be most effective in increasing
hardness at 3 I5 “C (600 “Fj. The increase in hardness caused by phosphorus, nickel. and silicon can be attributed to solid-solution
strengthening.
Manganese is more effective in increasing hardness at higher tempering
temperatures. The carbide-forming
elements retard coaJescence of cementite during tempering and foml numerous small carbide particles. Under
certain conditions, such as with highly alloyed steels, hardness may actually increase. This effect, mentioned previously.
is known as secondary
hardening.
Other Alloying Effects. In addition to ease of hardening and secondary hardening. alloying elements produce a number of other effects. The
higher tempering temperatures used for alloy steels presumably permit
greater relaxation of residual stresses and improve properties. Furthermore,
the hardenability
of alloy steels requires use of a less drastic quench so that
quench cracking is minimized. However, higher hardenability
steels are
prone to quench cracking if the quenching rate is too severe. The higher
hardenability
of alloy steels may also permit the use of lower carbon
content to achieve a given strength level but with improved ductility and
toughness.
Residual Elements. The elements that are known to cause embrittlement are tin. phosphorus. antimony, and arsenic.
The principal effect of carbon content is on as-quenched hardness. An
adjoining Figure shows the relationship
between carbon content and the
maximum hardness that can be obtained upon quenching. The relative
difference in hardness compared with as-quenched hardness is retained
after tempering. An adjoining Figure shows the combined effect of time.
temperature, and carbon content on the hardness of three carbon-molybdenum steels of different carbon contents. Another Figure shows the hardness
of these steels after tempering for I h. as a function of tempering temperature. The effect of carbon content is evident.
furnaces or in molten
salt. hot oil. or molten metal baths. The selection of furnace type depends
primarily on number and size of parts and on desired temperature. Temperature ranges. most likely reasons for use. and fundamental problems
associated with four types of equipment are given in an adjoining Table.
Selective tempering techniques
;LTeused to soften specific areas of
fully hardened parts or to temper areas that were selectively
hardened
previously.
The purpose of this treatment is to improve machinability,
toughness, or resistance to quench cracking in the selected zone.
such as in induction tempering, would be quite sensitive to both the
temperature achieved and the time at temperature.
By the use of an empirical tempering parameter developed by Holloman
and Jaffe (Ref IO), the approximate hardnesses of quenched and tempered
low- and medium-alloy
steels can be predicted. Reasonably good correlations are obtained except when significant amounts of retained austenite
are present.
Cooling Rate. Another factor that can affect the properties of a steel is
the cooling rate from the tempering temperature. Although tensile properties are not affected by cooling rate. toughness (as measured by notchedbar impact testing) can be decreased if the steel is cooled slowly through
the temperature range from 375 to 575 “C (705 to 1065 OF). especially in
steels that contain carbide-forming
elements. Elongation and reduction in
area may be affected also. This phenomenon is called temper embrittlement.
Tempering Procedures
Bulk processing
may be done in convection
Tempering
Effect of time at four tempering temperatures on room-temperature
Processes/Technology
/ 99
hardness of quenched 0.82% C steel. Note nearly straight lines
on logarithmic time scale. Source: Ref 9
Relationship between carbon content and room-temperature
hardness for steels comprising 99.9% untempered martensite
Temperature Ranges and General Conditions
Four Types of Tempering
PP of
Temperature range
OC
OF
equipment
Comection furnace
SO-750
Salt bath
l6O-7SO 320. I380
I70- I380
Oil hath
<‘TO
--_
S-l-180
Molten meud bath
>390
>735
of Use for
Service conditions
For large volumes of nearly common
parts: variable loads m&e control of
lemperattw moredifficul~
Rapid. uniform heating; low to medium
volume; should not be used for parts
whose configurations make them hard
toclean
Good if long exposure is desired; special
ventilation and fire control are required
Very rapid heating: special fixhning is
reauired (high densiw)
For certain steels, the tempering mechanism is enhanced by cyclic
healing and cooling. A particularly
important procedure employs cycles
between subzero temperatures and the tempering temperature to increase
the transformation
of retained austenite. The term used for this procedure.
multiple tempering, is also applied to procedures that use intermediate
thermal cycles to soften parts for straightening prior to tempering.
Cracking
Induction and flame tempering are the most commonly used seleclive
techniques because of their controllable
local heating capabilities. Immersion of selected areas in molten salt or molten metal is an alternative. but
some control is sacriliced.
Special processes that provide specitic properties. such as those
obtained in steam treating or the use of protective atmospheres. are available.
in Processing
Because of their carbon or alloy contents, some steels are likely to crack
if they are permitted to cool to room temperature during or immediately
following
the quenching operation. Causes include high tensile residual
stresses generated during quenching due to thermal gradients. abrupt
changes in section thickness, decarburization,
or other hardenability
gradients. Another potential source is cracking due to quenchant contamination
and the subsequent change in quenching severity.
100 / Heat Treater’s
Guide
Accordingly.
for carbon steels containing more than 0.4% C and alloy
sleek containing more than 0.35% C. transfer of parts to tempering furnaces hefore they cool to below 100 to IS0 “C (210 LO 300 “F) is recommended. Alternately,
quenching oil may he used in tempering operation
(martempering),
or 10 avoid cooling below I25 “C (255 “F). Steels that are
known to be sensitive IC) this type of cracking include 1060. 1090. 1340,
1063.4 I SO. 3340,52 IOO,6 I SO. 8650, and 9850.
Other carbon and alloy steels generally are less sensitive to Uris type of
delayed quench cracking but may crack as a result of part configuranon
or
surface defects. These steels include 1030. 1050. I I-II. I I-L!. -W7.-ll32.
-I I10.4640.8632.8710.
and 9840. Some steels, such as 1020. 1038, I IX.
1130. 5 130. and 8630. are not sensitive.
Before being lempered. parts should be quenched to room temperature
to ensure the transformation
of most of the austenhe to martensite and to
Effect of tempering
time at six temperatures
on room-temaerature hardness of carbon-molybdenum
steels with differznt carbon contents but with prior martensitic
structures
achieve maximum as-quenched hardness. Austenite retained in low-alloy
steels will. upon healing for tempering,
transform to an intermediate
structure. reducing overall hardness. However. in medium- to high-alloy
steels containing austenite-stabilizing
elements (nickel. for example). retained austcnite may transform LOmartensile upon cooling From tempering,
and such steels may require additional tempering (double tempering) for
the relief of transformation
stresses.
Temper Embrittlement
When carbon or low-alloy
steels are cooled slowly from tempering
ahove 575 ‘C ( 1065 “F) or are tempered for extended times between 375
and 575 “C (70s and 1065 “F). a loss in toughness occurs that manifests
itself in reduced notched-bar impact strength compared IO that resulting
from normal tempering cycles and relativelv fast cooling rates.
The cause of temper embrinlement
is belkved 10 be the precipitation
of
compounds containing trace elements such as tin, arsenic. antimony, and
phosphorus, along with chromium and/or manganese. Although manganese and chromium cannot he restricted. a reduction of the other elements
and quenching from ahove 575 “C (I065 “F) are the most effecuve
remedies for this type of embrittlement.
Steels that have been embrittled because of temper embrinlement
can he
de-embritkd
by heating 10 about 575 ‘C ( 1065 “F). holding a few minutes.
then cooling or quenching rapidly. The time for de-embrittlemen~
depends
on the alloying elements presenr and the temperature of reheating (Ref I I).
Blue Brittleness
The heating of plain carbon steels or some alloy steels to the temperature
range of 230 to 370 ‘C (-US to 700 “F) ma,y.result in increased tensile and
yield strength. as well as decreased ducuhty and impact strength. This
embrittling phenomenon is caused by precipitation
hardening and is called
blue brittleness because it occurs within the blue heat range.
If susceptible steels are heated H ithin the 230 IO 370 “C (US to 700 “F)
range. they may be embrittled
and thus should not be used in pru~s
suhjrcted to impact loads.
Tempered
Martensite
Embrittlement
Both inrergranular (Ref I3- IS) and transgranular fracture modes may be
observed in tempered martensite embrittlement
(Ref 13, 16). The comhination of the segregation of impurities such as phosphorus to the austenitic
grain boundaries during austenitizing
and the formation of cementite at
prior austenitic grain boundaries during tempering are responsible.
Effect of carbon content and tempering
temperature
on
room-temperature
hardness
of three molybdenum
steels.
Tempering time: 1 h at temperature
Tempering
There is a loss in impact toughness for steels tempered in the temperature
range of 250 to 300 “C (380 to 570 OF). Steels with lower phosphorus
content have superior impact properties than steels with a higher phosphorus level. Also. impact toughness decreases with increasing carbon content
(Ref 17). Generally, with steels containing either potent carbide forms such
as chromium or other impurities that make them susceptible to tempered
martensite embrittlement,
tempering between 200 to 370 “C (390 to 700
“F) should be avoided.
Hydrogen
Embrittlement
The selection of tempering temperature and the resultant hardness or
plasticity must include the consideration of the potential problem of hydrogen embrittlement
under these conditions:
the part will be exposed to
hydrogen through electroplating.
phosphating, or other means. or where
environmental
conditions will cause the cathodic absorption of hydrogen
during service.
Generally, the restricted notch ductilit) of steels with hardnesses above
10 HRC presents ideal conditions for the development of stress concentrations in parts containing notches or defects that would. in the presence of
relatively low hydrogen concentrations.
lead to failure at stresses far below
the nominal tensile strength of the material. Such parts should be tempered
to hardness below 10 HRC if they are to be subjected to relatively high
stresses and probable exposure to hydrogen.
References
I. C.S. Roberts, B.L. Auerbach. and M. Cohen, The Mechanism and Kinetics
of the Fit Stage of Tempering. Trarrs. ASM, Vol35. 1953, p 576-60-I
2. B.S. Lement. B.L. Auerbach. and hf. Cohen, Microstructural Changes on
Tempering iron Carbon Alloys, Trarrs. ASM. Vol46. 19%. p 85 l-88 I
3. F.E. Werner. B.L. Auerbach. and M. Cohen, TheTempering of iron Carbon
Martensitic Crystals. Trans. ASI%~.Vol-19. 1957. p 823-841
Martempering
tional process.
transformation
(b) Mattempering.
/ 101
4. G.R. Speich. Tempered Ferrous hlartensitic Structures. in Mm/s Huruibook. Vol8,8th ed., American Society for Metals, 1973, p 202-204
5. G.R. Speich and WC. Leslie. Tempering of Steel, Merd.
Trms., Vol 3,
197’. p l@l3-1054
6. S. Nagakwra. Y. Hirotsu. hl. Kusunoki. T Suzuki, and Y. Nakarnura,
C~stallog~aphic
Stud> of the Tempering of hlartensitic Carbon Steel by
Electron hlkroscopy
and Diffraction. hfe!o/l. Trorrs. A, Vol I4A. 1983, p
1025-1031
7. G. Krauss. Tempering and Structural Change in Ferrous Martensitic Struttures. in Ptme Insrrlrtt,u~nroriorls
in Fertms
Allop,
A.R. Marder and J.I.
Goldstein. Ed., TMS-AIhlE.
198-l. p 101-123
8. Modem
Sleek cm/ Ttreir Propenies.
Handbook 3757.7th ed., Bethlehem
Steel Corporation, 1972
9. EC. Bain and H.W. Paston. Altq\ing
Ekarrrm
in Steel. Anlerican
Society
for hletds, 1966, p 185, 197
IO. J.H. Holloman and L.D. Jaffe. Tie-Temperature
Relations in Tempering
Steels, Trans. A/ME, Vol 162. 1945, p 223-249
I I B.J. Schulz. Ph.D. thesis. University of Pennsylvania. 1972
I?. T. lnoue, K. Yamamoto. and S. Seki;ieuchi. Trms. /ml Srrel Insr. Jp., Vol
I-l. 1972. p 372
13. J.P. hlaterko~sski and G. Krauss. Tempered hlartensitic Embrittlement in
SAE -tNO Steel, hferd.
Trczrrs. 4. Vol IOA. 1979. p 1643-1651
I-4. SK. Bane@. C.T. hlcMahon. Jr., and H.C. Feng. lnter~ular
Fracture in
4340 Steel Types: Effects of Impurities and Hydrogen, Me&l. Trms. A,
Vol9A. 1978. p 737-347
IS. C.L. Briant and S.K. Banerji. Tempered Martensite Embrittlement
in
Phosphorus Doped Steels. Alrrtrll. Trms. A. Vol I OA, 1979, p l729- I736
16. G. Thomas, Retained Austenite and Tempered Martensite Embrittlement,
AlemIl. Trms. .4, Vol 9A, 1978. p 439150
17. F. Zia Ebrahimi and G. Krauss. hlechanisna of Tempered Martensitic
Embrittlement in h,ledium Carbon Steels, .4crcl h!eerul/., Vol 32 (No. IO).
198-&p 1767-1777
of Steel
The process entails an interrupted quench from the austenitizing
temperature of certain alloy, cast. tool, and stainless steels. Cooling is delq,ed
just above martensitic
transformation
for the lime needed to eyuahze
temperature throughout a part, for the purpose of minimizing
distortion.
Time-temperature
Processee/Technology
diagrams with superimposed
(c) Modified
mat-tempering
cracking. and residual stress. The resulting microsuucture
is primarily
martcnsitic. and is unvmperrd
and brittle.
Differences
bet\teen conventional
quenching and martempering
(aka
marquenching)
are shown in an adjoining Figure (see a and b).
cooling curves showing quenching
and tempering. (a) Conven-
102 / Heat Treater’s
Mechanical
Guide
Properties
of 1095 Steel Heat Treated by Two Methods
Specimen
number
Heat treatment
I
Water quench and temper
3
3
4
Water quench and temper
Martemper and temper
Martemper and temper
Eardoess,
ERC
J
Impact enemy
ft. Ibf
53.0
52.5
53.0
52.8
16
19
38
33
12
II
28
24
Eloogstion(a),
40
0
0
0
0
(a) In 25 mm or I in.
Marquenching
steps:
l
l
l
of wrought
steel and cast iron consists of the following
Cooling curves for 1045 steel cylinders quenched in salt,
water, and oil. Thermocouples were located at centers of specimens.
Quenching from the austenitizing temperature into a hot fluid medium
(oil, molten salt. molten metal, or a fluidized particle bed) at a temperature usually above the martensitic range (M, point)
Holding in the quenching medium until the temperature throughout a
part is uniform
Cooling. usually in air, at a moderate rate to prevent large differences
between temperatures on the outside and center of a section
During cooling
to room temperature.
the formation
of martensite
throughout
a part is fairly uniform.
which avoids excessive residual
stresses. When the still-hot part is removed from the bath. it is easy to
straighten or to form, and will hold its shape on subsequent cooling in a
fixture, or in air cooling after removal from a forming die. Following
marquenching, parts are tempered in the same manner as conventionally
quenched parts. The time lapse between martempering
and tempering is
not so critical as it is in conventional
quenching and tempering operations.
Advantages
of Martempering
Properties of steel treated in conventional
water quenching and tempering and steel treated in martempering are compared in an adjoining Table.
In martempering
residual stresses are lower than those developed in
conventional
quenching because the greatest thermal variations come
while the steel is still in its relatively
plastic austenitic condition and
because final transformation
and thermal changes occur throughout a part
at essentially the same time.
Other advantages of the process:
l
l
l
l
l
Susceptibility
to cracking is reduced or eliminated
When the austenitizing
bath is a neutral salt and is controlled by the
addition of methane or by proprietary rectifiers to maintain its neutrality.
parts are protected with a residual coating of neutral salt until they are
immersed in the marquench bath
Problems with pollution and tire hazards are greatly reduced if nitratenitrite salts are used. rather than marquenching oils
Quenching severity of molten salt is greatly enhanced by agitation and
by water additions to the bath
Martempering
often eliminates the need for quenching fixtures. which
are required to minimize distortion in comentional
quenching
Modified
Martempering
The only difference between this process and standard martempering is
the temperature of the quenching bath-it
is below that of the his pointwhich increases the severity of the quench (see c in Figure cited previously). This capability is important for steels with lower hardenabilitj
that require faster cooling to get greater depth of hardness.
When hot oil is used, the typical martempering
temperature in this
instance is I75 “C (34.5 “F). By comparison, molten nitrate-nitrite
salt baths
with water additions and agitation are effective at temperatures as low as
I75 “C (345 “F). The molten salt method has some metallurgical
and
operational advantages.
Martempering
Media
Molten salt and hot oil are widely used. Operating temperature is the
most common deciding factor in choosing between salt and oil. For oil, the
upper temperature is 205 “C (400 “F). Temperatures up IO 230 “C (445 “F)
are an occasional exception. The range for salt is 160 to 400 “C (320 to 750
“F).
Composition and Cooling Power of Salt. A commonly used salt
contains SO to 60% potassium nitrate, 37 to 50% sodium nitrite, and 0 to
IO%, sodium nitrate. This salt’s melting point is approximately
I40 “C (285
“F); its working range is I65 to 540 “C (330 to 1000 “F). Salts with a higher
melting point (they cost less than the one just described) can be used to get
higher operating temperatures. Their composition:
40 to SO8 potassium
nitrate. 0 to 30% sodium nitrite, and 20 to 60% sodium nitrate.
The cooling power of agitated salt at 205 “C (400 “F) is about the same
as that of agitated oil in conventional
oil quenching. Water additions
increase the cooling power of salt. as indicated by cooling curves in an
adjoining Figure and hardness values in a second Figure, in which the
cooling power of water is compared with that of water and three types of
oil.
Salt VS. Oil. Advantages of salt include the following:
l
l
l
Changes in viscosity are slight over a wide temperature range
Salt retains its chermcal stability. Replenishment. usually, is needed only
to replace dragout losses
Salt is easily washed from work u ith plain water
Disadvantages,
l
l
salt vs. oil include the following:
Minimum operating temperature of salt is 160 “C (320 “F)
Quenching from cyanide-based carburizing salt is hazardous because of
possible explosion: explosion and splatter can occur if wet or oily parts
Tempering
Processes/Technology
/ 103
Effects of quenchant and agitation on hardness of 1046 steel
Physical
of Steel
Properties
of Two Oils Used for Martempering
Value, for oil with operating
temperafurebf
95 to ISO~C
150 to 230 T
(200 to 300 T)(a)
(300 to 45oT)
f%shpoin~(min).“C(“F)
Fire pcin~ (min). “C (“F)
Vwosity. SUS, at:
38”C(IOO°F)
loo”C(210°~
150”C(300”R
17s”c(3so”F)
20.5 “C (400 OF)
230 “C (-IS0 “I3
Viscosity index (min)
Acid number
Faq -oil coment
C&on residue
Color
(a)Temperature
210~110)
2-u f-170)
23S-575
SOS-S I
36.5-37.5
9s
0.00
None
0.05
Optional
175 (525)
310(59S)
Oils For Martempering
Properties of two commonly used oils are listed in an adjoining Table.
Compounded
for the process, they provide higher rates of cooling than
conventional
oils during the initial stage of quenching.
At temperatures between 95 to 230 “C (205 to 445 “F) quenching oil
requires special handling. It must be maintained under a protective atmosphere (reducing or neutralj to prolong its life. Exposure to air at elevated
temperatures speeds up the deterioration
of oil. For every IO “C above 60
“C i I8 above I30 “F) the oxidation rate approximately
doubles, causing the
formation of sludge and acid, which can affect the hardness and color of
workpieces.
Oil life can be extended and the production
of clean work can be
maintained by using bypass or continuous filter units containing suitable
tiltering media (clay, cellulose cartridge. or waste cloth). Oils should be
circulated at a rate no lower than 0.9 m/s ( I80 ft/min) to break up excessive
vapor formed during quenching.
Advantages of oil vs. salt include the following:
118-122
5 I-52
-12-13
38-39
35-36
95
0.00
None
0.45
l
Optional
l
range for moctitied martempering
l
Oil can be used at lower temperatures
Oil is easier to handle at room temperature
Dragout is less
Disadvantages
l
l
l
of oil vs. salt include the following:
hlaximum operating temperature of oil is 230 “C (445 “F)
Oil deteriorates with usage
Workpieces require more time to reach temperature equalization
Oil, hot or cold, is a fire hazard
Soap or emulsifier is needed to wash off oil. Washers must be drained
and refilled periodically.
Oil wastes present disposal problems
are immersed in high-temperature
salt; and there is potential for explosive reactions when atmosphere furnaces are connected to martempering
salt quenches and atmospheres are sooty
Quenching salt can be contaminated
by high-temperature.
neutral salt
used for heating. To maintain quench severity. sludging is required
l
Niche for Fluidized Beds. Marquenching
Alloy steels generally are more adaptable than carbon steels to martempcring (see Figure). In general. any steel that is normally quenched in oil
can be martempered. Some carbon steels that are normally water quenched
can be mat-tempered at 205 “C (100 “F) in sections thinner than 5 mm
applications
are limited.
They have the advantage of equal heat transfer throughout
the entire
quenching temperature range. The quench rate is reproducible.
does not
degrade with time, and can be adjusted within wide limits.
l
l
Martempering
Applications
104 / Heat Treater’s
Guide
(0.1875 in.), using vigorous agitation of the martempering
medium. In
addition, thousands of flay cast iron parts are martempered on a routine
hasis.
The grades of steel that are commonly
martempered to full hardness
include 1090.3130. ~l3O,-llSO.
-1340. 300M (-!3AOhIj. -MO, 5 I-IO. 6150.
8630.86-H~. 8710. 8715. SAE I I-I I, and SAE 52 100. Carburizing Fades
such as 33 I2.163O.S 120.8620, and 93 IO also are commonly martempered
after carhurizing. Occasionally,
higher-alloy
steels such as type -l IO stainless are martempered. but this is not a common practice.
Temperature ranges of martensite formation
and low-alloy steels
in 14 carbon
Success in martempering is based on a knowledge of the transformation
characteristics (TlTcurvesj
of the steel being considered. The tempe.rature
range in which martensite forms is especially important.
Low-carbon and medium-carbon steels 1008 through 1040 are
too low in hardenability
to be successfully
martempered, except when
carhurized. The IIT
curve for the 1034 steel in an adjoining Figure is
characteristic
of a steel that is unsuitahle for martempering.
Except in
sections only a Few thousandths of an inch thick. it would be impossible to
quench the steel in hot salt or oil without encountering upper transformation products.
Borderline Grades. Some carbon steels higher in manganese content
such a< lo-11 and I I-II can be martempered in thin sections. Low-alloy
steels that have limited applications for martempering are listed (the lowercarbon grades are carburired before martempering):
1330 to I315.4017- to
Time-temperature transformation
diagrams for 1034 and
1090 steels. The 1090 steel was austenitized at 885 “C (1625 “F)
and had a grain size of 4 to 5.
Approximate maximum diameters of bars that are hardenable by martempering, oil quenching, and water quenching.
Effects of austenitizing temperature
temperature of 52100 steel
on grain size and M,
Tempering Processes/Technology
material being austenitized be uniform. Also, use of a protective atmosphere (or salt) in austenitizing is required because oxide or scale will act as
a barrier to unifomr quenching in hot oil or salt.
Process variables that must be controlled include austenitizing temperature. temperature of martempering
bath, time in mar-tempering bath, salt
contamination.
\vater additions to salt, agitation, and rate of cooling from
the martempering bath.
Austenitizing
temperature
is important because it controls austenitic grain size. degree of homogenization,
and carbide solution, and because
it affects the M, temperature and increases grain size. (See adjoining
Figure.)
Temperature control during austenitizing
is the same for mar-tempering
as for conventional
quenching: a tolerance of f8 “C (+I4 “F) is common.
The austenitizing temperatures most commonly used for several different
steels are indicated in an adjoining Table.
In most instances, austenitizinp
temperatures for martempering are the
same as those for conventional
oil quenching. Occasionally,
however,
medium-carbon
steels are austcnitized
at higher temperatures prior to
martempering to increase as-quenched hardness.
Salt Contamination.
When parts are carburized or austenitized in a
salt bath, they can be directly quenched in an oil bath operating at the
martempering temperature. However. if the parts are carburized or austenitized in salt containing cyanide. they must nor be directly mar-tempered in
salt because the two types of salts are not compatible and explosions can
occur if they are mixed. Instead, one of two procedures should be used:
Either air cool from the carburizing bath. wash. reheat to the austenitizing
temperature for case and/or core in a chloride bath, and then martemper; or
quench from the cyanide-containing
bath into a neutral chloride rinse bath
maintained at the austenitizing temperature and then martemper.
Temperature
of the mat-tempering
bath varies considerably,
depending on composition
of workpieces,
austenitizing
temperature, and
desired results. In establishing
procedures for new applications.
many
plants begin at 95 “C (205 “F) for oil quenching, or at about 175 “C (3-15
“F) for salt quenching, and progressively
increase the temperature until the
best combination
of hardness and distortion
is obtained. Mar-tempering
temperatures (for oil and salt) that represent the experience of several
plants are listed in the Tab12 pre\ iously cited.
4032,3118to4137.~22and4~27,1520,5015and50~6,6l1Xand6120.
8115.
Most of these alloy steels are suitable for mar-tempering in section
thicknesses of up to 16 to 19 mm (0.625 to 0.75 in.). Martempering
at
temperatures below 205 “C (-100 “F) will improve hardening response,
although greater distortion
may result than in mar-tempering at higher
temperatures.
Effect of Mass. The limitation of section thickness or mass must be
considered in mar-tempering. With a given severity of quench. there is a
limit to bar size beyond which the center of the bar will not cool fast enough
to transform entirely IO martensite. This is shown in an adjoining Figure.
which compares the maximum diameter of bar that can be hardened by
martempering, oil quenching, and water quenching for IO-t.5 steel and five
alloy steels in various hardenabilities.
For some applications, a fully martensitic structure is unnecessary and a
center hardness IO HRC units lower than the maximum obtainable value
for a given carbon content may be acceptable. By this criterion, maximum
bar diameter is 25 to 300%, greater than the maximum diameter that can be
made fully martensitic (see lower graph in Figure just cited). Non-martensitic transformation
products (pearlite. ferrite, and bainite) were observed
at the positions on end-quenched bars corresponding
to this reduced hardness value, as follows:
Steel
~ansformation
1045
159, pearlire
8630
1340
52100
IO% ferrite and hainite
20% ferrite and hainite
4150
SOCrpearlitemd btinirr
20% binite
1340
SQ binitc
Control
of Process
Variables
The success of martempering
depends on close control of variables
throughout the process. It is important that the prior structure of the
Typical Austenitizing
and Martempering Temperatures for Various Steels
Austenitizing
temperature
Grade
OC
Through-hardening
102-l
/ 105
Mat-tempering
temperature
Oil(a)
OF
T
Salt(b)
OF
OF
T
steels
I070
II46
1330
4063
4130
-II-to
-1140
4340. -1350
52100
52100
8740
Carburizing
steels
3312
1320
4615
1720
8617.8620
8620
9310
(a) Trme in oil varies from 1 to 20 min. depending on section thi&nrss. tb) hlutempttnng
range (and sometimes
aho\c range) are used for thinner sections and more intrtcate parts.
temperature
dcpads
on shape and ma>) of part, king
quenched:
higher temperatures
in
106 / Heat Treater’s
Guide
Time in the martempering bath depends on section thickness and
on the type, temperature. and degree of agitation of the quenching medium.
The effects of section thickness and of temperature and agitation of the
quench bath on immersion time are indicated in an adjoining Figure.
Because the object of martempering is to develop a martensitic structure
with low thermal and transformation
stresses, there is no need to hold the
steel in the martempering
bath for extended periods. Excessive holding
lowers foal hardness because it permits transformation
to products other
than martensite. In addition, stabilization may occur in medium-alloy
steels
that are held for extended periods al the martempering temperature.
The martempering time for temperature equalization
in oil is about four
fo five times that required in anhydrous salt at the same temperature.
Water Additions to Salt. The quenching severity of a nitrate-nitrite
salt can be increased significantly
by careful addition of water. Agitation of
the salt is necessary to disperse the water uniformly, and periodic additions
are needed to maintain required water content. The water can be added with
complete safety as follows:
l
l
l
l
Martempering time versus section size and agitation of
quench bath for 1045 steel bars. Effects of bar diameter and agitation of quench bath on time required for centers of 1045 steel
bars to reach martempering
temperature
when quenched
from a
neutral chloride bath at 845 “C (1555 “F) into anhydrous
nitrate-nitrite martempering
salt at 205,260,
and 315 “C (400,500,
and 600
OF). Length of each bar was three times the diameter.
Waler can be misted at a regulated rate into a vigorously agitated area of
the molten bath
In installations
where the salt is pump circulated.
returning salt is
cascaded into the quench zone. A controlled fine stream of water can be
injected into the cascade of returning salt
The austemperinp bath can be kept saturated with moisture by introducing steam directly into the bath. The steam line should be trapped and
equipped with a discharge Lo avoid emptying condensate directly into
the bath
Steam addition of water to the bath is done on baths with operating
temperatures above 260 “C (500 “F)
Austempering
of Steel
In this process, a ferrous alloy is isothermally
quenched at a temperature
below that of pearlite formation.
Workpieces are heated 10 a temperature within the austenitizing
range.
usually 790 to 915 “C (l-155 to 1680 “F).
Quenching is in a bath maintained at a constant temperature. usually in
a range of 260 Lo 400 “C (500 to 750 OF).
Parts are allowed to transform isothermally
to bainite in this bath.
Cooling to room temperature completes the process.
The basic differences between austempering and conventional
quenching and tempering is shown schemalically
in an adjoining Figure. In true
austempering. metal must be cooled from the auslenitic temperature to the
temperature of the austempering
bath fast enough to ensure complete
transformation
of austenite to bainite.
Compositions
austempering
and characteristics
Sodium nitrate. Q
Potassium nitrate. %
Sodium nitrite, B
Melting Point (approx). “C (“F)
Working temperature range. “C t0F)
of salts used for
tlibh range
Wide range
G-55
35-5s
O-25
15-55
25-55
150.165(300-330,
17s-540(315-1000,
220 (430)
360-595 (500- I IO0
Treatment of hardenable cast irons is another application. In this case, a
unique acicular matrix of bainitic ferrite and stable high-carbon austenite
is formed.
Advantages of austempering
include higher ductility.
toughness. and
strength at a given hardness (see Table) and reduced distortion. In addition,
the overall time cycle is the shortest needed to get through hardness within
the range of 35 to 5S HRC.
Quenching
Media
Molten salt is the most commonly used. Formulations and characteristics
of two typical baths are given in an adjoining Table. The high range of salt
is suitable for only austempering. while the wide range type is suitable for
ausrsmpering, martempering,
and variations thereof. Quench severities
under different conditions are compared in an adjoining Table.
The quenching severity of a nitrate-nitrite
salt can be boosted significandy with careful additions of water. The salt must be agitated to disperse
the water uniformly.
Periodic additions are needed to maintain required
water contenl.
Water usually is added bj directing a stream onto the molten salt at the
agitator vortex. A protective water shroud surrounds the water spray Lo
prevent spattering. Turbulence of the water carries it into the bath without
spattering. a hazard to the operator. Water should never be added from a
pail or dipper. Water is continuously
evaporating
from the bath at a rate
H hich increases as hot work is quenched. The amount of waler added to an
Tempering
Comparison of time-temperature
Mechanical
Properties
transformation
HtUdllesS,
HRC
Beat treatment
Water quenched and tempered
Waler quenched and tempered
Martempered and tempered
Martempered and tempered
Austempered
Austempered
I
2
3
4
5
6
open bath varies with the operating temperature
the following recommended concentrations:
Temperature
T
OF
205
260
315
370
400
500
600
700
quenching and tempering and for austempering
J
R Ibf
53.0
16
12
52.5
53.0
S2.8
19
38
33
61
5-t
1-l
28
2-I
4s
40
52.0
52.5
of the salt, as indicated
by
Water concenh-atioo,
%
‘4 to 2
‘/z 10 I
‘I4 10 ‘/2
‘4
The presence of water can be visually detected by the operator because
steam is released when hot work is immersed into the nitrate-nitrite
salt.
Oil as Quenching Media. Usage is restricted to quenching below
245 “C (475 “F), because of oil’s chemical instability, resulting in changes
of viscosity at austempering temperatures.
Quench
severity
comparison
l
II
8
for salt quenches
Still and dry
Agitated and dry
A@ated with 0.5% water
Agitated with 2% water
Agitated with IO%,water
131 Scr “Crossmann number (H)”
lb, Requirrs
feasible in treating
characteristics.
0.15-0.20
0.25-0.35
0.40-0.50
0.50-0.60
(a)
0.15
0.20-0.2s
0.30-0.40
0.50-0.60(r)
Nor possible
of Terms Related to Heat
090.I.?lbl
In the “Glossar)
special enclosed quenching apparatus
5140 and other
steels with
similar
transformation
steels include:
Steels
Selection is based on the transformation
characteristics
as indicated by time-temperature-transformation
(TIT)
important considerations
are:
l
in., %
Estimated Grossmann number (IQ at temperature
18o~C (36oOF)
370 Yz (7ooOF)
Agitation
Other austempering
l
Elongation
In
25 mm, or 1
Impactstrength
Trrating.”
Austempering
/ 107
of 1095 Steel Heat Treated by Three Methods
Specimen
No.
cycles for conventional
Processes/Technology
of a specific steel
diagrams. Three
Location of the nose of the IIT curve and the speed of a quench
Time needed for complete transformation
of austenite to bainite at the
austempering temperature
Location of the MS point
Because of its transformation
characteristics,
1080 carbon steel has
limited applicability
for austempering
(see Figure). Cooling must take
place in about I s to avoid the nose of the TIT curve to prevent transformation to pearlite on cooling. Because of this disadvantage, austempering
of 1080 is limited to thin sections-the
maximum is about 5 mm (0.1 in.).
On the other hand, 5 140, a low-alloy
steel. is well suited to the process
(see TIT curves for 1080.5 140, 1034, and 9261 in an adjoining Figure).
About 2 s are allowed to bypass the nose of the curve; transformation
to
bainite is completed within I to IO tin at 3 I5 to 400 “C (600 to 750 “F).
This means that sections thicker than those possible with 1080 steel are
l
l
l
l
Plain carbon steels containing 0.50 to I .OO% carbon and a minimum of
0.604 manganese
High-carbon steels containing more than 0.90% carbon and, possibly, a
little less than 0.60% manganese
Some carbon steels, such as IO-II. with less than O.SO%, carbon and
manganese in the range of I .OO to I .6S%
Certain low alloys, such as 5 IO0 series alloys, that contain over 0.40%
carbon, plus other steels such as -II-u). 6145, and 9440
Some steels sufficient in carbon or alloy content to be hardenable are
borderline or impractical because transformation
at the nose of the TIT
curve sms in less than I s. ruling out the quenching of all but thin sections
in molten salt witbout forming some pearlite. or transformation
takes
excessively long times.
Chemical composition
is the main determinant of the martensite start
(Ms) temperature. Carbon is the most significant variable. Direct effects of
other alloying elements are less pronounced, but carbide-forming
elements
such as molybdenum and vanadium can tie up carbon as alloy carbides and
prevent complete solution of carbon.
108 / Heat Treater’s
Time-temperature
Guide
transformation
When applied to wire, the modification
Transformation
diagram for 1080 steel, showing difference between conventional
and modified austempering.
shown is known as patenting.
characteristics of 1080,5140,1034, and 9281 steels, in relation to their suitability for austempering. 1080. limited
suitability for austempering because pearlite reaction starts too soon near 540 “C (1000 “F); 5140, well suited to austempering; 1034, impossible to austemper because of extremely fast pearlite reaction time at 540 to 595 “C (1000 to 1105 “F); 9261, not suited to austempering
because of slow reaction to bainite at 260 to 400 “C (500 to 750 “F)
Tempering
Hardness
of Various
Steels and Section
Sizes of Austempered
Section size
mm
in.
1050
1065
IQ66
108-t
3(b)
S(C)
7(C)
wi
13(c)
S(C)
1086
lo90
1090(e)
10%
1350
4063
-tlSO
436s
5140
5160(e)
8750
so100
20(C)
YC)
16(Cl
16(C)
13(C)
25(c)
26(C)
3(b)
8(c)
OF
0.12% b)
0.187(C)
0 281(C)
315
W
(d)
655
Id)
(d)
0.218(c)
0.516(c)
0.187(c)
0.810(c)
0.118(C)
0.625~)
0.625(c)
0.500(c)
(di
W
(d)
315(f)
Cd)
W
(d)
W
(di
345
315(f)
31s
(d)
(d)
td)
(d)
(a~Calculnted. (b) Sheet thickness. (c) Diamelerofsection.
(d) Salt temperature
condned pearlile as nell as binite. if) Salt with waler addilions. (g) Ehperiment3l
Typical
Production
Applications
hl, temperature(a)
T
I .ooo(c)
0.125(b)
I .035(C)
0. IX(b)
0.312(C)
3(b)
T
OF
Badness, HRC
320
610
52s
500
39s
430
-tl-47
53-56
53-56
55-58
ss-58
57-60
443 (a\*@
57-60
53-56
53-56
52 max
5-l m3.x
4348
46.7 (avg)
1748
57-60
27s
260
200
215
600( f)
adjusted logi~e
\nlur
/ 109
Parts
Salt temperature
steel
Processes/Technology
(d)
(d)
(d)
id,
(db
21o(gl
235
Z-IS
285
210
410(g)
-Iso
6SS
6OOtfj
600
td)
330
2.55
289
630
19Q
51s
maximum
-17s
S-IS
110
hardness and 1005, bsinite. (el hlodlfied
austempering:
microsuucr~re
of Austempering
Parts listed in order of increasing section thickness
Part
steel
hlaximum section
thiekness
mm
in.
Parts per unit weight
lb
kg
Salt temperature
OC
OF
77Olkg
360
3SS
330
330
370
360
370
360
345
34s
290
Immersion
time, mm
6ardlless,
ERC
IS
IS
I5
-I2
-I’
-I8
e-so
-I2
J2
1’
35
-Is-so
JS
53
so
so
Plain carbon steel parts
Clevis
Follower arm
Spring
Plate
Cam lever
Plae
7)pzbu
Tabulator srop
Lever
Chain link
Shoe-last link
Shoe-toe cap
Lawn mower Made
Leter
Fastener
Stabilizer bar
Boron steel bolt
1050
IOSO
I080
1060
106.5
1050
106s
106s
I050
IOSO
106s
1070
106s
1075
1060
1090
IOB20
0.75
0.7S
0.79
0.81
I .O
I .o
IO
1.2’
I.25
I.S
1.5
I.5
3.18
3.18
6.35
I9
6.35
0.030
0.030
0.03 I
0.032
0.040
0.041
0.0-w
0.048
0 OS0
0.060
0.060
0.060
0. I IS
0. I25
0.250
0.750
0.250
IlMig
22Okg
xx/kg
b2kg
0.S kg
I4llkg
UQlkg
187/lb
IQwlh
lonb
‘8nb
‘!iIh
6Mb
S72kg
86nig
26011b
39nh
xnh
?j I b
I l/lb
sonb
IOlh
4vlb
18/kl.
I Sb@
7alig
I I O/kg
‘? kg
I-iJ/kg
315
315
385
310
370
-110
680
675
625
b.10
6
7OO
IS
IS
IS
IS
IS
IS
b75
700
680
650
690
SSO
Et
72s
F90
700
790
30
60
IS
5
25
6-9
5
b9O
550
620
3nJ
IS
2s
-IS
I-l
700
700
700
72s
580
30
IS
15
IS
30
s3
18
-to
37
45
30
35-40
15
72s
72s
550-600
5
5
30
30-35(C)
30-39(C)
SO(C)
30-3s
so
-IO--IS
38-43
Alloy steel parts
Socket wrench
Chain link
Pin
Cylinder liner
Anvil
Shovel blade
Pin
Shaft
6lSO
Cr-Ni-V(a)
3140
1140
Gecv
Carburized
Lever
I :60
I60
‘5-1
0063
86-10
3.18
4068
3140
111Oibj
3.18
0.063
0.100
0. I25
0.115
6.39
9.53
0.250
0 37s
6150
12.7
o.sQn
0.3 kg
I IO/kg
s500/kg
I5 kg
165kg
‘jib
SO/lb
2mYlb
7 lb
‘,, lb
I wkg
0.5 kg
-I.-l kg
4vib
“, lb
2 Ih
365
290
37s
260
370
370
370
38s
305
33 kg
664
IS lb
30/Ib
honb
38S
385
290-3 I5
-IS
steel parts
1010
III7
Shti
Block
(a1ContainsO.65
8620
to0.7%
C (b) Ladedgrade.
3.06
6.35
II.13
0.1.56
O.lSO
0.438
ICI Case hardness
l3Yhg
110 / Heat Treater’s
Guide
Effect of carbon content in plain carbon steel on the hardness of fine pearlite formed when the quenching curve intersects the nose of the time-temperature diagram for isothermal transformation
pering is a tbo-step process: austenitizing
and isothermal transformation
in an austempering bath.
Generally, applications
are limited to parts made from small-diameter
bars or from sheet or strip which is small in cross section. The process is
especially suitable for the treatment of thin section, carbon steel parts
calling for exceptional toughness at hardnesses between 40 and 50 HRC.
Reduction in the area of austempered, carbon steel parts usually is much
greater than it is for parts conventionally
quenched and tempered, as
indicated in the following
tabulation for 5 mm (0.180 in.) bars of 0.85%
carbon, plain carbon steel:
Austempered mechanical properties
Tensile strength. MPa (ksi)
Keld strength. MPa (ksi)
Reduction in area. %,
Hardness, HRC
1780(258)
1450(210)
45
SO
Quenched and tempered mechanical properties
Tensile strength. MPa (ksi)
Yield strength. MI% (hi )
I795 (260)
1550(225)
28
Austenitizing
temperature has a significant eFfect on the time at which
transformation
begins. As this temperature rises above normal (for a given
steel) the nose of the TTT curve shifts to the right because of grain
coarsening. Use of standard austenitizing temperatures is recommended.
Reduction in area. %,
Hardness. HRC
Section Thickness
In commercial
austempering
practice, acceptable results are obtained
with parts having less than 100% bainite. In some instances, 85% bainite
is satisfactory. Representative
practice in a dozen plants for a variety of
parts and steels is summarized in an adjoining Table.
Dimensional Control. Dimensional change in austempering usually
is less than that experienced in conventional quenching and tempering. The
process may be the most effective way to hold close tolerances without
excessive straightening or machining after heat treating.
Modified Austempering. hlodifications
of the process that result in
mixed pearlitelbainite
structures are quite common in commercial practice.
Patenting of wire is an example. Wire or rod is continuously
quenched
in a bath maintained at 5 IO to 540 “C (950 to 1000 “F) and held forperiods
ranging from IO s (for small wire) to 90 s (for rod). Result: Moderately high
strength combined uith high ductility.
Modified practice varies from true austempering in that the quenching
rate is different; instead of being rapid enough to avoid the nose of the TIT
tune. it is sufficiently
slow to intersect the nose, which results in the
formation of tine pearlite.
Practice is similar for plain carbon steels at hardnesses between 30 and
12 HRC. In this instance. the hardness of steel quenched at a rate that
intersects the nose of the TIT curve varies with carbon content (see
Figure).
Limitations
Maximum section thickness is important in determining
if a part is a
candidate for austempering. The maximum for a 1080 steel, for instance,
is about 5 mm (0.2 in.), if the part requires a fully bainitic structure. Steels
lower in carbon are restricted to proportionately
less thicknesses. However.
heavier sections can be handled if a low-carbon steel contains boron. Also,
sections thicker than 5 mm (0.2 in.) are regularly austempered in production when some pearlite is tolerated (see Table that lists section thicknesses
for specific steels).
Applications
Austempering
usually is substituted
tempering for these reasons:
l
l
l
l
To
To
To
To
for conventional
quenching
and
improve mechanical properties
reduce the likelihood of cracking and distortion
upgrade wear resistance at a given hardness
add resistance to subsequent embrittlement
At times. austempering is more economical than conventional quenching
and tempering-most
likely when small parts are treated in an automated
setup in competition with conventional
quenching and tempering, which is
a three-step operation: austenitizing.
quenching, and tempering. Austem-
SO
Carbon
Designation
& Alloy
Steels
Introduction
System
Much study and effort have been put into providing a simplified list of
steel compositions to serve the metallurgical
and engineering requirements
of fabricators and users of steel products. These studies have resulted in the
carbon and alloy steel compositions
listed in Tables 2 to IO and are
generally known as the Standard Grades.
Table 1 Types and Approximate Percentages of
Identifying Elements in Standard Carbon and Alloy
Steels
Series
designation
AISI-SAE Grades
Carbon
With few exceptions. steel compositions
established by the American
iron and Steel Institute and the Society of Automotive Engineers (AISI and
SAE) use a four-numeral series to designate the standard carbon and alloy
steels. specified to chemical composition ranges. In two instances of alloy
steels. a five-numeral
designation is used.
In the alloy steel tables which are presented later in this section. some
grades bear the prefix letter E. This denotes that the steel was made by the
basic electric furnace process with special practice. In the designations of
certain carbon and alloy steels. the suffix letters H and RH signify that the
steel is made to comply with specific hardenability
limits
Carbon or alloy steel designations showmg the letter B inserted between
the second and third numerals indicate that the steel contains 0.0005 to
0.003 boron. The letter L inserted between the second and third numerals
of the designation indicates that this steel contains 0. IS to 0.35 lead for
improved machinability.
Table I represents an abbreviated listing of the AISI or SAE carbon and
alloy steels. The fust two digits of each series have a detinite meaning,
providing the approximate composition of elements other than carbon.
The last two digits of the four-numeral
designations and the last three
digits of the five-numeral
designations
indicate the approximate
mean
carbon content of the allowable carbon range. For example. in Grade 1035.
the 35 indicates a carbon range of 0.98 to 1.10. These last digits are
replaced by XX in Table I. It is ohen necessary to deviate slightl) from this
system and to interpolate numbers for some carbon ranges and for variations in manganese. sulfur, or other elements with the same carbon range.
Table 2 Compositions
steels
IOXX
IIXX
IZXX
ISXX
Alloy
Description
Nonresulhrize~.
RlWlfWiZ~d
Rephosphorized
Nonresulfurized.
I .oO manganese maximum
and resulfurized
over I .OO manganese mwmum
steels
13XX
4OXX
4lXX
43xX
46xX
17xx
-lxxx
51X.X
SIXXX
52xXx
61XX
86XX
87XX
88XX
92xx
SOBXX(ab
SIBXXw
BIBXX(a)
94BXXb)
I .7S manganese
0.20or0.25
molybdenum or0.2S molybdenum and 0.042 sulfur
0.50.0.80.or0.95shronium~d0.I?.0.30.or0.30molyhdenum
I .83 nickel. 0.50 to 0.80 chromium. and 0.25 molybdenum
0.85 or I .83 nickel and 0.20 or 0.25 molybdenum
I .OS nickel, 0.15 chronuum. 0.20or0.35
molphdenum
3.50 nickel and 0.25 molybdenum
0.80.0.88.0.93.0.9S.or
l.oOchromium
I 03shromium
I .4S chromium
0.60or0.9.5 chromium and 0. I3 or0. IS vanadium minimum
0.55 nickel. O.SOchromium. and 0.20 molybdenum
O.SS nickel, O.SOchromium. and 0.25 molybdenum
0.55 nickel, O.SOchromium. and 0 35 molybdenum
2 OOsilicon or I .40 silicon and 0.70 chromium
0.28 or 0.50 chromium
0.80 chromium
0.30 nickel. 0.45 chromium. and 0. I2 molybdenum
0.15 nickel. 0.40 chromium. and 0. I2 molybdenum
(a) B denotes horon steel. Sourw
r\/S/Swe/
Pmducrs Mmrrral
of Standard Carbon H-steels and Standard Carbon Boron H-steels
Steel
UNS
designation
AISI or SAE
Standard
carbon
carbon
ISBZIH,
lSB35H.
ISB37H
ISB-IIH
lSB-%H
lSB62H
ISBZIRH
15B35RH
C
H 10380
HI0450
H I5220
H 15240
H IS260
HI5110
0.3co.13
0.42-0.5 I
0.17-0.2s
0.18-0.26
0.2 I-O.30
0.35-0.4s
o.so- I .oo
o.so- I 00
I .OO- I .SO
1.25-I 7Ya,
1.00-1.50
I .25-l 75(a)
HIS211
HIS351
HI5371
HIS411
HIS381
HIS621
O.I7-0.21
0.31-0.39
0.30-0.39
0.3s-O.-IS
0.43-05.3
0.5-i-0.67
0.70-I .20
O.70- I.20
I .OO- I.50
1.25-1.7S(aJ
I .OO- I .50
I.OO-I 50
composition,
Pmar
I
S max
Si
0.040
0.040
0.040
0.010
0.040
0.040
0.050
0.050
o.oso
o.oso
0.050
0.050
0. I s-0.30
0. I s-0.30
0. IS-O.30
0. I s-o.30
0.15.0.30
0. IS-O.30
0.040
0.040
o.@lo
0.040
0.040
0.040
0.050
0.050
0.050
0.050
0.050
o.oso
0. IS-O.30
0. I s-o.30
0. I s-0.30
0. I s-0.30
0. I s-o.30
0.40-0.60
A-steels
l038H
IOJSH
lS22H
lS21H
lS26H
ISJIH
Standard
Cheoucal
hIo
No.
boron
(a) Standard AISI-SAE
E-steels
H-steels u ith I .7S manganese maximum
are slassitied
as cxhon
steels
112 / Heat Treater’s Guide
Table 3 Compositions of Standard Nonresulfurized
Carbon Steels (1 .O Manganese Maximum)
Table 4 Compositions of Standard Nonresulfurized
Carbon Steels (Over 1.O Manganese)
Steel
designation
Steel
UNS
AISlorSAE
No.
C
GlOO50
G 10060
GlOO80
GIOIOO
GlOl20
GIOI30
G10150
GlOl60
GlOl70
Cl0180
GlOl90
GIOXO
GlO210
G IO’20
Gl0230
GIO’SO
Gl0260
GIO290
Gl0300
G10350
G 10370
G I0380
Gl0390
GIWOO
GIO-PO
GlO430
GIOUO
Gl@iSO
Gl0460
GlO490
GIOSOO
Gl0530
GIOSSO
GlOS90
GlO6OO
GlO6-W
Cl0650
GlO690
Gl07Oil
Gl0750
Gl0780
Gl0800
GlO8-m
Gl0850
Cl0860
GlO900
GlO950
0.06 max
0.35 max
0 08 mas
0 25 max
0. IO mu.
0.30-O 50
0.30-0.60
0 30-0.60
0.50-0.80
0.30-0.60
0.60-0.90
0.30-0.60
0 60-O 90
0 70-1.00
0.30-0.60
0.60-0.90
0.70. I .oo
0.30-0.60
0 30-0.60
0 60-O 90
0.60-0.90
0 60-O 90
0 60-0.90
0.70. I Ml
0.60-0.90
0.70. I .OO
0.60-0.90
0 60-0.90
0.70. I .OO
0.30-0.60
0.60-0.90
O.70- I.00
0.60-0.90
0 60-0.90
0.70. I .OO
0.60-0.90
0.50-0.80
0.60-0.90
0.50-0.80
0.60-O 90
0.40-0.70
0.60-O 90
0.40-0.70
0.30-0.60
0 60-O 90
0.60-0.90
0.70-I .OO
0.30-0.50
0.60-O 90
0.30-O so
Ions(ab
lOO6ta,
1008
1010
1012
1013
IO15
IO16
1017
1018
1019
1020
1021
IO22
1023
102s
1026
1029
1030
I035
1037
IO38
IO39
IO-K)
IO-11
lo-l3
104-4
lo-15
1046
IO.49
1050
1053
IO.55
1059(a)
IO60
106-l
1065
1069
1070
107.5
1078
I080
108-l
IO85
1086(a)
I090
IO9S
0.08-O. I3
0.10-0.15
0.11-0.16
0.13-O. I8
0.13-0.18
0. I s-0.70
0.150 ‘0
0.15-o ‘0
0.18-0.23
0.18-0.23
0.18-0.23
0.20-0.25
0.22-0.28
0.22-O 28
0 15-0.31
0.28-0.3-I
0.32-0.38
0.32-0.38
0.35-O 12
0 37-0.4-l
0.37-0.4-l
0.10-0.17
o.mo.17
0.13-0.50
0.13-0.50
o.-l3-0.50
0 -16.O.S?
o.wo.ss
o.-l8-o.ss
0 SO-O.60
0.59-0.65
055-0.65
0.60-0.70
0.60-0.70
0.65-0.75
0.65-O 75
0.70-0.80
0.72-0.85
0.75-0.88
0.80-0.93
0.80-0.93
0.80-0.93
0.85-0.98
0.90. I .03
Chemical composition, “0
Pmav
hill
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.010
0.040
0.040
0.040
0040
0.040
0.040
0.010
0.0-N)
0.010
0.010
0.040
0.040
0.040
0.040
0.040
0.040
O.OXJ
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.010
0.040
0.040
UNS
AlSlorS.AE
No.
C
hln
0 OS0
IS13
1522
152-l
IS26
IS’7
I.541
IS-18
IS51
I5S2
1561
GlSl30
GlS220
G I SXO
GlS260
GlS270
GlS4lO
G IS180
GISSIO
G I.5520
Gl.5610
G IS660
0.10-0.16
0.18.0.24
0.19.0.2S
0.22-0.29
0.22-0.29
0 36-0.U
O.-wo.s2
O.-IS-O.56
0.-+7-0.55
0.55-O 65
0.60-0.7 I
l.lO-1.u)
1.10-I.-IO
1.35-1.65
1.10.I.40
I .20- I .so
1.35-1.65
l.lO-I.40
0851.15
1.20-1.50
0.75-1.05
OX?-I.15
0.050
o.oso
0.050
0.050
0 050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.040
0.050
0.050
0.050
0.050
0.050
O.OSO
0.050
0.050
0.050
0.050
0.050
0 050
0.050
0.050
0.050
0.050
0 OS0
0.050
0.050
0 OS0
o.oso
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
0.050
(a) Standard steel grades for w ire rods and u ire only
Detailed composition
ranges will be pro\tded
senes in other tables which follow.
Unified Numbering
Chemical composition, %
designation
S max
for each member of each
System
The standard carbon and alloy grades established by AISI or SAE have
now been assigned designations in the Unified Numbering System (UNS)
by the American Society for Testing and hlaterials (ASTM ES27) and the
Society of Automotive
Engineers (SAE Jl868). In the composition tables
which follow. the CJNS numbers are listed along with their corresponding
AISI-SAE numbers.
The UNS number consists of a single letter prefix followed
by Eve
numerals. The prefix letter G indicates standard grades of carbon or alloy
steels. while the pretix letters H and RH indicate standard grades which
meet certain hardenability
limits. The first four digits of the UNS designa-
Pmax
S may
004
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.050
o.oso
0.0.50
o.oso
0.050
0.050
0.050
0.050
0.050
0.050
0.050
tions usually correspond to the standard AISI-SAE designations, while the
last digit (other than zero) denotes some additional composition
requirement such as lead or boron. The digit is sometimes a 6. which is used to
designate steels which are made by the basic electric furnace with special
practices.
The tern1 carbon steel does not necessarily mean that the steel does not
contain any other alloying elements. There are, however. sharp restrictions
on the amounts of alloy that may be contained in carbon steels. These
generally agreed upon restrictions are summarized in the paragraphs which
follow.
Steel is considered to be a carbon steel when no minimum content is
specified or required for aluminum (except as related to deoxidization
or
gram size control). chromium. cobalt. columbium
(niobium).
molybdenum, nickel. tmum.m~. tungsten. vanadium. ztrconium. or any other element
added to obtarn a desired alloymg effect. Further restrictions include: (a)
when the specified minimum for copper does not exceed O.-IO or(b) when
the maximum content specified for any of the following elements does not
exceed the percentages noted: I .6S manganese. 0.60 silicon, 0.60 copper.
Boron may be added to carbon steels to improve hardenability
(see Table
2).
In all carbon steels. small quantities of alloying elements or residuals.
such as nickel. chromium. and molybdenum.
are present. Their existence
is unavoidable because they are retained from the raw materials used for
melting. As a rule, small amounts of these elements have little or no
meaning to the fabricator. For purposes of identity and because of the wide
variations in properties. compositions
of the standard carbon steels are
presented in five separate tables.
Standard
Nonresulfurized
Grades
Compositions
for -t8 standard nonresulfurized
grades. I.0 manganese
maximum. are given in Table 3.
hlany of these grades are available with an addition of 0. IS to 0.35 lead
to improve machinability.
When lead is added. it is denoted by the letter L
between the second and third digtts. For example. a leaded grade of 1035
IS denoted as I0L-G.
Similarly. many of these grades ‘are available with a boron addition. A
letter B IS mserted between the second and thud digits, such as lOB35.
Compositions
for I I additional standard carbon steels are presented in
Table -1. The essential difference
between the steels listed in Table 3,
assuming the same carbon content. and those listed in Table 4 is the higher
manganese content of the latter group. For one grade, it is as high as I .6S.
which is the borderline
between carbon steels and alloy steel. Higher
manganese increases hardenability.
The grades listed in Table -I may also
be produced with additions of lead or boron as described above for the
grades listed in Table 3.
Standard
Resulfurized
Carbon Steels
Compositions
listed in Table 5 represent those grades of standard carbon
steels which ha\e been resulfurizcd.
as high as 0.33 sulfur, for improved
Carbon
Table 5
Compositions
of Standard
Resulfurized
Note data point, 0
SICA
designation
AlSl or SAE
UNS
No.
C
GI 1080
GIIIOO
Glll30
Glll70
Glll80
Gll370
Gll390
GII-IOO
GIlllO
GIIUO
Gll460
GIISIO
0.08-o. I3
0.08-O. I3
0. I3 “,M
0.11-0.20
0.11-0.20
0.32-0.39
0.35-0.43
0.37-0.44
0.37-0.1s
0.40-0.48
0.12-0.49
0.18-0.55
Chemical
hlo
composition,
Pmax
0.50-0.80
0.30-0.60
0.70-I .OO
I .OO- I .30
1.30-1.60
I .35- I .6S
I .35- I .65
0.70-I 00
1.35-1.6.5
1.35-1.65
0.70. I on
0.70. I .OO
Table 6 Compositions
of Standard
and Resulfurized
Carbon Steels
Steel
designation
AISI or SAE
I211
I212
1213
1215
12LI-1
/ 113
Fig. 1 Relationship Between Carbon Content and Maximum
Hardness. Full hardness can be obtained with as little as 0.60 C.
Carbon Steels
1108
1110
1113
1117
1118
1137
1139
II-IO
1141
114-l
1146
1151
& Alloy Steels Introduction
UNS
No.
Gl2llO
GI2120
Gl2130
Gl2lSO
GI2I.U
Chemical
lull
C
0.13max
0.13max
0.13miu
009mrul
O.lSmax
0.60-0.90
0.70-1.00
0.70-1.00
0.75-1.05
0.85-1.15
Standard Rephosphorized
Carbon Steels
s
0.040
0.040
0.07-O. I2
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.010
0.040
0.08-O. I3
0.08-O. I3
0.24-0.33
0.08-O. I3
0.08-O. I3
0.08-O. I3
O.I3-0.20
0.08-O. I3
0.08-O. I3
0.2-t-0.33
0.08-o. I3
0.08-O. I3
Fig. 2 Relationship Between Carbon Content and Maximum
Hardness. Usually attained in commercial hardening
Rephosphorized
composition,
P
0.07-0.12
0.07-012
0.07-0.12
0.04-0.09
0.0-l-0.09
These grades are also available
funher improvement in machinability.
machinability.
8
%
S
&IO-0.15
0.16-0.23
0.2-bO.33
0.26-0.35
0.26-0.35
Pb
.__
0.15-0.35,
afith lead additions
for
and Resulfurized
Table 6 lists compositions
for four grades ofcarbon steels which contain
higher than normal amounts of phosphorus as Nell as sulfur. One grade.
IZLI-1. has been rephosphorized.
resulikized.
and leaded. All of the above
conditions and additions contribute
to the superior machining characteristics of these grades. Any steel from this group ma! be produced H ith
additions of 0. I5 to 0.35 lead.
Alloy Steels
A steel is considered to be an alloy grade u hen the maximum of the range
given for the content of alloying elements exceeds one or more of the
following limits: (a) I .6S manganese. (b) 0.60 silicon. (c) 0.60 copper. It is
also considered an alloy steel uhen a definite minimum quantity of any of
the following
elements is specified or requued mfithin the limits of the
recognized constructional
alloy steels: (a) aluminum. (b) chromium. (c)
cobalt. (d) columbium (niobium). (e) molybdenum.(f)
nickel. (g) titanium,
(h) tungsten. (f) vanadium. (b) zirconium. or any other alloying element
added to obtain a specific alloying effect. As a rule. the total amount of
alloy in these AISI-SAE Standard Grades of Alloy Steels does not exceed
approximately
4.0 over and abobe that amount normally permitted in
carbon steels.
Compositions of Standard Alloy Steels. Compositions for a total
of 58 different alloy steels are listed in Table 7. It might seem that there is
great similarity
among grades in some instances and that the liht could
easily be reduced in number of grades. Houe\er.
many different cornpow
tions are required to fulfill the thousands of mechanical and physical
propeny requirements for manufactured products. The demands of fabricability and economy are also factors which must be satisfied. often with ver>
precise chemical compositions.
While the various compositions
listed in Table 7 are not produced in
equal quantities. each of the steels listed in this table is produced in
significant quantities by numerous mills. A large number of them are also
available through steel service centers.
Almost all of the 58 compositions listed in Table 7 are available with lead
additions for improved machinabiliry.
and some manufacmrers produce
certain alloy grades as resulfunzed steels. also to induce better machinabilit).
Compositions of Standard Boron Steels. Compositions of the
standard alloq grades which contain 0.0005 to 0.003 boron are listed in
Table 8. The boron pro\ ides an increase in hardenability
for these steels
which are relativeI> lean alloys.
Hardenability
Hardenabilitj
and methods for increasmg this property. such as boron
additions. are referred to several times uithin this article. However. hardenability does not necessarily mean the ability to be hardened to a certain
Rockwell
or Brine11 value. For example. Just because a given steel is
capable of beI” hardened to 65 HRC does not necessarily mean that it has
high hardennblhtj.
Also. a steel that can be hardened to only 40 HRC may
have very high hardenability.
Hardenability
refers to capacity of hardening
tdeprh) rather than to mn\imum attainable hardness.
Role of Carbon
The carbon content of a steel deremtines the maximum hardness attainable. urith particular emphasis on rhe word attainable. The effect of carbon
on attainable hardness is demonstrated in Fig. I The maximum attainable
hardness requires onlj about 0.60 carbon. Houever. the data shohn in Fig.
I are actually theoretical. because the) are based upon heat treating of
wafer-thin sections which are cooled from their austenitizing temperature
to room temperature within a matter of seconds. thus developing
100%
114 / Heat Treater’s Guide
martensite throughout their sections. Therefore, the ideal condition shown
in Fig. I is seldom attained in practice. Figure 2 shows a better example of
hardness versus carbon content because it is a more accurate condition, one
expected in commercial practice.
The most important factor influencing
the maximum hardness that can
be attained is mass of the metal being quenched. In a small section, the heat
is extracted quickly, thus exceeding the critical cooling rate of the specific
Table 7 Compositions
Steel
designation
AISI or SAE
1330
I335
1340
I345
4023
4002-l
4027
4028
4037
4047
4118
4130
4137
1140
1142
4115
1117
3150
4161
4320
43-m
E1340
4615
4620
4626
3720
1815
4817
1820
5117
5120
5130
5132
5135
5140
5150
51s
5160
E5llOO
E52lOO
6118
6150
8615
8617
8620
8622
8625
8627
8630
8637
8640
8641
8645
8655
8720
8740
8822
9260
steel. The critical cooling rate is that rate of cooling which must be
exceeded to prevent formation of nonmartensitic
products. As section size
increases. it becomes increasingly
difficult to extract the heat fast enough
to exceed the critical cooling rate and thus avoid formation of nonmartensitic products. A typical condition is shown in Fig. 3, which illustrates the
effect of section size on surface hardness and is a good example of the mass
effect. For small sections up to I3 mm (0.5 in.), full hardness of approxi-
of Standard Alloy Steels
IJNS
No.
C
hill
Pmax
Gl3300
Gl3350
G13400
Gl31SO
G-40230
G-IO240
GUI270
G-l0380
G-l0370
G-IO-170
G-Ill80
G113OO
G4 I370
GII-KlO
G-l1420
G11150
G-II 470
G-l1500
G-l1610
GA3200
G-t3400
G-i3406
G-16150
G-t6200
G-l.6260
G17’OO
G-R? I50
G38 I70
G-18200
GSll70
GSl200
GSl300
G5 I320
G5 I350
GSI400
G51500
G5lSSO
GSl600
GSl986
GS2986
G6l I80
G615OO
G86 I so
G86170
G86200
G86220
G86250
G86270
G86300
G86370
G86400
G86120
G864SO
G86SSO
G87200
G87UKl
G88220
G92600
0.28-0.33
0.33-0.38
0.38-0.13
0.43-0.48
0.20-0.2s
0.20-0.25
0.25-0.30
0.25-0.30
0.35-0.40
O.-e-0.50
0.18-0.23
0.28-0.33
0.35-0.40
0.38-0.43
0.40-0.4s
0.13-0.48
0.45-0.50
0.18-0.53
0.56-0.6-l
0.17-0.22
0.38-0.13
0.38-0.13
0.13-0.18
O.I7-0.22
0.2-1-0.29
0.17-o 22
0.13-O. I8
0. I S-O.20
0.18-0.23
0.15-020
0.17-0.22
0.28-0.33
0.30-0.3s
0.33-0.38
0.38-0.13
0 48-0.53
0.5 I-O.59
0.56-0.64
0.98-1.10
0.98. I. IO
0.16-0.2 I
0.18-0.53
0.13-0.18
0.15-0.20
0.18-0.23
0.20-0.25
0.23-0.28
0.25-0.30
0.28-0.33
0.35-0.40
0.38-0.43
0.40-0.45
0.13-0.48
0.5 I-O.59
0.18-0.23
0.38-0.13
0.20-0.2s
0.56-0.64
I .60- I .90
1.60-1.90
I .60-I .90
1.60-1.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
O.-iO-0.60
0 70-0.90
0.7s I .OO
0.7s I 00
0.75-I 00
0.75-1.00
0.7s-I 00
0.75. I.00
0.15465
0.60-0.80
0.65-0.85
0.15-0.65
0.15-0.65
0.45-0.65
0.50-0.70
0.10-0.60
0.10-0.60
0.50-0.70
0.70-0.90
0.70-0.90
0.70-0.90
0.60-0.80
0.60-0.80
0.70-0.90
0.70-0.90
0.70-0.90
0.75-1.00
0.25.0.15
0.3-0.45
0.50-0.70
0.70-0.90
0.70-O 90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.70-0.90
0.75 I 00
0.7% I .OO
0.75-I .Oo
0.7sI Ml
0.75 I.00
0.70-0.90
0.7.5. I .oo
0.75 I .OO
0.75-l 00
0.03s
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.03s
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.039
0.02s
0.035
0.03s
0.035
0.03s
0.035
0.035
0.035
0.035
0.03s
0.035
0035
0.035
0.035
0.035
0 035
0.035
0.025
0.025
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.03s
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
Chemical
S max
composition,
0.040
0.040
0.040
O.UlO
0.040
0.035-0.050
0.040
0.035-O OS0
0.040
0.040
0.040
0.040
O.O-lO
o.o-lo
O.O-lO
0.040
0.040
0.040
0.040
0040
0.040
0 01s
0.040
0.040
0040
0.UK.l
0.040
0040
0Q-W
O.O-lO
O.UUl
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.03
0.03
0.040
0.040
0.040
OUUI
0.040
0040
0.040
0.040
0.040
0.040
0040
0.040
OUUI
0.O-U.l
O.WO
0.040
0040
0.040
%
Si
0. IS-O.30
0.15-0.30
0.15-0.30
0. IS-O.30
0. I S-0.30
0. I s-o.30
0.15-0.30
0. I SO.30
0. I s-o.30
0. I s-o.30
0. I S-O.30
0. I S-0.30
0.15-0.30
0.15-o 30
0.15-o 30
O.I5-0.30
0. I S-0.30
0.15-0.30
0. I S-0.30
0.15-0.30
0.15-0.30
0.15.0.30
0. IS-O.30
0. I s-o.30
0.15-0.30
0.15-0.30
0. I S-O.30
0. I s-o.30
0. IS-O.30
0. I s-0.30
0 IS-O.30
0. I s-0.30
0.15-O 30
0 IS-O.30
0 IS-O.30
0.15-o 30
0.15-0.30
0. IS-O.30
0. I s-0.30
0. I S-O.30
0.15-0.30
0. I s-o.30
0.15-0.30
0. I s-0.30
0. I s-o.30
0.15-0.30
0. I s-o.30
0.15.0.30
0.15-0.30
0.15-0.30
0. IS -0.30
0.15-0.30
0. I s-o.30
0. I s-o.30
0. I s-o.30
0 I s-0.30
0.15-0.30
I 80-2.20
Ni
Cr
0.40-0.60
I .hS-2.Ou
I .6S-2.00
I .65-2.00
I .65-2.00
I .65-2.00
070-,100
0.9U I .20
3.35-3.7s
3.25-3.7s
3.25-3.7s
0.40-0.70
0.40-0.70
0 40-0.70
0.40-0.70
0.10-0.70
0.40-0.70
0.40-0.70
0.10-0.70
0.4UO.70
0.4UO.70
0.40-0.70
0.40-0.70
0 30-0.70
0.10-0 70
0.10-0.70
0.8Ul.10
0.8Ul.10
0.8Ul.10
0.80- I. IO
0.8Ul.10
0.80-1.10
0.8Ul.10
0.7uo.90
0.40-0.60
0.7uo.90
0.7uo.90
0.35-0.55
0.7uo.90
0.7uo.90
0.80-1.10
0.7s- I 00
0.8U I .05
0.70-0.90
0.70-0.90
0.7uo.90
0.7uo.90
0.90-1.1s
I .3u I.60
o.suo.7o
0.80. I. IO
O.JUO.60
0.10-0.60
0.40-0.60
0.40-0.60
0.40-0.60
0.40-0.60
0.40-0.60
0.10-0.60
0.40-0.60
0.40-0.60
0 40-0.60
0.40-0.60
O.NLO.60
O.-K-O.60
0.40-0.60
MO
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.08-o. I5
0. IS-O.25
0. IS-O.25
0. IS-O.25
0. I s-o.25
0. IS-O.25
0. I s-o.25
0. I s-o.25
0.25-0.35
0.2UO.30
0.20-0.30
0.2uo.30
0.20-0.30
0.20-0.30
0. I s-0.25
0.15-0.25
0.20-0.30
0.20-0.30
0.2uo.30
0.10-0.15 v
O.lSVmin
0. IS-O.25
0.15-0.2s
0. I s-o.25
0.1%0.25
0.15.0.25
0. I s-o.25
0. I s-o.25
0. I s-o.25
0. I s-o.25
0. I5-0.25
0. I SO.25
0. I so.25
0.20-0.30
0.20-0.30
0.3uo.40
Carbon & Alloy Steels Introduction
Table 8 Compositions
Steel
designation
AISI or SAE
508-u
50B-l.6
SOB50
SOB60
SIB60
8lBxi
94817
93830
Steel
designation
AISI or SAE
I330H
I335H
l34OH
I .34SH
33lORH
4027H
4027RH
m28H
4032H
3037H
4042H
4047H
4118H
-lllOH
4I2ORl-l
-ll30H
413SH
Jl37H
414OH
1112H
4l4SH
ll45RH
ll47H
4150H
416lH
116lRH
1320H
J32ORH
434OH
U34OH
WOH
4626H
4720H
18lSH
4817H
4820H
4820RH
SW6H
5120H
5130H
513oRH
Sl32H
5135H
514OH
SI-IORH
SISOH
SISSH
516OH
516ORH
6ll8H
of Standard Boron (Alloy) Steels
UNS
No.
C
GSOUI
G504.61
GSOSO I
GSXOI
GSl601
G81351
G9-1171
G9330 I
0.43-0.48
0.44-0.19
0.48-0.53
0.56-0.6-I
0.56-0.6-l
0.43-0.48
0. I s-o.20
0.28-0.33
Table 9 Compositions
UNS
No.
HI3300
H I33SO
HI3400
H I3150
H40270
H-U)280
HA0320
HA0370
H40420
H40470
H-II I80
H41200
H-i1300
H41350
H1 I370
HJl400
HJI-120
HJl-450
HA1470
H1lSOO
H41610
H33200
H-t3400
H-13406
H-i6200
H-W60
H-17200
H48150
H48170
H-i8200
H50460
HSl200
HSl300
H51320
HSl350
HSl400
HSISOO
HS I550
H51600
H61180
/ 115
MO
0.75.
0.7s
0.7s0.75
0.7s0.7s
0.75-I
0.7s
I .OO
I .Ocl
I .OO
I .OO
I .OO
I Ml
.OO
I .OO
Pmax
Chemical
Smax
0.035
0.035
0.035
0.035
0.03s
0.035
0.035
0.035
0.040
0.040
0.040
0.040
0040
0.040
0.040
0040
composition,
%
Si
0.15-0.30
0.15-0.30
0. I s-0.30
0. IS-O.30
0.15-0.30
0. IS-O.30
0. IS-O.30
0. I s-o.30
Ni
Cr
MO
0.20-0.40
0.30-0.60
O.30-0.60
0.40-0.60
0.20-0.35
0.40-O 60
0.40-0.60
0.70-0.90
0.3s-0.55
0.30-0.50
0.30-0.50
0.08-O. IS
0.08-O. IS
0.08-O. I5
Ni
Cr
hlo
of Standard Alloy H- and RH-Steels
C
0.27-O 33
0.32-0.38
0.37-0.4-l
o.-lz-0 49
0.08-O. I3
0 240.30
0.2s-0.30
0.24-0.30
0.29-0.35
0.3-I-0.1 I
0.39-0.16
O.-w0.5 I
0.17-0.23
0 18-0.23
0.18-0.23
0.27-0.33
0 32-0.38
0.31-0.1 I
0.37-0.4-l
0.39-0.16
0.12-0.49
0.43-0.48
0.44-0.5 I
0.47.05-l
0.55-0.65
0.56-0.6-l
0.17-0.23
O.I7-0.22
0.37-0.-u
0.37.0.u
0.17-0.23
0.23-0.29
0.17-0.23
0.12-0.18
0.13-0.20
0.17-0.23
0.18-0.23
0.13.o.so
0.17-0.23
0.27-0.33
0.28-0.33
0.29-0.3s
0.32-0.38
0.37-0.44
0.38-0.33
0.47-0.54
O.SO-0.60
0.55-0.65
0.56-0.63
0.15-0.21
hln
I .-Is-1.05
I .-Is-2.05
I .J5-2.05
1.35-2.05
0.10-0.60
0.60- I.00
0.70-0.90
0.60. I.00
0.60- I.00
0.60-I .OO
0.60. I .OO
0.60-I .OO
0.60. I .OO
0.90-I .2O
0.90. I.20
0.30-0.70
0.60- I.00
0.60. I.00
0.65-1.10
0.65-1.10
0.65-1.10
0.75-1.0
0.65-1.10
0.65-1.10
065-1.10
0.75 I .o
0.40-0.70
0.45-0.65
0.55-0.90
0.60-0.95
0.35-0.7s
0.40-0.70
O.-IS-0.75
0 30-0.70
0.30-0.70
0.40-0.80
O.SO-0.70
0.65-1.10
0.60- I .OO
0.60-I .OO
0.70-0.90
0.50-0.90
0.50-0.90
0.60- I .OO
0.70-0.90
0.60- I .OO
0.60. I .OO
0.65- I .OO
0.75 I.00
0.40-0.80
Pmax
Chemical
Smav
composition,
B
Si
0 15-0.30
0 15-0.30
0.15-0.30
0 15-0.30
0.15-0.35
0. IS-O.30
0. IS-O.35
0. IS-O.30
0. I S-0.30
0. IS-O.30
0. IS-O.30
0. IS-O.30
0. I s-o.30
0. I s-o 35
0. I s-0.35
0.1s.0 30
0. I j-O.30
0. IS-O.30
0. I s-o.30
0. I s-0.30
0. I s-o.30
O.ls:b.30
0.15-0.30
0. I s-o.30
0.15-0.35
0. IS-O.30
0 15-0.3s
0. IS-O.30
0.15.0.30
0.15-0.30
0. IS-O.30
0 15-0.30
0. I s-o.30
0. IS-O.30
0.15-0.30
0 15-o 35
O.lS-0.30
0 15-0.30
0.15-0.30
0. I s-o.35
O.IS-0.30
0. IS-O.30
0. I s-0.30
11.IS-O.35
0. IS-O.30
0. I s-0.30
0. IS-O.30
0. I s-o.35
0. I s-o.30
3.2S-3.7.5
I .SS-2.00
I .6S-2.00
I .ss-2.00
I .ss-2.00
I .SS-2.00
0.65. I .05
0.85 I.25
3.20-3.80
3.20-3.80
3.20-3.80
3.25-3.7s
I.-u-I.75
0.30-0.70
0.40-0.60
0.40-0.60
0.75-l .?O
0.75-1.20
0.75- I.20
0.75-1.20
0.75-1.20
0.7sI.20
0.80-1.10
0.75 I.20
0.75-1.20
0.65-0.95
0.70-0.90
0.35-0.65
0.10-0.60
0.65.0.9s
0.65-0.95
0.30-0.60
O.I3-0.43
0.60-I .OO
0.75-l .20
0.80-l IO
0.65-1.10
0.70-1.15
0.60-I .cKl
0.70-0.90
0.60- I .cKl
0.60-I .Oo
of3 I .oo
0.70-0.90
0.U0.80
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.08-o. IS
0.13-0.20
0.13-0.20
0. I s-o.15
0. I so.25
0. I so.25
0. I s-o.25
0. I WI.25
0. I s-o.25
0. I S-O.25
0. I s-o.25
0.15-0.2.5
0.25-0.3s
0.25-0.3s
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0.20-0.30
0. I s-o.25
0. I so.25
0.20-0.30
0.20-0.30
0.204.30
0.20-0.30
0.10-0.15
118 / Heat Treater’s Guide
Table 9 Compositions
Steel
designation
AISI or SAE
6150H
8617H
8620H
8622H
8611RH
862SH
8617H
863OH
8637H
564OH
8642H
864SH
8650H
8655H
866OH
871OH
8720RH
874lH
XKEH
8811RH
YXOH
9310H
93 IORH
of Standard Alloy H- and RH-Steels (continued)
1rNs
No.
C
bin
Pmax
Chemical
S mar
H6lSOO
H86 I70
H862OO
H86220
0.17-0.51
0. I-LO.20
0.17-0’3
0. I9-0.25
0.20-0.2s
0.22-0.28
0.21-0.30
0 ‘7-0.33
0 3-l-0.41
0.37-0.4-l
0.39-0.46
0.42-0.19
0.47-0.51
0.50-0.60
0.55-0.65
O.I7-0.23
0.18-0.73
0.37-0.4-l
O.I9-0.25
0.20-O 25
O.SS-0.65
0.07-O 13
0.084. I3
0.60-l 00
0.60-0.95
0.60-0.95
0.60-0.95
0.70-0.90
0.60-O 9.5
0.60-O 95
0.60-0.95
0.70-I OS
0.70. I .OS
0.70-I .os
0.70-I OS
0.70. I 05
0.70. I 05
0.70. I .os
0.60-0.95
0.70-0.90
0.70-I .os
0.70-I .Oj
0.7% I .OO
0.65.I.10
0.10-0.70
0.45-0.65
0.03S
0.035
0.03s
0.035
0.040
0.040
0.040
0.040
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.035
0.040
0.040
0.040
0.040
0040
0.040
0.040
0.040
0040
0.040
0040
H862SO
H86270
H86300
H86370
H86400
H86-420
H86-150
H86SOn
H865SO
H866OO
H87200
H874OO
H88220
H926OO
H93100
Table 10 Compositions
Steel
designation
Al!31 or SAE
0025
0 035
00-m
0.040
0035
0.035
O.&J
0.040
Z
Si
Ni
0.1s0.30
0.15-O 30
0. I S-0.30
0. I s-o.30
0. I S-0.35
0. I s-o 30
0. IS -0.30
0. I S-O.30
0. I5-0.30
0. I s-o.30
0.15-030
0.15-0.30
0.15-0.30
0.15-0.30
0.15-0.30
0.15-0.30
0. IS-O.35
0 IS-O 30
0. I j-O.30
0.1s0.35
I .70-z 20
0.1%0.30
0. I s-o 35
0.35-0.75
0.3.5-0.7s
0.35-0.7s
0.10-0.70
0.35-0.7s
0.35-0.75
0.35-0.7s
0.35-0.75
0.35.0.7.i
0.35-0.7S
0.35-0.75
0.35-O 75
0.35-0.75
0.35-0.75
0.35-0.7s
0.10-0.70
0.35-0.7s
0.35-0.7s
0.40-0.70
2.95-3 55
3.00-3.50
Cr
MO
0.75 I.20
0.35-0.65
0.35-0.65
0.35-0.65
O.lSVmin
0. IS-O.25
0. I S-O.25
0. IS-O.25
0.15-0.25
0. I s-o.25
0.15-0.25
0.15-0.2s
0. I S-O.65
0. IS-O.25
0. IS-o.29
0.15-0.25
0. I5-0.25
0.15-0.25
0.15-0.25
0.40-0.60
0.35-0.65
0.35-0.65
0.35-0.6.5
0.3.5-0.6.5
0.35-0.65
0.35-0.65
0.35-0.65
0.35-0.65
0.35-0.65
0.35-0.65
0.35-0.65
0.40-0.60
0.3S-0.65
0.35-0.65
0.10-0.60
0.20-0.30
0.2uo.30
0.20-0.30
0.3uo.-lo
0.3uo.40
I .OO- I .45
I .OO- I .-IO
0.08-O. IS
0.08-o. IS
of Standard Boron (Alloy) H- and RH-Steels
UNS
No.
Chemical
S max
c
hln
Pmax
0.65-1.10
0.75. I On
0.65I.10
0.03s
0.040
0.035
0.035
0040
0 040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
0.040
SOB-NIH
HSOJOI
WB-IORH
SOBUH
50B16H
SOBSOH
SOB60H
5 I BhOH
81 B1SH
86830H
86815H
9-IBlSH
91B17H
Y-IB30H
0.37-0.u
0.38.O.-l3
HSOUI
HSO-161
HS050 !
HS060 I
H516Ol
H81151
H863111
H8615 I
H93151
H91171
H9-l-1301
0.42-O 19
0.43.O.SO
0.-!7-051
055-0.65
055-0.65
0.42-0.49
0.27-0.33
O.-EO.-l9
0.12-O I8
0. I-I-O 20
0.27-0.33
0.65-1.10
0.65-1.10
0.65-l IO
0.65-1.10
0.70. I .os
0.60.0.9s
0.70. I .os
0.70-I .os
0.70-I .os
0.70. I .os
0.035
0.035
0.03s
0.035
0.035
0.035
0.035
0.03.i
0035
mately 63 HRC is attainable. As the diameter of the quenched piece is
increased. cooling rates and hardness decrease. because the critical cooling
rate for this specific steel was not exceeded. Thus. Fig. 3 also serves as an
escellent example of a low-hardcnabilitj
steel. Plain carbon steels are
characterized by their low hardenability,
with critical cooling rates lasting
only for brief periods. Hardcnability
of all steels is directly related to
critical cooling rates. The longer the time of critical cooling rate. the higher
the hardenability
for a given steel. almost regardless of carbon content.
Role of Alloying
composition,
Elements
The principal reason for using alloying elements In the standard grades
of steel is IO increase hardenabilitj.
The alloying elements used in the
standard alloy steels in Table 7 are confined to:(a) manganese. (b) silicon.
(cl chromium. cd) nickel, (e) mol) bdenum. and (f) vanadium. Because of
the small amounts used, boron is not usually called an alloy. Steels that
contain boron. whether they are carbon or alloy grades. are more often
termed as boron-treated steels. The use of cobalt. tunps’en. zirconium. and
composition,
%
Si
0. I s-o.30
0 IS-O.35
0 IS-O 30
0 15-o 30
0. I S-O.30
0. I s-o. 30
0.15-0.30
0.15-0.30
0. I s-o.30
0.15-O 30
0.15.0.30
0.15-0.30
0. I s-0.30
Ni
0. I S-O.45
O..lS-0.75
0.35-0.7s
0.25-O 6S
0.50
65
0.25-0.6S
Cr
0.3uo.70
0.40-0.60
0.30-0.70
0.13-0.13
0.30-0.70
0.30-0.70
0.60-I MI
0.30-0.60
0.35-0.65
0.35-0.65
0.25-0.55
0.25-0.55
0.2s0.55
MO
0.08-O. IS
0.15-0.25
0. I s-025
0.08-o. IS
0.08-O. IS
0.08-0.15
titanium is generally confined to tool or other specialty steels. Tool steels
and other highly alloyed steels are covered in other sections of this book.
hlanganese. silicon. chromium. nickel. molybdenum. and vanadium all
have their separate and unequal effects on hardenability.
However, the
individual
effects of these alloying elements may be completely
altered
when two or more of these are used together. In periods of alloy shortages.
extensive investigations
were conducted. and it has been established that
more hardenabilitj
can be attained with less total alloy content when two
or more alloys are used together. This practice is clearly reflected in the
standard steel compositions shown in Table 7. This approach not only saves
alloys that x2 often in scarce supply. but also results in more hardenability
al lob4 er cost.
Therefore. all of the steels listed In Tables 7 and 8 have significantly
greater hardenability
than the carbon steels listed in Tables 3 to 6. It must
be further emphasized that the hardenability
varies widely among the alloy
grades. which is a principal reason for the existence of so many grades.
It is oh\ ious that hardenability
is an all important factor in the discriminating selection of a steel grade for heat treated parts. A standard procedure
Carbon & Alloy Steels Introduction
Fig. 3 Effect of Section Size on Surface Hardness of a 0.54
Carbon Steel. Quenched in water from 830 “C (1525 “F)
/ 117
Fig. 5 Method of Developing End-Quench Curve by Plotting
Hardness Versus Distance from Quenched End. Hardness
plotted every quarter inch for sake of clarity, although
readings
were taken in increments
of one-sixteenth
shown at top of illustration
Rockwell
inch,
C
as
Fig. 4 Standard End-Quench (Jominy) Test Specimen and
Method of Quenching in Quenching Jig
for evaluating the hardenability of steels is necessary for initial selection as
well as a tool for controlling
quality.
Methods for Evaluating
Hardenability
A number of hardenability
tests have been devised. each ha\ing its
advantages and limitations. Most of these tests are either no longer used or
their use is restricted to specialized applications.
The endquench test has proved to be the method u ith the highest
degree of reproducibility
and has thus heen almost universally adopted for
evaluating hardenability
of virtualI> all standard alloy steels and for some
grades of carbon steels. The test is relatively
simple to perform and can
produce much useful information
for the designer as well as for the
fabricator.
Test Bars for the End-Quench Test. Although \ ariations are sometimes made to accommodate specific requirements,
the test bars for the
end-quench test are nomlally 25.5 mm (I in.) in diameter b> I02 mm (1
in.) long. A 25.5 mm (I in.) diameter collar is left on one end to hold it in
a quenching jig. as illustrated in Fig. -I.
In this test. the water flow is controlled by a suitable valve. so that the
amount striking the end of the specimen (Fig. -I) is constant in volume and
velocib. The Hater impinges on the end of the specimen onI). then drains
away. By this means. cooling rates vary from about the fastest possible on
the quenched end to very slogs. essentially equal to cooling in still air. on
the opposite end. This results in a u Ide range of hardnesses along the length
of the bar.
After the test bar has been quenched. tno opposite and flat pamllel
surfaces are ground along the length of the bar to a depth of 0.381 mm
(0.015 in.). Rocknell C hardnessdeterminations
are then madeetery
I.588
mm (0.60 in.). A specimen-holding
indexing fixture is helpful for this
operation for convenience as well as accuracy. Such fixtures are available
as accessory attachments for conventional
Rocknell testers. The next step
is to record the readings and plot them on graph paper IO develop a curve,
as illustrated in Fig. 5. Bj comparing the curves resulting from end-quench
tests of different grades of steel. their relative hardenability
may be established. The steels having higher hardenability
will be harder a~ a given
distance from the quenched end of the specimen than steels having lower
hardcnabilit).
Thus, the flatter the curve. the greater the hardenability.
On
the end-quench curves. hardness is not usually measured beyond approximately 51 mm (2 in.). because hardness measurements beyond this distance are seldom of an! significance.
At about this 51 mm (2 in.) distance
from the quenched end. the effect of uater on the quenched end has
deteriorated. and the effect of cooling from the surrounding air has become
signiticant. An absolutely flat txn P demonstrates conditions of very high
hardenability
\< hich characterize an air-hardening steel such as some of the
highI> alloyed tool steels. u hich u ill be discussed later in this book.
Variations in Hardenability. Because hardenability
is a principal
factor in steel selection and because hardcnabilit)
varies over a broad range
for the standard carbon and alloy steels. many grades are available.
As a rule. hardenability
of the standard carbon grades is very ION.
although there is still a prsar deal of variation in hardenability
among the
118 / Heat Treater’s
Fig. 6 End-Quench
Guide
Hardenability
Curve for 1541 Carbon
Fig. 6 Hardenability
Band for an Alloy Steel. 4150H: 0.47 to
0.54 C, 0.65 to 1 .I0 Mn. Normalized
nealed at 845 “C (1555 “F)
Fig. 7 Hardenability
Curves for Several Alloy Steels
H and RH Steels
Because of the normal variations within prescribed limits of composition. it would be unrealistic to expect that the hardenability of a given grade
would always follow a precise curve such as shown in Fig. 6 and 7. Instead.
the hardenability
of any grade will vary considerably,
which results in a
hardenability
band such as the 1150H hand in Fig. 8. This steel was
normalized at 870 “C ( 1600 “F). then austenitized at 8-15 “C ( IS55 “F)
before end quenching. The upper and lower curves that represent the
boundaries of the hardenability
band not only show the possible variation
“F). An-
in hardness at the quenched end, caused by the allowable carbon range of
0.47 to 0.5-t. but also the difference
in hardenability
as a result of the
alloying elements being on the high or low side of the prescribed limits.
The need for hardenability
data for steel users has been recognized.
Cooperative
work by AlSl and SAE has been responsible for devising
hardenability
bands for a large numher of carbon and alloy steels, principally the latter. Steels that are sold with guaranteed hardenability
bands are
known as the H-steels. The numericaJ parts of the designation are the same
as for the other standard grades. but the suffix letter H. such as 4lAOH.
identifies it as a steel that will meet prescribed hardenability
limits.
Chemical
different grades. This variation depends to a great extent upon the manganese content and sometimes to a smaller extent on the residual alloys which
are sometimes present. A hardenahility
curve for a high-manganese grade
of carbon steel. 1511. is shobn in Fig. 6. This curve represents near
maximum hardenability
that can be obtained from any standard carbon
grade.
In contrast to the curve shohn in Fig. 6. typical hardenability
curves for
four different 0.50 carbon alloy steels are presented in Fig. 7. These data
emphasize the fact that maximum attainable hardness is provided by the
carbon content. while the differences
in alloy content markedly affect
hardenability.
Hardenability
also depends on grain size (i.e.. deoxidation practice) and
melting practice (i.e.. BOF vs electric furnace). Electric furnace steel tends
to have high levels of nickel. copper. chromtum. and molyhdenum residuals that improve hardenability.
On the other hand, fine gained. alummum
killed steels (premium grades with respect to formability)
have lower
hardenability
than coarser grained. silicon killed steels.
at 670 “C (1600
Composition
Limits
Not all of the steels listed in Tables 3 to 8 are available as H or RH steels,
although most of the alloy steels can be purchased as H-grades. Tables 2.
9. and IO list those carbon and alloy grades which are presently availahle
as H or RH steels.
In order to give steel producers the latitude necessary in manufacturing
for common hardenability
limits. the chemical compositions
of normal
grades have been modified to form the H and RH steels. These moditications permit adjustments in manufacturing
ranges of chemical composition. These adjustments correct melting practice for individual
plants
which might otherwise influence the hardenability
bands. However, the
modifications
are not great enough to influence the general characteristics
of the original compositions of the steels.
Figure 8 is presented merely as an example of a hardenability
band. In
the section which follows. the hardenahility
bands. if available. are included hith heat treating and other data for individual
carbon and alloy
steels.
Restricted hardenability
(RH) steels are defined in SAJZ Jl868. Composition ranges are the same as those for the standard alloy grades. and
hardenahility
hands are narrower than those for the H grades. For example.
3130 and -II-IO RH have the same specified composition
ranges, while
-II-IO H has broader ranges. The Jominy hardenability
band of4130 RH is
about half the width of the -II10 band.
RH grades open the door to substantial benefits to the heat treater. A
major metalworking
company. for instance. had a part forged to four
different dimensions. Four different procedures were required to heat treat
the parts to a set of common properties.
Restrictive
steel chemistries
eliminated the need for the four procedures and made it possible to consolidate specifrcations.
The RH grades also made it possible to design a new
specilication
that provides Jominy hardenability
bands lying with the
overlap of tUo older specifications.
Over a five year period, this company
was able to reduce its material specifications
in this manner from a total of
3 I down to nine.
Carbon & Alloy Steels Introduction
Alloying I Elements. Source: Climax Molybdenum
/ 119
120 / Heat Treater’s
Guide
Carbon Plus Grain Size. Source: Climax Molybdenum
Carbon
(1000,
Steels
1100,1200,
and 1500 Series)
introduction
Carbon steels are now classified in four distinct series, in accordance
with the AlSl system of designations:
the 1000 series. which are plain
carbon steels containing not more than I .OO Mn maximum; the I100 series,
which are resulfurized
carbon steels; the 1200 series, which are resultiu-ized and rephosphorized
carbon steels: and the I500 series. which are
high-manganese (up to 1.65) carbon steels and are nonresulfurized.
These
four series differ in certain fundamental
properties, thus justifying
the
series differentiation.
However, in temls of their response to heat treatment,
all four series can be discussed in temts of their carbon content, the
principal controlling factor in heat treating. Other factors areconsidered
for
the individual steels on the pages that follow. To simplify consideration of
the treatments for various applications.
the steels in this discussion are
classified as follows: Group I, 0.08 to 0.25 C; Group II. 0.30 to 0.50 C:
Group lfl. 0.55 to 0.95 C. A relatively few steels. such as 1026 and 1029.
can be assigned to more than one group. depending on thetrcarbon content.
Group I(O.08 to 0.25% C). The three principal types of heat treatment
used on these low-carbon
steels are: (aj process treating of material to
prepare it for subsequent operations;
(b) treating of finished parts to
improve mechanical properties: and t,c) case hardening. notably by carburizing or carbonitriding,
to develop a hard, wear-resistant surface. It is
often necessary to process anneal drawn products between operations, thus
relieving work strains in order to permit further working. This operation is
normally carried out at temperatures between the recrystallization
temperature and the lower transformation
temperatures. The effect is to soften by
recrystallization
of the grain growth of ferrite. It is desirable to keep the
recrystallized
grain size relatively fine. This is promoted by rapid heating
and short holding time at temperature. A similar practice may be used in
the treatment of low-carbon,
cold-headed
bolts made from cold-drawn
wire. Sometimes the strains introduced by cold working so weaken the
heads that they break through the most severely worked portion under
slight additional stratn. Process annealing is used to overcome this condition. Stress relieving at approximately
540 “C t 1000 “F) is more effecttve
than annealing in retaining the normal mechanical properties of the shank
of the cold-headed bolt.
Heat treating is frequently used to improve machinability.
The generally
poor machinability
of the low-carbon steels. except those containing sulfur
or other alloying elements. results principally
from the fact that the proportion of free ferrite to carbide is high. This situatton can be modified by
putttng the carbide into tts most voluminous form, pearlite. and dispersing
tine particles of this pearlite evenly throughout the ferrite mass. Normalizing is commonly
used with success. but best results are obtained by
quenching the steel in oil from 815 to 870 “C (1500 to 1600 “Fj. With the
exception of steels containing a carbon content approaching 0.255,. little
or no martensite is formed. and the parts do not require tempering.
Group II (0.30 to 0.50% C). Because of the higher carbon content.
quenching and tempering become increasingly
important when steels of
this group are considered. They are the most versatile of the carbon steels.
because their hardenability
(response to quenching) can be varied over a
wide range by suitable controls. Ln this group of steels. there is a continuous
change from water-hardening
to oil-hardening
types. Hardenability
is very
sensitive to changes in chemical composition. particularly
to the content of
manganese. silicon. and residual elements, as well as gram size. These
steels are also very sensitive to changes in section.
The medium-carbon
steels should be either normalized
or annealed
before hardening in order to obtain the best mechanical properties after
hardening and tempering. Parts made from bar stock are frequently given
no treatment prior to hardening (the prior treatment having been performed
at the steel mill). but it is common practice to normalize or anneal forgings.
These steels. whether hot Fished or cold finished, machine reasonably
well in bar stock fomt and are machined as received, except in the higher
carbon grades and small sizes that require annealing to reduce the as-received hardness. Fotgings are usually normalized to improve machinability
over that encountered with the fully annealed structure. These steels are
widely used for machinery parts for moderate duty. When the parts are to
be machined after heat treatment, the maximum hardness is usually held to
320 HB and is frequently much lower.
In hardening. the selection of quenching medium will vary with the steel
composition.
the design of the part. the hardenability
of the steel, and the
hardness desired in the finished part. Water is the quenching medium most
commonly used. because it is best known and is usuaUy least expensive and
easiest to install. Caustic soda solution (5 to 10% NaOH) is used in some
instances with improbed results. It is faster than water and may produce
better mechanical properties in all but light sections. It is hazardous,
however. and operators must be protected against contact with it. Salt
solutions (brine) are often successfully
used. They are not dangerous to
operators. but their corrosive action on iron or steel parts or equipment is
potentially serious. When the section is light or the properties required after
heat treatment are not very high. oil quenching is often used. Finally, the
medium-carbon
steels are readily case hardened by flame or induction
hardening.
Group Ill (0.55 to 0.95% C). Forged parts made of these steels should
be annealed because:
l
l
Refinement of the forged structure is important in producing a high
quality, hardened product
The parts come from the forging operation too hard for cold trimming of
the flash or for any machining operations
Ordinary annealing practice. followed by furnace cooling to approximately 600 “C t I I IO “F) is satisfactory for most parts.
Hardening by conventional
quenching IS used on most parts made from
steels in this group. However. special techniques are required at times. Both
oil and water quenching are used: water. for heavy sections of the lower
carbon steels and for cutting edges: oil. for general use. Austempering and
martempenng are often successfully applied. The principal advantages of
such treatments are considerably
reduced distortion, elimination of breakage. and. m many instances. greater toughness at high hardness.
Tools with cutting edges are sometimes heated in liquid baths to the
lowest temperatures at which the part can be hardened and are then
quenched in brine. The fast heating of the liquid bath plus the low temperature fail to put all of the available carbon into solution. As a result. the
cutting edge consists of martensite containing less carbon than indicated by
the chemical composition
of the steel and containing
many embedded
particles of cementite. In this condition. the tool is at its maximum toughness relative to its hardness, and the embedded carbides promote long life
of the cutting edge. Final hardness is SS to 60 HRC. Steels in this group are
also commonly hardened by Flame or induction methods.
122 / Heat Treater’s
Guide
Effect of mass and section size on cooling curves obtained for the water quenching of plain carbon steels
Carbon
Steels (1000, 1 100,1200,
Effect of mass and section size on cooling curves obtained for the oil quenching of plain carbon steels
and 1500 Series) / 123
124 / Heat Treater’s
Guide
Influence of tempering temperature on room-temperature
hardness of quenched carbon steels
Carbon
Influence of tempering temperature on room-temperature
Steels (1 000, 1 1 00.1200,
and 1500 Series) / 125
hardness of quenched carbon steels (continued)
126 / Heat Treater’s
Guide
Room-temperature hardness of three carbon steels after production tempering. (a) Automotive steering-arm forgings made of fine
grain 1035 steel. Section thickness varied from 16 to 29 mm (5/8to 1 ‘/sin.). Forgings were austenitized at 625 “C (1520 “F) in oil-fired pushe
conveyor furnace, held 45 min. quenched in water at 21 “C (70 “F), and tempered 45 min at 560 to 625 “C (1080 to 1160 “F) in oil-fired link
belt furnace to required hardness range of 217 to 285 HB. Hardness was checked hourly with a 5% sample; readings were taken on polishec
flash line of 29 mm (1 l/s in.) section. Survey of furnace revealed temperature variation at 605 “C (1120 “F) of 8, -4 “C (15, -7 “F). Data rep
resent forgings from four mill heats of steel and cover a 6-week period. (b) Woodworking cutting tools forged from 1045 steel. Section o
cutting lip was hardened locally by gas burners that heated the steel to 815 “C (1500 “F). Tools were oil quenched and tempered at 305 tc
325 “C (585 to 615 “F) for 10 min in electrically heated recirculating-air furnace to a desired hardness range of 42 to 48 HRC. Data wen
recorded during a g-month period and represent forgings from 12 mill heats. (c) Plate sections, 19 to 22 mm (3/d to 7/8 in.) thick, of 1045 stee
were water quenched to a hardness range of 534 to 653 HRB and tempered 1 h at 475 “C (890 “F) in continuous roller-hearth furnaces. Dat:
represent a e-month production period. (d) Forged 1046 steel heated to 830 “C (1525 “F), and quenched in caustic. Forgings were heater
in a continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings weighed 9 to 11 kg (20 to 24 lb) each; maxi
mum section, 38 mm (1 l/2 in.). (e) As-quenched forged 1046 steel shown in (d), tempered at 510 “C (950 “F) for 1 h. (9 As-quenched forget
1046 steel shown in (d), tempered at 525 “C (975 “F) for 1 h. Average hardness data for all but (c) obtained by calculating average of higt
and low extremes of hardness specification range for each batch.
Carbon
Steels (1 000, 1 100,1200,
and 1500 Series) / 127
1062: Heat-to-Heat Variations in Depth of Hardness. Heat-to-
heat variations in depth of hardness among three heats. Hubs
were flame hardened on the inside diameter to a minimum of 59
HRC at 1.9 mm (0.075 in.) below the surface. Parts were heated
12 s and quenched in oil. Hardness was measured on cross sections of heated area.
1052 and 1062: Flame hardening hubs. Distribution of dimensional change as a result of flame hardening. (a) Change in pitch diameterof
converter gear hubs made of 1052 steel. Gear teeth on inside diameter were heated for a total of 9.5 s. before being quenched in oil to provide a depth of hardness of 0.9 mm (0.035 in.) above the root. (b) Close-in of inside diameters of converter hubs made of 1062 steel. Inside
diameter was heated for a total of 12 s and then oil quenched to harden to 59 HRC min at a depth of 1.9 mm (0.075 in.) below the surface.
Inside diameter was finish ground after hardening.
128 / Heat Treater’s
Guide
1018 and 1024: Gas carburizing.
Effect of tempering
4.5 h, then oil quenched and tempered.
on hardness of 1018 and 1024 steel. Parts were carburized
at 925 “C (1700 “F) for
Carbon
Effect of time and temperature on case depth of liquid carburized steels
Steels (1000, 1 1 00,1200,
and 1500 Series) / 129
130 / Heat Treater’s
Nitriding
Guide
Carbon Steels. Effect of carbon content in cation
steels on the nitrogen gradient obtained in aerated bath nitriding
Typical
Steels
Normalizing
Temperatures
for Standard
Carbon
Ikmperatore(a)
Grade
Plain carbon steels
lOIS
I020
1022
102.5
I030
1035
IO-IO
IW5
IO50
1060
1080
1090
IWS
1117
1137
II-II
II-U
“C
OF
915
915
915
900
900
885
860
860
860
830
830
830
835
900
885
860
860
167.5
1675
I675
1650
1650
1625
1575
1575
1575
lS25
1525
1575
1550
1650
1625
1575
1575
(a) Based on production experience. normalizing
temperature may vary from as much
as 27 “C (50 “F) beloa. to as much as 55 “C ( IO0 “F) above. indicated temperature. The
steel should be cooled in still air from indicated temperature.
Properties
AM
grade(a)
1015
1020
I022
1030
IWO
IOSO
1060
I080
1095
III7
III8
1137
of Selected
Carbon Steels in the Hot-Rolled,
Condition ortreatment
As-rolled
Normalized at 9’S “C ( I700 T)
Annealed at 870°C ( 1600 “Fj
As-rolled
Normalizedat
87O”C( 1600°F)
Annealed at 870 “C ( I600 “FJ
As-rolled
Normalized at 925 “C ( I700 OF)
Annealed at 870 “C ( I600 “f?
As-rolled
Normalized at 9’S
& “C ( I700 “F)
Annealed at &t5 “C ( I S50 “F)
As-rolled
Normalizedat9OO”Ct
1650°F)
Annealed at 790 “C ( 1150°F)
AS-ldkd
Normalized at 900 “C ( 1650 “F,
Annealed at 790 “C ( I -ISO “R
As-rolled
Normalized at 900 “C t I650 “F)
Annealed at 790 “C ( 1150 “F)
As-rolled
Normalizedat
900°C (165O”F1
Annealed at 790 “C ( 1450 “F)
As-rolled
Normalized
Annealed at
As-rolled
Normalized
Annealed at
As-rolled
Normalized
Annealed at
As-rolled
Normalized
Annealed at
at 900 “C ( I650 “F)
790 “C ( 1450 “F)
at 900 “C ( 1650 “FJ
860 “C ( IS75 “F)
at 925 “C ( 1700°F)
790 “C ( I150 OF)
at 900 “C (1650°F)
790 “C ( l-l.50 “FJ
Tensile strengtb
ksi
MPa
420
-125
385
150
UO
395
SOS
185
450
5.50
525
160
620
995
520
725
750
635
815
775
625
964
1015
615
965
lOIS
655
190
-170
130
525
-175
150
625
670
985
61
62
56
65
64
57
73
70
65
80
76
67
90
86
7s
10s
109
92
II8
II3
91
I-IO
117
89
I10
117
95
71
68
62
76
69
65
91
97
as
Normalized,
Keld strength
k5i
MPa
315
325
285
330
31s
29.5
360
360
31s
315
345
3-15
-l15
370
350
415
130
365
385
3’0
370
585
s2s
380
570
so5
380
SOS
305
28.5
315
315
285
380
-loo
34s
46
-I7
JI
-I8
50
43
52
52
46
SO
SO
SO
60
5-l
51
60
62
53
70
61
4-l
8S
76
59
83
73
55
4-t
4-l
-II
-WA
-I6
-II
55
58
50
and Annealed
Conditions
q ardness,
Elongation(b),
Reduction
in area, 9%
HB
Imd impact
strength
ft. Ibf
J
61
70
70
59
68
66
67
68
6-l
57
61
58
SO
5.5
57
10
39
-IO
3-l
37
38
17
21
-IS
I8
I-l
21
63
s-1
58
70
66
67
61
-19
s-l
I36
121
III
l-13
I31
III
149
I13
I37
179
l-I9
I26
201
170
lJ9
229
217
I87
Yl
229
179
293
293
171
293
293
I92
143
137
121
119
I13
I31
192
197
17-l
III
I15
II5
87
II8
I23
81
117
121
75
94
69
49
65
35
31
27
I8
18
I-l
II
7
7
7
3
5
3
81
85
94
lo9
103
107
83
63
SO
39.0
37.0
37.0
36.0
35.8
36.5
35.0
B-I.0
35.0
32.0
32 0
312
2s 0
28.0
30.2
20.0
23.7
17.0
I8.O
22.5
17.0
I I.0
23.7
9.0
95
13.0
33 0
33.5
32.8
32.0
33.5
31.5
28.0
22.5
26.8
4%
82
85
85
64
87
91
60
87
89
55
69
51
36
48
33
23
20
I3
13
IO
8
5
5
5
3
‘I
2
60
63
69
80
76
79
61
17
37
Carbon
Properties
AlSl
grade(a)
1141
114-l
of Selected
Carbon Steels in the Hot-Rolled,
Condition or treatment
field strength
ksi
MPa
Tensile strength
MPa
ksi
As-rolled
Normalized at 900 “C ( 1650 “Fj
Annealedat81S°C(ISOO”F)
As-rolled
Normalized at 900 “C ( 16.50 “F)
Anneakd at 790 “C ( I-150 “R
675
710
600
705
670
585
Normalized,
98
103
87
102
97
89
360
40s
3.55
420
ml
31.5
Steels (1000, 1 1 00,1200,
and 1500 Series) / 131
and Annealed
Conditions
Elongation(b),
Reduction
in area, %
Hardness.
RB
38
56
19
-II
40
JI
192
201
163
212
197
167
52
59
51
61
58
50
?O
22.0
22.7
25.5
21.0
21.0
24.8
(continued)
Imd impact
strength
B Ibf
J
II
53
34
53
43
65
8
39
25
39
32
18
(a) All grades PIE tine grained except for those in the I 100 series. m hich are coarse grained. (h) In SO mm or 2 in.
Effect of Mass on Hardness
Alloy Steels
Grade
Normalizing
temperature
“F
“C
Carbon steels, carburizing
lOIS
I020
1022
III7
III8
92s
92s
92s
900
925
92s
900
900
900
900
900
900
900
900
Critical
Temperatures
5w.a
I26
I31
1.43
I43
IS6
IZI
I31
I13
137
I13
II6
I26
137
I37
137
II6
I21
I31
I26
131
l5b
183
223
229
293
302
201
207
201
l-+9
170
217
229
293
293
197
201
197
137
167
212
223
285
‘69
197
XI
I92
137
167
201
223
269
‘55
192
201
I91
heats
Carbon Steels
Steel
Critical temperatures on beating at 28 “C/h (50 OF/h)
ACI
ACJ
OF
T
OF
T
1010
I020
I030
I040
1050
1060
1070
1080
72s
725
72s
725
72s
72s
725
730
I335
1335
133s
1335
133s
1335
1335
I315
875
845
815
795
770
745
730
735
1w4
grades
1700
1650
l6SO
1650
1650
1650
1650
1650
1650
for Selected
231)
13(‘4
grades
Note: AU data are based on male
Approximate
Carbon and
Hardness, HB, for bar
with diameter, mm (in.), of
1700
1700
1700
1650
I700
Carbon steels, direct-hardening
1030
1040
1050
1060
lo80
1095
1137
I I-II
II-U
of Normalized
1610
ISSS
I-195
I460
111s
I375
I390
13%
Critical temperatws
h-3
OF
OC
850
815
790
75s
740
72s
710
700
I560
I SO0
I -Is0
139s
I365
I%+0
1310
1290
on cooling at 28 OC/b (SOOF/b)
h
“C
OF
680
680
675
670
680
685
690
695
1260
1260
I250
I240
1260
I 265
I275
I280
132 / Heat Treater’s
Recommended
Guide
Temperatures
and Cooling
Cycles for Full Annealing
of Small Carbon Steel Forgings
Data are for forgings up to 75 mm (3 in.) in section thickness. Time at temperature
thick; l/2 h is added for each additional 25 mm (1 in.) of thickness.
usually is a minimum of 1 h for sections up to 25 mm (1 in.)
Cooling cycle(a)
Annealing temperature
T
OF
Steel
ass-900
aswoo
aswoo
ass-900
84s.88s
845-8x5
790.870
790-870
790-870
790-84s
790-84s
790-84s
790.830
790-830
lo18
I ox
IO22
lo25
1030
1035
IO4O
IONS
1050
lO6O
I070
I 080
(a) Fumasecoolingar
OF
T
1575-1650
lS7S-1650
lS7S-1650
ls75-1650
1550-162.5
ISSO- I625
IJSO-IhOO
1X50- I600
l-150-I600
l-150- I550
IGO- 1550
1150-1550
1150-1525
11so-IS25
From
To
From
ass
ass
855
85s
845
84s
790
790
790
790
790
790
790
790
70s
700
700
700
6.50
650
650
650
650
6SO
650
650
6SO
655
IS75
IS75
IS75
IS75
IS50
ISSO
1150
l-150
1150
1150
l-Pi0
I450
14.50
1450
To
Eardness
range, FIB
111-119
Ill-149
111-119
Ill-187
126-197
137-207
137-207
156.217
156-217
156-217
167-229
167-229
167.229
167-219
28”C/h(5O”F/h)
Approximate
Grossmann Quenching Severity Factor of
Various Media in the Pearlite Temperature Range
Circulation
or agitation
Brine
None
Mild
hlodersre
GOOd
Strong
Violent
Grossmann
Numbers
2
-7-7-.- 7
hater
and Film Coefficients
32
90
55
130
F&I oi I
60
I10
2%
13
II0
polp\ rn) I py-rolidone
Conventional
hlancmpering
Air
oil
oil
69
I so
77
09-1.0
1.0.I.1
1.2-I.?
I-l-l.5
I 6-2.0
-I
5
Quenchant temperature
“F
T
Quenchant
Grossmann quench seberityfactor,
Water
Oil and salt
150
300
80
for Selected
0.25-o 30
0.30-0.3s
0.35-O 10
0.40 5
0 S-O.8
o.a-I.1
Air
0.01
Quenchants
Quenchant belocih
ft/min
m/s
0.00
0.25
0.51
0.76
0.00
0.25
03 I
0.76
0.00
0.3
0.5 I
0.76
0.00
0.25
0.5 I
0.76
0.51
0.5 I
0.00
2 s-l
5 ox
H
0
50
loo
IS0
0
SO
IO0
I50
0
50
loo
IS0
0
50
loo
I so
loo
loo
0
500
I ooo
Grossmann
number,
(H=h/2k)
I.1
21
1.7
2.8
0.2
0.6
I5
2.-l
0.s
I .o
I.1
I.5
0.8
1.3
I .s
1.8
0.7
I.2
0.05
0.06
0.08
Effectke fdm coefficient
w/m2 K
Btu/ft’ h OF
so00
9ow
880
I’OMI
12OOO
IO00
2500
6500
IO5oo
xoo
-1500
sooo
6500
3.500
6GOO
6500
7500
3ooo
sooo
200
250
350
2100
2100
la0
440
Iloo
1x50
350
790
880
I200
620
II00
1100
I300
530
880
3s
44
62
Carbon
Comparison
of the Cooling Power of Commercially
Magnetic Quenchometer
Test Results
Oil
sample
Types of quenching oil
Conventional
Fcljt
Martempering.
without speed improvers
Martempering.
with speed irnprobers
(a) SW
Saybolt universal
Comparison
to Magnetic
Typical
Grade
Viscosity
at 40 T
(1~W
SUS(a)
Quenching
105
107
so
9-t
107
II0
I20
329
719
‘550
337
713
2450
“C
OF
190
19.5
I 70
l-t.5
170
190
ias
190
23s
245
300
230
2-15
300
37s
380
340
290
33s
37s
370
375
45s
475
575
150
475
570
and 1500 Series) / 133
Oils According
to
Quenching duration from 885 T (1625 “I9
to 355% (t i70°F),s
At 27OC (80 OF)
At 120°C ( 2soT)
Chromized
Chromized
Ni-ball
Ni-ball
Ni-ball
Ni-ball
12.5
‘7.2
27.9
24.8
(a)
IS.0
17.0
19.6
17.8
27.6
19.0
32.0
fbl
179
17.0
17 a
16.0
7.0
9.0
lo.8
12.7
13.3
19.2
26.9
31.0
IS.3
16.-l
19.7
la.4
25. I
31.7
12.8
IA.0
IS.1
2’. I
30.4
32.8
(hJ
IS.6
IS.4
seconds. fb) Not a\uilahlc
of the Ranges of Cooling Power of Commercially
Available
Quenchometer
Test Results using Pure Nickel Balls
Hardnesses
of Various
Quenching
Quenchingduration
from885T
At 120 ‘T
(250 OF)
At 65 T
(15OT)
Id.22
7-l-t
18-3-l
I420
L+ithout speed imprmers
with speed improvers
Carbon
content,
%
and Mat-tempering
Flash point
IO?.
I
2
3
3
5
6
7
8
9
IO
II
I’
1;
II
‘@pe of quenching oil
Conventional
Ftisl
Martempering,
Martempeting.
Available
Steels (1000, 1100,1200,
(1625T)
and Martempering
to355”C
At 175°C
Oils According
(670 “F), s
At 23oT
(350 “F)
(450 “F)
21-38
16-27
47
=33
I-t-22
7-14
ix-34
13.18
Carbon Steels after Tempering
Hardness, ARC. after tempering for 2 h at
205 “C
260 T
315-x
370 “C
425T
48oT
595 T
650 OC
(400°F)
(500°F)
(6OOW
(7OO’T)
@OO°F~
(900°F)
(MOOoF)
540-T
(1100°F)
(12OO’=F)
Heat treatment
Normalized at 900 “C ( I650 “Ft. water quenched
From 830-845 “C t 1525 I SSO “FL averuae de\s
point. I6 “C (60 “F)
Carbon steels, water hardening
I030
0.30
50
15
43
39
?I
28
25
22
9Sta)
I040
1050
1060
0.40
0.50
0.60
51
S?
56
48
50
SS
46
16
so
11
4-l
42
37
10
38
30
37
37
27
31
SS
22
29
33
943,
22
I 080
109s
II37
0.80
0.95
O.-lo
S7
58
4-l
55
57
12
so
52
-IO
13
-17
37
-II
43
33
10
12
30
39
-II
27
38
10
‘I
3’
;;
91111)
II-II
11-l-l
0.40
0.40
19
5s
46
50
43
-17
-II
45
38
39
31
32
28
‘9
23
25
94at
97ta1
Data uere obtained on 25 mm r I in.) buts adequately
quenched to drielop
full hurdnrss. ISI Hardness. HRB
26
Normalized ut 885 “C I 1625 “Ft. water qucnchrd
from 800-S IS ‘T ( 1175. lSOO°Ft; aberage dea
potnt. 7 “C (-IS “F)
Nomtalizcd at9OO‘C t 1650°F). \raterqucnched
from 830-855 ‘T t I S?S- I575 “FL average dew
point 13Tt.55
“F)
134 / Heat Treater’s
Guide
Carbon Steels: Typical
Austempering
Applications
Parts listed in order of increasing section thickness
Part
Maximum seclion
thickness
l22Ul
in.
Steel
Parts per unit weight
lb
kg
Salt temperature
OC
OF
Immersion
time, mia
Eardness,
ERC
Plaii carbon steel parts
Clevis
Follower arm
Sp-ing
PhUe
Cam lever
Plate
-bPc~
Tabulator stop
Lever
Chain link
Shoe-last link
Shoe-toe cap
Lawn mower
blade
Lever
Fastener
Stabilizer bar
Boron steel bolt
IO50
IO50
1080
1060
1065
1050
106s
106s
IOSO
1050
1065
I070
1065
3.18
6.35
I9
6.35
107.5
1060
1090
IOBZO
Typical Operating
Section size
mm
in.
0.75
0.75
0.79
0.81
I .o
I .o
I .o
I .I?:!
I .2s
I .s
I .s
I.5
3.18
Conditions
Material
0.030
0.030
0.03 I
0.032
0.040
0.010
0.040
0.048
0.050
0.060
0.060
0.060
0 12s
77olkg
412/kg
22Olkg
88/Q
0.125
0.250
0.750
0.250
wkg
IlO/kg
22 kg
lOOIkE
for Through
Frequency(a),
Ez
Power(b),
kW
3SO/lb
I87Iib
lOO/lb
4011b
62Jh
28Ilb
‘A lb
6-Vlb
0.5 kg
14lnig
-uokg
2oonb
s73lkg
86Aig
l8nig
1.5 kg
Hardening
39nb
8/lb
?, lb
llnb
SO/lb
IO lb
Jsnb
360
35s
330
330
370
360
370
360
34s
34s
290
31s
31s
680
675
625
630
700
675
700
680
650
650
550
600
600
IS
IS
I5
6
IS
I5
IS
IS
IS
IS
30
60
IS
42
42
48
45-W
42
42
42
4s
45-50
45
52
so
so
385
310
370
420
725
590
700
790
5
25
6-9
5
30-3s
50
40-45
3843
Carbon Steel Parts by Induction
Process
Total
beating
time, s
Scao time
s/cm
Sri.
68.4
28.8
98.8
-14.2
11-l
51
0.71
0.71
I .02
I .03
I.18
I.18
I.8
I.8
2.6
2.6
3.0
3.0
7s
620
70
620
7s
620
I65
II50
160
II50
I65
II50
620
955
620
95s
620
955
II50
I750
II50
I750
II50
17.50
II3
II3
I41
I41
IS3
I53
250
250
311
311
338
338
0.085
0.054
0.057
0.053
0.050
II.3
IS
28 5
26.3
36.0
0.59
0.79
I SO
1.38
1.89
I .s
2.0
3.8
3.5
1.8
20
20
20
20
20
70
70
70
70
70
870
870
870
870
870
1600
1600
1600
I600
1600
lU9
IS76
1609
IS95
1678
3194
3474
3548
3517
3701
0.361
0.319
0.206
0.225
0.208
2.33
2.06
I .33
I.45
I .34
0.94
2.4
20
70
885
162.5
2211
4875
0.040
0.26
Work temperature
Entering coil
Leaving coil
OC
‘=F
“C
“F
Production rate
lb/h
kslb
Inductor
input(c)
kW/cmz kW/i&
Rounds
I9
‘4
1035 mod
25
I
lo-11
29
I ‘Ix
1041
I80
9600
%?
34
‘4
I
I ‘/8
1038
1038
1043
1036
1036
3000
3000
3000
300
332
336
304
311
3OQO
580
28.5
20.6
33
19.5
36
19.1
Flats
I6
I9
12
25
29
Irregular
shapes
17.5-33
“/16-1Vlb
1037 mod
25-l
Ia) NOW use ofdual frequencies for round secuons. (b) Po\rer transmitted by the inductorat the operaung frequency
mput IO the machine. because of losses within the machine. (c) AI the operating frequency of the inductor
indicated.
This poner is approximarely
2%
less than the power
Carbon
Operating
and Production
Section size
in.
mm
Material
Data for Progressive
Frequency,
Ez
Power(a),
kH
Induction
Total
beating
time, s
Steels (1000, 1 1 00,1200,
and 1500 Series) / 135
Tempering
Scan time
s/cm
Sri.
Work temperature
EnbXillg
Leaving
coil
coil T
OF
“C
“F
0.71
I .02
I.18
I.8
2.6
3.0
so
so
SO
I’0
I20
I20
510
565
565
0.59
0.79
I SO
I.22
1.57
I .s
2.0
3.8
3.1
4.0
40
40
40
-lo
40
IlKI
100
IO
IO0
100
290
315
‘90
290
290
0.94
0.67
2.-l
1.7
65
65
I50
IS0
550
-125
Production
rate
lblh
kP
Inductor
input(b)
kW/cm2 kW/ii.’
Rounds
I9
2s
29
%
I
I Vs
1035 mod
1041
1041
9600
9600
9600
12.7
18.7
20.6
%
%
‘4
I
I ‘/x
1038
I038
1043
IoJ3
1043
60
60
60
60
60
88
100
98
85
90
1037 mod
1037 mod
9600
9600
I92
IS-l
30.6
44.2
51
950
IO50
1050
II3
I41
IS3
30
311
338
0.050
0.054
0.053
0.32
0.35
0.34
I449
IS76
I609
I365
l-183
3194
3171
3548
3009
3269
0.014
0.013
0.008
0.011
0.009
0.089
0.08 I
0.050
0.068
0.060
2211
2276
-1875
SO19
0.043
0.040
0.28
0.26
Flats
I6
I9
22
25
29
123
16-l
312
25-l
328
SW
600
990
SSO
550
Irregular shapes
17.5-33
17.529
)‘/)e-15/)b
)&-I
l/x
64.8
46
(a) Power transmitted by the inductor ar the operating frequency indicated. For convened
because of losses within the machine. (b) AI the operating frequency of the inductor
1062:
Preliminary
Spot Flame Hardening
of a Free-Wheel
this power is approximately
254
less than the power inpur to the machine,
Cam
Hardness and pattern aim
operation
Turn on water. air, oxygen. power. and pmpane. Line pressures: water. 205 kPa (30
psi); air, 550 kPa (80 psi): oxygen. 82S kPa ( I20 psi): propane. 205 kPa (30 psi ). Ignite piloa.
Loading and positioning
Mounr cam on flame head. Cam positioned on locating plaw and MO wear pads. and
against three locating pins lhar are imegral pans of flame head. Disurnce from flame
head to cam surface. appmximalely
7.9 mm &)r, in.)
Cycle start and heating cycle
Propane and oxygen solenoid valves open (oxygen flow delayed slightly). Mixture of
propane and oxygen ignited a1 flame heads hy pilots. Check pmpane and oxygen pressures, Adjust flame by regulating pmpane. Heating cycle controlled by timer. lime
predetermined toobtain specilied hardening depth. Propane and oxygen solenoid
valves close (propane flow delayed slightly). Ejector plate (air operated) advances
and suips cam horn flame head.
Propane regulaled pressure. I25 kPa ( I8 psi); oxygen regulated pressure, 585 kPa (89
psi ): oxygen upsu-eam pressure. 425 kPa (62 psi); oxygen dounstream pressure. I IO
kPa ( 16 psi). Flame velocity (approximate).
I35 m/s (-150 ft/s). Gas consumption (approximate): pmpane. 0.01 m3 (0.4 ft3) per piece: oxygen. 0.04 m3 ( I .3 ft3) per piece.
Total heating time. I I s
Flame pm design: nine ports per row; eight mws; port size. No. 69 (0.74 mm. or
0.0292in.).whhNo.S6(1.2
mm.orO.O-%Sin.)counterbore
Quench cycle
Cam drops into quench oil. is removed from tank by conveyor.
S.6”C( l30f 10°F). Tie inoil (approximate),
30s
frequencies.
I020
800
Oil lemperarure.
S-1f
Hardness. 60 HRC minimum ar surface and 59 HRC minimum al adepth of I .3 mm
(0.050 in.) below surface. for\sidrh of 8.8 mm (0.345 in.) on cam rollersurface.
Dimemions below gven in inches
136 / Heat Treater’s
Guide
Gas Carburizing:
Flame Hardening
Response
of Carbon Steels
Material
‘Qpical hardness, ERC, as affected by quenchant
Air(a)
Water(b)
OW)
Steel
Carburized
SO-60
55-62
Q-S8
58-62
58-62
-15-55
so-55
52.S7lC)
SS-60
33-50
55-60
60-63
62-65
IS-55
55-62
58-6-l
1010
1018
1019
1020
1021
IO’.!
152-l
IS17
62-65
62-65
Resulfurized
grades of plain carbon steels(d)
1010-1020
1108-1120
Steel Compositions
Composition, %
Ni
Cr
C
Mn
0.08-0.13
0.15-O 70
0. IS-O.20
0.1X-0.23
0.18-0.23
0.18-0.23
0 19-O 25
0’1-029
0.30-0.60
0.60-0.90
0.70-I .OO
0.30-0.60
0.60-0.90
0.70-1.00
1.3.31-1.65
1.20-1.50
MO
Other
:::
la).(b)
(a).(b)
(a). lb)
(a). fb)
W.(b)
(a). fb)
(a,.(b)
Carbon steels
Plain carbon steels
102S- 103s
IcU@lost~
10.55-1075
1080-1095
11~5-1137
1138-114-l
II46llfil
Carburizing
5X-61
50-b0
SO-60
60-63
III7
:::
.._
_..
(a).(b)
steels
0.140’0
100-l
30
0.08-o. I3 S
tat Toobtain the hardness results indicated. those areas not dtrestly heated must be kept
relatively cool during the heating process. tbl Thin sections are susceptible to cracking
when quenched utth oil or water. tc) Hardness is slightly lower for material heated h)
spinningorcombination
progressike-spinning
methods than it is for material heated by
progresstbe or stationq
methods. (di Hardness values of carburized cases containing
0.9oto I.IOQC
Effect of Cyaniding
Temperaturesand
Time on Case Depth and Carbon and Nitrogen
Contents
Material thickness, 2.03 mm (0.080 in.); cyanide content of bath, 20 to 30%
Case depth after cjaniding
steel
Anal)& after 100 min at
temperature(a)
Carbon, %
Nitrogen, %
for:
15 min
100 min
mm
in.
mm
in.
0.038
0.038
0.05 I
0.0015
0.001s
0.0020
0.152
0.151
0.203
O.OOb
0.006
0008
068
0.70
cl.7L
0.5 I
0.50
051
0.076
0.076
0.089
0.0030
0.0030
0.0035
0.203
0.203
0.3-l
0.008
0.008
0.010
0.75
0.77
0.79
0.26
0.28
0.27
Cyanided at 76O’C (1400 “F)
1008
IOltl
1022
Qanided
1008
I010
IO’2
at 845 OC (1550 OF)
tat Carbon and nitrogen contents were determined
from analysis of the outermost
0.07b mm 10.003 in. J of cytnidsd
cases.
Carbon
Liquid Carburizing
Typical application
Carbon Steels in Cyanide
of carbon steel and resulfurized
Weight
Part
Steels (1000, 1100,1200,
and 1500 Series) / 137
Baths
steel
Depth of case
mm
in.
Temperature
T
OF
kg
lb
Steel
0.9
0.5
0.7
3.5
I.1
I .-I
0.03
0.09
09
1.75
0.05
0.007
0.007
0.7
0.15
7.7
0.05
2
I.1
1.5
7.7
2.5
3
0.06
0.’
2
10,s
0.12
0.015
0.015
I .b
I
17
0. I
CR
1020
CR
IO20
CR
I020
1020
ION
CR
1020
1020
1018
1010
CR
IO20
CR
IO22
I .o
I.5
I.5
1.3
1.3
I.3
0.1-0.5
I .s
I .o
1.3
0. I3-0.25
0.13-0.2s
0.25-0.-l
I.5
I .s
1,s
0.02-0.0.5
0.040
0.060
O.ObO
0.050
0.050
0.090
0.0 I s-o.020
0.060
0.040
0.0.50
0.005-0.010
0.00.5-0.010
0.010-0.015
0.060
0.060
0.060
0.00 I-O.002
940
940
910
940
910
910
81.5
940
910
940
8-15
845
81S
940
940
910
900
I720
I720
1720
I720
I720
I720
ISSQ
I720
I720
I720
IS50
1550
1550
I770
17’0
17’0
1650
0.0-l
3.6
0.0009
3.6
02
0.0-l
O.W3
0.007
0.31
0.0 I
0003
0.08
0.009
0.9
0.007
0.02
O.-IS
0.007
0.09
8
0.00~
8
0.5
0.09
0.007
0.015
0.75
0.03
0.007
0.18
0.02
2
0.015
0.05
I
0.015
III8
III7
III8
III7
III7
III3
III9
III3
III3
III8
Ill.7
III8
III8
III7
III8
III7
III7
IIIX
03-0.4
I.1
0. I3-0.25
I.1
0.7.s
0. I3-0.25
0 I3-0.25
0.0750. I3
O.I.w.25
0.x-0.1
0.075-0. I3
0.25-0.-l
0.x-o -I
I.1
0.13~0.2s
I.3
I.1
0.3-0.-l
0.0 I o-0.0 IS
0.045
0.005-0.010
0 015
0.030
0.005-0.010
O.WS-0.010
O.W3-0.005
o.ws-0.010
0010-0015
O.W3-0.005
0.0 I o-o.0 IS
0.010-0015
0.045
0.005-0.010
0.050
0.0-1s
0.010-0.015
8-15
915
845
91s
91.5
845
815
I345
81.5
8-15
845
8-lS
8-15
925
Y-IS
91s
91s
845
I550
1675
I SSO
1675
lb75
I SSO
IS50
ISSO
I550
I550
I SSO
IS.50
I SSO
I7W
ISSO
1675
I675
ISSO
Time, h
Quench
Subsequent
treatment
Eardness, ERC
Carbon steel
Adapter
Arbor, tapered
Bushing
Die block
Disk
Flange
Gage rings. knurled
Hold-down block
fnsen.tapered
Lever
Link
Plate
Plllg
Plug gage
Radius-cutout roll
Torsion-barcap
-I
6.5
6.5
5
5
5
1
b.5
-I
5
I
I
7
65
6.5
6.5
0.1’
AC
4C
AC
AC
AC
62-63
62-63
62-63
62-63
59-6 I
56-57
55 mm(d)
62-63
62-63
62-63
(e)
(b)
Oil
AC
AC
<AC
Oil
AC
Oil
AC
4C
AC
Causric
(e)
62-63
62-63
62-63
45-47
Resulfurized steel
Bushing
Dash sleeve
Disk
Dri\e shah
Guide bushing
NUI
Pin
Plug
Rack
Roller
SCRW
Shdi
Spring seat
Stop collar
Stud
Valve bushing
Vahe retainer
H’asher
2
7
!
7
s
I
I
0.5
I
2
0.5
2
7
65
I
8
7
2
Oil
4c
Brine
AC
(i)
Oil
Oil
Oil
Oil
Oil
Oil
Oil
Oil
AC
011
AC
(i)
Oil
(C)
(g)
(C)
(h)
(C‘J
(5)
(C)
(Cl
(C)
(C)
(C)
(CJ
(a
(CJ
(EJ
(Cj
(e)
58-63
(e)
58-63
58-63
(e)
(e)
(e)
(CJ
(e)
k)
(ei
(CJ
60-63
(e)
58-63
58-63
W
(a)Reheatedat
79O”C( I4SO”F).quenched
incauslic. tempered al lSO”C(3W
“F). (brTransferred
to neuualsalt al 79O”C( lXiO’F).quenched
incaustic. temperedat I75 “C(350
“F). (c)Tempered
at I65 “C (325 “F). (d) Or equivalent. (e) File-hard. (f) Tempered al 205 “C (-100 “F). (g) Rehealed ar 84.5 “C I I550 “F,, quenched in sall at I75 “C (350°F). (h)
Reheated al 77s “C( 1125”F~,quenched
in salt at l9.i “C 1380°F). ti)Tempered
at lb5 “C (325 “FJ and treated at -85 “C I-120°F)
Liquid Carburizing
Typical applications
Carbon Steels in Noncyanide
Weight
Part
Production mols
Bicycle forks
Shift leverand ball
Clock screus and studs
Flar head screfi s
(a) Partial immersion.
Baths
of carbon steels
lb
Steel
0.5-2.0
I .-I
I. I-1.1
3.1
1018
1017(a)
-1.5
O.W5
0.015
-3.3
0.0 I I
0.033
I@Mu). 1017(b)
IW6. I I I3
II22
kg
(b) Carhurizer
brass braze
Case depth
mm
in.
0.375
0.05-0.08
O.OlS
0 0020.003
0.3
0.010
0.08-O. IO o.O03-0.001
0. I5
O.Wb
Temperature
T
OF
Time, h
Quench
925
93
I700
I700
0.5. I .o
0.085
Brine
Brine
93
9s.i
925
I700
I750
I700
0.67
0.’
0.33
.Aircool?Ojinbrinr
Brine
hlollen salt. 290 “C
(550’;F1
Subsequent
treatment
Eardness,
ERC
SO-60
Temper at 425 “C
(795 “FJ
60
Fi Ie hard
62-6-l
56
138 / Heat Treater’s
Carbonitriding
Typical applications
Guide
Carbon Steels
and production cycles
Casedepth
0.001 ill.
Steel
mm
1020
1010
1010
101s
1015
1213(h)
I030
1015
1022
III7
1117
1010
1213(b)
III8
1018
1030
1018
I o-lo
0.05-O. IS
0.05-o. I5
0.38-0.45
0.08-o. I3
0.15-0.25
0.30-0.38
0.15-0.25
0.05-O. I5
0.30-0.38
0.20-0.30
-0.75
0.38-0.45
0.30-0.38
0.30-0.36
0.38-0.50
0.25-0.50
0.38-0.50
0.25-0.50
Part
Furnace temperature
OF
OC
Total time
in furnace
Quench
carboo steels
Adjusting yoke, 3-S by 9.5 mm ( I by 0.37 in.)
Bearing block 64 by 32 by 3.2 mm (2.5 by I .3 by 0. I3 in.)
Cam. 2.3 by 57 by 6-t mm (0. I by 2.25 by 2.5 in.)
cup. 13g(O.-t6oz)
Distributordrive
shaft I25 mm OD by I27 mm (5 by 5 in.)
Gear.44.5 tntndiam by 3.2 mm( I.75 by0.125 in.)
Hex nut. 60 3 by 9.5 mm (2-l by 0.37 in.)
Hood-latch bracket. 6.4 mm diam (0.25 in.)
Link. 2 by 38 hy 38 mm (0.079 hy I .5 by I .S in.)
Mandrel.4Og(l.-ll
oz)
Paper-cutting tool. 410 mm long
Segment,2.3by44.5by44.5mm(0.09by
1.7Shyl.7Sin.)
Shaft. 1.7 mm diam by IS9 mm (0.19 by 6.25 in.)
shtftcollar,59g(2.lozJ
Sliding spur gear, 66.7 mm OD (3.625 in.)
Spring pin. l-I.3 mm OD by I II mm CO.56by 4.S in. J
Spur pinion shti II 3 mm OD ( I.625 in.)
Transmission shift fork I27 by 76 mm (5 by 3 in.)
(a) Modifiedcarbonitriding
(g)Oilat
150°C(3W”Fk
2-6
2-6
15-18
3-5
6-10
12-15
6-10
2-6
12-1s
S-12
-30
15-18
12-15
12-l-I
IS-20
IO-20
IS-20
IO-20
77Sand745
775 and 745
855
790
SlSand7-tS
855
815attd715
775 and 7-U
855
8-E
I-IX and I375
lQSandl375
I575
1150
ISWand 1375
I575
15Wand 1375
l12S and I375
1575
I550
@mitt
tintin
2 ‘/z h
‘/2 h
I08 mm
I 3/, h
64min
Mmin
I ‘12 h
I ‘/? h
855
815
77s
870
815and715
870
815and7-15
I575
1500
1130
1600
15Wand 1375
1600
15Wand 1375
2’/: h
2 ‘h h
5t/; h
2h(n
Ij-lmitt
2h(D
162min
atmosphere. (b) Leaded. (c)Tempered
at 190 “C (375 “F). td) Tempered at IS0 “C (300 “P). (c)Tempered
tempetedat
150°C (300°F): for I h. (h)Oilat
ISO”C(3W”F):
temperedat XO”Ct5W”F)
for I h
Applications
Substrate material
AlSI
BSI
for Boride Carbon Steels
DtN
St37
1020
1043
II38
IO42
Clfi(CklS)
C-IS
stso- I
JSS20
Ck45
Application
Bushes. bolts. nozzles. conveyer tubes. base
plates. runners. blades. thread guides
t3eardrives.pumpshaft.s
Pins, guide rings, grinding disks. holts
Casting inserts. nozzles. handles
Shaft protection sleeves. mandrels
Swirl elements. nozzles (for oil burners).
rollers. bolts. gate plates
at 165 “C (325 OF). (f)Time
Oil
Oil
Oil
Oil
Gas(a)
oil(c)
Oil
Oil
Oil
Oil
oil
Gas(a)(d)
Oil(e)
oil(g)
Oil
Oil(h)
Gas(a)
at temperature.
Nonresulfurized
(1000
Carbon
Steels
Series)
1005
Chemical Composition. AISI and UNS: 0.06 C max. 0.35 Mn mity,
0.040 Pmax. 0.050 S max; (standard steel grade for wire rod and wire only)
Recommended
Case Hardening.
Heat Treating
Can he carhonitrided
Practice
1006
Chemical Composition. AISI and UNS: 0.08 C max. 0.25 hln max.
0.040 Pmax, 0.050 S max; (standard steel grade for wire rod and wire only)
Recommended
Case Hardening.
processes
Heat Treating
Carbonitriding
Practice
and liquid
carburizing
are suitable
1008
Chemical
COmpOSitiOn.
AISI and UNS: 0. IO C max. 0.30 to 0.50
Mn. 0.040 P max, 0.050 S max. UNS Cl0080 and AIM-SAElOOS
standard composition
ranges and limits: 0.10 C max. 0.25 to 0.50 Mn
Similar Steels (U.S. and/or Foreign). UNS G 10080: ASTM
A 108. A5 IO, A5 19. AS45. AS49. A575. A576; FED QQ-S-637 (C 1008).
QQ-S-698(C1008);
MILSPEC
ML-S-I1310(CS1008):
SAEJ403. J412,
J414; (Ger.) DfN 1.0204: (Ital.) UNI CB IO FU
Characteristics. Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction. Has excellent cold
formability
and is readily welded by any of the well-known
welding
processes. Brazing results also excellent, which accounts for widespread
use of furnace brazing in producing assemblies. Machinability
is extremely
poor
Recommended
Diagram. Containing
0.43 Mn; austenitized
at 915 “C (1680 “F). Grain
site transformation
temperatures
are estimates.
0.06 C,
size, 7. Marten-
Practice
Normalizing.
Heat to 925 “C (I 695 OF). This will restore the microstructure. which consists of a few pearlite plates dispersed among grains of
blocky ferrite
Annealing. When clean surfaces are required. heat to approximately
910 “C (1670 “F) in a lean exothermic
atmosphere. Cool in the cooler
section of a continuous furnace. Microstructure
following
this treatment
essentially the same as that obtained after normalizing
Tempering.
honitriding
Although the vast majority of parts case hardened by carare not tempered. they can be rendered less brittle by tempering
1008: Carbonitriding
1008: Isothermal Transformation
Heat Treating
140 / Heat Treater’s
Guide
1008: Microstructures.
(a) Aluminum-killed 1008 steel, normalized after 60% cold reduction to a final
ferritic structure contains fine pearlite (dark areas) at the grain boundaries. 4% nital. 1000x. (b) Same
595 “C (1105 “F) after normalizing. Ferritic structure contains some fine pearlite and some spheroidized
4% nital. 1000x. (c) Same as (a), except process annealed at 705 “C (1300 “F) after normalizing. The
mentite particles at the grain boundaries. 4% nital. 1000x
1008: Rimmed 1008 steel part, formed from sheet, with surface
roughness (orange peel). Not polished, not etched. Actual size
thickness of 0.8 mm (0.03 in.). The
as (a), except process annealed at
cementite at the grain boundaries.
ferritic structure contains some ce-
1008: Rimmed 1008 Steel Parts. Magnified cross section shows
the coarse surface grain that caused the orange peel. nital. 50x
Nonresulfurized
at 150 to 205 “C (300 to 400 “F) without
hardness
appreciable
loss of surface
Case Hardening.
Hard. wear-resisting
surfaces can be obtained on
parts by carbonitriding.
Depth of case developed depends upon time and
temoerature.
Carbonitride
at 760 “C ( 1300 “F) to 870 “C ( I600 “F).
Atmosphere usually comprised of an enriched carrier gas from an endothermic generator, plus about IO%, anhydrous ammonia. Case depths usually
range from approximately
0.008 to 0.25 mm (0.003 to 0.010 in. ). Maximum
Carbon
Steels / 141
surface hardness usually obtained by oil quenching directly from the
carbonitriding
temperature. Cyanide or cyanide-free
liquid salt baths and
gas carburizing may also be used for equi\&nt
results. Temperatures. time
at temperature. and quenching practice also approximately
the same
Process Annealing.
Heating to 600 “C (I I IO OF) will recrystallize
cold worked structures: often used as an intemrediate anneal prior to further
cold working
Nonresulfurized
Carbon
Steels / 141
1010
Chemical COIIIpOSitiOn.
AISI
0.60 Mn. 0.040 P max. 0.050 S max
and UNS: 0.08
to
0.13 c. 0.30 m
Annealing.
For clean surfaces. heat to approximately
9 IO “C (1670 OF)
in a lean exothemic
amlosphere. Cool in the cooler s&ion of a continuous
furnace
Similar Steels (U.S. and/or Foreign). UNSGIOIOO; AMS 5010.
5042. 504-t. 5047. 5053: ASThl A 108. A5 IO. AS 19. A545. A519. A575
AS76; MfLSPEC
MLS-11310
(CSIOIO); SAE J103. J-IIZ. J4l-l: (Ger.)
DJN I.IIZI;(Fr.)AFNORXC
lO;(Jap.)JISS
l0C.S
12C9CK
Tempering.
Characteristics.
Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction, accounting for excellent
cold formability.
However. as the carbon content increases the cold formability decreases, slightly reducing the severity it can withstand in cold
forming. Weldability
and brazing results are excellent. h,Jachinability
is
poor
Case Hardening. Carbonitride at 760 to 870 “C (l-t00 to 1600 “F) in
an enriched endothermic carrier pas. plus about IO%, anhydrous ammonia.
Case depths range from 0.076 to 0.25-l mm (0.003 to 0.01 in.). Oil quenching directly from carbonitridinp
temperature pro\.ides maximum surface
hardness. Salt baths produce similar results. Flame hardening, austemperinp. and liquid carburizinp are alternative processes
Recommended
Normalizing.
Heat Treating
Heat to 925 “C (I695
Practice
“F). Cool in still air
Optional. Tempering at IS0 to 205 “C (300
reduces hrittleness without appreciable loss of surface hardness
IO
100 “F)
PrOCeSS
Annealing.
Heating to 600 “C t I I IO “F) will recrystallize
cold \\orked structures: often used as an intemrediate anneal pnor to further
cold working
1010: Microstructures.
(a) Nital, 200x. Carbonitrided at 790 “C (1455 “F) and oil quenched, showing a high-carbon, low-nitrogen case,
Core (right half of micrograph) is predominantly ferrite. (b) 29/onital, 700x. Liquid nitrided 1 h at 570 “C (1060 “F) in aerated nitriding salt bath.
Nitrided layer, 0.0076 mm (0.0003 in.) deep. Core structure, blocky ferrite and grain-boundary carbide. No transition zone evident
142 / Heat Treater’s
Guide
1010: Time-Temperature
Diagram. Composition: 0.12 C, 0.50 Mn. 0.16 Si, 0.004 P, 0.010 S, 0.0005 N. Austenitized
for 15 min. Grain size: 9.9. Source: Atlas of Time-Temp. Diagrams for Irons and Steels
at 925 “C (1695 “F)
1010: Carbonitriding.
Effect of carbonitriding temperature on dimensional stability of three 1010 steel production parts. Parts were carbonitrided to produce a case depth of 0.13 to 0.20 mm (0.005 to 0.008 in.) with minimum surface hardness of 89 HR15N. Gas ratios and dew
points were essentially the same for all temperatures. Time at temperature was 15 to 45 min, depending on temperature. ID, inside diameter.
Part dimensions and tolerances given in inches
Nonresulfurized
Carbon
Steels / 143
1010: Cyanide-noncyanide
Treatments. Comparison of compound zone thickness produced by low-cyanide and cyanidebased treatments containing sulfur
Nonresulfurized
Carbon
Steels / 143
1012
Chemical
Composition.
AISI and UNS: 0.10 to 0.15 C. 0.30 to
Recommended
Heat Treating
Practice
0.60 Mn, 0.040 P max. 0.050 S max
Normalizing.
Similar
Steels (U.S. and/or
Foreign).
A5lO. A519. A545, A539. A575
(CSlOl2):
SAE J103, J412. J-II-t
AS76:
UNS
MIL
~10120:
ASTM
SPEC MLS-11310
Characteristics.
Extremely ductile in the normalized or annealed condition and often subjected to severe cold reduction. accounting for excellent
cold formability.
However. as the carbon content increases the cold formability decreases, slightly reducing the severity it can withstand in cold
forming. Therefore, this steel is best suited for production of stampings.
where the amount of drawing is minimal. Weldability
and brazing results
are excellent. Machinability
is poor
Heat to 925 “C t 1695 “F). Cool in still air
Annealing.
For clean surfaces. heat to approximately
885 “C f 1625 “F)
in a lean exothermic atmosphere. Cool in the cooler section of a continuous
furnace
Case Hardening. Carbonitride at 760 to 870 “C (1300 to 1600 “F) in
an enriched endothermic carrier gas. plus about IO% anhydrous ammonia.
Case depths range from 0.076 to 0.25-t mm (0.003 to 0.01 in.). Oil quenching directly from carbonitriding
temperature provides maximum surface
hardness. Salt baths produce simihar results. Flame hardening is an altemative process
Nonresulfurized
Carbon
Steels / 143
1013
Chemical
Composition.
AISI and UNS: 0. I I to 0.16 C. 0.50 to
0.80 Mn. 0.040 P max. 0.050 S max
Recommended
Case
Hardening.
processes
Heat Treating
Flame
hardening
Practice
and carbonitriding
are suitable
Nonresulfurized
Carbon
Steels / 143
1015
Chemical
Composition.
AISI and UNS: 0.13 10 0.18 C. 0.30 to
Forging.
Heat to 1290 “C (2.355 “F). Do not forge below 925 “C (1695 “E)
0.60 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign).
1.1~s
G10150:
~h1.s
5060; ASTM A5 IO. AS 19. A515 A539. A515 A576. A659: FED QQ-S698~C1015);MILSPECMIL-S-16971;SAE5~03,J~12.J~13;(Ger.)DIN
I.IIJI;(Fr.)AFNORXC
l5,XC
lS;(Jap.)JISS
15C.S l7C.S
15CK:
(Swed.) SSIJ I370
Characteristics.
Sometimes considered a borderline grade of steel.
Carbon content is high for best cold formability
and slightly low compared
with grades of carbon steel used for most carburizing apphcations. Excellent forgeability. reasonably good cold formability,
and excellent weldability. Machinability
is relatively
poor compared with the II00 and I200
grades
Recommended
Normalizing.
Heat Treating
Heat to 915 “C t I680 “F). Air cool
Annealing.
Heat to 885 “C (1625
cooler or by furnace cooling
Hardening.
Practice
‘F). Cool
slowly.
preferably
in a
hlav be case hardened by carburizing.
(See procedure for
1020.) More often.-it is subjected to light case hardening by carbonitriding
or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening,
gas nitriding. and electron beam hardening are alternative processes. In
many instances. forgings of this grade are used in service either as forged
or as forged and normalized
144 / Heat Treater’s
Guide
1015: Maximum Case Hardness vs Carbon Content
1015: Nitriding. At 565 “C (1050 “F), using aerated bath process
1015: Liquid Carburizing. Plots of carbon concentration versus
carbon penetration for 1015 steels that were carburized at 930 “C
(1705 “F) for 1 h with two different Durofer process base salt regenerators
1015: Microstructure.
The metallographic
appearance of AISI
1015 material after a 2-h vacuum-nitrocarburizing
treatment in an
ammonia/methane
mixture with 1% oxygen addition
Nonresulfurized
1015: Gas Nitriding. Comparative Amsler wear tests on AISI 1015 after various ferritic nitrocarburizing treatments. 1, untreated; 2, cyanide-based salt bath nitrocarburizing with sulfur; 3, subatmospheric
oxynitrocarburizing;
4, gaseous nitrocarburizing;
and 5, cyanidebased salt bath nitrocarburizing (treatment 1)
Carbon
Steels / 145
1015: Liquid Nitriding. Nitrogen diffusion
in AISI 1015 steel
Nonresulfurized
Carbon Steels / 145
1016
Chemical Composition. AISI
0.90 Mn, 0.040 P max. 0.050 S max
and UNS:
0. I? to 0.18 C, 0.60 to
Similar
Steels
(U.S. and/or Foreign). UNS Gl0160:
ASThl
A 108. AS IO. A5 13. AS-15 AS-18. AS19, AS76. A659; MIL SPEC hlIL-S866; SAE J403,J412. J-l14 (Ger.) DIN I.0419
Characteristics. Carbon content is high for best cold formabilit> and
slightly low compared with the grades of carbon steel used for most
carburizing
applications.
Excellent
forgeability
reasonabll
good cold
formability and excellent weldabilit>. Machinablhty
is relativeI> poor compared with the II00 and I200 grades
Forging.
Heat to I290 “C (2355 “F). Do not forge below 93 “C ( 1695 “F)
Recommended
Normalizing.
Heat Treating
Heat to 93
“C t 1695 “F). Air cool
Annealing. Heat to 885 “C (1625
cooler or by furnace cooling
Hardening.
Practice
‘F). Cool
slowly,
preferably
in a
hln\ be case hardened b! carburiring.
(See procedure for
1020.) hlore often.-it is subjected to light case hardening by a&o&riding
or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening
is an alternative process. In man! instances. forgings of this grade are used
m serwce either as forged or as k~rgsd and normalized
Nonresulfurized
Carbon
Steels / 145
1017
Chemical Composition.
AISI
0.60 Mn. 0.040 P max. 0.050 S mnx
Similar
and UNS:
0. IS IO 0.X
c. 0.30
to
Steels (U.S. and/or Foreign). UNS Glol70:
ASTAl
A 108, ASIO. ASl3, AS 19, A544. A549. x575. A576. A659: hllL SPEC
MIL-S-ll3lO(CS
1017);SAE5303.5412.5-113;Ger.)DIN
I.I14I;(Fr.)
AFNORXC
lS,XC
l&tJap.)JISS
1SC.S 17C.S liCK:(Swrd.)SS,;
I370
Characteristics.
Escellrnt
forgeahility.
reasonably good cold forrnability and excellent \~eldabilit>. As carbon content increases. strength also
increases. accompanied
b> ;1 small decrease in cold formability.
Machinnbilit> IS relativeI> poor comparsd with the II00 and I200 grades
Forging.
Heat to 1275 “C (2329 ;F). Do not forge below 910 “C (I670 “F)
146 / Heat Treater’s
Recommended
Normalizing.
Guide
Heat Treating
Heat to 885 “C (I625
Annealing.
Heat to 885 “C (I625
cooler or by furnace cooling
Hardening.
Practice
1017 Hardness
erage
OF). Air cool
“F). Cool
slowly,
preferably
m a
May be cnse hardened hy carburizing.
(See procedure for
1020.) More often, it is subjected to light case hardening by carbonitriding
or casing in a liquid bath. (See procedure for 1008 steel.) Flame hardening
is an alternative process. In many instances. forgings of this grade are used
in service either as forged or as forged and normalized
based
vs Tempering
on a fully quenched
Temperature.
structure
Represents
an av(no case hardening)
146 / Heat Treater’s
Guide
1018
Chemical Composition.
AISI and UNS: 0.15 to 0.20 C. 0.60 to
0.90 hln. 0.040 P max. 0.050 S max
Recommended
Similar
Normalizing.
Steels (U.S. and/or Foreign).
UNS
Gl0180;
AMS
5069; ASTM A 108. A5 IO. A5 13. AS 19, AS-U. A535. AS-N. A519. A576.
A659: MILSPEC
MIL-S-11310
(CSlOl8);
SAE J103. J-II?. J-II-l
Characteristics.
Excellent forgeability.
reasonahly good cold formability, and excellent vveldability. As carbon content increases. strength also
increases, accompanied
by a small decrease in cold formability.
Machinability is relatively poor compared with the I100 and 1200 grades. The
slightly higher manganese (compared with 1017) provides a slight increase
in strength in the nomralized or annealed condition. Higher manganese also
provides for a mild increase of hardenability
for case hardened parts
Forging.
Heat to 1275 “C (7375 “F). Do not forge below 910 “C (1670 OFJ
Heat Treating
Practice
Heat to 925 “C (I 695 “F). Air cool
Annealing.
Heat to 885 “C (I675
cooler or by furnace cooling
“F). Cool
slowly,
preferably
in a
Hardening. May be case hardened by liquid or gas carburizing, or by
flame hardening. (See procedure for 1020.) Quenchants include aqueous
polymers. hlore often. it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) In many
instances. forgings of this grade are used in service either as forged or as
forged and normalized. Grade 1018 is used to a considerable extent for
carburizing to deep case depths
1018: Carburized, Oil Quenched, and Tempered. 12.7-mm
(0.5in.)
diam bar, carburized
at 925 “C (1695 “F) for 4 l/2 h. oil
quenched,
and tempered
at indicated temperatures
Nonresulfurized
1018: Carburizing Temperature vs Depth of Case. Treated 3 h
at temperature.
Endothermic gas atmosphere,
enriched with
natural gas. Carbon potential automatically
controlled by dew
point method, producing 0.90 to 0.95% surface carbon.
Carburizing
Symbol
“F
%pera%!
,3.
1950
1065
0..
A
1900
1850
1800
1040
1010
980
8: : : : : : : :c%
E
L
Dew point
-7 to -5
-2 to
0
+2 to +14
+6 to +9
+14
+11 to +15
+13
-22
-19
-17
-14
“C
to
to
to
to
Steels / 147
1018: Hardness vs Tempering Temperature. Decrease of surface hardness with increasing tempering temperature. Rockwell
C converted from Rockwell 30-N. Carbonitrided 2 l/2 h
Symbol
‘.:I, .........................
..........................
t ..........................
A...........................145
NH,. ‘2
.1550
..155 0
.1450
0
845
845
790
790
1;
1:
-21
-18
-10
-13
-10
-12 to -10
-9
1018: Carbon, Nitrogen, and Hardness Gradients. Carbonitrided
verted from Tukon
Carbon
at 845 “C (1555 “F), 4 h. Oil quenched at 55 “C (130 “F). Hardness con-
148 / Heat Treater’s
Guide
1018: Effect of Tempering Temperature on Hardness Gradients. Tempered 1 h at temperature.
Rockwell C hardness converted from
dickers. (a) Carbonitrided at 790 “C (1455 “F) ,2 l/2 h; 5% NH,. (b) Carbonitrided at 790 “C (1450 “F), 2 l/2 h; 10% NH,. (c) Carbonitrided
at 845 “C (1555 “F), 2 l/2 h; 5% NH,. (d) Carbonitrided at 845 “C (1555 “F), 2 l/2 h; 10% NH,
1018: EfFect of Ammonia in Carbonitriding
Gas on Hardness Gradient. (a) Carbonitrided
at 845 “C (1555 “F), 2 l/2 h. Hardness converted from Vickers
at 790 “C (1450 OF), 2 l/2 h. (b) Carbonitrided
Nonresulfurized
Carbon
Steels / 149
1018: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure (no case hardening)
1018: Microstructures. (a) 1% nital, 500x. Carburized 8 h. Surface carbon content, 0.60 to 0.70%. Ferrite (light areas), outlining prior
austenite grain boundaries, and pearlite (dark areas). (b) 1% nital, 500x. Carburized 4 h. Surface carbon, 0.70 to 0.80%; wholly pearlitic.
Below surface, dark areas are pearlite. Areas of ferrite outline prior austenite grain boundaries. (c) 1% nital. 500x. Carburized 6 h. Surface
carbon, 0.90 to 1 .OO%. Thin film of carbide outlines pnor austenite grain boundaries in matrix of pearlite. (d) 1% nital. 500x. Carburized 16
h. Surfacecarbon, 1 .OOto 1 .lO%. Surface layer, carbide. Below surface, thin film of carbide outlines prioraustenite grain boundaries in pearlite matrix. (e) 1% nital. 500x. Carburized 18 h in continuous furnace. Cooled under atmosphere in furnace vestibule. Partly separated layer
of carbide (approximately 0.90% carbon) covers pearlite matrix. (f) 1% nital, 500x. Carburized 12 h. Surface carbon. approximately 1 .lO%.
Carbide surface layer. Film of carbide outlines prior austenite grain boundaries in pearlite matrix
(continued)
150 / Heat Treater’s
Guide
1018: Microstructures (continued). (g) 1% nital. 500x. Gas carburized, 5 h; 925 “C (1700 “F), pit-type furnace with air leak. Furnace
cooled to 540 “C (1000 “F) in 2 h 10 min. Air cooled to room temperature. Thin decarburized layer (ferrite), caused by furnace leak, covers
surface. Matrix is pearlite, with carbide at prior austenite grain boundaries. (h) 1% nital, 500x. Gas carburized, furnace cooled, and cooled
to room temperature under same conditions as (g), except furnace leak was more severe. Decarburized layer (ferrite) caused by leak is
thicker and covers matrix of pearlite. Carbon has diffused from grain boundaries. (j) 3% nital, 200x. Carbonitrided, 4h; 845 “C (1555 “F) in
3% ammonia. Propane, 6%; remainder, endothermic gas. Oil quenched. Cooled to -74 “C (-100 “F). Tempered 1 l/2 h at 150 “C (300 “F).
Tempered martensite: some bainite. (k) Nital, 100x. Carbonitrided 4 h; 845 “C (1555 “F). Oil quenched; not tempered. Stabilized by subzero
temperature. Normal case structure for carbon steel. Contains martensite, carbide particles, and small amount of retained austenite. (m)
Picral, 200x. Annealed by austenitizing at 885 “C (1625 “F), 2 h. Cooled in furnace. Fully annealed structure consists of patches of pearlite
(dark areas) in matrix of ferrite (light areas)
150 / Heat Treater’s
Guide
1019
Chemical
Composition.
AISI
I .OO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
and UN%
Foreign).
0.15 to 0.20 C. 0.70 to
UNS
Gl0190:
ASTM
Recommended
Normalizing.
Heat Treating
Practice
Heat to 935 “C i 1695 “F). Air cool
A510.A513.A519.A545.A548.A576:SAE5103.5412.5311
Characteristics.
Annealing.
Heat to 885 “C (I625
cooler or by furnace cooling
Forging.
Hardening. May be case hardened by gas carburizing. (See procedure
for 1020.) More often, it is subjected to light case hardening by carbonitriding or casing in a liquid bath. (See procedure for 1008 steel.) Flame
hardening is an alternative process. In many instances. forgings of this
grade are used in service either as forged or as forged and normalized
Excellent forgeability.
reasonably good cold fomlability. and excellent weldability.
As carbon content increases, strength also
increases, accompanied
by a small decrease in cold formability.
Machinability is relatively poor compared with the I 100 and I200 grades. The
slightly higher manganese (compared with IO1 8j provides a slight increase
in strength and hardenability
Heat to 1275 “C (2325 “F). Do not forge below 910 “C (I670 ‘F)
“F). Cool
slowly,
preferably
in a
Nonresulfurized
1019: Isothermal Transformation Diagram. Containing 0.17 C,
0.92 Mn. Austenitized at 1315 “C (2400 “F). Grain size, 0 to 2.
Martensite temperatures estimated
Carbon
Steels / 151
1019: End-Quench Hardenability. 12.7 mm (0.5in.) diam bar.
0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400
“F). Quenched from 870 “C (1600 “F)
1019: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure (no case hardening)
Nonresulfurized
Carbon
Steels / 151
1020
Chemical Composition.
AISI and UNS: 0.18 to 0.23 C. 0.30 to
0.60 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNSGIOXO:
AMS ~032.
5045; ASTM ASlO. A519, A54-I. A575. A576. A659; MU SPEC MU-S11310(CS1020);SAEJ403.J412,J411:(Ger.)DIN
l.O402:(Fr.)AFNOR
CC 20: (Ital.) UNI C 20; (Swed.) SS1-t I-150: (U.K.) B.S. 040 A 20.070 M
20
Characteristics.
Most widely used of several similar grades containing about 0.20% carbon. Available in a variety of product forms. Excellent
forgeability
and weldability.
Even with a maximum carbon content of
0.23%. no preheating or postheating
required for the vast majority of
welded structures. When most of the fabricating operations consist of some
form of machining. this grade is not recommended because machinability
is notably poor. Widely used as a carburizing steel
Forging.
Heat to 1260 “C (2300 “F). Do not forge below 900 T
( 1650
“F)
Recommended
Normalizing.
Annealing.
Hardening.
Heat Treating
Practice
Heat to 925 “C ( I695 “F). Air cool
Heat to 870 “C (1600 “F). Cool slowly,
preferably
in furnace
Can be case hardened by any one of several processes.
which range from light case hardening, such as carbonitriding
and the
others described for grade 1008. to deeper case carburizing in gas. solid. or
liquid media. Most carburiring
IS done m a gaseous mixture of methane
combined with one of several carrier gases. using the temperature range of
870 to 955 “C ( 1600 to 17.50 “F). Carburize for destred case depth with a
0.90carbon potential. Case depth achieved is always a function of time and
temperature. For most furnaces. a temperature of 955 “C (I 750 “F) approaches the practical maximum u ithout causing excessive deterioration in
the furnace. With the advent of vacuum carburizing,
temperatures up to
1095 “C (200.5 T) can be used to develop a given case depth in about one
half the time required at the more conventional
temperature of 925 “C
(I695 “F). Alternative
processes are flame hardening, boriding, liquid
nitriding. and plasma (ion) carburizing
Hardening
After Carburizing
is usually
achieved
using
one of
three procedures:
I. Quench directly into water or brine horn the carburizing temperature
2. After the desired carburizing cycle has been completed, decrease the
furnace temperature or use lower temperature zone of a continuous
furnace to 845 “C (I 5.55 “F) for a diffusion cycle. Quench in water or
brine
3. Cool slowly to room temperature after carburizing. Reheat to 815 “C
( I500 OF). Quench in water or brine
For rounds
usually can
also provide
also achieve
not over 6.35 to 9.53 mm (0.35 to 0.375 in.) diam. full hardness
be obtained by oil quenching. In carbonitriding, oil quenching will
full hardness. The liquid carburizing method using molten salt may
relatively deep cases on 1020 and similar grades of carbon steel
152 / Heat Treater’s
Guide
Tempering.
Although many carburized and hardened parts are placed in
sen ice b ithout tempering, it is considered good practice to temper at I SO
“C (MO “F) or somewhat higher for I h if some sacrifice in hardness can
be tolerated
Recommended
Processing
1020: Influence
Case Depth
l
l
l
l
l
l
l
l
Cyanide
25.4 mm (1 in.) diam bars, cyanided
Sequence
Forge
Normalize (omit for parts machined from bar stock)
Rough machine and/or rough grmd
Semifmish machine and grind
Carburize
Lower temperature for diffusion cycle
Quench
Temper
Finish grind (removing no more than IO ?, of the effective
Concentration
case per side)
1020: Normalizing. Effect of mass and section size on cooling
curves obtained in still-air at 23 “C (73 “F). 152.4 mm (6 in.) diam.
Approximately
64 kg (142 lb)
30 min at 815 “C (1500 “F)
Fo
91.3
76.0
SO8
13.0
30.2
20.8
IS.1
IO.8
52
1020: Effect of Cyaniding
Depth of Case
in.
mm
0.0060
0.0070
O.OMll
0.0060
0.0060
0.0055
o.wso
0.0040
0.0020
0.1574
0. I778
0.1524
0.1524
0.152-l
0. I397
0. I’70
0.1016
0.0508
Temperature
mm
ill.
Produced
by immersion
0 ow25
0.00 I35
OWl75
o.w.120
Produced
by immersion
Produced
by immersion
T
I300
I400
ISW
1600
705
760
815
870
I300
I400
IS00
1600
705
760
81s
870
I 300
I-MI
1500
1600
705
760
815
870
for 30 min
0.01270
0.06350
0.10160
0.12192
O.OOIOO
0.W37.5
o.wsw
0.00600
OF
for 15 min
0 w63s
0.03129
o.ou-ls
0.08 I28
O.WO50
0.00250
mo-un
0.00480
and Time on
Cyaniding
temperahwe
Depth of case
1020: Gas Carburizing. Catburized
on
Depth ofcase
NaCN,
l
of Sodium
for 15 min
0.03-10
0.G952.5
0. I2700
0. I5240
for 4 h in batch furnace
1020:
Effect of Cyaniding
Steel cyanided
Diameter
tn.
IS-min
0.25
0.50
0.75
I .w
2.00
3.00
at 815 “C (1500 “F)
Case depth
of specimen
mm
in.
mm
6.350
I3.7Go
19.050
25.400
50.800
76.200
0.0015
0.0035
0.0030
0.0027
0.0025
0 W23
O.ll43
0.0889
0.0762
0.0686
0.0635
6.350
12.700
19.050
3.4x)
SO.800
76.200
0.0045
0.0035
0.0030
0.0027
o.wx
0.0023
0. I I-13
0.0889
0.0762
0.0686
0.0635
0.0584
immersion
0.30
0 500
0 750
I .ooo
2.ooo
3 .ow
30-min
Mass on Depth of Case
0.0584
immersion
Nonresulfurized
1020: Oil Quenching. Effect of mass and section size on cooling
curves in oil quenching. Oil at 37 “C (99 “F). 152.4 mm (6 in.) diam.
Approximately 64 kg (142 lb)
Carbon
Steels / 153
1020: Liquid Carburizing. Effect of carburizing temperature and
time at temperature on case depth and case hardness gradient.
Specimens 19.05 mm (0.75 in.) diam by 50.8 mm (2 in.). Liquid
carburized, air cooled, reheated in neutral salt at 845 “C (1555 “F),
and quenched in salt at 180 “C (355 “F). (a) Carburized at 870 “C
(1600”F).(b)900”C(1650”F).(c)925”C(1695”F)
1020: Gas Carburizing.
Variations of carbon content, 0.25 mm
(0.010 in.) below the surface. Three similar batch furnaces (a, b, c)
used. Twenty-five tests in each
1020: Liquid Carburizing.
Comparison of case depth and case
hardness of 27 specimens, 11 .1125 mm (0.4375 in.) diam by 6.35
mm (0.25 in.). Liquid carburized, 2 h, at 855 “C (1570 “F). Brine
quenched and tempered, 150 “C (300 “F)
154 / Heat Treater’s Guide
1020: Liquid Carburizing.
Carbon gradients produced in low- and high-temperature
shown, at (a) 845 “C (1550 “F); (b) 870 “C (1800 “F); (c) 955 “C (1750 “F)
baths. 25.4 mm (1 in.) diam bar catburized,
for time
1020: Hardness vs Tempering Temperature.
Represents an average based on a fully quenched structure (no case hardening)
Nonresulfurized
1020: Liquid Carburizing.
case depth. (a) 25.4
Specimen carburized
11.1125 mm (0.4375
carburized at 855 “C
150 “C (300 “F)
Effect of time and temperature on
mm (1 in.) outside diam by 152.4 mm (6 in.).
at temperature indicated. Oil quenched. (b)
in.) diam by 6.35 mm (0.25 in.). Specimen
(1570 “F), brine quenched, and tempered at
Carbon
Steels / 155
1020: Liquid Carburizing of Typical Parts. Selective carburizing by partial immersion. Only that portion to be carburfzed
(shaded area) is immersed in bath. (a) Compression rod. Depth of
case, 0.508 to 0.635 mm (0.020 to 0.025 in.). Hardness, 55 to 60
HRC. (b) Control linkage. Depth of case, 0.127 to 0.254 mm
(0.005 to 0.010 in.). Hardness, 55 to 60 HRC. (c) Ball connecting
rod. Depth of case, 0.254 to 0.381 mm (0.010 to 0.015 in.). Hardness, 55 to 60 HRC
1020: Water Quenching. Effect of mass and section size on cooling curves in water quenching. Water at 46 “C (115 “F). No agitation. 152.4 mm (6 in.) diam. Approximately 64 kg (142 lb)
1020: Liquid Carburizing. Case hardness gradients, obtained in
ten tests, showing scatter from normal variations
156 / Heat Treater’s
Guide
1020: Gas Carbonitriding. Effects of ammonia concentration and inlet-gas dew point on carbon and nitrogen gradients. Carbonitrided at
845 “C (1555 “F), 4 h. Inlet gas: 5% methane; remainder, carrier gas. Air cooled. (a) 5% NH,. Dew point, -26 “C (-15 “F). (b) 5% NH,. Dew
point, 0 “C (+32 “F). (c) 5% NH,. Dew point, +24 “C (+74 “F). (d) 1% NH,. Dew point, -29 “C (-20 “F). (e) 1% NH,. Dew point, 0 “C (+32 “F).
(f) ) 1% NH,. Dew point, +22 “C (+72 “F)
Nonresulfurized
1020: End-Quench Hardenability: Carbonitriding and Carburizing. As-quenched hardenability measured along surface.
Carbon
Steels / 157
1020: Gas Carbonitriding.
of carbonitriding
Effects of temperature and duration
on depth of case. Total furnace time indicated
Inlet carbonitriding atmosphere was 5% ammonia, 5% methane,
and the remainder, carrier gas. Solid line: carbonitrided 4 h at 900
“C (1650 “F). Dotted line: carburized 3 h at 925 “C (1695 “F)
1020: Plasma (Ion) Carburizing. Carbon concentration profiles
in AISI 1020 steel after ion carburizing for 10, 20, 30, 60. and 120
min at 900 “C (1650 “F). Carbon profile after atmosphere carburizing for 240 min at 900 “C (1650 “F) shown for comparison
1020: Plasma (Ion) Carburizing. Carbon concentration profile in
AlSl 1020 steel after ion carburizing for 10 min at 1050 “C (1920
“F) followed by vacuum diffusing for an additional 30 min at 1000
“C (1630 “F). A similar carbon concentration profile is obtained by
atmosphere carburizing for 6 h at 918 “C (1685 “F)
158 / Heat Treater’s
Guide
1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles in AISI 1020 steel after ion carburizing for 10 min at 1050 “C
(1920 “F) followed by additional vacuum diffusing for 30 min at 1000 “C (1830 “F). Effective case depth is indicated by dotted line
Nonresulfurized
Carbon
Steels / 159
1020: Plasma (Ion) Carburizing. Carbon concentration and hardness profiles through cases on AISI 1020 steel after ion carburizing in
methane, natural gas, and in 8:l nitrogen/propane combination. Data are based on a boost-diffuse cycle of ion carburizing for 10 min at 1050
“C (1920 “F) followed by 30 min of diffusion at 1000 “C (1830 “F)
160 / Heat Treater’s
Guide
1020: Microstructures. (a) Nital, 500x. Carbonitrided and oil quenched, showing effect of too high a carbon potential. Outer white
cementite; followed by interlaced martensite needles in retained austenite. Martensite matrix on right. (b) 2% nital. 550x. Cyanided
bath. 845 “C (1555 “F), for 1 h. Water quenched. As-quenched condition shows coarse martensite with some carbide particles. Free
rite. (c) 2% nital 100x. Same as (b), but lower magnification; showing case, transition, and core structures. Dark impressions are
Tukon microhardness indentations, 0.0762 mm (0.003 in.) apart. Equivalent hardness, 61 HRC in case and 25.5 in core
layer,
in salt
of fer500-g
160 / Heat Treater’s
Guide
1021
Chemical
Composition.
AK1 and UNS: 0. I8 to 0.23 C. 0.60
to
0.90 hin. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign).
ASlO. ASl9.
l!NS Gl0210: ASThl
AS-IS. AS-W AS76. A659: SAE 1403. J-II,.
J-Ill
Tempering.
Characteristics.
Excellent forgeability
and weldahilitj.
Even u ith a
maximum carbon content of 0.234. no preheating or postheatIng is required for the vast majority of welded structures. hlachinability
is notably
poor. The slightly higher manganese content pro\ ides minor increases in
strength and hardenahility
compared itith 1020
Forging.
Heat to 1260 “C (2300 “FL Do not forge hrlow
900 “C t 1650
“F)
some sacrifice
Heat Treating
l
l
l
l
Practice
l
l
Heat to 925 “C (I695 “FL Air cool
l
Annealing.
Heat to 870 “C t I600 “FL Cool slam ly. preferably
in furnace
Optional. Temper at IS0 ‘C (300 “F) for I h, or higher if
of hardness can be tolerated
Recommended
l
Recommended
Normalizing.
Hardening. Can be case hardened by any one of several processes,
which range from light case hardening (by carbonitriding
and salt bath
nitriding described for grade 1008) to deeper case carburizing in gas. solid.
or liquid media. (See carhuriring
process described for grade 109-O)
l
Processing
Sequence
Forge
Normalize
Rough machine
Semifinish machine and grind
Carburize
Diffusion cycle
Quench
Temper
Finish grind
1021: Isothermal
Transformation
Grain size, 8 to 9. Austenitized
temperatures.
estimated
Diagram.
0.20 C, 0.81 Mn.
at 925 “C (1695
“F). Martensite
Nonresulfurized
1021: End-Quench
Hardenability.
12.7 mm (0.5 in.) diam bar.
0.17 C, 0.92 Mn. Grain size, 0 to 2. Austenitized at 1315 “C (2400
“F). Quenched from 870 “C (1600 “F)
Carbon
Steels / 161
1021: Hardness vs Tempering
Temperature.
Represents an
average based on a fully quenched structure (no case hardening)
Nonresulfurized
Carbon
Steels / 161
1022
Recommended
Chemical
Composition.
AISI and UN.9 0.18 IO 0.23 C, 0.70 to
I .OOMn, 0.040 P max. 0.050 S max
AMS
G10220;
Similar Steels (U.S. and/or Foreign). UNS
5070; ASTM AS IO. A5 19, AS44 AS45. AS-IX. AS76: hlfL SPEC MLS11310 (CSIOZO): SAE 5403. J-117. JAI-I: (Ger.) DfN 1.1133; (Ital.) l!NI
GE hln 3; (Jap.) JIS ShlnC 2 I
Characteristics.
Excellent forgeabilicy
and weldability.
Even mith a
maximum carbon content of 0.23%. no preheating or postheating is required for the vast majority of welded structures. hlachinability
is notably
poor. High manganese content results in increased hardenability.
thus
permitting achievement of full hardness by oil quenching of somewhat
thicker sections than 103-O.Quenching can be less severe because ofFeater
hardenability
Forging.
l
l
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Rough machine
Semifinish machine and grind
Carburize
Diffusion cycle
Quench
Temper
Finish grind
Heat to 1260 “C (2300 “F). Do not forge belo\{ 900 “C i 1650 “F)
Recommended
Normalizing.
Annealing.
Heat Treating
Practice
1022: Hardness
average
Heat to 925 “C (I 69s “F). Air cool
Heat to 870 “C ( I600 ‘F). Cool slow 14. prefsmbly
in furnace
Hardening. Can be case hardened by an) one of several processes.
uhich range from light case hardening (by carbonitriding
and salt bath
nitriding described for grade 1008) to deeper case carburizing in gas. solid.
or liquid media. (See carbunzinp process described for grade 1020.) Plasma
(ion) carburizing is an alternative process for shallow cases. Quenchants
include aqueous polymers
Tempering.
some sacrifice
Optional. Temper at IS0 ‘C (300 “Fj for I h. or higher if
of hardness can be tolerated
based
vs Tempering
on a fully quenched
Temperature.
structure
Represents
an
(no case hardening)
162 / Heat Treater’s
1022: Gas Carburizing.
Guide
Catburized
at 920 “C (1690 “F) in 20% CO, 40% H, gas, with 1.6 and 3.6% CH, added
1022: Gas Carburizing.
Carburized at 920 “C (1690 “F) with 20% CO, 40% H, gas. Contains enough H,O to produce carbon potentials
indicated: (a) 0.50%; (b) 0.75%; (c) 1.10%
Nonresulfurized
Carbon
Steels / 163
1022: Cyaniding. Effect of cyaniding bath temperature on carbon and nitrogen contents and on case hardness. Specimens heat treated 1
h in 30% NaCN bath at temperatures indicated. Composition specrmens air cooled; hardness specimens, water quenched. Cyanate concentrations: 0: 4.67% at 815 “C (1500 “F); 0: 3.37% at 845 “C (1555 “F); A: 2.71% at 870 “C (1600 “F). Note: Rockwell C measurements
unreliable. Thin, brittle case incapable of supporting Rockwell C load. Dip in surface hardness on Rockwell 15-N scale (0 and 0) indicative
of effect of retained austenite
164 / Heat Treater’s
Guide
1022: Liquid Carburizing. Effect of time and temperature on
case depth. Bars: 25.4 mm (1 in.) square by 177.8 mm (7 in.) long.
Carburized at 925 “C (1695 “F). Water quenched
164 / Heat Treater’s
Guide
1023
Chemical Composition.
AISI and UNS: 0.20 to 0.25 C. 0.30 to
0.60 hln. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign). l!NS G10130;
ASTM
AS IO. AS7S. AS76. A659 SAE J-103. J-l I?. J-l 1-I: (Grr.) DIN I I IS I ; (Fr.)
AFNOR
XC I8 S. XC 25; (Jup.) JIS S ‘0 C. S 22 C. S 20 CK
Characteristics.
Quite \~rldablz. Hov,rtwr. \\ hen carbon content is in
the upper end of the allouahls
range. it hecomes borderline In tern15 of
requiring preheating and postheating. I+ ha conlplcx structures are being
welded. hlachinabilit)
IS poor. Forgeahilitg
IS excellent
Forging.
Tempering.
soms sacrifice
Normalizing.
Heat Treating
Practice
Heat to 925 ‘C t I695 “FL AU cool
Heat to 870 “C (I600 <FL Cool slowly. preferubl!, in furnace
l
Forg?
Normalize
Rough machiw
Scmifini~h ~nnchi~w
l
Carbunze
l
Diffusion cycle
Quench
Temper
Finish _gind
l
l
l
Hardening.
l
which
l
Can be case hardened b) an) ow of weral
procssse~.
range from light case hurdcning (t-q carbonitridin_e and salt bath
Optional. Tzmper at I50 ‘C (300 ‘F) for I h, or higher if
of hardness can be tolemt~d
Recommended
l
Heat to I160 ‘-C (2300 “F). Do not fogs helo\\ 900 “C I 1650 “F)
Recommended
Annealing.
nitriding described for grade 100X) to deeper case curbwiring
in gas. solid,
or liquid media. (See carburizing process described for grade 102O.j When
carhorl
content is near the high end of the range. the core strength of case
hardened parts u ill be slight11 greater than that of IOZO
Processing
and
Sequence
grind
1023: Hardness vs Tempering Temperature.
Represents an average based on a fully quenched structure (no case hardening)
Nonresulfurized
Chemical Composition.
AISI
0.60 Mn. 0.040 P max. 0.050 S max
Similar
and UNS: 0.21 ICI 0.z
Steels (U.S. and/or Foreign).
UNS
C, 0.30 IO
G 10250; AMS 5075.
5077; ASTM AS IO. AS 13. AS 19. AS75, A576: FED QQ-S-700 (C 1025):
MlL SPEC MLS-11310
(CSlO25):
I. I 158; (Jap.) JIS S25 C. S 28 C
SAE 5303. J-112. 5114; (Ger.) DIN
In aerospace practice,
quenched in water
Recommended
A horderline or transition grade between case hardening and direct hardening types. It is used for both. Because of higher carbon
content. it is less suitable forcold forming than 1018 and 1020. Machinability is poor. because it does not contain additives for free machining.
Excellent forgeability
and good weldahility.
With the carbon near the
higher side of the range, preheating and/or postheating may be required.
depending upon the carbon equivalent and complexity
of the weldtnent
Forging.
Heat to I245 “C (2275 “F). Do not forge below 900 “C ( 1650 ‘F)
Recommended
Heat Treating
Practice
Normalizing.
Heat to 925 “C (I695 “F). Cool in still air.
in aerospace practice, parts are normalized at 900 “C ( I650 “F)
Annealing.
Heat to 870 “C ( I600 OF). Cool to 675 “C ( I245 OF). at a rate
not to exceed 28 “C (SO ‘Fj per h.
In aerospace practice, parts are annealed at 885 “C ( 1625 “F) and
allowed IO cool IO below 510 “C ( 1000 “F)
Direct Hardening.
Austenitize
at 870 “C (I600
“F). Quench in water
parts are austenitized
Processing
Steels / 165
at 870 YY (I600
“F) and
Sequence
Direct Hardening
l
Characteristics.
Carbon
l
l
l
l
l
l
l
Forge
Normalize
Anneal (if necessary)
Rough machine
Austenitize
Quench
Temper to desired hardness
Finish machine
Case Hardening
Forge
Normalize
l
Rough machine
l
Semifinish machine and grind
. Carburize
l
Diffusion cycle
l
Quench
l
Temper
l
Finish gnnd
l
l
or brine
Tempering.
Asquenched
hardness of 400 HB can be expected for
sections up to approximatel)
25.4 mm (I in.j. Initial hardness can be
decreased as desired. bj tempering. Water is qucnchant. Parts may be
tempered at 370 “C (700 “F) for tensile strengths in the range of 630 IO 860
MPa (90 to I25 ksi)
Case Hardening.
Can be case hardened by any of sebernl processes.
which range from light case hardening (bj carbonitriding
and salt bath
nitriding described for grade 1008) to deeper case carburizing in gas. solid.
or liquid media. (See carburizing process described for grade 1020.) Other
processes include flame hardening and plasma lion) carhurizing.
Qucnchants Include water and aqueous polymers.
1025: Hardness
erage
based
vs Tempering
on a fully quenched
Temperature.
structure
Represents
an av(no case hardening)
166 / Heat Treater’s
Guide
1025: Microstructures. (a) Picral, 500x. Normalized by austenitizing, 1095 “C (2005 “F). Air cooled. Coarse grain structure; pearlite (black
areas) in ferrite matrix (white areas). (b) Picral, 500x. Normalized by austenitizing, 925 “C (1695 “F). Air cooled. Finer grain size due to lower
temperature
166 / Heat Treater’s
Guide
1026
Chemical
Composition.
AISI and UNS: 0.22 to 0.78 C. 0.60 to
0.90 Mn, 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
A273. ASIO, ASl9.
A545
Foreign).
A576; SAEJ403.
UNS
Gl0260:
J412. J-II-t
ASTM
Characteristics.
A borderline or transition grade between case hardening and direct hardening types. It is used for both. Because of its higher
carbon content, it is less suitable for cold forming than 1018 or 1020.
Machinability
is poor, because it does not contain additives for free machining. Excellent forgeability,
and good weldability.
However. the slightly
higher manganese range increases hardenability,
which can be significant
in welding. The tendency to weld crack increases with increasing manganese. so that preheating or postheating may have to be used. Increased
hardenability
will pernut through hardening of sections that are somewhat
thicker when compared to 1025
Forging.
Heat to I245 “C (2275 “F). Do not forge below 900 ‘C ( I650 “F)
Case
Hardening. Can be case hardened by any one of several processes, which range from light case hardening (by carbonittiding
and salt
bath nitriding described for grade 1008) to deeper case carburizing in gas,
solid. or liquid media. (See carburizing process described for grade 1020.)
Flame hardening is an alternative process
Recommended
Direct Hardening
l
l
l
l
l
l
l
l
Recommended
Normalizing.
Heat Treating
Practice
l
Heat to 870 “C ( I600 OFI. Cool to 675 “C ( I215 “F). at a rate
not to exceed 28 “C (50 “F) per h
l
Direct Hardening.
l
Austenitize
at 870 “C (1600 “F). Quench in water
or brine
Tempering.
As-quenched
hardness of 400 HB can be expected for
sections up to approximately
25-i mm (I in.). Initial hardness can be
decreased as desired. by tempering
Forge
Normalize
Anneal t if necessary)
Rough machine
Austenitize
Quench
Temper to desired hardness
Finish machine
Case Hardening
Heat to 925 “C (1695 “F). Cool in still air
Annealing.
Processing
l
l
l
l
l
l
Forge
Normalize
Rough machine
Semifinish machine and grind
Carburize
Diffusion cycle
Quench
Temper
Finish grind
Sequence
Nonresulfurized
1026: Hardness vs Tempering Temperature. Specimen 3.175
mm (l/8 in.) to 6.35 mm (l/4 in.) thick. Tempering time: 0: 10 min;
.:l h;A:4h;A:24h
1026: Hardness vs Tempering Temperature. Represents an
average based on a fully quenched structure (direct hardening)
Carbon
Steels / 167
1026: Hardness vs Tempering Time. Textile machine forging,
304.8 mm (12 in.) long by 28.575 mm (1 l/8 in.) diam. Heated in
pusher conveyor furnace, 900 “C (1650 “F). Water quenched.
Tempered at 315 “C (600 “F) in muffle furnace. Both furnaces gas
fired: no atmosphere control. Hardness measured on polished
flash line
Nonresulfurized
Carbon Steels / 167
1029
Chemical Composition. AIM and UN!% 0.25 to 0.31 C. 0.60 to
0.90 Mn, 0.040 P max. 0.050 S max
Annealing. Heat to 870 “C ( I600 “FL Furnace cool to 650 “C ( I200 “F),
at a rate not to exceed 28 “C (SO “F) per h
Similar Steels (U.S. and/or Foreign).
Hardening. Flame hardening and carbonitriding are available surface
hardening processes. Austenitize at 860 “C (I 580 “F). Quench in water or
brine. except for rounds under 6.35 mm (0.25 in.) diam. These may be
quenched in oil for near full hardness
A273, A510, A576;SAE
UNS
G 10290;
ASThl
J303, J412
Characteristics.
With few exceptions. this grade of steel is not case
hardened. May be given a wear-resisting
surface by quenching from a
carbonitriding
atmosphere. (See procedure for 1008.) As a rule, it is used
either in the normalized or annealed condition or is subjected to direct
hardening and tempering. While cold formability
is poor compared with
lower carbon grades, grade 1029 can be purchased to specific quality
requirements, which permit its use for applications that require cold estrusion or cold heading. Machinability
is poor. Forgeability
is excellent. Can
be readily welded, but preheating and postheating are generally required for
steels of this carbon content
Tempering.
Using the austenitizing
practice described above. an asquenched hardness of near 425 HB should be attained. The desired hardness can then be developed by tempering
Recommended
l
l
l
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 885 “C (I625 “F)
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 915 “C ( I680 “FL Cool in still air
l
Processing
Forge
Normalize
Anneal (if necessary for machining)
Rough machine
Austenitize
Quench
Temper
Finish machine
Sequence
166 / Heat Treater’s Guide
1029: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
168 / Heat Treater’s
Guide
1030
Chemical
COmpOSitiOn.
AISI and LJNS: 0.28 to 0.31 C. 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or Foreign). CJNS ~10300; ASTM
AS IO. AS 12. AS 19. AS-M. AS36. AS76. A682; FED QQ-S-635 CC 1030).
QQ-S-7OO(ClO3Oj;
MILSPEC
ML-S-I
l3lO(CSlO3O):
SAE 5103, J112.
5114; (W. Ger.) DIN I.1 172: (Ital.) UNI CB 35
Characteristics.
With few exceptions. used in the normalized or annealed condition. or subjected to direct hardening and tempering. Cold
formability
is poor compared M ith lower carbon grades. hlachinability
IS
poor. Forgeabilib
is excellent. The slightly
- - higher carbon content has some
negative effect on weldability.
Unless preheating and postheating practices
are used. weld cracking may occur. Widely used for producing forgings and
parts machined from hot rolled or cold drawn bars. Also available in cold
heading quality for fabrication processes involving
cold heading or cold
extrusion
Annealing.
Heat to 870 “C ( 1600 “F). Furnace cool to 650 “C ( I200 “F)
at a rate not to esceed 28 “C (SO “F) per h
Hardening. Austenitire at 860 “C t 1580 “F). Surface hardening processes include flame hardening. induction hardening. carbonitriding.
and
plasma (ion) carburizing. Quench in Water or brine, except for rounds under
6.35 mm (0.25 in.) diam. These ma! be quenched in oil for near full
hardness
Tempering.
An as-quenched
tained by usmg the austenitizing
be reached bj tempering
Recommended
l
l
l
Forging.
Heat to 1215 “C (2275 “F). Do not forge below 885 “C (I625 “‘F)
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 9 IS “C ( I680 “F). Cool in still air
l
hardness of near 425 HB should be atpractice described. Desired hardness can
Processing
Sequence
Forge
Normalize
Anneal (if necessary for machining)
Rough machine
Austenitize
Quench
Temper
Finish machine
1030: Isothermal Transformation
coupons.
Austenitized
Diagram. Rolled from cast
at 905 “C (1660 “F). Grain size, 7 to 8
Nonresulfurized
1030: Hardness vs Tempering Temperature. Specimen, 9.525
to 25.4 mm (0.375 to 1 in.) thick
Carbon
Steels / 169
1030: End-Quench Hardenability. Effect of high-quenching temperature on hardness. Specimen contains 0.30 C, 0.10 Cr, 0.94
Mn, 0.012 P, 0.028 S, 0.18 Si. ASTM grain size, 1.8. Quenched at
temperatures indicated
1030: Hardness vs Tempering Temperature. Specimen, 3.175
to 6.35 mm (0.125 to 0.25 in.) thick. Tempering time: 0: 10 min; 0:
1 h;&4h;A:24h
1030: Microstructures. (a) Picral, 1000x. Austenitized at 925 “C (1695 “F), 1 h; then 775 “C (1425 “F), 2 h 40 min; held at 710 “C (1310 “F),
4 h for isothermal transformation of austenite; brine quenched. Ferrite and coarse pearlite. (b) Picral, 1000x. Austenitized at 800 “C (1475
“F), 40 min; held at 705 “C (1300 “F). 15 min, for isothermal transformation; reheated to 710 “C (1310 “F), held 192 h. Partly spheroidized
pearlite. Ferrite matrix
Nonresulfurized
Carbon
Steels / 169
1035
Chemical Composition.
AISI
0.90 Mn. 0.040 P ma.\. 0.050 S rnzx
Similar
and UNS:
0.32 to 0.38 C. 0.60 to
Steels (U.S. and/or Foreign). UNS G 10350: AhlS 5080.
5082: ASTM A.510. A.519. AS-M, AS1S. AS16. AS76. A682; FED QQ-S635 (ClO3S). QQ-S-700 (ClO.35): SAE J-103. Jll?. J-ll-k (Ger., DIN
1.0501: tFr.) AFNOR CC 35: rltnl.) UN1 C 35; (Swed.) SS1.t ISSO; (U.K.,
B S. 060 A 3s. (Ml A 32.080 A 35.080 A 37.080 hl 36
Characteristics.
One of the most \\ idsI\ used medium-carbon
grades
for mxhincry
parts. A\ailnbk
principally
in bars or billets for forging.
Escellent forgenhilit!.
Special quality Lgradrs available for cold heading,
170 / Heat Treater’s
Guide
cold forging, and cold extrusion. Because of carbon content, preheating and
postheating are required when welding. Interpass temperature must be
controlled. Machinability
is only fair. Wide range of mechanical properties
can be attained by quenching and tempering
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 870 “C (1600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Ln aerospace practice, parts are austenitized
quenched in water, polymer. or oil
Tempering.
As-quenched hardness should be approximately
45 HRC.
Hardness can be reduced by tempering. When quenching in water, parts
may be tempered at 455 “C (850 “F) to get tensile strengths in the range of
620 to 860 MPa (90 to I25 ksi): for oil or polymer quenching, parts may be
tempered at 370 “C (700 %) to get tensile strengths in the range of 620 to
860 MPa (90 to 125 ksi)
Heat to 9 I5 “C ( I680 OF). Cool in air.
In aerospace
practice.
parts are normalized
at 900 “C (I 650 “F)
Annealing.
Heat to 870 “C ( 1600 “F). Furnace cool to 650 “C ( I200 “F).
at a rate not to exceed 28 “C (50 “F) per h.
In aerospace practice, parts are annealed at 870 “C (1600 OF) and
allowed to cool below 540 “C (I000 “F)
Recommended
l
l
l
l
Hardening.
Austenitize at 855 “C (1570 “F). Flame hardening, induction hardening, austempering, liquid nitriding. and carbonitriding
are suitable treatment processes. Quench in water or brine, except for rounds under
6.35 mm (0.25 in.) diam. These may be oil quenched.
1035: Normalizing. (a) Specimen,
in.) diam. Approximately
1035: Water Quenching.
proximately
at 845 “C (1555 “F) and
101.6-mm (4-in.) diam. Approximately
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (if necessary for machining)
Rough machine
Austenitize
Quench
Temper
Finish machine
20 kg (43 lb). Still air at 20 ‘C (70 “F). (b) Specimen,
127-mm (5-
39 kg (85 lb). Still air at 25 “C (75 “F)
Specimen, 127 mm (5 in.) diam. Ap39 kg (85 lb) Water at 51 “C (125 “F). No agitation
1035: Oil Quenching. Specimen! 127 mm (5 in.) diam. Approximately 39 kg (85 lb). Oil at 32 “C (90 “F)
Nonresulfurized
1035: Hardness vs Tempering Temperature. Specimen, 31.8 to
6.35 mm (0.125 to 0.25 in.) thick. Tempered at 0: 10 min; 0: 1 h;
A:4h;A:24h
Carbon
Steels / 171
1035: Hardness vs Tempering Temperature. Automotive steering arm forgings. Section thickness, 15.875 to 28.575 mm (0.625
to 1.125 in.). Fine-grained steel. Forgings austenitized at 825 “C
(1520 “F) in oil-fired pusher conveyor furnace. Held 45 min.
Quenched in water at 20 “C (70 “F). Tempered 45 min at 580 to
625 “C (1075 to 1160 “F) in oil-fired link-belt furnace to required
hardness, 217 to 285 HB. Hardness, checked hourly with 5%
sample. Readings on polished flash line of 28.575 mm (1 ,125 in.).
Furnace variation at 550 “C (1120 “F) of -9 and -21 “C (+15 and
-7 “F). Four mill heats and six-week period
1035: Microstructures.
(a) 1035 steel bar, austenitized 1
h at 850 “C (1560 “F), water quenched, and tempered 1 h
at 175 “C (350 “F). Cross section shows light outer zone of
martensite and a dark core of softer transfom-ration products 10% nital and 1% picral. Actual size (b) 10835 steel
bar (same as 1035, except boron treated) after same heat
treatment as bar shown in (a). Effect of boron on hardenability is evident from the greater depth of the martensite zone. 10% nital and 1% picral. Actual size (c) SAE
1035 modified (0.20% Al added) steel, salt bath nitrided 90
min at 580 “C (1075 “F) and water quenched. Surface
layer of iron nitride over a matrix of ferrite and pearlite. 1%
nital. 500x
172 / Heat Treater’s
Guide
1037
Chemical
Composition.
AK1 and UN!? 0.32
to
0.38 C. 0.70 IO
I .OO hln. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
Gl0370;
ASThl
A510. AS76: SAE J403. J112, Jill
Characteristics.
Excellent forgeahilit).
Special quality grades available for cold heading, cold forging. and cold extrusion. Because of the
carbon content. preheating and postheating are required lvhen welding.
Interpass temperature must he controlled. Machinability
is only fair. \Vide
range of mechanical properties can be attained by quenching and tempering. The higher manganese content provides additional
hardenabilitj.
Slightly thicker sections can he fully hardened u ith a less severe quench.
compared u ith parts made from I035
Annealing.
Heat to 870 ‘C I 1600 “FL Furnace cool to 650 “C ( I200 OF).
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Austenitize at 855 “C i IS70 “F). Quench in water or brine.
except for rounds under 6.325 mm (0.25 in.) diam. These may be oil
quenched. Carbonitriding
is a suitable surface hardening process
Tempering.
As-quenched hardness should be approximately
Hardness can he reduced b> tempering
Recommended
l
l
l
Forging.
Heat to I ?-IS “C (2275 “FL Do not forge below 870 “C t I600 “F)
l
l
Recommended
Normalizing.
Practice
l
Heat to 9 IS “C ( I680 “F). Cool in air
l
Heat Treating
1037: Hardness vs Tempering Temperature.
average
based
on a fully quenched
structure
l
Represents
an
Processing
45 HRC.
Sequence
Forge
Normalize
Anneal (if necessary for machining)
Rough machine
Austenitize
Quench
Temper
Finish machine
1037: Water-Quenched Part. Cross section of a water-quenched
SAE/AISI 1037 steel track shoe with 0.25 mm (0.010 in.) distortion
caused by lightening
groove. Redesigning
of the shoe to remove
the grooves
improved
uniformity
of the section and reduced the
distortion to a maximum of 0.08 mm (0.003 in.)
172 / Heat Treater’s
Guide
1038,1038H
Chemical
Composition.
1038. AISI and UNS: 0.35 to 0.41. C. 0.60
to 0.90 Mn. 0.040 P mttx, 0.050 S max. 1038H. UNS H10380 and
SAE/AISI 1038H: 0.34 to 0.43 C. 0.50 to 1.00 Mn. 0.15 to 35 Si
Similar
Steels (U.S. and/or
Foreign).
1038.
CJNS
G 10380:
ASThl ASIO. AS-U. AS-IS. A.546. AS76: SAE J403. J-II?. J-II-I; (Ger.) DIN
I.1 176: (Fr.) AFNOR XC 38TS. 1038H. l!NS Hl0380; SAE Jl268: (Ger.)
DIN I I 176: (Fr.) AFNOR XC 38 TS
Characteristics.
One of the most widely used carbon steels ha\ ing ;1
medium-carbon
content. Most widely used for producing forgings to he
used in the heat treated condition. Also available as an H steel. Welded only
with the precautions used for welding of any medium-c&on
steel: przheating, postheating, and control of interpass temperature
Forging.
Annealing.
Heat to 855 “C ( Is70 ‘F). Furnace cool to 650 “C ( 1100 9%
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 855 “C (IS70 “F). Carbonitriding
is a suitable
surface hardening process. Quench in water or brine. Rounds under 6.35
mm (0.15 in.) diam ma! bs oil quenched for titll hardness
Recommended
l
l
l
l
Heat to I215 “C (7275 OF). Do not forge below 870 ‘C t I600 “F)
Practice
l
Heat to 900 “C (,I650 “FL Cool in air
l
Recommended
Normalizing.
l
Heat Treating
l
Processing
Forge
Normalize
Anneal (if necessary for machiningj
Rough machine
Austenitize
Quench
Temper
Finish machine
Sequence
Nonresulfurized
1038H: End-Quench Hardenability. Normalized at 870 “C (1600 “F). Austenitized
Distance frum
quenched
surface
‘/l6h
mm
I
1.s
2
2.5
3
3.5
-I
1.5
5
5.5
1.58
2.37
3.16
3.95
4.74
5.58
6.32
7.11
7.90
8.69
Eardness,
ARC
max
miu
58
56
55
53
49
13
37
33
30
29
51
i2
31
29
26
24
23
21
22
21
Distance From
quenched
surface
‘/I,5m. mm
6
65
7
7.5
8
9
IO
I2
1-l
16
9.48
IO.27
Il.06
I I X5
12.64
l-l.22
IS.80
18.96
22.12
25.x3
Carbon
Steels / 173
at 845 “C (1550 “F)
Hardness.
ERC
max
miu
28
27
27
26
26
2s
25
2-l
23
21
?I
20
:::
‘1:
..,
.,.
1038: Cooling Curve. 0.38 C. 0.70 Mn, 0.015 P, 0.030 S 0.25 Si, 0.063 Al, 0.003 N. Austenitized 1095 “C (2005 “F). Grain size, ASTM 5.
Solid coolina curves are for bars of indicated diameters. M, is 225 “C (435 “F); M, is 400 “C (750 “F);Ac, is 710 “C (1310 “F); AC, is 760 “C
(1400°F)
”
1
174 / Heat Treater’s
Guide
1038: Cooling Curve. Austenitized at 870 “C (1600 “F). Grain size, ASTM 8. Solid cooling curves are for bars of indicated diameters.
numbers are hardness, HV. Bold face numbers, ASTM grain size
italic
1038: Hardness vs Tempering Temperature. Quenched specimen, 3.175 to 6.35 mm (0.125 to 0.25 in.). Tempered
1038: Microstructures.
1h
(a) 2% nital, 50x. Longitudinal section, as forged. Secondary pipe from original bar stock (black areas). Pearlite
(gray). Ferrite (white). (b) 2% nital. 100x. Transverse section, as forged. Severely overheated, showing first stage of burning. Ferrite (white)
outlines prior coarse austenite grains. Matrix of ferrite (white) and pearfite (black). (c) 2% nital, 550x. Same as (b), at higher magnification.
Massive ferrite outlines coarse austenite grains. Contains particles of oxide (black dots). Matrix of ferrite (white) and pearlite (black)
Nonresulfurized
1038H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
Hardness
Purposes
I distance,
mm
1.5
3
5
7
9
II
13
I5
!O
15
3s
845 “C (1550 “F)
Limits for Specification
Eardncss,EIRC
Minimum
Maximum
S8
56
49
33
29
27
26
25
24
22
51
37
25
22
20
Hardness Limits for Specification
Purposes
I distance,
/I6 in.
I
1.5
!.5
i.5
1.5
i.5
5.5
1.5
Aardoess. EIRC
Minimum
Maximum
58
56
55
53
39
43
37
33
30
29
28
27
27
26
26
‘5
‘5
24
23
21
51
42
3-l
29
26
24
23
‘2
22
71
21
20
temperatures
recommended
Carbon
by SAE. Normalize (for forged or rolled specimens
Steels / 175
only): 870 “C
176 / Heat Treater’s
Guide
1039
Chemical
Composition.
AISI and UNS: 0.37 to 0.44 C. 0.70 to
I .OO hln. OWO P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
G 10390;
ASTM
ASIO. 4516. AS76; SAE J103. J-II?. J-II-I: (Ger.) DIN I.1 157: (Fr.) AFNOR 35 M 5; (U.K.) B.S. 120 h,l36. IS0 M 36. CDS lOS/lO6
Characteristics.
hledium-carbon
steel. Widzl~ used for forgings that
will be heat treated. Machinability
is onl! fair. Since ueldability
is poor,
the best preheating and postheating practice is required when welding is
in~olvcd. The slightly higher manganese cont2nt off2rs thz possibility
of
slightly increased hardenability.
compared hith IO-IO
Forging.
Heat to I I-15 YY (2175 ‘F). Do not forg2 b2lou 900 “C ( 1650 “F)
Recommended
Normalizing.
Heat Treating
Practice
Hrat to 900 “C (I 650 “F). Cool in au
Annealing.
Tempering
After Hardening. As-quenched hardness
mateI) 5?. HRC. Hardness can be reduced by tempering
Tempering After Normalizing.
For large sections, normalize by
comentional
practice. Resuhs in a structure of fine pearlite. A tempering
treatment up to about 510 “C (I000 “FJ is then applied. Mechanical
properties not equal to those achie\,ed by quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing
and
tcmpcring oftsn applied to hea\> forgings
Recommended
Processing
Sequence
Forgings
l
l
l
Heat to 8-0 “C (I 55s “F). Furnace cool to 650 “C ( I200 “F).
at a rate not to exceed 3 “C (50 “F) per hour
l
Hardening.
l
Heat to 815 &C t IS55 “F). Carbonitriding
is a suitablz
stufacc trzating process. Quench in eater or brin2. Rounds less than 6.35
mm to.75 in.) diam may be oil quenched to full hardness
of approxi-
l
l
l
Forge
Normalize
Anneal (ifnecessarj
Rough machine
Awtenitize
Quench
Tempzr
Finish machine
J or
telllper
(optional)
1039: Hardness vs Tempering Temperature.
erage based on a fully quenched structure
Represents
an av-
1039: Microstructures.
(a) 1% nital, 750x. Gas carburized roller for use in contact fatigue tests. Inclusions and “butterfly” alterations at center, about 0.127 mm (0.005 in.) from contact surface. Alterations believed to be work-hardened ferrite, caused by breakdown of martensite.
(b) 2% picral, 1950x. Same as (a), but enlarged in electron micrograph of two-stage, carbon-chromium-shadowed
replica. Lighter etching
than (a). “Butterfly” alterations, formed at inclusions are believed to be oriented in direction of principal stress
Nonresulfurized
Carbon
Steels / 177
1040
Chemical
Composition.
AI.9 and UNS: 0.37 to 0.44 C, 0.60 LO
0.90 Mn. 0.040 P max. 0.050 S rnxx
Similar
Steels (U.S. and/or Foreign). ASTM
~5 IO.
A5 19.
AS16, A576, A681; MILSPEC
MLL-S-I~~~~(CS~O-~~J;
SAEJ103. J-II?.
J-tl4; fCier.1 DfN 1.1186; (Jap.) JIS S 4OC; (U.K.) B.S. 080 A-IO.? S. 93
Characteristics.
Medium-carbon
steel. Widely used for forgings that
will be heat treated. Machinability
is only fair. Since weldability
is poor.
the hest preheating and postheating practice is requtred when nelding is
involved
Forging.
Heat to 1235 “C (2275 OF). Do not forge below 870 “C ( 1600 OF)
Recommended
Normalizing.
Heat Treating
Heat to 900 “C ( I650 OF). Cool in air
After Normalizing.
For large sections. normalize by
comentional
practice. This results in a structure of line pearlite. A tempering treatment up IO about 510 ‘C ( IO00 “F) is then applied. Mechanical
properties not equal to those achieved b> quenching and tempering. Resulting strength is far higher than that of annealed structure. Normalizing
and
tempering often applied to heavy forgings
Recommended
l
Hardening. Heat to 845 ‘C ( IS55 “F). Flame hardening carbonitriding.
and liquid carburizinp are suitable surface hardening processes. Quench in
water or brine. Rounds less than 6.35 mm (I/-l in.) diam may he oil
quenched for full hardness
0.39%
C - 0.72%
Mn - 0.23%
S. Grain size: 7-8
Processing
l
l
l
l
l
l
Forge
Normalize
Anneal tif necessa@
Rough machine
Austenitize
Quench
Temper
Finish machine
Sequence
Si - 0.010%
P -
or temper (optional)
1040: Hardness
Specimen,
63.5
thick. Quenched
vs Tempering
to 92.075
Tempwng
2””
I
1040: Hardness vs Tempering Temperature. Specimen,
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
of approxi-
Tempering
l
Heat to 835 “C ( IS55 JF). Furnace cool to 650 “C ( I X0 “F).
at a rate not to exceed 78 “C (SO “F) per h
1040: CCT Diagram. Composition:
After Hardening.
As-quenched
hardness
mately 52 HRC. Hardness can be reduced hy tempering
Forgings
Practice
Annealing.
0.018%
Tempering
3.175
Legend: 0: 10
Temperature.
mm (2.50
remwrarure
400
I
to 3.62
in.)
C
500
I
1040: Hardness vs Tempering Temperature.
600
I
Normalized
at
870 “C (1600 “F). Oil quenched from 845 “C (1555 “F). Tempered
at 56 “C (100 “F) intervals,
13.716
mm (0.54 in.) rounds.
12.827 mm (0.505 in.) rounds. Source: Republic Steel
Tested
in
178 / Heat Treater’s
Guide
1040: Normalizing. (a) Specimen, 177.8 mm (7 in.)
diam. Approximately 105 kg (230 lb). Still air at 22 “C
(72 “F). (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185 kg (410 lb). Air at 35 to 24 “C (94 to 74
“F). (c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Air at 22 “C (72 “F)
1040: Oil Quenching.
(a) Specimen, 177.8 mm (7
in.) diam. Approximately 105 kg (230 lb). Oil at 31 “C
(88°F). (b) Specimen, 209.55 mm (8.25 in.) diam.
Approximately 185 kg (410 lb). Oil at 50 “C (120 “F).
(c) Specimen, 266.7 mm (10.50 in.) diam. Approximately 335 kg (735 lb). Oil at 30 “C (85 “F)
Nonresulfurized
1040: Estimating Jominy Equivalent Hardenabilii. Method forestimating Jominy equivalent cooling rates (J,) in gears of specific size
and configuration. Gears made from shallow hardening (1040) steel.
Hardened in production. Hardness measured at various depths below
surface at pitch line and mot locations. Compared with hardnesses at
various (J,) distances on end-quenched bar made from same 1040
bar and quenched from same austenitizing conditions
Carbon Steels / 179
1040: Flame Hardening of Wear Blocks. Clean blocks of scale
and rust, preferably by sand or shot blasting. Load blocks on conveyor. Flame head has two rows of number 54 drill size 1.397 mm
(0.055 in.) flame holes. 24 of 49 holes are plugged. 152.4 mm (6
in.) between centers of end holes. Head also contains single row
of water-quench holes. Head set at 15.875 mm (0.625 in.) total
gap. Cone point clearance of flame. 4.763 mm (0.19 in.). Gas
pressure: acetylene, 82.738 kPa (12 psi); oxygen, 151.686 kPa
(22 psi). Conveyor speed, 148.08 mm (5.83 in.). Total flame hardening time, 1.5 min per pad. Hardness, 53 to 58 HRC. Total depth
of hardening to core, 3.97 mm (0.16 in.)
1040: Water Quenching. (a) Specimen, 177.8 mm (7 in.) diam.
Approximately 105 kg (230 lb). Water at 57 “C (135 “F). No agitation. (b) Specimen, 209.55 mm (8.25 in.) diam. Approximately 185
kg (410 lb). Water at 55 “C (130 “F). No agitation. (c) Specimen,
266.7 mm (10.50 in.)diam. Approximately 335 kg (735 lb). Water
at 50 “C (120 “F). No agitation
180 / Heat Treater’s
Guide
1040: Hardness vs Tempering. Effect of mass: when normalized
at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 540 “C (1000 “F). Tested in 12.827 mm (0.505 in.)
rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel
1040: Microstructures.
1040: Hardness vs Tempering. Effect of mass: when normalized
at 870 “C (1600 “F); oil quenched from 845 “C (1555 “F); tempered at 650 “C (1200 “F). Tested in 12.827 mm (0.505 in.)
rounds. Test from 38.1 mm (1.5 in.) diam bars and over, at half-radius position. Source: Republic Steel
(a) Nital 200x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 OF), 30 min. Cooled slowly in furnace. Ferrite
(white areas) and pearlite (dark). (b) Nital. 500x. Same as (a), at higher magnification. Pearlite and ferrite grains more clearly resolved. Wide
difference in grain size in (a) and (b). (c) Picral, 1000x. Austenitized at 800 “C (1475 “F), 40 mm. Held at 705 “C (1300 “F), 6 h, for isothemal
transformation. Structure is spheroidized carbide in ferrite matrix. (d) Nital, 500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F).
Quenched 30 min in salt bath at 420 “C (785 “F). Air cooled. Abnormal amount of ferrite (white) indicates partial decarburization at surface
(top). (e) Nital. 500x. Same as (d). Interior of bar. White areas are ferrite, outlining prioraustenite grains. Black and gray are pearlite. (9 Nital,
500x. 25.4 mm (1 in.) diam bar. Austenitized at 915 “C (1680 “F). 30 min. Oil quenched. Tempered at 205 “C (400 “F). Tempered martensite
(gray); ferrite (white)
Nonresulfurized
Carbon
Steels / 181
1040: Microstructure.
rite-pearlite
500x
Effect Of prior microstructure on spheroidking
1040: MiCrOStrUCtUreS.
microstructure (as-quenched). (b) Starting from a ferrite-pearlite
1000x
SitiC
a 1040
steel
microstructure
A fully annealed 1040 steel showing a fermicrostructure.
Etched in 4% picral plus 2% nital.
at 700 “C (1290 “F) for 21 h. (a) Starting from a marten(fully annealed).
Etched in 4% picral plus 2% nital.
Nonresulfurized
Carbon
Steels / 181
1042
Chemical COInpOSitiOn.
AK1
0.90 hln. 0.040 P max. 0.050 S max
and UNS:
0.40 to 0.17 C. 0.60 to
Similar
~273.
AS IO.
Steels (U.S. and/or Foreign). ASTM
A576;FEDQQ-S-635tC1042).SAE5403.5312.
J-iI-t:tGer.)DIN
I.1 191:
(Fr.) AFNOR XC 42. XC -!2 TS. XC -IS. XC 38; (Jap.) JIS S -15 C. S 48 C;
tSwed.) SS1.t 1672
Characteristics.
Machinability
is only fair. Weldahilitj
is poor. The
best preheating and postheating practice is required when welding is
involved. As-quenched hardness can be slightI> higher than 1040
Forging.
Heat to 1%
Recommended
Normalizing.
“C (2275 “F). Do not forge below 870 “C t 1600 ‘F)
Heat Treating
Practice
Heat to 900 ‘C t 1650 “F). Cool in air
Annealing.
Heat to 815 “C t IS55 “F). Furnace cool to 650°C t 1200°F).
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 845 “C t IS55 “F). Flame hardening. induction
hardening. horiding. and carhonitriding
are suitable surface hardening
processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.)
diam ma) be oil quenched for full hardness
Tempering
After Hardening.
As-quenched
hardness
can be re-
duced as desired b) tempenng
Tempering
After Normalizing.
For large sections. normalize by
conventional
practice. This results in a structure of fine pearlite. A tempermg treatment up IO about S-IO ‘C t 1000 “F) is applied. Mechanical properties not equal to those achieved ly quenching and tempering. Resulting
182 / Heat Treater’s
Guide
strength is far higher than that of annealed
tempering often applied to heavy forgings
Recommended
Processing
Forgings
structure.
Sequence
Normalizing
and
l
l
l
l
l
l
l
Forge
1042: Change in AC, Temperature
l
Normalize
Anneal (if necessary)
Rough machine
Austenitize
Quench
Temper
Finish machine
or temper (optional)
1042: Hardness vs Tempering Temperature. Tempered at 205
to 705 “C (400 to 1300 “F), 10 min to 24 h. Quenched specimen,
3.175 to 6.35 mm (0.125 to 0.25 in.). Legend: 0: 10 min; 0: 1 h; A:
4h:&24h
1042: Induction Process. Effect of prior structure and rate of heating on AC, transformation
temperature
of 1042 steel
182 / Heat Treater’s Guide
1043
Chemical Composition.
AISI and UNS: 0.40 to 0.47 C. 0.70 to
I .OO Mn, 0.040 P max. 0.050 S max
Similar Steels (U.S. and/or Foreign). UNS GlO430: ASTM
A510. A576; SAJZ J403, J412.5414; (Ger.) DIN 1.0503; (Fr.) AFNOR CC
45: (Ital.) UNI C 45; (Swed.) SSt4 1650: (U.K.) B.S. 060 A-17.080 H 46.
080 M 40,080 M 46
Characteristics. Machinability is only fair. Weldability is poor. The
best preheating and postheating
practice is required when welding is
involved. Added manganese provides increased hardenability.
compared
with 10-E
Forging.
Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 “F’)
Nonresulfurized
Recommended
Heat Treating Practice
Normalizing. Heat to 900 “C ( 1650 “F). Cool in air
Annealing. Heat to 845 “C (1555 “F). Furnace cool to
ties not equal to those achieved by quenching and tempering. Resulting
strength is far higher than that of annealed StrucNre. Normalizing
and
tempering often applied to heavy forgings
650 “C (I 200 “F).
at a rate not to exceed 28 “C (50 “F) per h
Hardening. Heat to 845 “C (I 555 “F). Flame hardening, boriding. and
carbonitriding
are suitable surface hardening processes. Quench in water,
brine, or aqueous polymers. Rounds less than 6.35 mm (0.25 in.) diam may
be oil quenched for full hardness
Tempering After Hardening.
As-quenched
hardness
can be re-
duced by tempering
Tempering After Normalizing.
Carbon Steals / 183
For large sections, normalize
by
of tine pearlite. A temperconventional practice. This results in a SullCNre
ing treatment up to about 540 “C (I 000 “F) is applied. Mechanical proper-
Recommended
Processing
Sequence
Forgings
l
Forge
l
Normalize
l
Anneal (if necessary)
Rough machine
Austenitize
Quench
Temper
Finish machine
l
l
l
l
l
or temper (optional)
1043: Hardness vs Tempering Temperature.
average based on a fully quenched
structure
Represents
an
Nonresulfurized
Carbon Steels / 183
1044
Chemical Composition. AISI and UNS: 0.43 to 0.50 C. 0.30 to
0.60 Mn. 0.040 P max. 0.050 S max
Similar Steels (U.S. and/or Foreign).
A510, A575. A576;SAE
UNS
~104.40;
ASTM
J403. J412.J414
achieved by quenching and tempering. Resulting strength is far higher than
that of annealed structure. Nomralizing
and tempering often applied to
heavy forgings
Recommended
Processing
Sequence
Characteristics.
Low-manganese
version of widely used mediumcarbon 1045. Often selected in preference to 1045 for surface hardening by
flame or induction, because lower manganese decreases hardenability
and
susceptibility
to quench cracking. Excellent forgeability.
Fair machinability. Responds readily to heat treatment. As-quenched hardness of at least
55 HRC. Slightly higher, when carbon is near high side of the allowable
range. Used extensively
for parts that will be furnace heated or heated by
induction prior to quenching
Forging.
Heat to 1245 “C (2275 “F). Do not forge below 870 “C (1600 “F)
l
l
l
l
l
l
l
l
Recommended
Normalizing. Heat
Annealing. Heat to
Heat Treating
Practice
to 900 “C ( I650 “F). Cool in air
845 “C ( 1555 “F). Furnace cool to 650 “C (I 200 “F),
at a rate not to exceed 28 “C (50 “F) per h
Hardening. Austenitize at 845 “C (I 555 “E). Flame hardening, induction hardening, and carbonitriding
are suitable surface hardening processes. Quench in water or brine. Rounds less than 6.35 mm (0.25 in.) diam
may be oil quenched for full hardness
Tempering After Hardening.
erly austenitized
and quenched.
Hardness of at least 55 HRC if propHardness can be adjusted by tempering
Tempering After Normalizing.
Forge or machine (bars)
Normalize (if forged. Not required for parts machined from hot rolled or
cold drawn bars)
Anneal (if necessary. Bar stock usually received in condition for best
machining)
Rough machine (forgings)
Austenitize (parts from bars or forgings)
Quench
Temper
Finish machine
Often normalized and tempered, as
for 1040. For large sections, normalize by conventional
practice. This
results in a structure of tine pearlite. A tempering treatment up to about 540
“C (1000 “F) is then applied. Mechanical
properties not equal to those
1044: Hardness vs Tempering
Temperature.
average based on a fully quenched structure
Represents
an
184 / Heat Treater’s
Guide
1045,1045H
Chemical Composition.
1045. AK1 and UNS: 0.13 to 0.50 C. 0.60
to 0.90 hln. O.O-lO P max. 0.050 S max. 1045H. UNS H10-150 and
SAE/AISI
104-W: 0.42 to 0.5 I C. 0.50 to 1.00 Mn. 0. I5 to 0.35 Si
Similar
Steels (U.S. and/or
Foreign).
1045.
UNS
GlO4SO;
ASTM ASIO. ASl9. AS76. A682: FED QQ-S-635 (ClO-!5). QQ-S-700
(ClO-l5):SAEJ~03.J1I2.J-lII:~Ger.)DIN
1.119l;(Fr.)AFNORXC-l7.
XC -12 TS. XC -IS, XC 48; (Jap.) JIS S 35 C. S -I8 C; (Stved.) SSt4 1672.
1045H. UNS HIO-ISO: SAE Jl268; (Ger.) DIN 1.1191: (Fr.) AFNOR XC
-12. XC-lI!TS,XC-%
XC18:(Jap.)JIS
S15C.S18C:(S\ved,jSS14
I673
Characteristics.
Most often specified
medium-c&on
steel. Also
available as special quality grades ofproprietary
steel compositions. Available in a barieb of product forms. mainly as stock for forging. Excellent
forgeability.
Fair machinabilit).
Responds readily to heat treatment. Available as an H grade. As-quenched hardness of at least 55 HRC. Sli8htl>
hipher. when carbon is near high side of the allowable range. llsed extensively for parts to he furnace heated or heated by induction prior to
quenching
Forging.
Heat to 17-15 “C (1375 “F). Do not forge beIon 870 “C ( 1600 “F,
Recommended
Normalizing.
Heat Treating
Practice
Heat to 900 “C ( 1650 “FL Cool in air
Annealing.
Heat to 8-15 “C ( I555 ‘F). Furnace cool to 650 ‘C (I ZOO “F),
at a rate not to exceed 38 “C (50 “Fj per h
Hardening. Austenitize at 845 “C t IS55 “F). Flame hardening. mduction hardening. liquid nitriding. carbonitidine,
martempering. and electron
beam hardening are suitable surface hardening processes. Quench in eater
or brine. Rounds under 6.35 mm (0.7S in.) diam may be oil quenched for
full hardness. Other quenchants include aqueous polymers
for 630 to 860 hlPa (90 to 125 ksi); -I?_5 “C (795 ‘Fj for 860 to 1035 MPa
(125 to I50 ksi)
Tempering
After Normalizing.
Normalize and temper as for IO-IO.
For large sections, normalize b> conventional
practice. This results in a
structure of fine pearlite. A tempering treatment up to about 540 “C (1000
“F) is then applied. Mechanical properties not equal to those achieved hy
quenching and tempering. Resulting strength is far higher than that of
annealed structure. Normalizing
and tempering often applied to heavy
forgmgs
Recommended
l
l
l
l
l
l
l
l
Processing
Sequence
Forge or machine (bars)
Normalize (if forged. Not required for parts machined from hot rolled or
cold drawn bars)
Anneal (if necessary. Bar stock usualI> received in condition for best
machining)
Rough machine (forgings)
Austenitize (parts from bars or forgings)
Quench
Temper
Finish machine
1045: Mass and Section Size vs Cooling Rate in Oil. Specimen: 101.6 mm (4 in.) diam;
at 35 “C (94 “F)
approx.
20 kg (43 lb). Oil quenched
Tempering
After Hardening. Hardness of at least SS HRC. ifproperly austenitized and quenched. Hardness can be adjusted by tempering.
IVhen quenching in water. parts may be tempered at a range of temperatures to get specific ranges in tensile strength: 565 “C (I050 “F) for 670 to
860 hlPa (90 to I25 ksi); -I80 ‘C (895 OF) for 860 to 1035 hlPa (I 75 to IS0
ksi): 370 “C (700 ‘Fj for 1035 to II75 MPa (150 to 170 ksi). when
quenching in oil or polymer. parts may be tempered at: 510 “C ( 1000 “F)
1045: Cooling Rates in Quenching.
ums on cooling rates.
mm (4 in.). Quenched
centers of specimens
Effect of quenching
mediCylinders,
25.4 mm (1 in.) diam by 101.6
in salt, water, and oil. Thermocouples
at
1045: Induction Hardening. Effect of heating time on depth of
hardening.
Tendency
toward cracking
of machined
and ground
spectmens.
Specimens,
25.4 mm (1 in.) diam, with a 50 kw, 450
000 cycle generator.
Water quenched.
Hardness,
61 to 63 HRC
Nonresulfurized
1045: Isothermal Transformation
Diagram. Composition:
Carbon
Steels / 185
0.45 C, 0.67 Mn, 0.26 Si, 0.06 Ni, 0.009 Mn, 0.009 P, 0.012 S
1045: Mass and Section Size vs Cooling Rate in Water. Speci-
1045: Hardness vs Tempering Temperature, Specimen, 3.175
men: 101.6 mm (4 in.) diam; approximately
quenching at 46 “C (115 “F). No agitation
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
min; 0: 1 h; A: 4 h; A: 24 h
20 kg (43 lb). Water
Legend: 0: 10
188 / Heat Treater’s
Guide
1045: Cooling Rates in Martempering.
Effects of section size and agitation of quench bath on time required for centers of steel bars to
reach martempering temperature. Quenching bath is a neutral chloride bath at 845 “C (1550 “F), into anhydrous nitrate - nitrate martempering salt at: (a) ; 205 “C (400 “F); (b) 260 “C (500 “F); (c) 315 “C (600 “F). Length of each bar, 3x diam
1045: Hardness Distribution
in Water-Quenched Bars
1045: Variations in Hardness After Production
Tempering.
Plate sections, 19.05 to 22.23 mm (0.75 to 0.875 in.) thick. Water
quenched to hardness range of 534 to 653 HB. Tempered at 475
“C (890 “F) for 1 h in continuous roller hearth furnaces. Data represent two-month production period
Nonresulfurized
1045: Hardness Distribution
in Oil-Quenched
Bars
Carbon
Steels / 187
1045: Induction Hardening. Efficiency of energy transfer at several frequencies. Bars of various sizes heated to 1095 “C (2005
“F). Inside diam of inductors, 28.575 mm (1.125 in.) larger than
outside diam of bars
1045: Hardness vs Tempering Temperature. Effect of time at
tempering temperature on Brinell hardness of four handgun frame
forgings, 101.6 mm (4 in.) by 152.4 mm (6 in.) by 19.05 mm (3/d
in.). Heated at 845 “C (1555 “F) in pusher conveyor furnace. Oil
quenched. Tempered at 545 “C (1000 “F) in muffle furnace. Both
furnaces gas fired, without temperature control. Hardness measured after removal of 0.635 mm (0.025 in.) of material by grinding.
20 heats
1045: Hardness vs Tempering Temperature. Specimen, 38.1 to
63.5 mm (1.5 to 2.5 in.) thick. Quenched
1045: Variations in Hardness After Production
Tempering.
Forged woodworking cutting tools. Section of cutting lip hardened
locally by gas burners that heated steel to 815 “C (1500 “F). Oil
quenched and tempered at 305 to 325 “C (585 to 615 “F), 10 min,
in electrically heated, recirculating-air
furnace to desired hardness, 42 to 48 HRC. Data recorded for g-month period and represent forgings from 12 mill heats
188 / Heat Treater’s
Guide
1045: Laser Hardening of Steel Gear
1045H: End-Quench Hardenability
Distauce fmm
quenched
surface
‘/lb in.
mm
Eardness,
ERC
max
min
I
IS8
I .s
2
2.31
3.16
62
61
59
55
52
-I2
2.5
3
3.95
4.71
5.53
6.32
56
52
46
38
31
31
29
28
7.1 I
7.90
8.69
9.18
10.27
3-l
33
32
32
31
27
26
26
2s
25
3.5
1
4.5
5
5.5
6
6.5
Distance 6-um
quenched
surface
L/lain.
mm
7
7.5
8
Eardness.
ERC
max
mill
II.06
11.85
12.61
31
30
30
9
IO
I2
I-l
13.22
15.80
18.96
22.12
29
29
28
27
I6
18
20
22
7-l
X.28
28.4-I
31.60
34.76
37.92
26
25
23
22
21
Nonresulfurized
1045H: Hardenability
Curves. Heat-treating
870 “C (1600 “F). Austenitize:
Hardness
Purposes
I distance,
nm
1.5
5
3
II
I.7
IS
!O
!5
IO
iardness
Purposes
I distance,
/If, in.
.5
!.5
1.5
1.5
is
i.5
‘3
1
0
2
-I
6
8
10
!2
‘!-I
temperatures
845 “C (1550 “F)
Limits for Specification
Hardness, ERC
hlinimum
Maximum
62
60
53
36
32
31
30
29
28
27
55
15
31
27
25
24
23
22
20
Limits for Specification
Eardoess, HRC
hlinimum
Maximum
62
61
59
56
52
46
38
3-l
33
32
32
31
31
30
30
29
29
28
27
26
25
23
21
21
55
52
32
34
31
29
28
27
26
26
2s
25
25
2-l
24
23
2’
21
‘0
recommended
Carbon
by SAE. Normalize (for forged or rolled specimens
Steels / 189
only):
190 / Heat Treater’s
Guide
1045 : Microstructures.
(a) 2% nital, 500x. 25.4 mm (1 in.) bar stock. Normalized by austenitizing at 845 “C (1555 “F). Air cooled. Tempered at 480 “C (895
“F), 2 h. Fine lamellar pearlite (dark) and ferrite (white). (b) Picral, 500x. Sheet,
3.175 mm (l/8 in.) thick. Normalized by austenitizing at 1095 “C (2005 “F).
Cooled in air. Structure is peariite (dark gray) and ferrite (light). (c) Picral, 500x.
Same as (b), except bar specimen used. Grain size much larger. Pearlite (gray)
with network of grain-boundary ferrite (white) and a few side plates of ferrite. (d)
Picral, 330x. Forging air cooled from forging temperature of 1205 “C (2200 “F).
The structure consists of envelopes of proeutectoid ferrite at prior austenite
grain boundaries, with emerging spines of ferrite, in matrix of pearlite. (e) 4% picral, 500x. 50.8 mm (2 in.) bar stock, austenitized at 845 “C (1555 “F), 2 h. Oil
quenched, 15 sec. Air cooled, 5 min. Quenched to room temperature. Ferrite at
prior austenite grain boundaries. Acicular structure probably upper bainite.
Pearlite matrix (dark). (f) 2% nital, 100x. Forging austenitized at 900 “C (1650
“F), 3 h. Air cooled. Tempered at 205 “C (400 “F) for 2 h. At top is layer of chromium plate. Below, layer of martensite, due to overheating
during abrasive cutoff. Remainder, ferrite and pearlite. (g) Picral. 500x. Austenitized at 1205 “C (2200 “F), 10 min. Held at 340 “C (640 “F)
for 10 min, for partial isothermal transfonation.
Cooled in air to room temperature. Lower bainite (dark) in matrix of martensite (white). (h)
2% nital, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 h at 845 “C (1555 “F). Oil quenched, 15 sec. Air cooled, 3 min. Water quenched to
room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark stripes at prior austenite grain boundaries are probably upper
bainite. Matrix is martensite. (j) 4% picral, 500x. 50.8 mm (2 in.) bar stock. Austenitized 2 l/2 h at 845 “C (1555 “F). Water quenched, 4 sec.
Air cooled, 3 min. Water quenched to room temperature. Specimen from 3.175 mm (l/8 in.) below surface. Dark, acicular structure probably
lower bainite. Light matrix of martensite. (k) 4% picral, 500x. Same as (j), except somewhat different structure. Gray aggregate probably
upper bainite. Fine, acicular dispersion probably lower bainite. Martensite matrix
Nonresulfurized
Carbon
Steels / 191
1046
Chemical Composition.
AISI and UNS: 0.43 to 0.50 C, 0.70 to
1.OOMn, 0.040 P max, 0.050 S max
Similar Steels (U.S. and/or Foreign).
A510, A576; SAE J403,5412,5414
UNS G10460; ASTM
Characteristics.
Higher manganese version of 1045 provides for
slightly higher hardenability. As-quenched hardnessof at least 55 HRC.
Slightly higher when carbon is near high side of the allowable range. Used
extensively for parts to be furnace heated or heatedby induction prior to
quenching. Excellent forgeability. Fair machinability
Recommended
l
l
l
l
l
l
Forging.
Heatto 1245“C (2275 “F). Do not forge below 870 “C (1600 “F’)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 900 “C (1650 OF).Cool in air
Annealing. Heat to 845 “C (1555 “F). Furnacecool to 650 “C (1200 “F),
at a rate not to exceed28 “C (50 OF)per h
l
l
Processing
Sequence
Forge or machine (bars)
Normalize (if forged. Not required for parts machined from hot rolled or
cold drawn bars)
Anneal (if necessary.Bar stock usually received in condition for best
machining)
Rough machine (forgings)
Austenitize (parts from bars or forgings)
Quench
Temper
Finish machine
1046: Quenchina Specimen. 22.225 mm (0.875 in.) diam by
76.2 mm (3 in.). Quenched from 815 “C (1506 “F)
Hardening. Austenitize at 845 “C (1555 “F). Flame hardening, induction hardening, and carbonitriding are suitable surface hardening processes.Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam
may be oil quenched for full hardness
Tempering After Hardening. Hardnessof at least 55 HRC if properly austenitized and quenched.Hardnesscan be adjustedby tempering
Tempering After Normalizing.
Normalize and temperas for 1040.
For large sections, normalize by conventional practice. This results in a
structure of line pearlite. A tempering treatmentup to about 540 “C (1000
OF)is then applied. Mechanical properties not equal to those achieved by
quenching and tempering. Resulting strength is far higher than that of
annealed structure. Normalizing and tempering often applied to heavy
forgings
1046: Variations in Hardness After Tempering. Forged specimen heated to 830 “C (1525 “F). Quenched in caustic. Tempered
1 h to range of hardness, 285 to 321 HB. Forgings heated in continuous belt-type furnace and individually dump quenched in agitated caustic. Forgings, 44 to 53 kg (95 to 115 lb) each. Maximum
section was 38.1 mm (1.50 in.)
1046: Hardness vs Tempering Temperature. Specimen, 57.15
to 63.5 mm (2.25 to 2.50 in.) thick. Quenched
192 / Heat Treater’s
Guide
1049
Chemical Composition.
AISI
0.90 Mn. 0.040 P max. 0.050 S max
and UNS: 0.16 to 0.53 C. 0.60 to
Similar
Steels (U.S. and/or Foreign). UNS G 104YO; ASTM
AS IO. AS76: SAE J-103.531 7.53 I-t: (Ger.) DIN I I301 : (Fr.) AFNOR XC
48 TS; (Jap.) JIS S SO C: (Swed.) SS1.t 1660
Hardening. Heat to 830 “C ( 1525 “Ft. Flame hardentng and carbonitridinp are suitable surface hardening processes. Quench in water or brine.
Rounds less than 6.35 mm (0.75 in.) diam may be fully hardened by oil
quenching. Normalize and temper as for IO-IO
Tempering.
downward
Characteristics.
As-quenched hardness of at least 57 HRC. e\en with
carbon on the lo\\ side of the allowable range. As-quenched hardness will
usually approach 60 HRC. when the carbon is near the maximum. 0.53.
Excellent forgeability.
Fairly good machinability.
\!‘eldability
is poor
Forging.
Heat to I230 “C (2250 “F). Do not forge belou 8-U “C t IS55 “F)
Recommended
Normalizing.
Heat Treating
Heat to 900 “C (I650
Practice
l
l
l
“F). Cool in air
l
l
Annealing.
Heat to 830 “C (I 525 “FL Furnace cool to 650 “C ( I ZOO “FL
at a rate not to exceed 28 “C (SO “F) per h
1049: Hardness
vs Tempering
Temperature.
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
Specimen,
Tempered
3.175
1h
Processing
Sequence
Forgings
l
Recommended
As-quenched hardness of 57 to 60 HRC can be adjusted
by proper tempering temperature
l
l
Forge
Normalize
Anneal
Rough machine
Austenitire
Quench
Temper
Finish machine
1049:
Hardness
34.925
to 79.375
vs
Tempering
mm (1.375
Temperature.
Specimen,
to 3.125 in.) thick. Quenched
192 / Heat Treater’s
Guide
1050
Chemical
COIIIpOSitiOn.
MS1
and
UNS:
0.48
to 0.55 C. 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max
AhlS
Steels (U.S. and/or Foreign). GINS G~osoo;
5085; ASTM A5 IO. A5 19. AS76. A683: FED QQ-S-635 (C 1050). QQ-S700(C1050):~i~SPECMIL-S-1697~:SAEJ-103.5117.J-II-I:(Ger.)DIN
I. I2 IO; (Jap.) JIS S 53 C. S 55 C
Similar
Characteristics.
Carbon content as high as 0.55. Borderline between
I medium carbon and a high-carbon grade. Used extensively for producing
small to medium size forgings. Often selected for parts to be induction
hardened. Fully quenched hardness of at least 58 to 60 HRC, especially
when carbon is on the high side of the range. Excellent forgeabilib.
Fair11
good machinability.
Weldability
is poor. Not available as an H grade
Forging.
Heat to I230 “C (2250°F).
Recommended
Normalizing.
Annealing.
Do not forge below 845 “C (IS55 “F)
Heat Treating
Practice
Tempering.
Recommended
Forgings
l
Forge
Normalize
l
Anneal
l
Rough machine
Austenitize
Quench
Temper
Finish machine
l
l
t I200 OF).
hardening, induchardening are suitbrine. Rounds less
by oil quenching.
As-quenched hardness of 58 to 60 HRC can be reduced by
the proper tempering temperature
l
Heat to 900 “C (I650 “F). Cool in air
Heat to 830°C (I 525 “F). Furnace cool to 650°C
at a rate not to exceed 18 “C (SO “F) per h
Hardening. Austenitize at 830 “C t, IS25 W. Flame
tion hardening. carbonitridinp.
austempering. and laser
able surfrlce hardening processes. Quench in water or
than 6.35 mm (0.15 in.) diam may be fully hardened
Normalize and temper as for IWO
l
l
Processing
Sequence
Nonresulfurized
1050:
As-Quenched
Hardness
(Oil)
round
in.
mm
Surface
Eardness, ERC
‘/r radius
Center
‘/2
I
2
4
12.7
25.-l
SO.8
101.6
57
33
27
98 HRB
37
30
25
95 HRB
34
26
21
91 HRB
Source: Bethlehem
Steels / 193
1050: Isothermal Transformation
to 0.55 C, 0.80 to 0.90 Mn, 0.090 P max, 0.050 S max;
grain
Grade:.0.48
size 5 to 7
Si
Carbon
C, 0.91 Mn. Austenitized
Martensite temperatures
Diagram. Composition: 0.50
at 910 “C (1670 “F). Grain size, 7 to 8.
estimated
Steel
1050: Effect of Carbon and Manganese on End-Quench Hardenability. Modified 1050. 0: 0.51 C, 1.29 Mn, 0.06 residual Cr;
0: 0.52 C, 1.27 Mn, 0.06 residual Cr; LO.48 C, 1.07 Mn. 0.06 residual Cr; kO.51 C, 1.04 Mn, 0.08 residual Cr
1050: Flame Hardening
1050:
As-Quenched
Hardness
(Water)
Grade: 0.48 to 0.55 C, 0.60 to 0.90 Mn. 0.040 P max, 0.050 S max;
grain size 5 to 7
Si
round
in.
mm
‘/:
II.7
25.1
SO.8
101.6
I
2
4
Source: Bethlehem
Steel
Surface
6-t
60
SO
33
Eardness. HRC
‘/z radius
59
35
32
27
Center
57
33
16
20
1050: Hardness vs Tempering Temperature and Chemical
Composition
194 / Heat Treater’s
Guide
1050: End-Quench
1050: Hardness vs Tempering Temperature. Specimen, 3.175
Mn. Austenitized
Hardenability. Composition: 0.46 C, 0.99
at 845 “C (1555 “F). Grain size, 7
to 6.35 mm (0.125 to 0.25 in.) thick. Quenched.
1050: Furnace vs Induction
Tempered 1 h
Hardening. Brine quenched from
855 “C (1570 “F)
1050: Tempering. Effect of tempering temperature on room-temperature mechanical properties of 1050 steel. Properties summarized are
for one heat of 1050 steel that was forged to 38 mm (1.50 in.) in diameter, then water quenched and tempered at various temperatures.
Composition of heat: 0.52% C. 0.93% Mn
Nonresulfurized
1050: Induction Heating. Variations of room-temperature hardness with tempering temperature for furnace and induction heating
Carbon
Steels / 195
1050: Austempering. Variation in pitch length of 2 mm (0.080 in.)
thick link plates after austempering and after oil quenching and
tempering. All link plates were austenitized at 855 “C (1570 “F) for
11 min; austempered link plates were held in salt at 340 “C (650
“F) for approximately 1 h, a time dictated by convenience in processing but not required to attain complete transformation
1050: Microstructures. (a) Nital, 825X. Austenitized at 870 “C (1600 “F). l/2 h. Oil quenched. Slow quenching permitted formation of some
grain-boundary ferrite and bainite (feathery areas). Matrix is martensite (white). (b) Austenitized at 870 “C (1600 “F); 1 h. Water quenched.
(c) Nital,
Tempered at 260 “C (500 “F), 1 h. Structure is fine-tempered martensite. No free ferrite visible, indicating quench was effective.
825x. Same as(b) except tempered at 370 “C (700 “F), 1 h. Tempered martensite. (d) Nital, 825x. Same as (b), except tempered at 480 “C
(895 “F), 1 h. Tempered martensite. Ferrite and carbide barely resolved. (e) Nital, 825x. Same as (b), except tempered at 595 “C (1105 “F).
Tempered martensite. Ferrite and carbide better resolved. (f) Nital. 913x. Same as (d). Replica electron micrograph. Typical of a thoroughly
quenched structure
Nonresulfurized
Carbon
Steels / 195
1053
Chemical
Composition.
AISI and UNS: 0.18 to 0.55 C, 0.70 to
I .OO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
ASIO. AS76: SAE J-103. J-II?. J-II-I
Foreign).
UNS
Gios30;
ASTM
196 / Heat Treater’s Guide
Characteristics.
Similar IO 1050. except a higher manganese content
which slightly increases hardenability.
In some application.
higher hardenability
is useful. Ln induction hardening. higher hardenability
ma)
cause quench cracking. Excellent forgeability.
Fairly good machinabilit>.
Weldability
is poor
Forging.
Heat IO I230 “C t2250 “F). Do not forge below MS “C t IS55 “F)
Recommended
Normalizing.
Heat Treating
Annealing.
Heat to 830 “C t IS25 ‘Ft. Furnace cool to 650 ‘C t 1200°F).
at a rate not to exceed 28 “C (SO “F) per hour
Hardening. Heat to 830 “C t 1525 ‘FL Carbonitriding
and induction
hardening are suitable processes. Quench in Water or brine. Rounds less
than 6.35 mm tO.3 in.) diam may be oil quenched for full hardness.
Normalize and temper. as for 1040
Tempering.
As-quenched hardness of 58 to 60 HRC can be reduced bj
proper tempermg temperature
Forgings
l
l
Forge
Normalize
Processing
l
l
l
l
l
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Practice
Heat 10 900 “C t I650 “FL Cool in air
Recommended
l
Sequence
1053: Hardness vs Tempering Temperature. Represents
average based on a fully quenched
structure
196 / Heat Treater’s
Guide
1055
Chemical
Composition.
AISI and UN% 0.50 10 0.60 C. 0.60 to
0.90 hln. O.WO P max. 0.050 S max
Similar
l
Steels (U.S. and/or Foreign).
ASIO. AS76. A682 FEDQQ-S-7OO(ClOSS):
DIN I.1209
LINS G 10550: ASTM
SAE J403. J-112. J-l I-l: (Ger.)
Characteristics.
Generally
considered
a high-carbon
steel. When
carbon approaches 0.60 a near saturated martensite is formed after austemtiring and severe quenching. As-quenched hardness of 60 to 6-I HRC is
ohtained. depending on carbon content. A shallou hardening or low-hardenabilib steel. Good forgeability.
Poor machinabilit).
Not recommended
for welding
Forging.
Heat to I205 “C (2200 “F). Do not forge below 8 IS “C ( I SO0 ‘F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to YOO “C ( 1650 “FL Cool in au
Annealing.
Heat to 830°C ( IS25 “F). Furnace cool to 650 “C ( 1200°F).
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 830 ‘C (I 525 “F). Flame hardening and carbonitriding are suitable surface hardening processes. Quench in inter or brine.
Rounds less than 6.35 mm (l/-l in.) diam may be oil quenched for full
hardness. Nomlalize and temper as for I040
Tempering.
As-quenched hardness of 60 to 6-l HRC can be reduced b!
proper tempering temperature
Recommended
Forgings
l
l
l
l
Forge
Normalize
Anneal
Rough machine
Processing
Austrnitize
Quench
@ Temper
l
Finish machine
l
Sequence
1055: Isothermal Transformation
C, 0.46 Mn. Austenitized
Martensite temperatures
Diagram. Composition: 0.54
at 910 “C (1670 “F). Grain size, 7 to 8.
estimated
Nonresulfurized
Carbon
Steels / 197
1055: End-Quench
1055: Hardness vs Tempering Temperature. Represents
Mn. Austenitized
average based on a fully quenched
Hardenability. Composition: 0.47 C, 0.57
at 845 “C (1555 “F). Grain size, 6 to 7
an
structure
1055: Microstructures. (a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod, patented by austenitizing 2 l/3 min at 930 “C (1705 “F). Quenched
35 set in lead bath at 550 “C (1020 “F). Air cooled. Unresolved pearlite (dark). Ferrite (white), at prior austenite grain boundaries. (b) Picral,
1000x. 3.353 mm (0.132 in.) diam wire. Air patented by austenitizing 1 112 min at 1032 “C (1890 “F). Air cooled in strand form. Line lamellar
peadite with discontinuous precipitation of ferrite at prior austenite grain boundaries
Nonresulfurized
Carbon
Steels / 197
i 059
Chemical COIIIpOSitiOn.
AISI and UNS: 0.55 to 0.65 C. 0.50 to
0.80 Mn, 0.040 P max. 0.050 S max (standard steel grade for wire rod and
wire only)
Recommended
Hardening.
hardening
Heat Treating
Flame hardening
processes
Practice
and carbonitriding
are suitable
surface
Nonresulfurized
Carbon Steels / 197
1060
Chemical Composition. AI!31 and UNS:
0.90 Mn. 0.040 P max. 0.050 S max
0%
to 0.65 C. 0.60 IO
AMS
Similar Steels (U.S. and/or Foreign). LINS G IOhoo;
7230; ASTM ASIO. AS76, A682 MLL SPEC MlL-S-16973:
SAE J-103.
J-113. J-II-I: (Ger.) DIN 1.0601: (Fr.) AFNOR CC 55: (Ital.) LINI C 60:
(U.K.) B.S. 060 A 63
Characteristics.
Versatile high-carbon grade. Product forms include
\ erious thicknesses of flat stock for fabricating parts to be spring tempered.
Good forgeability.
Not recommended for welding. As-quenched hardness
of near65 HRC. This is near maximum Rockwell hardness. When properly
quenched. consists of 3 carbon-rich martensite structure with essentially no
free carbide
198 / Heat Treater’s Guide
Forging.
Heat to I205 “C (2200 “FJ. Do not forge below 8 IS “C ( IS00 OF)
Recommended
Heat Treating Practice
Normalizing. Heat lo 885 “C (I625 “FJ. Cool in air
Annealing. Heat to 830 “C (IS25 ‘VI. Furnace cool to 650
1060: Isothermal Transformation
C, 0.87 Mn. Austenitized
Mattensite temperatures
Diagram. Composition: 0.63
at 815 “C (1500 “F). Grain size, 5 to 6.
estimated
“C ( I200 “F),
at a rate not fo exceed 28 “C (SO “F) per h
Hardening.
austempering,
Heat to 8 IS “C (1500 “F). Flame hardening, carbonitriding,
and martempering are suitable surface hardening processes.
Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be
oil quenched for full hardness
Tempering.
As-quenched hardness from 62 to 65 HRC. This maximum
hardness can be reduced by proper tempering temperature
Austempering.
Thin sections (typically springs) are austempered. Re-
sults in a bainitic structure and hardness of approximately
46 to 52 HRC.
Austenitize at 8 IS “C ( IS00 “F). Quench in molten salt bath at 3 IS “C (600
“F). Hold at temperature for at least I h. Air cool. No tempering required
Recommended
Forgings
Processing
Sequence
Forge
l
l
Normalize
l
Anneal
Rough machine
l
l
Austenitize
Quench
Temper
l
Finish machine
l
l
1060:
1060: Hardness vs Tempering Time. Machine tool component
forging, 114.3 mm (4.5 in.) long. Rectangular cross section,
15.875 by 22.225 mm (0.625 by 0.875 in.). Heated at 815 “C
(1500 “F) in pusher conveyor furnace. Oil quenched. Tempered at
480 “C (895 “F) in muffle furnace. Both furnaces gas fired. No atmosphere control. Hardness measured on polished flash line. 20
heats
As-Quenched Hardness (Oil)
Grade: 0.55 to 0.65 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max:
grain size 5 to 7 (90%); 1 to 3 (10%)
In.
Size round
IlUll
Surface
Eardness, ERC
‘/r radius
Center
‘/2
12.7
25.1
SO.8
IOl.6
59
3-l
30.5
29
37
32
27.5
26
35
30
25
2-l
I
2
-I
Source: Bethlehem
Steel
1060: End-Quench
1060: Hardness vs Tempering Temperature. 4.673 to 104.775
Mn. Austenitized
mm (0.19 to 4.125 in.) thick. Quenched
Hardenability. Composition: 0.63 C, 0.87
at 815 “C (1500 “F). Grain size, 5 to 6
Nonresulfurized
Carbon Steels / 199
Equipment Requirements for Austenitizing, Austempering, and Corrosion Protection of Parts Made of 1035 and 1060 Steels
Equipment comprises a manually operated monorail heat-treating
line
Production requirements
Pall
Steel
Section Ihickness. mm fin.,
Weight of part. kg (lb)
Load weight (gross). kgflb)
Number of pieces per h
Preheating, “C (“Fk min
Austenitizing,
“C(“F); min
Austempering, “C (OF); min
Equipment requirements
Preheting furnace
Amount ofchloride
sah. kg (lb)
Austenitizing
furnace
Amount ofchloridesalt.
kg(lb)
Ausrempering furnace
Amount of nitrate-niuite
salt, kg (lb)
Heat input. kJ (Btu) per h
Agitation
Two washing and rinsing tanks
Capacity. each tank
Heat input. each tank, kJ (Btu, per h
Tank for corrosion protection, m fin.)
Fabricated
disk
12.5 (0.492,
I.1 (2.5)
Recuwgular tube
1060
I.4 fO.055,
0.2 (0.425)
163 (360)
332
705 ( 1300); 10
815-870 ( I SSO-1600); 10
425 (800); IO
35.7(78 75)
720
705 ( 1300): 5
83Ot 1525): IO
345 (650): 6
1035
Rectangular pkue
1060
0.8 (0.032)
0.01 (0.024
7.3 ( 16)
3!900
70.5( 1300); 5
83Ofl525);
IO
330 (630); 6
Immersed-electrode
sah bruh. 0.45 hy 0.6 bj I .6 m ( I8 by 2-l hy 62 in.)
590(1300)
Immersed-electrode
salt bath. 0.45 by 0.6 hp I .6 m ( I8 by 3-l hy 61 in. 1
59Ofl300)
Gas-fwd salt halh. 0.6 by I.2 hy I .8 m 121 hy 18 by 72 in. I
2270 (SOOO,
7-lO.000 (7OO.000)
IXvo 150mmf6in.~impellers
Gas-tired, hot water: each 0.5 by 0.9 hy I 1 m (20 b! 36 hy 18 in.)
57oLfl5ogal~
316.000~300.COO,
0.5 by 0.9 hy I.2 m (20 by 36 by 18 in.)
1060: Miichrres.
(a) Picral, 1000x. 6.35 mm (0.25 in.) diam rod. Cooled from hot rolling in single strand by high-velocity air blast. Mostly unresolved
peartiie. Some diinctly lamellar pearliie. Few scattered white areas are ferrite, partly outlining ptioraustenite grains. (b) Picral, 1000x. 6.747 mm (0.266
in.) dim rod, patented by austenitizing at St.5 “C (1730 “F), 2.50 min. Quenched in lead bath at 530 “C (WI “F), 55 sec. Aircooled. Peariiie (dark areas)
and ferrite (wbiie) at prior austenite grain boundaries. (c) Picral, 1000x. 7.137 mm (0.281 in.) diam win?. Air patented by austenitizing at 1055 “C (1930
OF),3 min. Air cooled in strand form. Partly resolved peadiie (dark). Ferrite (white) at prior austenltizing grain boundaries. (d) Piiral, lOOOx. 2.515 mm
(0.099 in.) diam wire. Air patented by austenitizing at 1015 “C (1860 “F), 1 min. Air cooled in strand form. Fine pearfiie (dark), mostly unresolved. Some
ferrite at prior austenite grain boundaries. (e) Picral, 100x. Decarburized. Heated to 1205 “C (2200 “F), 1 h before rolling to size. Thin layer of scale at
surface(topofmicrograpb). Decarburizedwhiielayerneartop.
Unresolvedpeartiie,fenfte. (9 Picral, 500x. Decatburfzed. Heatedto870to925”C(1600
to 1695 “F), 12 min. Air cooled. Scale at top of micrograph Partly decarburfzed layer, below scale. Pearfiie (dark). Some grain-boundary ferrite
200 / Heat Treater’s
Guide
1064
Chemical COIIIpOSitiOrl.
AISl
0.80 hln. 0.040 P max. O.OSO S max
and LJNS: 0.60 to 0.70 C. 0.50 to
Recommended
Hardening. Flame
hardenmg processes
1064: Microstructure. 1064 cold-rolled steel strip, heated to 745
“C (1370 “F), furnace cooled to 650 “C (1200 “F), and air cooled
to room temperature. Structure is fine spheroidal cementite in a
matrix of ferrite. This structure is preferred for subsequent heat
treatment. Picral. 500x
Heat Treating
hardening
Practice
and carhonitiding
are suitable
surface
1064: Microstructure. 1064 cold-rolled steel strip, austenitized
at 815 “C (1500 “F), quenched to 315 “C (600 “F) and held tocomplete isothermal transformation, air cooled, and tempered at 370
“C (700 “F). The structure is a mixture of bainite and tempered
martensrte. Picral. 500x
200 / Heat Treater’s
Chemical
Guide
Composition.
AISI and UN% 0.60 to 0.70 C. 0.60 to
Recommended
Heat Treating
Practice
0.90 hln. 0.040 P max. 0.050 S niax
Hardening.
ma-tempering
Flame
hardening.
carhonitriding.
are suitahle processes
austempering,
and
1065: Microstructure.
1065 steel wire, 3.4 mm (0.14 in.) in diameter, patented by austenitizing 1.5 min at 930 “C (1705 “F),
quenching 30 s in a lead bath at 545 “C (1015 “F), and air cooling.
The structure is mostly unresolved pearlite with some grainboundary ferrite. Picral. 500x
Nonresulfurized
Carbon
Steels / 201
1069
Chemical
Composition.
AK1 and IJNS: 0.65 to 0.75 C. 0.40 to
Recommended
Heat Treating
Practice
0.70 Mn. 0.040 P max. 0.050 S max
Hardening.
hardening
Flame hardening
processes
and carbonitriding
are suitable
surface
Nonresulfurized
Carbon
Steels / 201
1070
Chemical
0.90Mn,
Composition.
AISI and UN% 0.65 to 0.75 C. 0.60 to
0.040 P max. 0.050 S max
Steels (U.S. and/or Foreign). UNS Gl0700; AMS
51 IS; ASTM A510. A576, A682; MLSPEC
MIL-S-11713
(2):SAEJ303,
J4 12. J4 14: (Ger.) DIN I. I23 I ; (I?.) AFNOR XC 68; (Swed.) SS~J 1770.
1778
Similar
Characteristics.
Low hardenability.
Widely used in hardened and
tempered (notably, spring tempered) condition.
Good forgeability
and
shallow hardening. Used extensively
for making hand tools. such as hammers and woodcutting
saws. Fully hardened microstructure
is carbon-rich
martensite with some small undissolved carbides. Carbides not present in
1060. due to lower carbon content. Although same hardness as 1060 (65
HRC). existence of some free carbide gives 1070 greater resistance to
abrasive wear. Not recommended for welding
Forging.
Heat to I I90 “C (2 I75 “F). Do not forge below 8 I5 “C ( I500 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Annealing.
Heat to 830 “C (I525 “F). Furnace cool to 650 “C (I 200 “F).
at a rate not to exceed 28 “C (50 “F) per h
austempering, and martempering are suitable surface hardening processes.
Quench in water or brine. Rounds under 6.35 mm (0.25 in.) diam may be
oil quenched for full hardness
Tempering.
As-quenched hardness approximately
can be reduced by proper tempering
Austempering.
Thin sections (typically, springs) are austempered. Results in a bainitic structure and hardness of approximately
46 to 52 HRC.
Austenitize at 8 I5 “C (I 500 “F). Quench in molten salt bath at 3 IS “C (600
“F). Hold at temperature for at least I h. Air cool. No tempering required
Martempering.
I75 “C(3-kS
hardening,
Heat to 815 “C (1500 “F). Flame hardening, induction
carbonitriding.
laser hardening.
electron beam hardening,
1070: Isothermal Transformation
Diagram. Composition: 0.75
C, 0.70 Mn, 0.017 P, 0.016 S, 0.33 Si, 0.20 Ni, 0.17 Cr. Austenitized at 600 “C (1470 “F). Grain size, 5 to 6. Time held in constant
temperature bath from start of quench
Austenitize
at 8-U “C ( IS55 “F). Martemper
“F)
Recommended
Processing
Sequence
Forgings
l
l
l
l
l
l
Hardening.
65 HRC. Hardness
l
l
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
1070: Temperature
vs Depth of Case
in oil at
202 / Heat Treater’s
Guide
1070: Hardness vs Depth of Case
1070: Hardness vs Tempering Temperature. Represents
average based on a fully quenched
an
structure
1070: Microstructures. (a) 2% nital, 100x. Hard drawn steel valve-spring wire, Longitudinal section. Tensile strength, 1689 MPa (245 ksi,
obtained by 80% reduction. Deformed pearlite. Prior structure, fine lamellar pearlite. (b) 2% nital, 1000x. Valve-spring wire. Quenched and
tempered. Austenitized at 870 “C (1600 “F). Oil quenched. Tempered at 455 “C (850 “F). Mainly tempered martensite. Some free ferrite
(white)
202 / Heat Treater’s Guide
1075
Chemical Composition. AISI
0.70 Mn, 0.040 P max. 0.050 S max
and UNS:
0.70 to 0.80 C. 0.40 to
Recommended
Heat Treating
Hardening. Flame
suitable processes
hardening,
Practice
carbonitriding.
and austempering
are
202 / Heat Treater’s
Guide
1078
Chemical Composition.
AISI
0.60 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
A510.A576;SAEJ4O3,Jdl2.Jll-k(Ger.)DIN
75: (Swed.) Ss1.1 1774
Characteristics.
and UNS:
Foreign).
0.72 to 0.85 C. 0.30 to
UNS
G10780;
ASTM
l.l218:(Fr.)AFNORXC
High carbon allov+s more free carbide particles in
quenched microstructure.
Because lower manganese decreases hardenabil-
ity. 1078 is often induction hardened. As-quenched hardness of 64 to 66
HRC. if properly austenitized and quenched. Forgeability
is good. Never
recommended for welding
Forging.
Heat to I I75 “C (2lSO”FL
Recommended
Normalizing.
Do not forge below 815 “C (IS50 “F)
Heat Treating
Practice
Heat to 870 “C ( I600 OF). Cool in au
Nonresulfurized
Annealing.
Heat to 8 IS “C ( I SO0 “F). Furnace cool to 650 “C ( I200 “F).
at a rate not to exceed 28 “C (SO “F) per h
315 “C (600 “F).
tempering required
Hardening. Heat to 815 “C ( 1500 “F). Carbonitriding,
laser surface
hardening, and induction hardening are suitable processes. Quench in
water or brine. Rounds under 6.35 mm (0.25 in.) diam may be oil quenched
for full hardness
Recommended
Tempering.
Asquenched
hardness of approximately
ness can be reduced by proper tempering temperature
65 HRC.
Hard-
at temperature
Processing
Steels / 203
for at least I h. Air cool.
No
Sequence
Forgings
l
l
l
l
Austempering.
Because of low hardenability,
thin sections only are
austempered, as for 1060. Thin sections (typically
springs) are austempered. Results in a bainitic structure and hardness of approximately
46 to
52 HRC. Austenitize at 815 “C (1500 “F). Quench in molten salt bath at
Hold
Carbon
l
l
l
l
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
1078: Isothermal Transformation Diagram. Composition: 0.75 C, 0.50 Mn, 0.007 P, 0.020 S, 0.27 Si. Horizontal lines: formation of
martensite on cooling. Curved lines: formation of bainite on isothermal holding. Dotted lines: beginning of isothermal transfomation
of holding below M,
1078: Hardness vs Tempering Temperature. Represents
average based on a fully quenched structure
an
204 / Heat Treater’s
Guide
1078: Laser Surface Hardening. Laser surface transformation
hardening of SAE 1078 using optical integrator with 1.27 x 1.27 cm (0.5 x
0.5 in.) laser spot
1078: Microstructure. Picral, 550x. Hot rolled bar. Air cooled
from rolling temperature. Predominantly pearlite. Large amount of
partly resolved lamellar pearlite. Some grain-boundary ferrite
204 / Heat Treater’s
Guide
1080
Chemical COIIIpOSitiOn.
AISI
0.90 hln. 0.040 P max. 0.050 S mux
Similar
and UNS:
Steels (U.S. and/or Foreign).
5110: ASTM
hIIL-S-16974;
0.75 to 0.88 C. 0.60 to
UNS
Gl0800;
ASIO. AS76. A68’: FED QQ-S-635 (CIOSO,: hlfL
SAE 5403. J-II?. 141-J
AMS
SPEC
Characteristics.
Higher manganese content of 1080 can provide
greater hardenabilit> than 1078. particulruly
if manganese is near the high
side of the range. 0.90. As-quenched hardness near 65 HRC. As carbon
content increases. there is a gradual increase in amount of free carbide. This
enhances abrasion resistance and decreases ductility. Forgeability
is good.
Weldabilitj
is poor
Nonresulfurized
Forging.
Heat to I I75 OC (2 I50 OF’). Do not forge below 815 “C (I 500 “F)
Recommended
Normalizing.
Heat Treating
Heat
to 870 “C (1600
Practice
“F).
Cool
Recommended
l
Annealing.
Heat to 815 “C (I 500 “F). Furnace cool to 650 “C (I 200 OF),
at a rate not to exceed 28 “C (SO “F) per h
Hardening.
Heat to 8 I5 “C (I 500 “0. Induction hardening, carbonitriding, and austempering are suitable processes. Quench in water or brine.
Rounds under 6.35 mm (0.25 in.) diam may be oil quenched for full
hardness
l
l
l
l
l
l
l
As-quenched
hardness of approximately
ness can be reduced by proper tempering
65 HRC.
As-Quenched
Hardness
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Hard-
Austempering.
Because of low hardenability,
thin sections are
austempered, as for 1060. Thin sections (typically
springs) are austempered. Results in a bainitic structure and hardness of approximately
46 to
52 HRC. Austenitize at 815 “C (IS00 “F). Quench in molten salt bath at
315 “C (600 “F). Hold at temperature
for at least I h. Air cool. No
tempering required
1080:
Steels / 205
Forgings
in air
Tempering.
Processing
Carbon
1080: Isothermal Transformation Diagram. Composition: 0.79
C, 0.76 Mn. Austenitized at 900 “C (1650 “F). Grain size, 6.
Martensite temperatures estimated
(Oil)
Grade: 0.75 to 0.88 C, 0.60 to 0.90 Mn, 0.040 P max, 0.050 S max;
grain size 80%, 5 to 7; 20%, 1 to 4
Size round
in.
mm
‘/z
I
2
.I
12.7
25.1
50.8
101.6
Source: Bethlehem
Surface
60
-I5
43
39
Eardness, ERC
t/z radius
43
42
40
37
Center
-IO
39
37
32
1080: Hardness vs Tempering Temperature. Specimen, 3.175
to 6.36 mm (0.125 to 0.25 in.) thick. Quenched.
Tempered 1 h
Steel
1080: End-Quench Hardenability. 12.7 mm (0.5 in.) diam bar.
Composition: 0.79 C, 0.76 Mn. Austenitized at 900 “C (1650 “F).
Grain size, 6
1080:
P&s
Equipment
austenitized
Production
for Austempering
requirements
Weight ofeach piece. kg (lb)
Production per hour
Equipment
Requirements
at 925 “C (1695 “F)
I. I to I .8 (2.-l to 3.9)
I SO0 pieces
requirements
Austempering furnace
Size of furnace. m3 (ft 3)
Nitrae-write
salt. kg (Ih,
Tempenturr.
“C (“FI
Agitauon
Cooling
Submerged fuel-fired salt pot
6.6(233)
I I 340 (29 000)
34%360(65@675)
Pump. directed at delivery chute
Forced ar through humer tube
206 / Heat Treater’s
Guide
1060: TIT Diagram. Time-temperature
austempering.
transformation diagram for 1080 steel, showing difference
When applied to wire, the modification shown is known as patenting
1080: Induction Heating. Effect of heating rate on AC, and AC, temperatures
for annealed
1080 steel
between
conventional
and modified
Nonresulfurized
Carbon
Steels / 207
1080:
Microstructures. (a) Picral. 2000x. Hot rolled bar, austenitized at 1050 “C (1920 “F), l/2 h. Furnace cooled to room temperature at
28 “C (50 “F) per h. Mostly pearlite. Some spheroidal cementite particles. (b) Thin-foil specimen, 2000x. Same as (a), except cooling rate
increased to 56 “C (100 “F) per h. Thin-foil transmission electron micrograph. Fine lamellar pearlite. (c) As polished. Not etched. 250x. Inclusions in flat spring. 0.20 mm (0.008 in.) thick. Longitudinal section. Thickness shown as height in micrograph. Black spots are iron aluminide. Thin gray stringers near center are sulfide
Nonresulfurized
Carbon Steels / 207
1084
Chemical Composition.
AISI and UNS: 0.80
to
0.93 C, 0.60 to
0.90 Mn. 0.040 P max. 0.050 S max
LINS ~10810;
ASTM
(C108-1); SAE 5303. J412. J-II-I: (Ger.) DIN
Heat to II75 “C (2lSO”Fl
Forge
Normalize
l
Anneal
l
Rough machine
l
Austenitize
9 Quench
l
Temper
l
Finish machine
l
Do not forgebelow
815 “C (l5OO’F)
1084: Hardness
Recommended
Normalizing.
Heat Treating
Practice
average
Heat to 870 “C (1600 “F). Cool in air
Annealing. Heat to 8 I5 “C ( I500 “F). Furnace cool to 650 “C ( I 200 “F).
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 8 IS “C ( I500 “F). Carbonitriding and austemperinp
are suitable surface hardening processes. Quench in water or brine. Rounds
under 6.35 mm (0.25 in.) diam may be oil quenched for full hardness
Tempering.
Asquenched
hardness of approximately
ness can be reduced by proper tempering
Austempering.
Sequence
l
Characteristics. Composition nearly identical to that of 1080. Asquenched hardness near 65 HRC. As carbon content increases. there is a
padual increase in amount of free carbides. This enhances abrasion resistance and decreases ductility. Forgeability
is good. Weldabilitj
is very poor
Forging.
Processing
Forgings
Similar Steels (U.S. and/or Foreign).
A510, A576; FED QQ-S-700
I .0647
Recommended
65 HRC.
Hard-
Very thin sections, because of relatively
low hardenability can be austempered. using the technique for 1060. Thin sections
(typically
springs) are austempered. Results in a bainitic structure and
hardness of approximately
46 to 52 HRC. Austenitize at 8 I5 “C ( IS00 “F).
Quench in molten salt bath at 3 I5 “C (600 “F). Hold at temperature for at
least I h. Air cool. No tempenng required
based
vs Tempering
on a fully quenched
Temperature.
structure
Represents
an
208 / Heat Treater’s
Guide
1085
Chemical
Composition.
AISI and CJNS: 0.80 to 0.93 C. 0.70 to
I .OOMn. O.@IOP max. 0.050 S max
Recommended
Hardening.
Heat Treating
CarbonitridinS is a suitable surface hardening process
1085: Effects of Quenching on Hardness and Dimensions.
Hardness values and changes in dimensions
test specimen after quenching in water, fast oil, and conventional oil
Quenching
medium
Maximum
Water . . . . . . . . . . . . . . . . . . . . . . . . . . 67.0
Fast oil . . . . . . . . . . . . . . . . . . . . . . . . 66.0
Conventional oil . . . . . . . . . . . . . . . . 65.5
Gap A
mm
Water . . . . . . . . . . . 0.3404
Fast oil . . . . . . . . . 0.0533
Conventional oil . 0.0559
in.
0.0134
0.0021
0.0022
Hardness, H RC
Minimum
Variation
63.0
63.0
43.0
Dimensional
Diameter 6
mm
0.2591
0.0813
0.0965
Practice
in.
0.0102
0.0032
0.0038
4.0
3.0
22.5
change
Diameter
mm
0.2946
0.0610
0.0965
C
in.
0.0116
0.0024
0.0038
of a 1085 plain carbon steel
208 / Heat Treater’s Guide
1086
Chemical Composition.
Recommended
0.50 hln. 0.040 P nk.
wire only)
Hardening.
AISI and CJNS: 0.80 to 0.93 C. 0.30 to
0.050 S max: (standard steel grade for uue rod and
Heat Treating
Carbonitriding
Practice
and austempering
are suitable processes
208 / Heat Treater’s
Guide
1090
Chemical
Composition.
AISI and LINS: 0.85 IO 0.98 C. 0.60
IO
0.90 h*ln. 0.040 P max. 0.050 S max
Similar
Sll2:ASTM
Steels (U.S. and/or Foreign).
A510. A576: SAEJ403.J-Il2.
LINS
J-tl4:Ger.j
MIS
GlO200;
DIN I.1273
Characteristics.
CommonJy referred to as a commercial
grade of
carbon tool steel. Essentially same composition
as WI tool steel, hut not
made hy tool steel practice and not expected IO meet quality level of W 1
tool steel. Easily forged. Blanking (coldj from strip or thin plate is common
method of fabrication. Available in a variety of product forms. As hard as
66 HRC, fully quenched. Microstructure
of carbon-rich
martensite and
considerable amount of free carbide. assuming normal austenitizing temperature used
Forging.
Heat to I I50 ‘C (3 IO0 “Fj. Do not forge below 815 “C ( 1500 “Fj
Nonresulfurized
Recommended
Normalizing.
Heat Treating
Recommended
Practice
Heat to 855 “C (1570 OF). Cool in air
Processing
Carbon
Steels / 209
Sequence
Forgings
Annealing.
As is generally true for all high carbon steels, bar stock
supplied by mills in spheroid&d condition. Annerded with structure of fine
spheroidal carbides in ferrite matrix. When parts are machined from bars
in this condition, no normalizing or annealing required. Forgings should
always be normalized. Anneal by heating to 800 “C (1475 “F). Furnace
cool to 650 “C (1200 “F). at a rate not to exceed 28 “C (50 “F) per h. From
800 “C (I475 “F’) to ambient temperature, cooling rate is not critical. This
relatively simple annealing process will provide predominantly
spheroidized structure, desired for subsequent heat treating or machining
Hardening. Heat to 800 “C (1375 “F). Carbonitriding and austempering
are suitable processes. Quench in water or brine. Rounds under 6.35 rnrn
(0.25 in.) diam may be oil quenched for full hardness
Tempering.
Asquenched hardness of as high as 66 HRC. Hardness can
be reduced by proper tempering
Austempering.
Responds well to austempering (bainitic
hardening).
Austenitize at 800 “C ( 1475 “F). Quench in agitated molten salt bath at 3 I5
“C (600 “F). Hold for 2 h. Cool in air
l
l
l
l
l
l
l
l
Forge
Normalize
Anneal
Rough machine
Semitinish machine
Austenitize
Quench
Temper
1090: Hardness vs Section Thickness. Specimen, 20.828 mm
(0.820 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in
salt at 370 “C (700 “F), 7 min. Rockwell hardness C, converted
from microhardness readings taken with 100 g (4 oz) load. Low
values of surface hardness result from decatburization
I
1090: llT Curves. Transformation characteristics of a hypereutectoid steel after mattempering. Austenitized at 885 “C (1825 “F).
Grain size, 4 to 5
1090: Properties
Sway Bars
Tensile suer@, hlPa (ksi)
Yield strength. hPa (ksi)
Elongation. 4.
Reduction ofarea %
Hardness. HB
Fatigueqcles(d)
(a) Alerage
in diameter
95.220
of Austempered
and Oil-Quenched
Austempered
at 400 “C
(750 W(b)
Quenched sod
tempered(c)
l-115 (205)
1020(148)
II.5
30
115
105.OOChel
1380 (200)
895 (130)
6.0
10.2
388
58.6W f,
values (b) Six I~SIS. tc)lko
tests cd) Fatigue specimens2 I mrn(O.812 in.)
(et Seven tests: range, 69 050 to I37 000. (fj Eight tests; range, 13,120 to
1090: Hardness vs Section Thickness. Specimen,
1090: Hardness vs Tempering Temperature.
average based on a fully quenched structure
Represents
an
17.272 mm
(0.680 in.) diam. Austenitized at 885 “C (1625 “F). Quenched in
salt at 370 “C (700 “F), 7 min. Hardness, HRC, converted from microhardness readings taken with 100 g (4 oz) load. Low values of
surface hardness result from decarburization
210 / Heat Treater’s
Guide
1090: Microstructures. (a) Picral, 2000x. Hot rolled bar, 25.4 mm (1 in.). As cooled from finish-rolling temperature of 870 to 900 “C (1800
to 1850 “F). Replica electron micrograph. Entirely lamellar pearlite. (b) Picral, 1000x. 8.712 mm (0.343 in.) diam rod. Patented by austenitizing at 955 “C (1750 “F), 4 l/2 min. Quenched in lead bath at 505 “C (940 “F), 70 sec. Air cooled. Mostly unresolved pearlite with bainite.
(c) Picral, 8000x. Strip, cold reduced 80% after hot rolling. Rolling direction vertical in this replica electron micrograph. Deformed lamellar
pearlite. (d) 2% nital, 100x. Modified steel music wire. 0.38 Mn. Cold drawn to 1813 MPa ( 283 ksi) tensile strength by 75% reduction. Deformed pearlite. Prior structure, fine pearlite. (e) 2% nital, 500x. Same as (d), but higher magnification. Drawing direction is horizontal. Prior
structure produced by lead patenting
210 / Heat Treater’s Guide
1095
Chemical COmpOSitiOn.
AK1
0.50 Mn. 0.010 P max. 0.050 S max
and UNS:
0.90 to 1.03 C. 0.30
to
AMS
Gl0200;
UNS
5121. 5122. 5132. 7304; ASTM A510. A576. A682; FED QQ-S-700
(ClO95); MfL SPEC MB-S-16788
(CSlO95):
SAE J303, JJIZ. J4l-k
(Ger.) DIN I. 1274; (Jap.) JIS SUP 3: ISwed.) SS1.t 1870; (U.K.) B.S. 060
A96.EN44B
Characteristics. Easily forged. Blanking (cold) from strip or thin plate
also a common method of fabrication.
Available in a variety of product
forms. As hard as 66 HRC, fully quenched. Microstructure
of carbon-rich
martensite and considerable
amount of Free carbide. assuming normal
austenitizing temperature is used. Carbon range slightly higher and manganese content lower than for 1090. This results in the possibility of more
undissolved carbide in the microstructure
and slightly lower hardenability
Heat to I I50 “C (2 100 “F). Do not forge below 8 I5 “C ( 1500 ‘F)
Recommended
Normalizing.
Heat Treating
practice.
parts are normalized
at 900 “C ( 1650 “F)
Annealing.
Similar Steels (U.S. and/or Foreign).
Forging.
In aerospace
Practice
Heat to 855 “C (1570 “F). Cool in au
As is generally true for all high-carbon
steels, bar stock
supplied by mills in spheroidized condition. Annealed with structure of fine
spheroidal carbides in ferrite matrix. When parts are machined from bars
in this condition. no normalizing
or annealing required. Forgings should
always be normalized.
Anneal by heating to 800 “C (1475 OF). Soak
thoroughly. Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C
(50 “F) per h. From 650 “C ( I200 “F) to ambient temperature, cooling rate
is not critical. This relatively simple annealing process will provide predominantly spheroidized structure, desired for subsequent heat treating or
machining.
ln aerospace practice. parts are annealed
allowed to cool to below 510 “C (I000 “F)
at 815 “C (1500 “F) and
Hardening. Heat to 800 “C (l-l75 “FL Carbonitriding and austempering
are suitable processes. Quench in water. brine. or aqueous polymers. Oil
quench rounds under A.7 mm (0. I9 in.) for full hardening. Responds well
to austempering (same procedure as for 1090).
In aerospace practice, parts are austenitized at 800 “C (1475 “F). and
quenched in oil or polymers
Nonresulfurized
Tempering.
As-quenched hardness as high as 66 HRC. Hardness can be
reduced by proper tempering. When quenching with oils or polymers, parts
may be tempered at a number of different temperatures to get specitic
ranges of tensile strengths as follows: 675 “C (I 245 OF) for 620 to 860 MPa
( 90 to 125 ksi); 620 “C (I I50 “F) for 860 to 1035 MPa ( I25 to I50 ksi);
540 “C ( 1000 “F) for 1035 to I I70 MPa ( I50 to I70 ksi): 480 “C (895 “F)
for 1170 to I240 MPa ( I70 to I85 ksi); 425 “C (795 “F) for 1240 to I380
MPa (185 to 200 ksi); 370 “C (700 “F) for I380 to I520 hiPa ( 200 IO 220
ksi)
Recommended
Responds well to austempering (bainitic hardening).
Austenitize at 800 “C (1475 “F). Quench in agitated molten salt bath at 3 I5
“C (600 “F). Hold for 2 h. Cool in air
Steels / 211
Sequence
Forgings
l
l
l
l
l
l
Austempering.
Processing
Carbon
l
l
Forge
Normalize
Anneal
Rough machine
Senlitinish machine
Austenitize
Quench
Temper
1095: Effect of Prior Microstructure on Hardness After Tempering. Steel tempered at 565 “C (1050 “F)
1095: isothermal Transformation
C, 0.29 Mn. Austenitized
Diagram. Composition:
0.89
at 885 “C (1625 “F). Grain size, 4 to 5
1095: End-Quench
1095: Isothermal Transformation
Diagram. Modified.
sition: 1.13 C, 0.30 Mn. Austenitized
size, 7 to 8. Martensite
temperatures
at 910 “C (1670
estimated
Compo“F). Grain
Mn. Austenitized
Hardenability. Composition:
0.89
at 885 “C (1625 “F). Grain size, 5
C, 0.34
212 / Heat Treater’s
1095:
As-Quenched
Guide
Hardness
(Water)
0.90 to 1.03 C, 0.30 to 0.40 Mn. 0.040 P max, 0.050 S max;
grain
Grade:,srze 50%, 5 to 7; 500/b, 1 to 4
Size round
in.
mm
I
.’ ,
12.7
3.1
SO.8
I2
-I
gas quenching
(forced air), and nor-
Center
55
Ib
48
4-l
63
43
-IO
63
38
30
b5
6-l
I0l.b
Source: Rcpuldic
Hardness, HRC
% radius
Surface
1095: As-Quenched Hardness. Forged steel disks, 101.6 mm (4
in.) thick, after oil quenching,
malizing (cooling in still air)
Steel
1095: Hardness vs Tempering Temperature.
average based on a fully quenched
Represents
an
structure
1095: Cooling Curves. Center cooling curves showing the effect
of scale on the cooling curves of 1095 steels quenched without
agitation In fast oil at 51 “C (125 “F). Specimens were 13 mm
(0.50 in.) diam by 64 mm (2.50 in.) long
1095: End-Quench Hardenability.
C, 0.28 Mn. Austenitized
Modified. Composition: 1.17
at 925 “C (1695 “F). Grain size, 7 to 8
1095: Quenching. Differences in Brinell hardness of forged 1095
steel disks, 100 mm (4 in.) thick, after oil quenching, gas quenching (forced air), and cooling in still air (normalizing)
1095: Mechanical Properties
Treated by Two Methods
Specimen
number
I
2
3
4
Beat treatment
Water quench and temper
Waterquench and temper
hlartrmpcr and temper
Matemper
and temper
(13) In 25 nun or I in.
of 1095 Steel Heat
Hardness,
ARC
53.0
52.5
53.0
sz.l3
Impact
energ
J
16
I9
38
33
ft
Ibf
I2
I-l
28
2-l
ElongaIion(
%,
0
0
0
0
Nonresulfurized
1095: Microstructures.
Carbon Steels / 213
(a) Picral, 1000x. Bar, normalized by austenitizing at 870 “C (1800 “F). Cooled in air. Partly unresolved pearlite
(black); partly lamellar peariite. (b) Nital, 1000x. Hot rolled bar, 31.75 mm (1.25 in.) diam. Spheroidized by holding at 875 “C (1245 “F), 15
h. Air cooled. Spheroidal cementite particles in ferrite matrix. (c) 2% nital, 500x. Wire, austenitized at 940 “C (1725 “F). Oil quenched. Mixture of fine pearlite and lower bainite (dark areas). Untempered martensite (light areas). Structure resulted from slack quenching. (d) Picral,
1000x. Austenitized at 870 “C (1800 “F); austenitized at 815 “C (1500 “F). Water quenched. Fine, untempered martensite. caused by more
severe quench. Some spheroidal cementite. (e) Picral, 1000x. Same as (d), except tempered at 150 “C (300 “F) after quench. Tempered
martensite. darker than (d). Some spheroidal cementite particles. (f) 2% nital, 550x. Wire. Austenitized at 885 “C (1625 “F), l/2 h. Quenched
to 625 “C (330 “F). Held 5 min. Oil quenched. Lower bainite (dark). Untempered martensite (light). (g) 2% nital, 550x. Same as (f), except
held for 20 min in 329 “C (625 “F) quench. Air cooled. Lower bainite (dark). Untempered marlensite (light). (h) 2% nital, 550x. Same as (f),
except held 1 h in 445 “C (850 “F). Air cooled (austempered). Mainly upper bainite. (j) Nital, 500 x. Die steel induction hardened to 2.54 mm
(0.10 in.). Shown are transition-zone constituents from some fine martensite (top) to prior structure of spheroidal cementite in ferrite matrix
(bottom). (k) Nital, 500x. Same as (j), except area shown is nearer surface of steel. Fine martensite (gray) and fine unresolved pearlite
(black). Small white particles are spheroids of cementite from prior structure. (n) Nital, 1000x. Same as (m), except higher magnification
214 / Heat Treater’s Guide
1095: Tempering. Effect of prior microstructure on room-temperature hardness after tempering. (a) 1095 steel tempered at 565 “C (1050
“F) for various periods of time. (b) Room-temperature
hardness before and after tempering, as well as amount of martensite present before
tempering in 4320 steel end-quenched hardenability specimens tempered 2h
Resulfurized
(1100
Carbon
Steels
Series)
1108
Chemical
0.80Mn,
Composition.
AISI and UNS: 0.08 to 0.13 C, 0.50 to
Recommended
Heat Treating
Practice
0.040 P max. 0.08 to 0. I3 S
Hardening.
hardening
Flame hardening
processes
and carbonitriding
are suitable
surface
1110
Chemical Composition. AISI and UNS:
0.60Mn. 0.040 P max. 0.08 to 0.13 S
Similar Steels (U.S. and/or Foreign).
0.08 to 0.13 C. 0.30 to
UNS
Gi I 100; ASTM
A 107; FED QQ-S-637 (C I I 10): SAE J-%03,J-l I?; (Ger.) DfN I .0702; (Jap.)
JIS SUM II, SUM I2
Characteristics.
Available principally
in bar form. Costs more than
low-carbon steels of the 1000 series. because it has been resulfurized
to
improve machinability.
Sulfur addition impairs some mechanical properties. mainly impact and ductility in the transverse direction. Also. adversely
affects forgeability,
cold formability,
and weldability.
Use of this steel
should be confined principally
fabricating operation
Recommended
Hardening. Large
to applications
Heat Treating
where machining
is the main
Practice
portion of parts are used as machined. Can be surface
hardened by carbonitriding.
salt bath nitriding, or flame hardening
Normalizing and Annealing.
or hot roiled and cold drawn
normalized or annealed
Generally furnished in the hot rolled
condition
for best machinability.
Rarely
1113: Case Hardening Gradients. Case-hardness gradients
scatter from normal variations in noncyanide liquid carburizing
1113
Chemical Composition.
AISI and UNS: 0. I3
C max.0.70 to l.OOMn.0.07
to0.12 P.O.14 too.33
S
Recommended Heat
Treating Practice
Hardening. Liquid carburizing is a suitable surface hardening process
of 1113 steel showing
216 / Heat Treater’s Guide
1117
Chemical Composition.
AISI and UNS:
I.30 hln. 0.040 P max. 0.08 to 0. I3 S
Similar Steels (U.S. and/or Foreign).
A107. Al08; FED QQ-S-637 (Clll7r;
J-103.J-III. J-II-t
hlfL
0. I-4 to 0.20 C. 1.00 to
GINS
Gl I 170:
SPEC ML-S-IMII;
ASThl
SAE
Characteristics. Morecostly than the 1020 or IO2 I grades. because tt
has heen resulfurized
for improved machinability.
This impairs certain
mechanical properties. forgeability.
and cold formability.
Manganese content is substantially higher than that of 1020 and I02 I. Hardenahility
is not
significantly
higher. because a portion of the manganese combines viith the
higher sulfur to form manganese sulfide stringers. These promote chip
breakage and excellent machinability.
Available only in bar stock for
machining directly into parts. most often tn automatic machines
Recommended
Case Hardening.
Heat Treating
Practice
Almost always used as machined or case hardened.
(See process for 1020). Flame hardening. carbonitriding,
liquid carbutizmg, gas carhuriring.
austempering.
and mat-tempering are suitable processes
Normalizing and Annealing.
normalizing
teGtperature
Rarely required by fabricator.
is 900 Y-( I hS0 “F) -
1117: Gas Carburizing.
Effect of normal variations
burizing on hardness gradients. 10 tests
Qpical
_.
in gas car-
1117: Gas Carbonitriding.
Carbonitrided at 815 “C (1500 “F), 1
l/2 h. Oil quenched. Required minimum hardness of 630 Knoop
(500 g load) at 0.001 in. below surface was met by reducing percentage and flow rate of ammonia or by adding a diffusion period
after carbonitriding, as indicated. Atmosphere consisted of: endothermic carrier gas, dew point of -1 “C (+30 “F), at 4.245 m3 (150
ft3) per h; natural gas at 0.170 m3 (6 W) per h; and ammonia in
amounts indicated.0 : 3% NH, at 5 fWh. 0: 11% NH, at 20 ff/h and
diffused last 15 min. A: 11% NH, at 20 ff/h
Resulfurized
1117: Liquid Carburizing. Comparative case depth and case
hardness. Specimen, 15.875 mm (0.625 in.) diam. Carburized at
900 “C (1650 “F), 2 h. Brine quenched. 22 tests
1117:
As-Quenched
Hardness
52
I
2
-I
12.7
25.4
SO.8
101.6
Source: Bethlehem
Surface,
(Water)
‘/z radius
ERC
HRB
12
37
33
32
96
90
83
Center
HRC
HRB
3S.J
::
HRC
‘9.5
93
86
81
Steel
1117: Hardness vsTempering
Steels / 217
1117: Gas Carburizing. Effect of time and temperature on case
depth. (a) Bars, 177.8 mm (7 in.) long. Carburized at 900°C (1650
“F). Water quenched. (b) Bars, 177.8 mm (7 in.) long. Carburized
at 925 “C (1695 “F). Water quenched. (c) 12.7 mm (0.5 in.) round
bars. Carburized at 900 “C (1650 “F). Quenched in 10% brine
Effect of mass on as-quenched hardness of steel bars, quenched in
water; contents: 0.19 C, 1 .lO Mn, 0.015 P, 0.084 S. 0.11 Si; grain
size: 2 to 4
Size round
tn.
mm
Carbon
Temperature. Represents an av-
erage based on a fully quenched structure
L
218 / Heat Treater’s Guide
1117: Selective Carburizing. Typical part selectively
in the bath. Area to be carburized is shaded
1117: Microstructures.
carburfzed by partial immersion. Only the portion that is to be carbutized
is immersed
(a) Picral. 200x. Steel bar normalized by austenitizing at 900 “C (1650 “F), 2 h. Cooled in still air. Blocky ferrite
(light). Traces of Widmanstatten ferrite. Fine pearlite (dark). Round particles of manganese sulfide. (b) 3% nital, 200x. Carbonitrided 4 h at
845 “C (1555 “F) in 3% ammonia, 6% propane, and remainder, endothermic gas. Oil quenched. Tempered 1 l/2 h at 150 “C (300 “F). Retained austenite (white) and globules of manganese sulfide (dark) in matrix of tempered martensite. (c) Nital, 200x. Carbonitrided and oil
quenched. Surface layer of decarburized ferrite, superimposed on a normal case structure of martensite (left side of micrograph). Core material (right) shows patches of ferrite (white)
Resulfurized
Carbon Steels / 219
1117: Case Hardness Gradients. Case hardness gradients for two carbon steels and four low alloy steels, showing effects of carburizing
temperature and time. Specimens measuring 19 by 51 mm (0.75 by 2 in.) diam were carburized, air cooled, reheated in neutral salt at 845
“C (1555 “F), and quenched in nitrate/nitrite salt at 180 “C (355 “F)
Resulfurized
Carbon Steels / 219
1118
Chemical COmpOSitiOn.
AK1 and UNS: 0.14
I .60 Mn, 0.040 P max. 0.08 to 0.13 S
Similar Steels (U.S. and/or Foreign).
Al07,
Al08;
FED QQ-S-637
Characteristics.
to
0.20
C.
UNS
G1 I 180;
(Cl 118); SAE 5403, J412. J414
1.30
to
ASTM
More costly than the I020 or IO2 I grades, because it
has been resulfurized
for improved machinability.
This impairs certain
mechanical properties, forgeability,
and cold formability,
While a portion
of the manganese (relatively
high) combines with sulfirr, there is still a
sufftcient amount left over to result in higher hardenability
1020or 1021
Recommended
Heat Treating
compared
with
Practice
Case Hardening. Almost always used as machined or case hardened,
as described for 1020. Greater hardenability.
compared with 1020, allows
the section thickness of carburized I I I8 to be extended at least to 12.7 mm
(0.5 in.). Fully hardened by oil quenching. Flame hardening. carbonitriding, liquid carburizing. and martempering are suitable processes
220 / Heat Treater’s
Guide
1118: Liquid Carburizing.
Carburized
at 955 “C (1750 “F).
Slowly cooled
1118: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
1118:
As-Quenched
Hardness
(Water)
of steel bars, quenched in
0.08 S, 0.09 SI; grain size:
Size round
in.
mm
‘!I,
I‘
2
1
Source
Surface,
ERC
IZ 7
25.-l
SO.8
101.6
Brrhlcheni
Srrrl
43
36
34
32
‘,$ radius
HRC
36
___
_..
Center
HRB
ERC
ClRB
33
9s,
91
8-i
96.5
87.0
82.0
structure
220 / Heat Treater’s
Guide
1137
Chemical
Composition.
AISI and UNS:
I .6S Mn. 0.040 P mari. 0.08 to 0. I3 S
Similar
C: ASTM
J-111
Steels (U.S. and/or Foreign).
Al07,
AlO9. A3ll;
FEDQQ-S-637
0.31 to 0.39 C. 1.35 IO
LINS G10200: AhlS 502-t
(Cll37):
SAE J-tO3. Jll2.
In aerospace practice. parts are normalized
allowed to cool below S-10 ‘C t 1000 “F)
at 785 “C (1350 “F) and
Hardening.
Characteristics.
Essentially a high-manganese version of 1037. which
has been resulfurized for improved machinabilib.
Higher manganese content provides higher hardenability.
although not as much as indicated by the
manganese content t I .3S to I .65). Some of this manganese combines with
increased sulfur to foml manganese sulfide stringers. Available only as hot
rolled or hot rolled and cold drawn bars. for producing parts by machining
processes. Too high m carbon for good weldability.
Sulfur content can
cause hot shortness. Should not be used L+hen welding is imolved
Recommended
Annealing.
Heat IO 885 “C t 1625 OF). Furnace cool to 650 “C (1300 “F)
at a rate not to exceed 38 ‘C (SO “F) per h to 650 “C ( 1200 “F).
Heat Treating
Practice
Normalizing.
Not usually required If necessary, heat to 900 “C (I650
“FL Cool in air.
In aerospace practice, parts are normalized at 900 “C (I650 “F)
Heat to 845 “C t I SSS “F). Flame hardening and carbonitridinp are suitable surface hardening processes. Quench in water. brine. or
aqueous polymers.
In aerospace practice. parts are austenitized at 845 “C (IS55 “F) and
quenched in oil. \+ater. or polymer. For full hardness, oil quench sections
not esceeding 9.535 mm (0.375 in.) thick
Tempering.
As-quenched
hardness of approximately
45 HRC. Hardness can be reduced bq tempering In quenching with oils or polymers. parts
ma> be tempered at several different temperatures to get specitic ranges of
tensile strengths: 380 “C (895 “F) for 620 to 860 MPa (90 to 12.5 ksi); 329
“C (625 “F) for 860 to 1035 MPa (I 25 to I50 ksi). In quenching with water.
more options are available. as follows: S-IO ‘C (I000 “F) for 620 to 860
hlPa t90 to I25 ksi); 480°C (895 “F) for 860 to 1035 MPa ( I25 to IS0 ksi):
125 ‘C (795 “FJ for 1035 to II70 hlPa t IS0 to 170 ksi): 370 “C (700 “F)
Resulfurized
for ll75to
1240MPa(l60to
MPa(l80to2OOksi)
Strengthening
180ksij;3lS”C(6OO”F)for
12-lOto 1380
Recommended
l
by Cold Drawing
and Stress Relieving.
l
l
1137
1137
As-Quenched
Hardness
(Water)
Effect of mass on as-quenched hardness of steel bars, quenched in
water: contents: 0.37 C, 1.40 Mn, 0.015 P, 0.08 S, 0.17 SI; grain size:
1 to4
Size round
in.
mm
‘92
11.7
15.1
SO.8
101.6
I
2
-l
Source: Bethlehem
Steel
Surface
Hardness, HRC
‘12radius
l
Sequence
As-Quenched
Hardness
(Oil)
Effect of mass on as-quenched hardness of steel bars, quenched in
pdlicontents: 0.37 C, 1.40 Mn. 0.015 P, 0.08 S, 0.17 Si; gram size: 1
Surface
Etardness, ERC
‘/z radius
48
31
28
21
13
‘8
22
IX
Size round
Center
Steels / 221
Rough machine
Austenitize
Quench
Temper
Finish machine
Grade I I37 bars and other medium-carbon
resulfurized
steels are frequently strengthened to desirable levels without quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress
relieve by heating at approximately
3 I5 “C (600 “F). Produces yield
strengths of up to 690 MPa (100 ksi) or higher in bars up to about 19.05
mm (0.75 in.) diam. Machinability
is very good
l
Processing
Carbon
in.
1.II
I2
-I
Source: Bethlehem
mm
12.7
3.4
50.8
I0l.h
Center
42
73
I8
I6
Steel
1137: Hardness vs Tempering Temperature.
erage based on a fully quenched structure
Represents
an av-
Resulfurized
Carbon
Steels / 221
1139
Chemical
Composition.
AISI
and UNS:
0.35 to 0.43 C. 1.35 to
1.65Mn.0.040Pmax.0.13to0.20S
Similar
Steels (U.S. and/or
Foreign).
LINS GI 1390; FED QQ-
S-637 (Cl 139); SAE 5103
Characteristics.
Characteristics
neat+ parallel with I 137. Carbon and
sulfur contents slightly higher. These differences result in slight11 higher
as-quenched hardness tas high as -I7 HRC). slightly lower hardenabilit)
t because of higher sulfur content), and even better machinability
than I 137.
Never recommended for welding or forging
Recommended
Normalizing.
Heat Treating
Not usually
required.
Practice
If necessary, heat to 900 “C t 1650
“FJ. Cool in air
Hardening. Heat to 8-tS ‘C t IS55 “FL Flame hardening and carbomtridmg are suitable surface hardening processes. Quench in water or brine. For
full hardness. oil quench sections not exceeding 9.525 mm (0.375 m.) thick
Tempering.
As-quenched
hardness of approximately
ness can be reduced bq tempering
Strengthening
Heat to 885 “C t I675 “FL Furnace cool to 650 ‘C t 17-00 “FL
at a rate not to exceed 28 “C (SO ‘Fj per h
Hard-
and Stress Relieving.
Grade II39 bars and other medium-carbon
resulfurired
steels are frequentl) strengthened to desirable Ie~els \\ithout quench hardening. Increase the draft during cold drawing by IO to 35% above normal. Stress
relirbe b> hsatntg at approsunatel)
315 “C (600 “F). Produces yield
strengths of up to 690 hlPa (,I00 ksit or higher in bars up to about 19.05
mm to.75 In.) dinm. hlachinability
is ~2t-y good
Recommended
l
l
l
Annealing.
by Cold Drawing
47 HRC.
l
l
Rough machine
r\ustsnitize
Quench
Temper
Finish machine
Processing
Sequence
222 / Heat Treater’s
Guide
1139: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
222 / Heat Treater’s
Guide
1140
Chemical
Composition.
AISI and UNS: 0.37 to 0.44 C, 0.70
to
I .OOMn, 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or
S-637(Cl 140); SAE 5403. J412.
35 MF 4; (Swed.) SSt4 1957
Foreign). UNS G11400; FED QQJ-113; (Ger.) DIN 1.0726; (Fr.) AFNOR
Hardening. Heat to 835 ‘C ( IS55 “FL Flame hardening and carbonitriding are suitable surface hardening processes. Quench in water or brine. For
full hardness, oil quench sections not exceeding9.525
mm (0.375 in.) thick
Tempering.
As-quenched
hardness of approximately
ness can be reduced by tempering
50 HRC.
Hard-
Strengthening
Characteristics.
Slightly higher carbon range, compared with I 139. of
no practical significance.
Hardenability
is lower because of lower manganese content. Otherwise, same characteristics
as I I37 and I 139, including
response to abnormal drafts in cold drauing and a subsequent stress relief.
Not used where forging or welding is involved. Machinability
is excellent
Recommended
Normalizing.
Heat Treating
Not usually
required.
Practice
If necessary. heat to 900 “C ( 1650
“F). Cool in air
by Cold Drawing and Stress Relieving. Grade
1140 bars and other medium-carbon
resulfurized
steels are frequently
strengthened to desirable levels without quench hardening. Increase the
draft during cold drawing by IO to 358 above normal. Stress relieve by
heating at approximately
3 IS “C (600 “F). Produces yield strengths of up
to 690 MPa (100 ksi) or higher in bars up to about 19.05 mm (0.75 in.)
diarn. Machinability
is very good
Recommended
l
l
l
Annealing.
Heat to 885 “C ( I625 “F). Furnace cool to 650 “C ( 1200 “F).
at a rate not to exceed 28 “C (50 “F) per h
l
l
Processing
Sequence
Rough machine
Austenitize
Quench
Temper
Finish machine
1140: Hardness vs Tempering Temperature.
erage based on a fully quenched structure
Represents
an av-
222 / Heat Treater’s
Guide
1141
Chemical
Composition.
AISI and UNS: 0.37 to 0.45 C, 1.35 to
I .65 Mn. 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or Foreign).
A107.A108,A311;FEDQQ-S-637;SAE5403.5412,5411
UNS
GI 1410:
ASTM
Characteristics.
Most widely used medium-carbon
resulfurized steel.
As-quenched full hardness of approximately
52 HRC, when carbon is near
high side of the range. Slightly lower hardness for middle or lower end of
the range. High manganese content imparts higher hardenability
compared
with I I-IO, but almost the same as I 139. Available in pretreated condition.
Resulfurized
Subjected to abnormally
heavy drafts followed by stress relieving.
grade I 137.) Never recommended for forging or welding
Recommended
Normalizing.
Heat Treating
Not usually
required.
(See
Practice
If necessary. heat to 885 “C (I 615
1141
As-Quenched
Hardness
Carbon
Steels / 223
(Oil)
Effect of mass on as-quenched
hardness
of steel bars, quenched
in
oil; contents:
0.39 C, 1.58 Mn, 0.02 P, 0.08 S, 0.19 Si; grain size:
90%, 2 to 4; 1 O%, 5
“FJ. Cool in air
Annealing.
llsually purchased by fabricator in condition for machining.
If required. may be annealed by heating to 835 “C ( I555 “F). Furnace cool
to 650 “C ( IXIO “F) at a rate not to exceed 28 “C (50 “F) per h
Size round
in.
mm
‘/:
1
2
4
12.7
‘5.4
SO.8
101.6
Hardening. Austenitize at 830 “C (IS?5 “F). Flame hardening. carbonitriding, and martempering are suitable processes. Quench in water or brine.
For full hardness. oil quench sections under 9.525 mm (0.375 in.) thick
Tempering.
Depending upon precise carbon content. as-quenched hardness is usually 48 to 52 HRC. Hardness can be reduced by tempering
Recommended
l
l
l
l
l
Rough machine
Austenitize
Quench
Temper
Finish machine
Processing
Sequence
Source: Bethlehem
Surface
52
18
36
27
Eat-does,
ERC
‘4 radius
49
43
28
22
based
46
38
22
18
Steel
1141: Hardness vs Tempering Temperature. Represents
erage
Center
on a fully quenched
structure
an av-
Resulfurized
Carbon
Steels / 223
1144
Chemical
Composition.
AISI and IJNS: 0.10 to 0.38 C. I.35 to
I .65 Mn. 0.040 P max. 0.2-I to 0.33 S
brim. For full hardness,
10.375 in.) thick
Similar
Tempering.
Steels (U.S. and/or Foreign).
UNS
GI 14.40;
ASTM
A108.A311:FEDQQ-S-637(CII~?);SAEJ403.J41?.J413
Characteristics.
Special-purpose
grade. Very high sulfur content.
equal to free-machining
1213. permits extremely
fast machining with
heavy cuts. Machined fmishes unusually good. High sulfur content reduces
transverse impact and ductility. Can be drawn by heavy drafts at elevated
temperature, 370 “C (700 “F). which results in relatively high strength and
high hardness. up to 35 HRC. Machinability
is excellent. Widely used for
producing machined parts put in service without heat treatment. Can be
purchased in cold drawn condition
and heat treated. Depending upon
precise carbon content, as-quenched and fully hardened I I44 should be
approximately
52 to 55 HRC. Never used I$ here forging or welding is
involved
Recommended
Normalizing.
Heat Treating
Seldom required.
Annealing.
Seldom necessary. May be annealed by heating to 845 “C
( I555 “F). Furnace cool to 650 “C ( I200 “F), at a rate not to exceed 28 “C
(SO “F) per h
Hardening.
sections
less than 9.525
mm
Depending upon precise carbon content, as-quenched hardness of usually 52 to 55 HRC. Hardness can be reduced by tempering
Recommended
l
l
l
l
l
Processing
Sequence
Rough machine
Austenitize
Quench
Temper
Finish machine
1144:
As-Quenched
Hardness
(Oil)
Effect of mass on as- uenched hardness of steel bars quenched in
oil. contents: 0.46 C, ? .37 Mn, 0.019 P, 0.24 S. 0.05 hi; grain size:
75+/o, 1 to 4; 25%, 5 to 6
Practice
If necessary. heat to 885 “C ( I625 “FL
Cool in air
carbonitriding
oil quench
Austenitize
at 830 “C (I 525 “F). Flame hardening and
are suitable surface hardening processes. Quench in water or
Size round
ill.
mm
Surface
‘/J
12.7
25.4
50.8
101.6
39
36
30
27
I
2
1
Source: Bethlehem Stzcl
Hardness, ERC
‘/r radius
32
29
27
.._
1::
98
Center
28
23
22
__
1::
97
224 / Heat Treater’s
Guide
1144: Hardness vsTempering Temperature. Represents an average based on a fully quenched
structure
224 / Heat Treater’s
Guide
1146
Chemical
Composition.
AISI and UNS: 0.X
to
0.49 c. 0.70 to
I .OO Mn. O.O-tO P max. 0.08 to 0. I3 S
Similar
(U.S. and/or Foreign).
Steels
UNS GI 1460; FED QQ-
S-637 (Cl 136): SAE J-103, J-tl?. J-II-t; tGer.) DIN
35 MF 1; (Swed.) SSt4 1973
1.0727; (Fr.) AFNOR
Annealing.
Seldom required by the fabricator. If necessary, heat to S-0
“C ( I SSS “F). Furnace cool to 650 ‘C ( 1200 “F) at a rate not to exceed 28
“C (SO ‘F) per h
Hardening. Austenitire at 830 “C ( IS25 “FL Flame hardening, carbonitriding, austemperinp. and mar-tempering are suitable processes. Quench in
water or brine. For full hardness. oil quench sections less than 9.525 mm
(0.375 in.) thick
Characteristics.
An I I-IO with higher carbon. Excellent machinability
and relatively
low hardenability.
Amenable to strengthening
by heavy
drafts and stress relieving.
Higher carbon, lower manganese. and lower
hardenability
make it popular for induction hardening. Never use uhen
forging or welding is involved.
Can be quenched and tempered. Asquenched hardness of 55 HRC or slightly higher. depending on carbon
content
Tempering.
Recommended
l
Heat Treating
Practice
nrss is usually
recommended
Martempering.
Cool in air
Seldom required.
If necessary. heat to 885 “C ( l62S “F).
Austenitize
at 815 “C ( IS00 “F). Martemper
in oil at
I75 “C (345 “F)
Recommended
l
l
Normalizing.
Depending upon prectse carbon content. as-quenched hardSS HRC. Hardness can be reduced by tempering. under
practice
l
l
Processing
Sequence
Rough machine
Austenitize
Quench
Temper
Finish machine
1146: Hardness vs Tempering Temperature. Represents an average based on a fully quenched
structure
Resulfurized
Carbon
Steels / 225
1151
Composition.
Chemical
AISI and UNS: 0.48 to 0.55 C, 0.70 10
I .OO Mn, 0.040 P max. 0.08 to 0. I3 S
Similar
Steels (U.S. and/or Foreign).
Al07. Al08. A3ll; FEDQQ-S-637tCllSl):
SAEJ403. J4l2, J-II-I
UNS Cl IS IO; ASThl
hlILSPEC hlIL-S-30137A;
Characteristics.
Resulfurized
version of 1050. Carhon ranges the
same. Although rhe I I5 I manganese comenl is slightly higher. some of this
manganese combines \\iith the high sulfur, so that the hardenabihty
is
almost the same as 1050. As-quenched hardnesses of 1050 and I I51 are
essentially the same. SS HRC or slightly higher. I IS I also used for induction hardening. 1050 used for parts to be forged. I IS I used for parts 10 be
machined from bars
Recommended
Normalizing.
Cool in air
Seldom
Heat Treating
used. If necessary,
Practice
heat to 870 “C ( 1600 “F).
Annealing.
Heat IO 870 “C ( 1600 “F). Furnace
81 a rate not to exceed 28 “C (50 “F) per h
cool
IO
650 “C ( 1200 “F)
Hardening. Austenitize 31 830 “C ( 1525 “F). Flame hardening, induction. and carbonitriding
are suitahle surface hardening processes. Quench
in nater or brine. Oil quench sections under 6.35 mm (0.25 in.) thick
Tempering
erly austenitizcd
After Hardening.
and quenched.
Recommended
l
l
l
l
l
Hardness of at least 55 HRC. if propHardness can be adjusted by tempering
Processing
Sequence
Rough machine
Austenilize
Quench
Temper
Finish machine
1151: Hardness vs Tempering Temperature.
erage based on a fully quenched structure
Represents
an av-
1151: Microstructure.
2% nital, 500x. Manganese sulfide stringers (black) in steel bar. Remainder is dispersion of spheroidized
carbide in ferrite matrix. Micrograph is cross section, taken perpendicular to rolling direction
1211
Chemical Composition.
UNS GlZllOand
AlSI/SAE
1211: 0.13 C
max. 0.60 to 0.90 Mn. 0.07 to 0.12 R 0. IO to 0. IS S
Similar Steels (U.S. and/or Foreign).
ms
G I?. I IO;
ASTM
AlO7.Al07(BIIII),Al08.Al08(BIIII);FEDQQ-S-637(Cl2ll);S~
5403
Characteristics.
Machinery
steel that has been resulfurized
and rephosphorized has better machinability
than that of grade I I IO. Furnished
in hot rolled or hot rolled and cold drawn condition. The latter condition is
the better for machinability.
Intended for fabrication
recommended for forging. cold forming, or welding
Recommended
Heat Treating
Normalizing and Annealing.
Light Case Hardening.
bath nitriding
process described
by machining.
Never
Practice
Seldom required
hlay be desired. See carbonitriding
for 1008
and salt
1212
Chemical
COIIIpOSitiOn.
UNS and SAE/AISI:
1.00 Mn, 0.07 to 0.12 P. 0. I6 to 0.23 S
Similar
0.13 C max. 0.70 to
Steels (U.S. and/or
D; ASTM A107. Al07
(Cl212);SAEJ403;(Ger.)
Foreign). LJNS G 12 120; AMS 5010
(81212). A108. Al08 (Bl212);
FED QQ-S-637
DIN I.071 I:(ltal.) LINI IOS ZO;(Jap.)JISSLJM
21
Characteristics.
Similar
tents are higher. Machinability
to 121 I, except sulfur and manganese conbetter than that of I2 I I. Adverse effects of
sulfur and phosphorus
greater
Recommended
Normalizing
on mechanical
Heat Treating
and Annealing.
Light Case Hardening.
bath nitriding
and fabrication
process described
properties
are slightly
Practice
Seldom required
May he desired. See carbonitriding
for 1008
and salt
1213
Chemical
COtnpOSitiOn.
UNS and SAE/AISI:
I.00 Mn, 0.07 to 0.12 P. 0.2-t to 0.33 S
0.13 C max. 0.70 to
Similar
Steels (U.S. and/or Foreign). UNS G 12 I 30: ASME
Al07,Al07(BlIl3j,Al08.AIO8(BIll3);FEDQQ-S-637(Cl9l3);SAE
J403; (Ger.) DIN I .0715; (Ital.) UNI 9 SMn 23: (Jap.) JIS SUM 22: (U.K.)
B.S. 220 M 07
Characteristics.
Nearly identical
sulfur further enhances machinability
fabrication properties
to those of I2 12. Greater content of
at the sacrifice of mechanical and
Recommended
Normalizing
Heat Treating
and Annealing.
Light Case Hardening.
bath nitriding
process described
Practice
Seldom required
May be desired. See carbonitriding
for 1008
and salt
Rephosphorized
and Resulfurized
(1200 Series) / 227
12l.14
Chemical Composition.
UNS and SAE/AISI:
0. I5 C max. 0.85 to
I. I5 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S. 0. I5 to 0.35 Pb
Similar Steels (U.S. and/or Foreign). UNS Gl214-k
A107, Al08; SAE 5403, J412, J414; (Ger.) DIN 1.0718; (Ital.)
SMnPb 23; (Jap.) JIS SUM 22 L. SUM 24 L; (Swed.) SS)4 1913
Characteristics.
ASTM
UNI 9
Contains a lead addition of 0. I5 to 0.35% indicated
by L in designation.
Represents the ultimate in free-machining
characteristics. but an even further sacrifice of mechanical and fabricating properties. such as forgeability.
cold formability,
and weldability.
Addition of
lead further enhances machinability
in terms of high speeds with heavy cuts
and provides excellent finishes on machined surfaces. Sometimes saves an
extra machining operation
Recommended
Heat Treating
Normalizing and Annealing.
Light
Case
bath nitriding
Hardening.
process described
Practice
Seldom required
May be desired. See carbonitriding
for I008
and salt
Rephosphorized
and Resulfurized
(1200 Series) / 227
1215
Chemical
COIIIpOSitiOn.
UNS and SAE/AISI:
I.05 Mn. 0.04 to 0.09 P. 0.26 to 0.35 S
Similar
Steels (U.S. and/or Foreign).
0.09 C max. 0.75 to
UNS Gl~lso;
FED QQ-
S-637: SAE J4 12
Characteristics.
Compared with I?. 13. with minor adjustments in
carbon, manganese, phosphorus. and sulfur contents. No major effects on
mechanical or fabricating properties. Represents another free-machining
steel. Commonly used for parts completed in automatic multispindle machine tools
Recommended
Normalizing
Heat Treating
and Annealing.
Practice
Seldom required
Light Case Hardening. May be desired. See carbonitriding and salt
bath nitriding process described for 1008
1215: Microstructures.
(a) As polished (not etched), 1000x. Cold drawn steel tube. Longitudinal view. Segmented
polished (not etched), 1000x. Cold drawn steel tube, at lower magnification. Sulfide inclusions shown
sulfide inclusion. (b) As
High
Manganese
Carbon
(1500
Steels
Series)
1513
Chemical
Composition.
MS1
I .-IO Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
and UNS:
Foreign).
0.10 to 0.16 C. I. IO
UNS G
to
IS 130; SAE J-103.
J-II2
Characteristics.
Essentially
the high-manganese
version of 1012.
However. the higher manganese content provides slightly greater strength
in the normalized or annealed condition and some\< hat better core properties when case hardened. Excellent forgeability
and weldabili?.
Rsasonably good cold formability,
only slightly less than IO1 2. hlachmability
is
very poor when compared with the II00 and 1200 grades. Generally
avarlable in wrious product forms. includinp flat stock. bars. and forging
stock
Forging. Heat to approximately
1290 “C (2355 “F). Finish forging
fore temperature drops bclou 925 “C t 1695 “F)
Recommended
Normalizing.
Heat Treating
Heat to 885 T
be-
Practice
t 1625 “F). Cool in still air
Annealing.
For clean surfaces. heat to approxmlately
885 “C (163-S “F)
in lean exothermic atmosphere. Cool in cooler section of continuous furnace
Case Hardening. Carbonitride at 760 to 870 “C (1400 to 1600 “F) in
an enriched sndothemtic carrier gas. plus ahout 10% anhydrous ammonia.
Case depths from 0.076 to 0.26 mm (0.003 IO 0.01 in.). Oil quench directly
from carbonitriding
temperature. Pro\ ides maximum surface hardness. Salt
baths can produce similar results
1582lH,
Chemical
15821RH
COWpOSitiOn.
15BZlH.
UNS H15211 and SAE/AISI:
0.17 to 0.74 C. 0.70 to 1.10 hln. 0. IS to 0.35 Si. t0.0005 to 0.003 B can be
expected). SAE 15B21RH: 0.17 to022 C.O.80 to 1.10 hln.0.15 too.35
Si (0.0005 to 0.003 B can be expected)
Similar
Steels (U.S. and/or
SAEJl168.51868:
Foreign).
15BZlH.
UNS H IS2 I I :
(Ger.) DIN 1.5513: ASTh1Yl-l
Characteristics.
Nonfree machining
steel. Can be cold formed to
some degree. Readily weldable. When carbon IS on the high side and with
the higher manganese and addition of boron. a combination can exist where
some preheating prior to welding is necessary to avoid weld crackng.
Combination of higher manganese and boron provides whstantial increase
in hardenabilit),
compared with 1020
Annealing.
Excellent forgeahilitj.
below 925 “C ( 16% “F)
Heat to I260 “C (1300 ‘F). Do not forge
Heat Treating
Tempering.
some sacrifice
l
l
l
l
Normalizing.
Heat to 925 “C ( 1695 “FL Air cool
in the
Optional. Temper at ISO “C (300 “F) for I h or higher if
of hardness can be tolerated
Recommended
l
l
Practice
preferably
Can he case hardened bj an! one of several processes. from
light case hardening h) carhonitridinp
and salt bath nitriding described for
grade IO08 to deeper case carhuriring
in gas. solid. or liquid media.
Because of higher hardenahility.
oil quench thicker sections for full hardness. Carburize and quench as for 1020
l
Recommended
“F). Cool slo~lp.
Hardening.
l
Forging.
Heat to 870 <C iI
furnace
l
Processing
Forge
Normalize
Roy!
machine
Semltlnish machine and grind
Carburize
Diffusion c>cIe
Quench
Temper
Finish grind
Sequence
High Manganese
15B21H: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize: 925 “C (1700 “F)
Hardness
purposes
J distance,
mm
Hardness
purposes
J distance,
‘/,6 ill.
1
1,s
?
3
3
3s
4
4.5
i.s
5
55
7
7.5
3
9
limits for specification
Hardness,
hlaximum
HRC
hlinimum
limits for specification
Hardness,
Masimum
HRC
hlinimum
41
-II
-IO
SY
38
36
30
13
20
temperatures
recommended
Carbon
Steels (1500 Series) / 229
by SAE. Normalize (for forged or rolled specimens
only): 925
1
230 / Heat Treater’s
Guide
15621RH: Hardenability
“C (1700 “F). Austenitize-
Hardness
purposes
J distance,
%a in.
I
2
3
4
5
6
7
8
9
IO
II
12
13
I4
IS
16
I8
20
22
24
26
28
30
32
Hardness
purposes
J distance.
mm
I.5
3
5
7
9
II
13
IS
10
15
30
35
lo
1s
Curves. Heat-treating
925 “C (1700 “F)
limits for specification
Hardness,
Maximum
ARC
Minimum
47
46
44
43
37
30
24
22
20
42
II
39
33
24
20
limits for specification
Hardness,
Maximum
41
46
44
40
32
24
22
20
HRC
Minimum
42
II
38
29
21
temperatures
recommended
by SAE. Normalize for forged or rolled specimens
only: 92:
High Manganese
Carbon
Steels (1500 Series) / 231
15821 H: Hardness vs Tempering Temperature.
average based on a fully quenched structure
15B21H: End-Quench
Dktance frum
quenched
surface
&in.
mm
I
I .s
2
2.5
3
3.5
4
4.5
5
I.58
2.37
3.16
3.95
4.1-l
5.53
6.32
1.11
7.90
Hardenability
Hardness,
HRC
min
max
18
48
-1-l
4-l
-I6
-Is
4-l
42
40
-II
41
-IO
39
38
36
30
23
20
Distance from
quenched
surface
mm
‘/,a in.
6
6.5
1
1.5
8
9
IO
I2
I-1
Eardness,
HRC
max
9.48
10.27
35
32
II.06
II.85
12.64
l-l.22
IS.80
18.96
22.12
27
22
20
Represents
an
High Manganese Carbon Steels (1500 Series) / 231
1522,1522H
Chemical Composition.
1522. AI.9 and UNS: 0.18 to 0.21 C. I. IO
to 1.40 h4n. 0.040 P max. 0.050 S max. 1522H. UNS H15220 and
SAE/AISI 1522H: 0.17 to 0.25 C. I .OO to I SO Mn. 0. IS to 0.35 Si
Recommended
Similar Steels (U.S. and/or Foreign). 1522. UNS G 15220:
Annealing.
J403, J412. 15228. UNS HI5220; SAE Jl268:
UNI G 22 Mn 3; (Jap.) JIS SMnC 21
furnace
(Ger.) DIN
SAE
1.1133: (Ital.)
Normalizing.
Heat Treating
Practice
Heat to 92s “C t 1695 “F). Air cool
Heat to 870 “C t 1600 “F). Cool slowly,
preferably
in the
Hardening.
Characteristics.
Represents the principal
carburizing
grade of the
I SO0 series. Characteristics
similar to I SB2 I H. Nominal manganese content is higher which increases hardenability
to a considerable extent. However. contains no boron. As a result, hardenability
bands are not .greatl!
different for steels ISBZIH and lS22H. Weldability
and forgeability
are
good
Forging. Heat to I260 “C (2300 “F). Do not forge below 925 “C t 1695
“F). For lS22H. drop forge from 900 to I250 “C (I650 to 2380 OF)
Can be case hardened b) any one of several processes. from
light case hardening by carbonitriding
and salt bath nitriding described for
grade 1008 to deeper case carburizing
in gas. solid. or liquid media. See
carhurizing process described for grade 1020. For lS22H. use carburizing
temperature of 900 to I250 “C t I650 to 2280 “F). Use oil for cooling
medium. Because of higher hnrdenabilib.
thicker sections can be oil
quenched for full hardness
Tempering.
some sacrifice
Optional. Temper at IS0 “C (300 “F) for I h or higher if
of hardness can be tolerated
232 / Heat Treater’s
Recommended
l
l
l
l
l
l
l
l
l
Guide
Processing
Sequence
1522, 1522H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
Forge
Nomlalize
Rough machine
Semifinish machine and grind
Cxburize
Diffwion
cycle
Quench
Temper
Finish grind
1522H: End-Quench
Distance from
quenched
surface
l/j6 in.
mm
I
1.5
2
2.5
3
3.5
-I
4.S
5
5.5
I.58
2.37
3.16
3.95
4.7.l
s.s3
6.32
7.1 I
7.90
8.69
Hardenability
Eardness,
HRC
max
min
so
-18
JI
41
17
46
1.5
-12
39
37
3-l
32
32
27
22
21
70
.,.
Distance from
quenched
surface
‘ii6 h.
mm
6
6.5
7
7.5
8
9
IO
12
I-I
I6
9.48
IO.27
I I.06
II58
126-l
l-1.22
IS.80
18.96
Z’.II
‘5 ‘Y
__.-
Hat-dries.
HRC
max
30
28
27
__.
25
23
22
20
Repre-
High Manganese Carbon Steels (1500 Series) / 233
1522H: Hardenability Curves. Heat-treating temperatures
(1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification
purposes
J distance,
mm
Eardness,
Maximum
ARC
hlinimum
Hardness limits for specification
purposes
I distance,
‘/,6 in.
I
I.5
3
!.5
3
3.5
+
4,s
i.5
5
i.S
Hardness,
Maximum
SO
48
17
16
-IS
12
39
37
3-l
32
30
28
27
HRC
hlinimum
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
234 / Heat Treater’s
1522: Continuous
Guide
Cooling Transformation
Diagram. A British steel with a chemical composition roughly equivalent to 1522: 0.19 C, 1.20
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized
at 870 “C (1600 “F)
234 / Heat Treater’s
Guide
1524,1524H
Chemical
Composition.
1524. AISI and UNS: 0.19 to 0.25 C. I.35
to 1.65 Mn, 0.040 P max. 0.050 S max. 15248. UNS H15240 and
SAE/AISI 1524H: 0.18 to 0.26 C, I .2S to I .7S Mn. 0. I5 to 0.35 Si: 152-I
was formerly
Similar
designated
Foreign).
1524:
UNS
G15240:
ASTM A510, AS13 (1023). A519. AS-45: SAEJ403.J312,J414:(W.
DfN I. I 160. 1524H. UNS H 15210: SAE J 1268; (Ger.) DfN I. I I60
Ger.)
Characteristics.
Essentially a higher manganese version of 1023. Has
higher hardenability.
Grade lS24H is now available with a guaranteed
hardenability
band. Considered a borderline grade because it can be case
hardened by carburizing or carbonitriding.
Popular for this purpose because
of relatively high core hardness. This permits use of thinner cases, which
conserve thermal energy and decrease processing cost. I524H also used in
the hardened and tempered condition where moderate strength is needed.
As-quenched hardness of43 HRC or slightly higher can be expected. Even
though the carbon content is only 0.26 max. welding must be done with
care. because the high manganese may raise the carbon equivalent to a
dangerous degree unless preheating and postheating practices are used.
Forgeability
is excellent. Grade lS21H may be obtained in various product
forms
Practice
Direct Hardening.
brine. Quenchant
Tempering.
by tempering.
Heat to 1215 ‘C (2275 “F). Do not forge below 900 “C ( 1650
“F). For lS24H. drop forge between 900 to I250 “C ( I650 to 2280 “F)
Austenitize at 885 “C (1625 “F). Quench in oil or
depends on section thickness
As-quenched
as required
hardness of 43 HRC or higher can be reduced
Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding
and salt bath nitriding
described for grade 1008 to deeper case carburizing in gas. solid, or liquid
media. Plasma (ion) carburizing is an alternative process. (See carburizing
process described for grade 1020). For 1524H. use carburizing temperature
of 900 to 925 “C ( I650 to I695 “F). Use oil for cooling medium
Recommended
l
l
l
l
l
Forging.
Heat Treating
Heat to 925 “C ( I695 “FL Cool in air
Annealing. Heat to 900 “C ( I650 “FL Furnace cool to 675 “C ( I245 “F)
at a rate not to exceed 28 “C (SO “F) per h
as IOXX grade
Steels (U.S. and/or
Recommended
Normalizing.
l
l
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Processing
Sequence
High Manganese
1524: Continuous Cooling Transformation
at 870 “C (1600 “F)
1524H: End-Quench Hardenability
from
quenched
s&ace
916 in.
mm
Distance
El~dlleSS.
ERC
max
min
ti-om
quenched
surface
‘/,6 in.
mm
Elardness.
ERC
max
I
1.5
I.58
2.37
51
49
42
42
6
6.5
918
10.27
32
30
2
2.5
3.16
3.95
18
41
38
3-l
7
7.5
II.06
I I.58
29
28
3
3.5
4
4.5
5
5.5
1.74
5.53
6.32
7.1 I
1.90
8.69
15
43
39
38
35
34
29
35
‘2
20
12.6-I
14.71
IS.80
18.96
22. I?
25.28
27
26
25
23
22
20
8
9
IO
I?
I-l
I6
Steels (1500 Series) / 235
Diagram. A British steel with a chemical composition roughly equivalent to 1524: 0.19 C, 1.50
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled and austenitized
Distance
Carbon
236 / Heat Treater’s
Guide
1524, 1524H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
1524: Microstructure.
Picral and mtal, 500x. Sheet, 3.175 mm
(0.125 in.) thick. Austenitized at 1095 “C (2005 “F). Cooled in air.
Dark areas are fine pearlite with some bainite. Light areas are envelopes of ferrite at prior austenite grain boundaries and Widmanstatten platelets of ferrite within grains
1524: Plasma (Ion) Carburizing. Carbon concentration profiles
in AISI 1524 steel after ion carburizing for 15 min at 1050 “C (1920
“F) in atmospheres and with flow conditions indicated
High Manganese
1524H: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
870 “C (1600 “F)
iardness
wrposes
I distance,
urn
.5
/
1
,
I
I
3
5
10
15
iardness
w-poses
distance.
‘16io.
.s
.s
._5
.5
._5
5
limits for specification
Eardness,
Maximum
HRC
Minimum
51
19
4-l
38
3-l
30
‘7
2s
13
42
39
26
21
limits for specification
Eardness.
Maximum
51
49
48
47
45
43
39
38
3s
34
32
30
29
28
27
26
25
23
22
20
HRC
hlinimum
42
42
38
34
29
25
22
20
temperatures
recommended
Carbon
Steels (1500 Series) / 237
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
238 / Heat Treater’s Guide
1526,1526H
Chemical Composition.
1526. ALSI and UNS: 0.22 to 0.29 C. I. IO
to I .-IO Mn, 0.040 P max. 0.050 S max. 15268. UNS H15260, SAE/AISI
15268: 0.21 to 0.30 C, 1.00 to I.50 Mn. 0. I5 to 0.35 Si
Similar Steels (U.S. and/or Foreign). 1526:
UNS GlS260;
ASTM A5 IO; SAE J403. J-l 12: (Ger.) DfN I. I I6 I ; 15268. UNS H 15260:
SAE Jl268
Considered a borderline grade because it can be case
hardened by carburizing or carbonitriding.
Popular for this purpose because
of relatively high core hardness. This permits use of thinner cases, which
conserve thermal energy and decrease processing cost. I526H also used in
the hardened and tempered condition where moderate strength is needed.
As-quenched hardness of 43 HRC or slightly higher can be expected. Even
though the carbon content is onlv 0.26 max. welding must be done with
care, because the higher manganese may raise the carbon equivalent to a
dangerous degree. unless preheating and postheating practices are used.
Forgeability
is excellent. Grade l526H may be obtained in various product
forms
Forging.
Heat to I235 “C (2275 “F). Do not forge below 900 “C ( I650
“F). For I526H. drop forge between I205 to 850 ‘C (2200 to 1560 “F)
Normalizing.
Heat Treating
Heat to 925 “C (I695
1526: Continuous
Direct Hardening.
brine or oil. Quenchant
hardness
Tempering.
Characteristics.
Recommended
Annealing. Heat to 900 “C ( I650 “F). Furnace cool to 675 “C ( 1245 OF)
at a rate not to exceed 28 “C (SO “F) per h
Cooling
Practice
“F). Air cool
Transformation
Mn, 0.020 P, 0.020 S, 0.20 Si. Hot rolled
by tempering,
Diagram.
As-quenched
as required
hardness of 43 HRC or higher can be reduced
Case Hardening. Can be case hardened by any one of several processes. from light case hardening by carbonitriding
and salt bath nitriding
described for grade 1008 to deeper case carburizing in gas. solid. or liquid
media. See carburizing process described for grade 1020. For 15268, use
carburizing temperature of 900 to 925 “C ( I650 to 1695 “F). Use oil for
cooling medium
Recommended
l
Processing
Anned
l
Rough machine
Austenitize (or case harden)
Quench
Temper
Finish grind
l
l
l
Sequence
Normalize
l
l
and austenitized
Austenitize at 885 “C (I625 “F). Quench in water,
will depend on section thickness and required
A British steel with a chemical
at 870 “C (1600 “F)
composition
roughly
equivalent
to 1526: 0.28 C, 1.20
High Manganese
1526H: Hardenability Curves. Heat-treating
(1650 “F). Austenitize:
Hardness
purposes
I distance,
mm
1.5
3
5
7
1
11
13
15
20
iardness
wrposes
distance,
46 in.
.5
!.5
1.5
1.5
i.5
i
i.5
1.5
1
0
.2
i4
16
18
870 “C (1600 “F)
limits for specification
Hardness,
Maximum
ARC
hlinimum
53
50
44
37
32
28
25
24
.
44
39
24
20
.
.
.
.
limits for specification
Hardness,
Maximum
53
50
49
47
46
42
39
37
33
31
30
28
27
26
26
24
24
23
22
21
20
ERC
hfinimum
44
42
38
33
26
25
21
20
.
..
.
temperatures
recommended
Carbon
Steels (1500 Series) / 239
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
240 / Heat Treater’s
Guide
1526, 1526H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
1526H: End-Quench Hardenability
Distance from
quenched
surface
‘46in.
mm
I
I.5
z
2,s
3
3.5
-I
4.5
5
5.5
6
1.58
2.37
3.16
3.95
1.7-l
5.58
6.37
7.1 I
7.90
8.69
9.48
Hardness,
HRC
mia
may
53
so
49
17
46
-12
39
37
33
31
30
4-t
11
38
33
26
25
21
20
Distance from
quenched
surface
1,,,6 in.
mm
6.5
7
7.5
8
Y
10
12
II
16
18
IO.27
I I.06
I I .8S
12.6-I
l-l.22
IS.80
lg.96
22.12
2s 18
28.44
Hardness.
HRC
mar
28
‘7
xi
26
2-l
21
23
22
21
20
240 / Heat Treater’s
Guide
1527
Chemical
Composition.
AISI and UNS: 0.32 to 0.29 C. 1.20 to
I SO hln. 0.040 P max. 0.050 S max. UNS Cl5270 and AISI/SAE
1527:
Standard composrtion range for manpanese IS I.20 to I.55 hln: uas formerly designated as I OXX grade
Similar
Steels (U.S. and/or Foreign).
A510.A513(1027);SAE5403.J-!12:(Ger.)DIN
UNS
~15270:
I.1161
Kr-hl
Characteristics.
Considered a borderline grade because tt can be case
hardened bq carburizing orcarbonittiding.
Popular for this purpose because
of relatively high core hardness. This pemtits use of thinner cases. u hich
consene thermal energy and decrease processing cost. IS27 also used in
the hardened and tempered condition IShere moderate strength is needed.
As-quenched hardness of-13 HRC or slightly higher can be expected. Even
though the carbon content IS onJ> 0.29 mas. itelding must be done with
care. because the higher manganese may raise the carbon equivalent to a
dangerous degree. unless preheating and postheating practices are used.
Forgeability
is excellent. Grade IS37 ma> be obtained in various product
forms
Forging.
Heat to IX5
C (2275 “Ft. Do not forge beIon about 900 “C
(16S0°F,
Annealing.
Heat to 900 “C ( I650 “F). Furnace cool to 675 ‘C ( I235 “F)
at a rate not to escsed 28 “C (SO ‘F) per h
Hardening. Can be case hardened b! any one of several processes. from
light case hardening by carbonitriding
and salt bath nitriding described for
grade 1008 to deeper case carburizinp
in pas. solid. or liquid media. (See
carburizinp process described for pads 1020). For lS22H. use carburizing
temperature of 900 to 925 “C (I650 to I695 “F). Use oil for cooling
medium
Direct Hardening. Austenitize at 885 “C t 1625 “F). Quench in oil.
Uater or brine. Quenchant will depend on section thickness and required
hardness
Tempering.
by tempering
Recommended
Heat Treating
Practice
Normalize
l
XMGll
l
Rough machine
Austenitize (or case harden)
Quench
Temper
Finish machine
l
l
Normalizing.
Heat to 925 “C (I695
“F). Cool in air
Processing
l
l
Recommended
As-quenched hardness of 43 HRC or higher can be reduced
as required (see tune)
l
Sequence
High Manganese
Carbon
Steels (1500 Series) / 241
1527: Hardness vs Tempering Temperature. Represents
average based on a fully quenched
structure
an
High Manganese
Carbon
Steels (1500 Series) / 241
15B28H
Chemical
Composition.
025 to0.31C.
expected)
Similar
15BZSH. UNS H15281 and SAE B28H:
l.OOto 1.50Mn.0.15 to0.3.5Si.~O.OOOS to0.003 Bcnn be
Hardening.
Steels (U.S. and/or Foreign).
Curves. Heat-treating
“C (1650 “F). Austenitize:
870 “C (1600 “F)
I distance,
nm
5
II
3
5
!O
!5
!O
i5
Lo
IS
i0
Heat Treating Practice
Clubonitriding
is a suitrlbk surface hardening process
WE 51X8; AST~I ~304
15828H: Hardenability
iardness
wrposes
Recommended
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
limits for specification
Hardness, HRC
hlanimum
hlinimum
53
53
53
5’
51
50
18
15
35
29
26
2s
21
23
20
(continued)
242 / Heat Treater’s Guide
15B28H: Hardenability
Curves (continued).
mens only): 900 “C (1650 “F). Austenitize:
Hardness limits for specification
purposes
J distance,
‘/la in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
-
Earduess, BRC
Maximum
Minimum
53
53
52
51
51
50
49
48
46
43
40
31
34
31
30
29
27
25
25
24
23
22
21
20
41
41
46
45
42
32
25
21
20
..
. ..
...
.
..
. .
...
..
...
.
...
...
.
.
...
Heat-treating
670 “C (1600 “F)
temperatures
recommended
by SAE. Normalize
(for forged or rolled speci-
242 / Heat Treater’s
Guide
15B30H
Chemical
Composition.
0.35C.0.70to
Similar
UNS H15301 and SAE 15B30H: 0.27 to
l.ZOMn.0.15 to0.35Si~0.0005to0.003Bcanbeexpected)
Steels (U.S. and/or Foreign).
SAE J 1268; ASTM ~30-4
Recommended
Hardening.
Heat Treating
Practice
Carbonitriding is a suitable surface hardening process
High Manganese
15B30H: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
iardness
wrposes
I distance,
46in.
L
1
I
0
1
2
3
4
5
6
8
!O
870 “C (1600 “F)
limits for specification
Hardness, ARC
Maximum
Minimum
55
54
53
52
49
45
38
31
26
23
20
48
47
45
38
25
20
.
.
...
...
limits for specification
Hardness, ARC
hlinimum
blaximum
55
53
52
51
50
48
43
38
33
29
21
26
25
24
23
22
20
48
47
46
44
32
22
20
.
.
.
..
..
.
...
.. .
.
..
.. .
temperatures
recommended
Carbon
Steels (1500 Series) / 243
by SAE. Normalize (for forged or rolled specimens
only): 900
244 / Heat Treater’s
15B35H,
Guide
15B35RH
Chemical Composition.
CJNS HI5351
and SAE/AISI
158358:
0.31 toO.39C.0.70to
1.20hln.0.15
to0.3SSi,~0.000Sto0.003Bcanhs
expected). SAE 15B35RH: 0.33 to 0.38 C. 0.80 to I.10 Mn. 0.15 to 0.25
Si’(O.OOOS to 0.003 B can he expected)
Similar
Steels (U.S. and/or
WE Jl268.Jl868:
ASThl
J 1868; ASThl A9 I-l
A914.
Foreign).
lSB35RH.
15B35H.
LJNS H IS35 I ;
l!NS HlS3Sl;
SAE 51268.
Characteristics.
Excellent forgability.
Special qualit) grades for cold
heading. cold forging. and cold estnwion.
Can he welded. Because of
c&on
content. preheating and posthenting
are required and interpass
temperature must be controlled.
Machinability
on14 fair. Wide range of
mechanical properties can be attained by quenching and tempering. Similar
to 1035. Higher manganese content and horon addition increase hardenahility
Annealing.
Heat to 870 “C ( I600 “‘F). Furnace cool to 650 “C ( I200 “F)
at a rate not to esceed 18 “C (50 “F) per h
Hardening. Austenitize a1855 “‘C I I575 “F). Cllrbonitriding
surface hardking
process. Depending on section thicknine&
usually oil quenched
Tempering.
Heat IO IX5
“C (2275 “F). Do not forge bslo\v 870 “C t I600
“F)
Recommended
l
l
l
l
Recommended
Normalizing.
15835H:
Heat Treating
l
Heat to 915 “C i I680 ‘FL Cool in air
End-Quench
Distance from
quenched
surface
‘/lb in.
mm
l
Practice
of approximntsl~
-15 HRC can be reduced
hy
tempering
l
Forging.
Hardness
is a suitable
this steel is
l
Forge
Nomlalize
Anneal (if nccessar)
Rough machine
Austenitize
Quench
Temper
Finish machine
Processing
Sequence
for machining)
Hardenability
Distance from
quenched
surface
1.
‘16 in.
mm
Hardness.
HRC
mas
I
7
;
I .5X
13
20.5-l
1.74
S.lb
15
l-l
22.
23.70I?
2b
4
s
6
7
8
Y
6.32
7.90
9 43
I I a6
I2.b-l
11.22
I6
I8
xl
22
2-l
16
25.28
28 44
31 60
31.7b
37 92
11.08
3
IO
II
I2
IS 80
17.38
18.96
28
30
32
u.2-l
‘0
47.40
SO.56
:.:
ii
‘2
15B35H: Hardness vs Tempering Temperature.
average based on a fully quenched structure
Represents
an
High Manganese
Carbon
Steels (1500 Series) / 245
15835H: Microstructures. Microstructures of 15835 steel. (a) In
the as-received
hot-rolled condition, microstructure
is blocky
pearlite. Hardness is 87 to 88 HRB. (b) In the partially
spheroidized condition following annealing in a continuous furnace. Hardness is 81 to 82 HRB. (c) In the nearly fully
spheroidized condition following annealing in a bell furnace. Hardness is 77 to 78 HRB
246 / Heat Treater’s
Guide
15835H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
Hardness
purposes
1 distance,
mm
limits for specification
Hardness, ARC
Minimum
hlaximum
58
51
56
5-l
52
41
39
32
27
25
2-l
23
22
20
iardness
wrposes
I distance,
116io.
51
50
39
-IS
32
2-l
II
20
limits for specification
Hardness, HRC
hGnimum
Maximum
58
56
5s
5-l
53
51
37
II
48
18
39
‘8
2-l
22
30
30
51
so
I
0
1
2
3
-I
S
6
8
10
12
!I
:6
:8
80
27
26
2s
24
22
‘0
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
High Manganese
Carbon
Steels (1500 Series) / 247
1536
Chemical
Composition.
UNS G15360, SAE/AISI:
I.20 to I.50 Mn. 0.040 P max. 0.050 S max: was formerly
grade
0.30 to 0.37 C,
designated
IOXX
Recommended
Hardening.
Heat Treating
Carbonitriding
Practice
is a suitable surface hardening
process
High Manganese Carbon Steels (1500 Series) / 247
15B37H
Chemical Composition.
UNS15371 and SAE/AISI
to 0.39 C, 1.00 to 1.50 Mn, 0.15 to 0.35 Si (0.0005
expected)
Similar Steels (U.S. and/or Foreign).
15B37H: 0.30
to 0.003 B can be
UNS H IS37 I ; SAE J I168
Characteristics. Same characteristics. exceot treater hardenabilitv ,
than 15B35H because of higher manganese content. Maximum hardness
about the same. 15B37H is an oil hardening grade because hardenability
equals that of some alloy grades. Excellent forgeability.
Fair machinability
.
Forging.
Hardening. Austenitize at 855 “C ( I575 “F). Carbonitriding
surface hardening process. Quench in oil
Tempering.
As-quenched
reduced by tempering
Recommended
l
l
l
Normalizing.
Heat Treating
35 HRC can be
L
Heat to I245 “C (2275 “F). Do not forge below 870 “C ( 1600 OF’)
Recommended
hardness of approximately
is a suitable
Practice
l
l
Heat to 915 “C (1680 “F). Cool in air
l
Annealing.
Heat to 870 “C ( I600 “F). Furnace cool to 650 ‘C ( IXU “F)
at a rate not to exceed 28 “C (50 “F) per h
l
l
Processing
Sequence
Forge
Normalize
Anneal (if necessary for machining)
Rough machine
Austenitize
Quench
Temper
Finish machine
15837H: End-Quench Hardenability
Distance from
quenched
surface
‘/,ain.
mm
Eardness,
FIRC
max
min
Distance from
quenched
surface
916 in.
mm
I
I S8
x3
SO
13
2o.s-I
2
3
3.16
4.74
6.32
7.90
9.48
II.06
12.64
11.22
56
ss
S-l
53
52
51
so
SO
49
38
13
37
33
26
l-l
IS
16
I8
20
22
2-l
26
22 I2
23.70
‘5.28
‘8.44
31.60
31.76
37.92
11.08
IO
IS.80
4s
ii
II
17.38
IS.96
40
21
28
30
32
4-t 26
17.10
SO56
3
S
6
7
8
9
I2
Hardness,
ERC
max
min
..,
33
.,,
29
20
27
.._
.._
2s
23
1::
21
15B37H: Hardness vs Tempering Temperature. Represents
average
based
on a fully quenched
structure
an
248 / Heat Treater’s
Guide
15637H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
temperatures
recommended
Hardness limits for specification
wrposes
I distance,
nm
Hardness, HRC
Maximum
hlinimum
.5
58
57
56
54
53
51
50
47
38
30
28
26
25
23
.
1
3
5
!O
!5
10
I5
10
15
i0
iardness
wrposes
I distance,
/I6 in.
0
1
2
3
4
5
6
8
!O
:2
14
:6
:8
‘0
‘2
50
50
49
46
39
31
26
23
20
limits for spe cification
Hardness, HRC
hlav
imum
58
56
55
54
53
52
51
50
50
50
49
48
43
37
33
26
45
.
40
22
33
20
21
29
27
25
.
23
21
hlinimum
by SAE. Normalize (for forged or rolled specimens
only): 870
1
High Manganese
Carbon
Steels (1500 Series) / 249
1541,154lH
Chemical
COITIpOSitiOrL
1541. AK1 and UNS: 0.36 to 0.41 C, I .3s
to I .65 Mn. 0.040 P max. 0.050 S max. 1541H. UNS 15410 and SAE/AISI
1541H: 0.35 to 0.45 C. I.25 to I .75 Mn. 0. IS to 0.35 Si; IS-l I was fotmerl)
designated as IOXX grade: Composition
range and limits for 1JNS G IS-I IO
and AISVSAE IS-II: 0.36 to 0.45 C. 1.30 to I.65 Mn
Similar Steels (U.S. and/or Foreign). 1541. UNS Gls110:
ASTM AS IO, AS 19. A53.5. AS-l6: SAE J-103. J-II?. J-II-l; tGer.j DIN
I.1 Ihl:(Fr.)
AFNOR-IOMS:(Jap.)
JISSMn 2 H,SMn2,SCMn3:
(Swed.)
SSll 2120. 1541H. LINS HISJIO: SAE 51268; (Ger.) DIN 1.167; (Fr.)
AFNOR 40 M 5; (Jap.) JIS Shin 2 H. SMn 2, SChln 3; (Swed.) SS 1-12 I20
Characteristics.
Essentially a 1030 with a higher manganese content.
This greatly increases its hardenahility.
As-quenched hardness about 52
HRC or slightly greater. L+hen fully hardened. However.
IS-11 H is relatively deep hardening. so that oil quenching can he used for considerably
heavier sections when compared with IWO. Grade IS-11 H is available in
various product forms. Forgeability
is good. Machinabilit]
is fair. Can be
welded. using practice recommended for other high-hardenabilit)
steels
Hardening. Heat to 845 jC (ISSS “F). Carbonitriding
is a suitable
surface hardening process. Except for very heavy sections. oil quench from
austenitizing
temperature. as u ith alloq steels. Water of brine quenching
may cause quench cracking. Full precautions should be taken when parts
made from I S-l I H are induction hardened. Overly severe quenching may
also result in quench cracking
Tempering
matel)
Normalizing.
Recommended
l
l
l
Practice
Heat to 900 “C ( I650 “FL Cool in air
l
Heat Treating
Annealing.
Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 ‘IF)
at a rate not to exceed 28 “C (SO “F) per h
1541: Continuous
Cooling Transformation
“C(1320”F).Ac,at790”C(1455”F)
Diagram. Composition:
of approxi-
After Normalizing.
Normalize
large sections by conventional practice. u hich results in a structure of fine pearlite. Temper to
about 530 “C (I000 “F). hlechanical properties not equal to those achieved
b> quenching and tempering. Resulting strength is far higher than annealed
structure. Normalize and temper heavy forgings
l
Recommended
hardness
Tempering
l
Forging. Heat to IZ-IS “C (177S “F). Do not forge below 870 “C (I600
“F). For 1511 H, drop forge from I205 to 850 “C (2200 to I560 “F)
After Hardening. As-quenched
57 HRC can be reduced by tempering
l
l
Processing
Sequence
Forge
Normalize
Anneal c’if necessary) or temper (optional)
Rough machine
Austenitizc
Quench
Temper
Finish machine
0.39 C. 1.56 Mn. 0.010
P, 0.024
S, 0.21 Si. Grain
size, 8. AC, at 715
250 / Heat Treater’s
Guide
3
1541 H: End-Quench Hardenability
I
I.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
1.58
2.31
3.16
3.95
4.74
5.58
6.32
7.1 I
7.90
8.69
9.18
10.27
60
59
59
58
57
56
55
53
52
SO
48
46
53
52
50
47
4-l
41
38
35
32
29
27
26
7
7.5
8
9
IO
I’
l-4
I6
18
20
22
2-t
II.06
I I .85
12.64
13.22
15.80
I8.%
22.12
25.28
28.U
31.60
34.76
37.92
44
II
39
35
33
32
31
30
30
29
28
26
25
24
23
23
22
21
20
1541: Hardenability of Oil-Quenched Bolts. Curves represent
average as-quenched hardnesses of 15 bolts 19 mm (0.75 in.)
from one heat. C is center of bolt; 0.5R is mid-radius; S is sur-
1541: Isothermal Transformation Diagram. Composition: 0.43
C, 1.57 Mn, 0.011 P, 0.029 S, 0.23 Si, 0.20 Ni, 0.12 Cr, 0.07 MO.
Austenitized at 900 “C (1650 “F)
1541, 1541H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
High Manganese
1541 H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
II
13
IS
20
25
30
845 “C (1550 “F)
limits for specification
Hardness, ARC
Minimum
Maximum
60
59
57
53
49
4-l
38
35
32
30
53
50
4.3
36
29
25
23
‘2
20
Hardness limits for specification
3urposes
I distance,
VI/la
in.
I.5
,
!.S
1.5
1.5
i.5
is
‘S
I
0
2
4
6
8
10
12
!I
Hardness, EIRC
hlaximum
hlinimum
60
59
59
58
57
56
55
53
52
50
48
46
44
41
39
3s
33
32
31
30
30
29
28
26
53
52
SO
47
4-l
41
38
35
31
29
27
26
25
2-l
23
23
22
21
20
temperatures
recommended
Carbon
Steels (1500 Series) / 251
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
252 / Heat Treater’s
Guide
1541: Microstructures. (a) Nital, 330x. Forged at 1205 “C (2200 “F). Cooled in air blast. Widmanstatten platelets of ferrite at prior austenite
grain boundaries and within grains. Martensite matrix. (b) Nital, 550x. Forged at 1205 “C (2200 “F), but cooled in milder air blast. Slower
cooling rate resulted in upper bainite formation (dark areas). Martensite matrix. (c) Nital, 2850x. Forging and cooling same as (b). Replica
electron micrograph. Etched areas are upper bainite, consisting of carbide particles in ferrite. Smooth, featureless areas are martensite. (d)
2% nital, 110x. Hot rolled steel bar. 23.82 mm (0.94 in.) in diam. Transverse section. Top surface shows 0.254 mm (0.010 in.) deep seam
and partial decarburization
(white areas). Ferrite core (white) outlining prior austenite grains in pearlite matrix (dark). (e) 1% nital, 100x.
Forging lap of steel austenitized at 870 “C (1600 “F) for 2 h. Water quenched. Tempered at 650 “C (1200 “F) for 2 h. Iron oxide (dark); ferrite
(light); tempered martensite. Core is ferrite and tempered martensite. (f) 1% nital, 100x. Elongated forging flap in steel that was austenitized.
Water quenched. Tempered to hardness, 25 to 30 HRC. Iron oxide (dark). White area surrounding flap is caused by decarburization.
Hemainder is tempered martensite
252 / Heat Treater’s
Guide
15B41H
Chemical Composition.
UNS H15411 and SAE/AISI: 0.35 IO 0.45
C. I.75 to I .75 hln. 0. I.5 to 0.35 Si (0.0005 to 0.003 B can be expected)
Similar
Steels (U.S. and/or
Foreign).
LINS
HI s-11 I;
SAE
J 1268: (Ger.) DIN I .5X7
Characteristics.
A boron treated IS-II H. Significant
increase in hardenability caused b) boron addition. Forgeability
is good. hlachinabilit)
is
fair. Weldability
IS poor
Forging.
Heat to IX5
Recommended
Normalizing.
“C (2775 “FL Do not forge below 870 “C I 1600 “F)
Heat Treating
Practice
Heat to 900 “C ( I650 “F). Cool in air
Annealing.
Heat to 830 “c ( IS15 “F). Furnace cool to 650 “C t I ZOO “FJ
at a rate not to exceed 28 “C (SO “F) per h
Hardening.
Heat to 8-15 “C t IS_55 “F).Carbonitriding
is a suitahle surface hardening process. Should he regarded as an alloy steel in quenching
from austenitiring
temperature. Usually quenched in oil. except for very
hea\! sections. L\‘ater or brine quenching likely to result in quench cracking. Full precautions should be taken when parts are induction hardened.
Overly severe quenching can also cause quench cracking
Tempering
After Hardening.
Hardness
of nppmximntely
52 HRC
can be reduced b! tempenng
Tempering After Normalizing.
For large sections, normalize
by
cowentional
practice. Results in structure of tine pearlite. Temper up to
about S-10 “C (I000 “F). hlechanical properties not equal to those achieved
h) quenching and tempering
Resulting strength far higher than that of
annealed structure. Normalize and temper heavy forgings
High Manganese
Recommended
l
l
l
l
l
l
l
l
Processing
For&e
Normalize
Anneal (if necessxy)
Rough machine
Austenitize
Quench
Temper
Finish machine
I
1
3
.I
5
6
7
8
9
IO
II
1 I2
I.33
3.16
4.74
6.3’
7.90
9.18
II 06
12.6-i
11.22
IS.80
17.38
18.96
15841 H: Hardness
average
or temper (optional)
15B41H: End-Quench
Distance from
auenched
Sequence
Hardenability
Distance from
auenched
Hardness.
60
59
59
58
5x
57
s7
56
55
55
s-l
53
53
51
s2
51
51
50
49
-18
44
37
32
28
I3
II
15
I6
I8
20
22
24
26
28
30
32
Hardness,
20 5-l
‘2.12
23.70
25.28
52
91
50
49
26
25
25
2-l
xu
31.60
31.76
37.92
41.08
44.2-l
17.40
50 Sh
16
12
39
36
3-l
33
31
31
3
22
II
21
20
based
Carbon
vs Tempering
on a fully quenched
Steels (1500 Series) / 253
Temperature.
structure
Represents
an
254 / Heat Treater’s
Guide
15841 H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1550 “F)
Hardness
purposes
J distance,
mm
1.5
3
5
I
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
I distance,
‘/,fj in.
limits for specification
Eardoess, ARC
Maximum
Minimum
60
60
59
58
58
51
56
55
53
50
45
39
35
32
31
limits for specification
Eardness, q RC
Maximum
hlinimum
1
60
2
3
59
59
58
58
51
51
56
55
55
54
53
52
51
50
49
4
5
6
I
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
53
52
52
51
50
49
47
41
26
24
23
21
20
46
42
39
36
34
33
31
31
53
52
52
51
51
50
49
48
44
37
32
28
26
25
25
24
23
22
21
21
20
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
High Manganese
15B41H: Continuous
Cooling Transformation
Diagram. Composition:
ASTM 7 to 8. AC, at 725 “C (1335 “F). AC, at 780 “C (1435 “F)
Carbon
Steels (1500 Series) / 255
0.42 C, 1.61 Mn, 0.006 P, 0.019 S. 0.29 Si, 0.004 B. Grain size.
High Manganese Carbon Steels (1500 Series) / 255
1548
Chemical
COInpOSitiOn.
AISI and UNS: 0.35 to 0.56 C. 0.85 to
I. I5 Mn, 0.040 P max. 0.050 S max. UNS Cl5480 and AISl/SAE
15-W
Standard composition ranges and limits: 0.42 to 0.43 C. I .OS to I .-IO Mn;
was formerly designated as IOXX grade
Similar Steels (U.S. and/or Foreign).
A510; SAEJ403.
Wl2,
IJNS
GlS180;
ASTM
J-II-I: (Ger.) DIN I.1226
Characteristics.
High-manganese
version of 1045. Slight difference
in composition provides for higher hardenability.
As-quenched hardness of
at least 55 HRC or slightly higher. when carbon is near the high side of the
allowable range. Used extensively
for parts to be furnace heated or heated
by induction prior to quenching. Excellent forgeability.
Fair machinability
Forging.
Heat to I245 “C (2275 “R. Do not forge below 870 “C ( 1600 “F)
Recommended
Heat Treating Practice
Normalizing. Heat to 900 “C (1650 “F). Cool in air
Tempering After Hardening.
erly austemtized
Hardness of at least 55 HRC. if propHardness can be adjusted by tempering
Tempering After Normalizing. For large sections. normalize by
conventional
practice. This results in a structure of fine pearlite. A tempering treatment up to approximately
540 “C (I000 “F) is then applied.
Mechanical
properties not equal to those achieved by quenching and
tempering. Resulting strength is far higher than that of annealed structure.
Normalizing
and tempering often applied to heavy forgings
Recommended
l
l
l
Annealing. Heat to 84 “C (I555 “F). Furnace cool to 650 “C ( 1200 “F)
at a rate not to exceed 28 “C (SO “F) per h
l
Hardening.
l
Austenitize at 815 “C (1555 “Fj. Carbonitriding
is a suitable
surface hardening process. Because of high hardenability,
a less severe
quench may be desired for a given section thickness
and quenched.
l
l
l
Processing
Sequence
Forge or machine (from bars)
Normalize (if forged. Not required for parts machined from hot rolled or
cold drawn bars)
Anneal (if necessary. Bar stock usually received in condition for best
machining)
Rough machine (forgings)
Austenitize (parts from bars or forgings)
Quench
Temper
Finish machine
256 / Heat Treater’s
Guide
1548: Hardness vs Tempering Temperature.
average based on a fully quenched
structure
Represents
an
256 / Heat Treater’s
Guide
15B48H
Chemical
Composition.
to0.53
expected)
C. 1.00 to I.50 hln. 0.15 to 0.35 Si (0.0005 to 0.003 B can be
0.13
UNS HI5481
and SAE/AISI
ISBJSH:
Tempering
After Hardening.
As-quenched
hardness
of 55 HRC
can be reduced hy tempering
Characteristics.
Composition
similar to 15-18 with boron added.
Characteristics,
other than hardenahility.
are the same. Forgeability
is
excellent. Machinability
is fair
Tempering After Normalizing.
For large sections. nomlalize
hy
conventional
practice. This results in a structure of fine pearlite. A tempering treatment up to approximately
S-IO YY (1000 “F) is then applied.
hlrchanical
properties not equal to those achieved by quenching and
tsmperin~. Resulting strength is far higher than that of annealed structure.
Normnhrmg and tempering often applied to heavy forgings
Forging.
Recommended
Similar
Steels (U.S. and/or
Foreign).
1JNS H Is181 : WE
J 1268
Heat to ILIS “C (2275 OF-,. Do not forge below 870 “C ( 1600 ‘F)
Recommended
Normalizing.
Heat Treating
l
Practice
l
Heat to 900 C. i I650 “F). Cool in air
l
Annealing.
Heat to 815 “C ( IS55 “FL Furnace cool to 650 “C t I200 “F)
at a rate not IO exceed 28 “C (SO “F) per h
l
l
Hardening.
Austenitize at MS “C I ISSS “F). Carbonitriding
surface hardening process. Quench in oil except for thicker
induction hardened, use extreme care when \\ater quenching
is a suitable
sections. If
from
I
1
3
4
5
6
7
8
9
IO
II
I2
from
quenched
Distance
Eardness,
HRC
mar
min
I.98
63
56
1.7-l
3.16
6.32
1.90
948
II.06
I2.64
1122
IS.80
17.38
18.96
62
61
60
59
58
57
56
s.5
53
51
56
55
s-l
43
52
-12
3-l
31
30
29
28
Aardness,
surface
&in.
I3
I-l
IS
I6
I8
30
22
2-l
26
28
30
31
ARC
mm
20.51
22. I2
23.70
25.23
28.U
3 I ho
34.76
37.92
41.08
u.21
47 -IO
50.56
l
l
15848H: End-Quench Hardenability
Distance
l
max
min
48
-Is
II
3x
31
32
31
30
19
29
28
‘8
27
37
26
26
IS
2-l
73
22
21
20
Processing
Sequence
Forge or machine t from bars)
Normalize tif forged. Not required for parts machined from hot rolled or
cold dran n bars)
Anneal tif necessary. Bar stock is usually received in condition for best
machining)
Rough machine (forgings)
.Austenitize
Quench
Temper
Finish machine
High Manganese
15848H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
J distance,
‘/,,jin.
1
2
3
1
5
5
7
3
2
IO
I1
12
13
14
I5
I6
18
!O
!2
!4
!6
!8
10
12
845 “C (1550 “F)
limits for specification
Eardness,
Maximum
ERC
hlinimum
63
63
62
61
60
59
57
56
49
39
33
31
30
29
28
56
55
55
54
53
45
33
30
27
25
24
23
22
.
...
limits for specification
Eardoess,
Maximum
63
62
62
61
60
59
58
57
56
55
53
51
48
45
41
38
34
32
31
30
29
29
28
28
HRC
hlinimum
56
56
55
54
53
52
42
34
31
30
29
28
27
27
26
26
25
24
23
22
21
20
temperatures
recommended
by SAE. Normalize
Carbon
Steels (1500 Series) / 257
(for forged or rolled specimens
only): 870
258 / Heat Treater’s
Guide
15848H: Hardness vs Tempering Temperature. Represents an
average based on a fully quenched
structure
258 / Heat Treater’s
Chemical
Guide
Composition.
AISI and UNS: 0.45 to 0.56 C. 0.85 to
I .I5 Mn. 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS Gl5510;
ASTM
ASIO; SAEJ403. J413, J414
Characteristics.
Carbon content as high as 0.56. Borderline
grade
hetween medium carbon and high carbon. Available in various product
forms. Used extensively
for producing small to medium size forgings.
Often selected for parts to be induction hardened. Excellent forgeability.
Fairly good machinability.
Weldability
is poor. Similar to 1050. Higher
manganese content increases hardenability
Forging.
Heat to 1230 “C (2250 “F). Do not forge below 845 “C ( IS55
Hardening. Heat to 830 “C ( I525 “F). Carbonitriding
and induction
hardening are suitable surface hardening processes. Quench in water or
hrine. For full hardening, oil quench rounds less than 6.4 mm (‘/J in.) thick.
High hardenability
must be considered in quenching. Normalize and temper as for I54 I. if desired
Tempering.
Recommended
l
l
“F)
l
Recommended
Normalizing.
Annealing.
Heat Treating
Practice
l
l
Heat to 900 “C ( 1650 “Ft. Cool in air
Heat to 830 “C (I 525 “F). Furnace cool to 650 “C t I200 “F)
at a rate not to exceed 28 “C (SO “F) per h
As-quenched
hardness of 58 to 60 HRC can be reduced by
tempering
l
l
l
Processing
Sequence
Foge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
1551: Hardness vs Tempering
average
based
on a fully quenched
Temperature.
structure
Represents
an
High Manganese
Chemical
Composition.
AISI and UNS: 0.47 to 0.55 C. 1.20 to
I .50 Mn. 0.040 P max. 0.050 S max. UNS Cl5520 and AISI/SAE 1552:
Composition
limits
formerly designated
Similar
and ranges: 0.46 to 0.55 C. 1.20 to I.55 Mn: uas
as I OXX grade
Steels (U.S. and/or Foreign).
A510: SAEJ403.
J412.5414;
UNS
G 15520;
ASTM
(Ger.) DIN I.1226
Characteristics.
Carbon content as high as 0.55. Borderline
grade
between medium carbon and high carbon. Available in various product
forms. Used extensively
for producing small to medium size forgings.
Often selected for parts to be induction hardened. Excellent forgeability.
Fairly good machinability.
Weldability
is poor. Similar to 1050. Higher
manganese content increases hardenability
Heat to I230 “C (2250 “F). Do not forge below 815 “C ( I555
“F3
Heat to 830 “C ( IS25 “FL Furnace cool to 650 “C ( I200 “F)
at a rate not to exceed 28 “C (SO “F) per h
Hardening. Heat to 830 “C ( 1525 “F). Carbonitriding
and induction
hardening are suitable surface hardening processes. Because of higher
hardenability. oil quench heavier sections for full hardness. When induction
hardening, use the least severe quench that \rill produce full hardness. This
minimizes the possibility of quench cracking
Tempering.
Recommended
l
l
l
Heat Treating
Practice
l
l
Normalizing.
Heat to 900 “C ( 1650 “F). Cool in air
As-quenched
hardness of 58 to 60 HRC can be reduced by
tempering
l
Recommended
Steels (1500 Series) / 259
Annealing.
l
Forging.
Carbon
l
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
1552: Hardness
average
based
vs Tempering
on a fully quenched
Temperature.
structure
Represents
an
High Manganese
Carbon
Steels (1500 Series) / 259
1561
Chemical
COI?IpOSitiOn.
AK1 and UNS:
I .OS Mn. 0.040 P max. 0.050 S ma-x
Similar
Steels (U.S. and/or Foreign).
0.55 to 0.65 C. 0.75 to
LINS
G 15610;
ASTM
Tempering.
A510: SAE J403. J112
Characteristics.
Versatile high-carbon grade. Available in a variety of
product forms. including various thicknesses of flat stock used for fahricating parts to be spring tempered. Good forgeahility.
Not recommended for
welding. As-quenched hardness of near 65 HRC can be expected. When
properly quenched. consists of a carbon-rich
martensite structure with
essentially no free carbide. Similar to 1060. with slightly higher hardenability and manganese content
Forging.
Hardening. Heat to 815 ‘C. t IS00 “F). Carbonitriding
surface hardening process. Hardenability
must be considered
Oil quench sections thicker than for 1060
Heat to 1205 “C (2200 “F). Do not forge below 815 “C ( IS00
“F)
Austempering.
Thin sections ttypically
springs) usually austempered.
Results in hainitic structure. Hardness of approximately
46 to 52 HRC.
Austenitire at 8 IS “C t I500 “F). Quench in molten salt bath at 3 IS “C (600
“F). Hold at temperature for I h. Air cool. No tempering required
Recommended
l
l
Normalizing.
Annealing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Heat to 830 ‘C t I535 “FL Furnace cool to 650 “C t I200 “F)
at a rate not to exceed 28 “C (50 “F) per h
hardness near 65 HRC can be reduced by tem-
pering
l
Recommended
Maximum
is a suitable
in quenching.
l
l
l
l
l
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Processing
Sequence
260 / Heat Treater’s
Guide
1561: Hardness vs Tempering Temperature.
average based on a fully quenched
structure
Represents
an
260 / Heat Treater’s
Guide
15B62H
Chemical COfIIpOSitiOfI.
CJNS HlS621 and SAE/AISI lSB62H:
0.5-f to 0.67 C. I .OO IO I SO hln. O.-IO to 0.60 Si (0.0005 to 0.003 B can be
expected)
Similar
Steels (U.S. and/or
Foreign).
IINS H 1562 I : SAE J I 368
Austempering.
Thin sections (typically
springs) commonly austempsred. resulting in bainitic structure and hardness of approximately
45 to
52 HRC. Austenitizr at 8 IS ‘C t I SO0 “Ft. Quench in molten salt bath at 3 IS
“C (600 “Ft. Hold at this temperature for I h. Air cool. No tempering
required
Characteristics.Similx
to 1060. Good forgeability.
Poor uvldability.
Maximum as-quenched hardness of 65 HRC. Higher manpanese content.
boron addition, and higher silicon content all contribute to its relatively
high hardenability.
Extensively
used in the spring temper hardness range.
generally 35 IO 52 HRC. for springs having relatively thick sections
Forging.
Heat to 1205 “C t7200 “FL Do not forge below 8 IS “C I I SO0 “F)
Tempering.
As-quenched hardness from 63 IO 65 HRC. This maximum
hardness can be reduced by tempering
Recommended
l
Recommended
Normalizing.
Heat Treating
Practice
l
l
Heat to 885 “C (1625 “FL Cool in au
l
Annealing.
Heat IO 830 “C t IS25 “FL Furnace cool to 650 “C t I200 “FJ
at a rate not to exceed 28 “C (SO “FJ per h
Hardening. Austenitizc at 8 IS ‘C t 1SO0 ‘:‘F). Carbonitriding
surface hardening process. Quench in oil
15662H: End-Quench Hardenability
Distance from
quenched
surface
&in.
mm
Hardness.
ERC
max
min
I
-3
3
-l
5
6
7
8
9
I0
II
I?
1.5x
3.16
47-i
6.32
7 90
9 18
Il.06
116-I
l-t.22
IS.80
17.38
IX.96
60
60
60
60
59
58
57
52
43
39
37
s5
I
&
65
6-t
6-l
6-1
63
63
63
Distance from
quenched
surface
I,/16in.
mm
13
I-l
IS
I6
I8
20
22
2-I
26
28
SO
32
30.54
22.12
23.70
3.28
3 4-l
3 1.60
34.76
37 92
11.08
44.2-I
47.40
SO.56
is a suitable
l
l
l
l
Forge
Nomlalizs
.Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Processing
Sequence
High Manganese
15B62H: Hardenabilitv
Curves. Heat-treating
“C (1600 “F). Austenitiie:
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
temperatures
recommended
by SAE. Normalize
Carbon
Steels (1500 Series) /
(for forged or rolled specimens
only): 87C
845 “C (1550 “F)
limits for spec ification
Hardness,
Maximum
ARC
Minimum
60
60
60
..
65
65
65
65
64
64
63
60
56
48
42
37
34
59
58
56
50
42
34
32
31
30
29
27
26
I
Hardness
purposes
J distance,
‘&j in.
limits for specification
Hardness,
Maximum
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
.
65
65
64
64
64
63
63
63
62
62
61
60
58
54
48
43
40
31
35
34
H RC
Minimum
60
60
60
60
59
58
57
52
43
39
31
35
35
34
33
33
32
31
30
30
29
28
21
26
262 // Heat
Heat Treater’s
Treater’s
262
Guide
Guide
15662H: Hardness vs Tempering Temperature. Represents an
average based on a fully quenched
structure
262 / Heat Treater’s
Guide
1566
Chemical
Composition.
AISI and UN% 0.60 to 0.71 C. 0.85 to
I. I5 Mn, 0.040 P max. 0.050 S max
Similar
Steels (U.S. and/or
Foreign).
UNS
G15660;
ASThl
AS IO; SAE 5403. J4 12; (Ger.) DIN I. I260
Characteristics.
High-manganese
version of 1070. Widely used in the
hardened and tempered (notably spring tempered) condition. ?iood forgeability and shallow hardening. Extensively used for making hand tools such
as hammers and woodcutting
saws. Not recommended for welding
Forging.
Heat to I 190 “C (2 175 “F). Do not forge below 8 IS “C ( I500 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 885 “C ( I625 “F). Cool in air
Austempering.
Thin sections
(typically
springs)
are commonly
austempered. resulting in bainitic structure and a hardness range of approximitely
46 to 53~HRC. Austenitize 91 815 “C (I500 “F’). Guench in
molten salt bath at 3 IS “C (600 “F). Hold a1 temperature for I h. Air cool.
No tempering required
Tempering.
Recommended
l
l
l
Annealing.
Heat to 830 “C ( IS25 “F). Furnace cool to 650 “C ( I200 “F)
at a rate not to exceed 28 “C (50 “F) per h
Hardening. Heat to 815 “C (IS00 “F). Carbonitriding
is a suitable
surface hardening process. Lessen severity of quench to avoid cracking
compared with quenching of 1070
Maximum
hardness near 65 HRC can be reduced by tem-
pering
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
1566: Isothermal
Transformation
Diagram. Contains 0.64 C
and 1 .13 Mn. Grain size 7. Austenitized at 910 “C (1670 “F).
Martensite temperatures estimated
High Manganese
Carbon
Steels (1500 Series) / 263
1566: End-Quench Hardenability.
Contains 0.68 C and 1 .OOMn.
Grain size, 6 to 7. Austenitized at 845 “C (1555 “F)
1566: Hardness vs Tempering
Temperature.
average based on a fully quenched structure
Represents
an
(1300
Alloy
Steels
through
9700
The alloy steels discussed in this section. as \vell as their subsequent
heat treatment. are those listed in the latest issue of the 41SI Steel Products
hlanual on alloy steel bars. They include both ths standard alloy steels and
the standard H and RH steels. H hich have modified hardenability
limits.
They also have sliphtly different carbon ranges. generally broader than the
standard alloy steels. These steels are similar to standard grades in other
respects. including thek general characteristics
and recommended
heat
treating practice.
There are fourteen separate families of alloy steels that rve considered
standard. In numericnl sequence. these steels begin with the I300 manpanese steels and conclude with 9160 manganese-silicon
steels.
Boron-modified
allo! steels generalI) contain 0.0005 to O.O03r(~ boron. There are five families of boron-modified
allo) steels bepmnlng with
Series)
SOB00 chromium steels and concluding u ith the WBOO nickel-chromiummolybdenum
steels. Because of the very small amounts of boron used,
boron is not considered as an alloy. These steels. which are denoted by the
USP of the letter “B” bet\\een the second and third digits of their designations. are instead commonI> referred to as boron-treated
steels. Boron is
used for the purpose of increasmg
hardenability.
When the endquench data for an! specific boron steel are compared with its counterpart
not containing boron. the effect of boron hecomes evident. The use of boron
steels has provided an economic advantage because It offers high bardenability
in IOU-allo! steels. significantly
louer in cost than the higher
allo) grades that would be necessary to provide the hardenability
required
u ithout the boron.
1330,133OH
Chemical Composition.
1330. AISI and ZJNS: 0.18 to 0.23 C. I .60
to I .90 hln. 0.035 P milx. 0.040 S max. 0. IS IO 0.30 Si. UNS H13300 and
SAE/AlSI 1330H: 0.27 IO 0.33 C. I .-iS to 2.05 hln. 0. IS to 0.35 Si.
Similar Steels (U.S. and/or Foreign).
l!NS
G 13300:
1330.
ASTM A304. A322. 44331. 4519: hllL SPEC hlR--S-16974;
SAE J4o-I.
J-ii?. 5770; (Ger.) DIN I.1 165: tJap.j JIS Shln I H. SChln 2. 1330H. LINS
Hl3300: ASThI A3O-k SAE JlZ68: tGer.) DIN I.1 165: tJap.) JIS Shin I
H, SChln 2
Characteristics. A medium-carbon iteel of the manganese allo! steel
series. While the manganese content of I330H can overlap \\ nh the manganese content of the high-manganese
carbon steels. the nominal manganese content IS considerably
higher for 1330H. givmg the steel higher
hardenability.
Thus. with a carbon content in thr middle of the range.
as-quenched hardness can be expected to approach SO HCR. This steel is
usually oil quenched. although large sections may have IO be irater
quenched to develop maximum hardness. H’ater quenching of l330H is
hazardous because high-manganese steels are susceptible to quench cracbing. This applies especialI) to induction or name hardenmg. M’hen these
processes are used. the quenching phase of the process must be extremeI>
\rell controlled.
l33OH can be welded only when close,l>, controlled preheating and postheattng practices are follo\<ed. Forgeabtlrt)
is \er> good.
but machinabilit)
is only fair
Recommended
Heat Treating Practice
Normalizing. Heat to 900 jC t l6SO “F). Cool in air
Annealing. For a predominately pearlitic structure. heat
to 855 “C (I 570
“F). and cool IO 620 ‘C t I IS0 “F) at a rate not to esceed I I “C (30 “F) per
h: or cool fairly rapidlq IO 620 “C ( I I SO “F) and hold for 4 t/z h after which
cooling rate is not critical. To obtain a structure predominately
composed
of femte and spheroidired
carbide. heat IO 750 “C (I 380 OF). cool fairly
rapidly to 730 “C t I350 “Fj. Then cool to 6-lO “C ( I I85 “F) at a rate not to
exceed 6 C t IO “F) per h and hold for IO h. after which cooling rate is no
longer critical
Hardening. Austenitize at 860 “C t IS80 “F). and quench in oil. Use
water or brine for hea\> secttons. Carbomtriding.
austempering.
and
niartsnipcring
are suitable processes.
Tempering.
Recommended
Processing
see 1335 and 1335H)
l
l
l
l
l
l
Forging.
Heal to I230 ‘C i224S “F). Do not forge after temperature
belo\v approsimately
870 “C ( I600 “F)
drops
Temper to desired hardness
l
l
Rough machine
Slress relic\ e
Finish machine
Preheat
Auslrnilize
Quench
Temper
Final grind to size
Sequence
(if forged,
266 / Heat Treater’s Guide
1330H: End-Quench Hardenablllty
Distance from
quenched
surface
916 in.
mm
Ehrdoess,
ERC
max
min
Distance from
quenched
surtkce
‘/la in.
mm
Eardlless,
ERC
max
min
I
2
3
1.58
3.16
4.74
56
56
55
49
47
44
13
I4
I5
20.54
22.12
23.10
38
31
36
4
5
6
7
8
9
IO
II
12
6.32
1.90
9.48
Il.06
12.64
14.22
15.80
17.38
18.96
53
52
50
48
45
43
42
40
39
40
35
31
28
26
25
23
22
21
I6
18
20
22
24
26
28
30
32
25.28
38.44
31.60
3-1.76
37.92
41.08
44.24
47.40
50.56
35
3-l
33
32
31
31
31
30
30
Source: Metals Handbook.
20
___
9th ed.. Vol I. American Socier) for Metals. 1978
1330: Effect of Hot Working and Location of Test Bars on End-Quench Hardenability.
diam. (c) 203 mm (8 in.) diam. (d) 152 mm (6 in.) diam.
(a) 305 mm (12 in.) diam. (b) 254 mm (10 in.)
Alloy Steels (1300 through
1330H: Hardenability
Curves. Heat-treating temperatures
(1650 OF). Austenitize:
870 “C (1600 “F)
Hardness
Purposes
J distance,
mm
1.5
3
5
7
9
II
13
15
20
25
30
35
40
45
SO
Hardness
Purposes
J distance,
‘46in.
I
2
3
1
5
5
1
3
2
IO
II
12
13
I4
IS
16
I8
!O
!2
!4
!6
!8
IO
i2
Limits for Specification
Eardness, ERC
Minimum
Maximum
56
56
55
53
51
48
45
43
39
35
33
32
31
31
30
49
41
44
38
32
28
25
24
20
.
Limits for Specification
Eardoess, EIRC
Minimum
Maximum
56
56
55
53
52
50
48
45
43
42
40
39
38
37
36
35
34
33
32
31
31
31
30
30
49
47
4-l
40
35
31
28
26
2s
23
22
21
20
recommended
9700 Series) / 267
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
266 / Heat Treater’s
Guide
1330: Continuous
Cooling Transformation
(1580 “F). Previous treatment, rolled
Diagram.
Composition:
0.30 C. 1.80 Mn, 0.020 P, 0.020 S. 0.15 Si. Austenitized
at 860 “C
268 / Heat Treater’s
Guide
1335,1335H
Chemical Composition.
1335. MS1 and UN.9 0.33 LO 0.38 c. I .60
to I .YO hln. 0.035 P max. 0.040 S max. 0.15 LD0.30 Si. UNS H13350 and
SAE/AISI
13358:
0.32 IO 0.38 C. I .-IS m 2.05 hln. 0. IS to 0.35 SI
SAE J-107; (Ckr.1 DIN I. 1167; tFr.) AFNOR
Shln 2. SChln 3: ~S\rsd.) S.514 2120:
Characteristics.
Similar
Steels (U.S. and/or
Foreign).
1335.
ClNS
GI 3350:
ASTh,l ,432. A3.31. A5lY. A547: hllL SPEC hlK-S-16974:
S.L\E J-10-l.
J-II?. 5770: (Ger.) DIN I.1 167; tFr.) .L\FNOR 40 hl S: ~Jap.) JIS Shln ? H.
Shln 2, SCh4n 3; tSutd.) S.SIJ 2120. 13358. UNS Hl.1350; XSThl.-\304:
-IO hl 5: (Jnp.) JIS Shln 2 H.
The general chzuxkrisric~
me warI> the sane ;LS
those pilen for I73OH. Expected ns-quenched h:udnrs
for l33SH is
sliphtlb hiphsr than that for 133OH. appro\inwl4>
52 HRC. Hwdenubilitl
pnltttm, ;ue i1lw knilur. Thib stesl is uzuull> oil quenched. although larg?
wctionb nxq hn\s ICYbs \\~er qwnchsd
10 develop marimuni
hxdnsss.
Alloy
Steels (1300 through
9700 Series) / 269
LVater quenching high-manganese
steels is hazardous because of their
susceptibility
to quench cracking. This applies especially to induction or
flame hardening. When these processes are used. the quenching phase of
the process must be extremely well controlled.
l33SH can be welded. but
only when closely controlled
preheating and postheating practices are
followed. Forgeability
is very good, hut machinability
is only fair
exceed 6 “C I IO “F) per h and hold for IO h. after which cooling
longer critical
Forging.
Tempering.
drops helou
Heat to 1230 “C (3345 “F). Do not forge atier temperature
approxtmately
870 “C i I600 “F)
Recommended
Normalizing.
Heat Treating
Heat to 900 “C (I650
l
“Ft. Cool in air
l
Annealing.
For a predominately
pearlittc structure, heat to 855 “C ( IS70
“F). and cool to 610 “C ( I I SO OF) at a rate not to exceed I I “C i30 “F) per
h: or cool fairly rapidly to 620 “C (I I SO “F). and hold for-t vz h. after u hich
cooling rate is not critical. To obtain a structure predommately
composed
of ferrite and spheroidized carbide. heat to 750 “C ( I385 “F). cool fairly
rapidly to 730 ‘C ( I350 OF). Then cool to 640 “C ( I I85 “F) at a rate not to
1335: Isothermal Transformation
Diagram. Composition:
1335: End-Quench Hardenability
Hardness,
ARC
max
min
-I
;
4
I S8
98
1.74
3.16
6 32
s7
56
5s
51
-19
47
4-l
1,
7
8
9
IO
II
I2
9.48
7 90
I Ia6
I’64
13.12
15.80
17.38
18.96
92
5-I
so
18
46
4-l
12
41
38
34
31
29
‘7
26
25
21
I
Distance from
quenched
surface
‘/16 in.
mm
I3
II
IS
I6
I8
‘cl
22
2-l
26
2x
SO
32
20. s-l
22 II
‘3.70
25.28
28.44
3 I .hO
31.76
37 92
4l.08
4-l 2-l
47.30
SO.56
Temper to desired hardness
Eardness,
HRC
max
min
10
39
38
37
3s
34
33
32
31
31
30
30
l
l
l
l
l
l
‘3
2’
‘2
21
20
.._
Processing
Sequence
Forge
Nomralize
Anneal
Rough machine
Austenittze
Quench
Temper
Finish machine
0.35 C. 1.85 Mn. Austenitized
No. 2
Distance from
quenched
surface
‘116 in.
mm
Hardening. Austenitize at 855 ‘C (IS70 “F). and quench in oil. Use
water or hrine for heal y sections. Carhonitriding
and mattempering
are
suitable surface hardening processes
Recommended
Practice
rate is no
at 845 “C (1555 “F). Grain size: 70% No. 7,30%
270 / Heat Treater’s Guide
1335H: Hardenability
(1600 “F). Austenitize:
Curves. Heat-treating
845 “C (1550 “F)
Hardness Limits for Specification
Purposes
I disiance,
nm
1.5
3
5
7
9
11
13
15
!O
!5
IO
15
lo
15
i0
Eklrdness, ERC
MaximlUU
58
58
51
55
53
50
47
45
41
37
35
33
32
31
30
MillilIlUUl
51
49
46
42
36
31
28
21
23
21
. .
Hardness Limits for Specification
Purposes
I distance,
h6 in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
Eardness,
Maximum
58
57
56
55
54
52
50
48
46
44
42
41
40
39
38
37
35
34
33
32
31
31
30
30
ERC
Millhull
51
49
41
44
38
34
31
29
27
26
25
24
23
22
22
21
20
...
...
...
.
..
..
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steels (1300 through
1335, 1335H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
9700 Series) / 271
1335: IlT Curve. Composition: Fe, 0.35 C, 1.85 Mn. Grain size:
70% No. 7,30% No. 2. Austenitized at 843 “C (1550 “F)
Alloy Steels (1300 through 9700 Series) / 271
1340,134OH
Chemical Composition. 1340. AI.9 and UNS: 0.38 to 0.43 C. I .60
to 1.90 Mn, 0.035 P max. 0.040 S max, 0. I5 to 0.30 Si. UNS 813400 and
SAE/AISI 134OH: 0.37 to 0.44 C, I.45 to 2.05 Mn, 0. I5 to 0.35 Si
Hardening. Austenitize at 830 “C (IS25 “F). and quench in oil. Use
water or brine for heavy sections. Electron beam, carbonitriding.
and
austempeting are suitable processes
Similar Steels (U.S. and/or Foreign). 1340.
Tempering.
ASTM A322, A331. A519, A547:
J412.5770.
13408. UNS Hl3400:
I SO69
UNS
G13400;
MfL SPEC MLS-16974;
SAE J404.
ASTM A304; SAE J407; (Ger.) DIN
Recommended
l
Characteristics.
Comparable to those outlined for I330H and I335H.
As carbon content is increased, a higher as-quenched hardness can be
expected (about 54 HRC for I340H. depending on precise carbon content).
The hardenability
pattern is also quite similar to those shown for grades
l330H and 1335H. As is true for all of the I300 grades, hardenahility
band
is relatively
wide, caused primarily
by the broad range in manganese
content
Temper immediately
l
l
l
l
l
l
l
after quenching
Processing
to desired hardness
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Forging.
Heat to 1230 “C (2245 “F). Do not forge after temperature
drops below 870 “C ( 1600 “F)
Recommended
Normalizing.
Annealing.
Heat Treating
Practice
1340:
Specimens
As-Quenched
quenched
Hardness
in oil from 830 “C (1525 “F)
Heat to 870 “C (1600 “F). Cool in air
For a predominately
pearlitic structure, heat to 830 “C ( I525
“F). and cool from 730 “C (1350 “F) to 610 “C (I 130 “F) at a rate not to
exceed I I “C (20 “F) per h; or cool rapidly from 730 “C (I350 “F) to 620
“C (I IS0 “F). and hold for 4.5 h. For a predominately
ferritic and
spheroid&d
structure, heat to 750 “C (1380 “F), and cool from 730 “C
( 1350 “F) to 610 “C ( I I30 “F) at a rate not to exceed 6 “C ( IO “F) per h; or
cool fairly rapidly from 750 “C (1380 “F) to 640 “C ( I I85 “F). and hold for
8h
In.
Size rouad
mm
Surface
Eardness, ERC
‘/z radius
Center
‘/2
13
15
51
IO:!
58
57
39
32
51
56
34
30
57
50
32
26
I
7
4
Source: Bethlehem Steel
272 / Heat Treater’s
Guide
1340: Isothermal Transformation
Diagram. Composition:
0.43 C. 1.58 Mn. Austenitized
at 885 “C (1625 “F). Grain size: 8 to 9
1340H: End-Quench Hardenability
Distance from
quenched
surface
1/16in.
mm
Distance From
Hardness,
HRC
max
min
quenched
surface
916 in.
mm
Hardness,
ARC
max
min
I
1.58
2
3.16
60
60
53
52
13
II
20.5-l
22.12
46
44
26
3
3
-I
5
6
7
9
1.7-l
6.32
7.90
9.1x
I I.06
12.64
11.23
59
58
57
56
55
5-l
51
51
49
46
10
35
33
31
I5
I6
18
‘0
22
24
26
23 70
15.28
‘8.U
3 I .60
34.76
37 92
41 08
-II
-II
39
38
37
36
35
29
2-l
23
23
22
22
21
IO
II
I?
I S.80
17.38
18.96
51
50
-I8
29
18
27
33
30
32
Al.24
47.40
50.56
35
34
3-l
21
20
20
8
hwx
Mrrc~ls Mudbook. %h ed.. Vol I, imericm
Socirr)
ior hlrmls.
1978
1340: IlT Diagram. Composition:
size: 8-9. Austenitlzed
Fe, 0.43 C, 1.58 Mn. Grain
at 885 “C (1625 “F)
Alloy S teels (1300 through
1340H: Hardenability Curves. Heat-treating
(1800 “F). Austenitize:
iardness
‘urposes
distance,
trn
1.5
3
5
7
9
1
3
5
0
5
0
5
0
5
0
845 “C (1555 “F)
Limits for Specification
Hardness, HRC
Maximum
Minimum
60
60
59
58
57
56
54
52
41
41
39
37
36
35
34
53
52
50
48
42
36
32
30
26
24
23
22
21
20
20
hardness Limits for Specification
‘urposes
distance,
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
8
0
2
4
6
8
0
2
Hardness, HRC
Maximum
Minimum
60
60
59
58
51
56
55
54
52
51
50
48
46
44
42
41
39
38
37
36
36
35
34
34
53
52
51
49
46
40
35
33
31
29
28
27
26
25
25
24
23
23
22
22
21
21
20
20
temperatures
recommended
9700 Series) / 273
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
274 / Heat Treater’s Guide
1340: Hardness vs Tempering Temperature. Normalized at 870
“C (1800 “F). Quenched from 845 “C (1555 “F) in oil and tempered at 58 “C (100 “F) intervals in 13.718 mm (0.540 in.) rounds.
Tested in 12.827 mm (0.505 in.) rounds. (Source: Republic Steel)
274 / Heat Treater’s Guide
1345,1345H
Chemical Composition. 1345. AISI and UNS: 0.43 to 0.48 C, 1.60
to 1.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. UNS H13J50 and
SAE/AlSI 13458: 0.42 to 0.49 C. I .45 to 2.05 Mn, 0. I5 to 0.35 Si
Similar Steels (U.S. and/or
UNS
G 13450;
Foreign).
1345.
ASTM A322, A331. A519; SAE J404. J412, 5770; (Ger.) DIN 1.0912;
(U.K.) B.S. 2 S 516. 2 S 517. 13458. UNS Hl3450; ASTM A304; SAE
J407; (Ger.) DIN 1.0912: (U.K.) B.S. 2 S 516.2 S 517
Characteristics. The general characteristics of 1345H closely parallel
those given for other medium-carbon
1300 series steels (see details for
133OH). There are exceptions.
As-quenched
hardness is higher. Fully
hardened l345H should provide a minimum hardness of approximately
56
HRC, slightly higher if the carbon content is at the high end of the allowable
range. Weldability
is further decreased. Susceptibility
to quench cracking
is intensified as the carbon content is increased. The hardenability
pattern
for 1345H is very similar to that of 1340H. but adjusted upward because of
the higher carbon content of I345H
Forging.
Heat to 1230 “C (2245 “F). Do not forge after temperature
drops below 870 “C ( I600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 870 “C (1600 “F). Cool in air
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (I525
“F). and cool from 730 “C ( I350 “F) to 6 IO “C ( I I30 “F) at a rate not to
exceed I I “C (20 “F) per h: or cool rapidly from 730 “C (I 350 “F) to 620
“C (I I50 “F). and hold for 1.5 h. For a predominately
ferritic and
spheroidized structure, heat to 750 “C (1380 “F), and cool from 730 “C
(1350”F)to610”C(1130”F)ataratenottoexceed6”C(10”F)perh:or
cool fairly rapidly from 750 “C ( I380 “F) to 640 “C ( I I85 “F). and hold for
8h
Hardening. Austenitize at 830 “C (I525 “F). and quench in oil. Use
water or brine for heavy sections. Flame hardening and carbonitriding
are
suitable processes
Tempering.
Temper immediately
Recommended
l
Forge
NormaJize
l
Anned
l
Rough machine
Austenitize
Quench
Temper
Finish machine
l
l
l
l
l
after quenching
Processing
to desired hardness
Sequence
Alloy Steels (1300 through 9700 Series) / 275
1345: Continuous Cooling Transformation Diagram. Composition: 0.46 C, 1.60 Mn, 0.020 P, 0.015 S, 0.25 Si. Austenitized
(1560°F)
1345H:End-Quench Hardenability
Distance from
quenched
surface
/16h.
I
2
3
4
5
6
7
8
9
IO
II
I2
mm
I .58
3.16
4.74
6.32
7.90
9.48
II.06
12.64
14.22
IS.80
17.38
I8.%
Eardness.
ElRC
max
mlu
63
63
62
61
61
60
60
59
58
57
56
55
56
56
55
54
51
4-t
38
35
33
32
31
30
Distance from
quenched
surface
‘&jh.
mm
13
14
1s
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.4-l
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Eardness,
ERC
min
max
54
53
52
51
49
47
45
4-l
47
46
45
45
29
29
28
28
‘7
27
26
26
25
25
24
24
at 850 “C
1
276 / Heat Treater’s
1345H: Hardenability
(1600 “F). Austenitize:
Guide
Curves. Heat-treating
845 “C (1555 “F)
iardness Limits for Specification
Durposes
I distance,
urn
1.5
)
1
3
5
!O
!5
LO
15
Kl
I5
i0
iardness
‘urposes
distance,
‘16io.
0
1
2
3
4
5
6
8
0
2
4
6
8
0
2
Hardness, HRC
Maximum
Minimum
63
63
63
62
61
60
59
58
55
51
48
47
46
45
45
56
56
54
52
46
38
35
31
29
27
26
25
24
24
24
Limits for Specification
Hardness. HRC
Maximum
hlinimum
63
63
62
61
61
60
60
59
58
57
56
55
54
53
52
51
49
48
41
46
45
45
45
45
56
56
55
54
51
44
38
35
33
32
31
30
29
29
28
28
21
21
26
26
25
25
24
24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
Alloy Steels (1300 through 9700 Series) / 277
1345, 1345l-l: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
Alloy Steels (1300 through
9700 Series) / 277
3310RH
Chemical
COIIIpOSitiOn.
133ORH. AISI and UNS: 0.08 to 0.13 C,
Characteristics.
Applications include carburized bearing and gears
0.40 to 0.60 Mn, 0.15 to 0.35 Si, 3.25 to 3.75 Ni, 1.40 to 1.75 Cr
Recommended
Similar
Steels (U.S. and/or
Foreign).
SAE 3310RH. Has been
added to SAE 51868 and ASTM A914. There is no existing standard
H-grade
3310RH: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize: 845 “C (1555 “F)
temperatures
Heat Treating
Practice
Hardening. Suitable processes include gas carburizing, liquid nitriding,
gas nitriding, carbonitriding, and flame hardening
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
(continued)
278 / Heat Treater’s
Guide
3310RH: Hardenability Curves (continued)Heat-treating
only): 925 “C (1700 “F). Austenitize: 845 “C (1555 “F)
iardness
Qrposes
I distance,
om
1.5
3
5
I
9
II
I3
:5
!O
!S
LO
15
lo
15
i0
Limits for Specification
Hardness, HRC
Maximum
Minimum
42
42
42
41
41
40
40
39
38
37
36
35
35
34
34
37
37
37
36
3.5
34
33
32
30
29
28
27
27
26
26
temperatures recommended by SAE. Normalize (for forged or rolled specimens
278 / Heat Treater’s Guide
4023
Chemical
0.9OMn.O.15
COIIIpOSitiOn.
to0.30Si.0.035
AISI and UNS: 0.20 to 0.25 C. 0.70
Pmax.0.040S
max.0.20 too.30 MO
Similar Steels (U.S. and/or Foreign).
UNS
G40230;
to
ASTM
l
Characteristics.
One of the two straight molybdenum
steels, used
almost exclusively
for making parts that will be case hardened by carburizing or carbon&riding.
When fully quenched, surface hardness is in the range
of 40 to 45 HRC. While its hardenability
is higher than that of a plain
carbon steel of like carbon conte.nt, 4023 is not considered a high-hardenability grade This steel does not have an H counterpart. Grade 4023 is
readily forgeable and weldable. Before welding, the carbon equivalent
should be checked to determine the need for preheating and postbeating
Forging. Heat to 1245 “C (2275 “F) maximum. Do not forge after the
temperature of the forging stock drops below approximately 900 “C ( 1650 “F)
Heat Treating
Normalizing. Heat to
Annealing. Annealing
Case Hardening.
procedures
l
l
l
l
Processing
4023: Approximate
Specimens
Reheat temperature
OF
T
925 “C ( I695 “F). Cool in air
See recommended carburizing.
described for 4 I I8H
carbonitriding,
and
Sequence
Forge
Normalize
Anneal (optional)
Rough and semitinish machine
Austenitize
Case harden
Temper
Finish machine (carburized parts only)
Practice
is not usually required for this grade. Structures
that are well suited to machining are generally obtained by normalizing or
by isothermal annealing after rolling or forging. Isothermal annealing may
be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h
tempering
l
l
A322. A33 I. A5 19, A534; SAE 5404. J4 12.5770
Recommended
Recommended
l
1125
1125
1575
1700(a)
(a) Pseudocarburized
775
775
855
925
Core Hardness of Heat Treated
Eardoess, EB
O.Wiu.
l-in. (25.4mm)
285
293
321
331
223
229
218
155
for 8 hand quenched. Source. Republic
(13.7-mm)
rounds
rOU0d.S
Steel
Alloy Steels (1300 through
9700 Series) / 279
4023: Hardness vs Tempering Temperature.
average based on a fully quenched
4023:
Approximate
Critical
Points
Temperature
lhmsformatioo
point
AC,
AC,
w
&I
Source: Republic Steel
OC
1350
1540
I-l40
1250
750
840
780
670
structure
Represents
an
Alloy Steels (1300 through 9700 Series) / 279
4024
Chemical Composition.
Similar Steels (U.S. and/or Foreign).
UNS
G40240;
ASTM
A322. A33 I, A5 19; SAE J404. J4 12, J770
Characteristics. One of the two straight molybdenum steels. used
almost exclusively
for making parts that will be case hardened by carburizing or carbonitriding.
When fully quenched, surface hardness is in the range
of 40 to 45 HRC. While its hardenability
is higher than that of a plain
carbon steel of like carbon content. 4024 is not considered a high-hardenability grade. This steel does not have an H counterpart. Grade 4024 is
readily forgeable and weldable. Before welding, the carbon equivalent
should be checked to determine the need for preheating and postheating.
With the exception of a slightly higher allowable sulfur content. grades
4023 and 4024 are identical. This difference in sulfur content provides a
slight improvement
in machinability,
but is not sufficient to significantly
impair forgeability
or weldability
Forging.
temperature
“F)
Recommended
AI!31 aod UNS: 0.20 to 0.25 C. 0.70 10
0.90 Mn, 0.15 to 0.30 Si. 0.035 Pmax, 0.035 to 0.050 S. 0.20 fo 0.30 MO
Heat to 1245 “C (2275 “F) maximum. Do not forge after
of the forging stock drops below approximately
900 “C (I 650
4024: End-Quench
Hardenability.
Composition: 0.24 C, 0.88
Mn, 0.33 Si. 0.23 MO. Quenched from 925 “C (1695 “F)
Heat Treating
Normalizing. Heat to
Annealing. Annealing
Practice
925 “C (1695 “F). Cool in air
is not usually required for this grade. Structures
that are well suited to machining are generally obtained by normalizing or
by isothermal annealing after rolling or forging. Isothermal annealing may
be accomplished by heating to 700 “C ( I290 “F) and holding for 8 h
Case Hardening.
tempering
process
procedures
Recommended
l
l
l
l
l
l
See recommended carburizing, carbonitriding,
and
described for4 I l8H. Martempering
is also a suitable
Processing
Sequence
Forge
Normalize
Rough and semifinish machine
Case harden
Temper
Finish machine (carburized parts only)
4024: Hardness vs Tempering
Temperature.
average based on a fully quenched structure
Represents
an
280 / Heat Treater’s
Guide
4024: Cooling Transformation
Diagram. Composition: 0.24 C, 0.88 Mn, 0.33 Si, 0.23 MO. Austenitized
AC,, 825 “C (1520 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite
at 925 “C (1695 “F). Grain size: 8.
280 / Heat Treater’s
4027,4027H,
Guide
4027RH
Chemical Composition.
4027. AK1 and UN.% 0.25 to 0.30 c. 0.70
to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P ma\. 0.040 S max. 0.20 to 0.30 hlo.
Uh'S A10270 and SAE/AISI1027H:0.24 to0.30C.0.60to
1.00Mn.0.15
to0.35Si.0.~0to0.30Mo.SAEJ027RH:0.2Sto0.30C,0.70to0.90~ln.
0.15 to 0.35 Si. 0.20 to 0.30 MO
Similar
ASTM
ASTM
Steels (U.S. and/or Foreign). 4027.
G40~70;
LINS
A322. A33 I. AS 19; SAE J-IO-L J-II?. J770.4027H.
UNS H-10270;
A304 A9 I-l; SAE J 126X. J I868
Characteristics.
Often considered horderline between a carhuriring
grade and a direct-hardening
grade. Commonly used for either cnse-hardening or direct-hardening
applications.
The hardenability
of 4037H is
somewhat higher than a carbon steel of equivalent carbon content. although
not as high as a I300 grade having the same c&on content. As-quenched
hardness (no carburizingj
is generally -IS to 48 HRC. Has excellent forgeability, but only fair machinability.
Can be welded using alloy steel practice.
Preheating and postheating are required because of the relati\el>
high
carbon equivalent
Forging.
forging
Heat to IUS “C (2275 “FL Do not forge after temperature
stock drops below approsimatelj
870 “C (1600 OF)
Recommended
Normalizing.
Heat Treating
of
Practice
Heat to 900 “C t I650 “FL Cool in air
Annealing.
For a predominately
psarlitic structure, heat to 855 “C (1570
“F). and cool rapid11 to 750 “C ( I380 “FL then to 610 “C ( I I85 “F) at a rate
not to exceed I I “C (20 I-‘F) per h: or heat to 870 “C ( 1600 “F). cool rapidly
to 660 “C i I210 “FL and hold for 5 h. For a predominately
spheroidized
structure, heat to 775 “C ( 1125 “FL cool from 745 “C ( I370 JF) to 640 “C
( I I85 “F) at a rate not to exceed 6 “C ( IO “F) per h: or heat to 775 “C (I 425
“F). cool rapid11 to 660 ;C. ( I?20 “F) and hold for 8 h
Direct Hardening.
As-quenched
Tempering.
Heat to 855 “C ( IS70 “F).
hardness. 12 to 48 HRC. Gas carburizing
Reheat to obtain desired hardness
Case Hardening.
tempering
and quench in oil.
is a suitable process
procedures
See recommended cmhutizing.
described for 4 I I8H
carhonitriding.
and
Alloy
Recommended
l
l
l
l
l
l
l
l
Processing
4027:
Sequence
4027: Isothermal
Transformation
quenched
0.565
l.ccMl
2.ooo
-i.ooo
at 925 “C (1695 “F) and fin-
Diagram.
Composition:
9700
Series) / 281
in water
Size round
in.
Sourx
4027: Gas Carburizing.
Carburized
ished at 845 “C (1555 “F)
(1300 through
As-Quenched Hardness
Specimens
Forge
Normalize
Anneal
Rough machine
Austenitize or case harden
Quench
Temper
Finish machine
Steels
Bshlrhrm
mm
I-i.35 I
‘5 400
SO.YOO
101.600
Surface
50 HRC
50 HRC
47 HRC
X3 HRB
Badness,
HRC
‘12 radius
Center
SOHRC
47 HRC
27 HRC
77 HRB
50 HRC
44HRC
27 HRC
7SHRB
Steel
4027: Hardness vs Tempering Temperature.
Tempered at indicated temperatures showing effect of time at temperature
0.26 C. 0.87 Mn, 0.26 MO. Austenitized
at 855 “C (1570 “F). Grain size: 7
282 / Heat Treater’s
Guide
4027H, 4028H: Hardenability
900 “C (1650 “F). Austenitize:
hardness
Purposes
I distance.
um
1.5
3
5
7
3
I1
13
I5
20
25
30
35
iardness
‘urposes
di!aallce,
‘16 in.
0
1
2
3
4
5
6
8
D
2
Curves. Heat-treating
870 “C (1600 “F)
Limits for Specification
Eardness, ERC
MXlXiUllUll
MillhllUU
52
51
45
40
32
29
26
25
23
22
21
45
41
32
23
20
. ..
..
Limits for Specification
Eardness, ERC
Maximum
Minimum
52
50
46
40
34
30
28
26
25
25
24
23
23
22
22
21
21
20
45
40
31
25
22
20
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens only):
Alloy Steels (1300 through
9700 Series) / 283
4027H: End-Quench Hardenability
Distance fkom
quenched
surfsee
‘/,a in.
mm
E=-d=s
ERC
min
max
Distance from
quenched
surface
‘/la in.
mm
Badness,
ERC
max
I
1.58
52
45
I3
20.54
23
2
3
4
3.16
4.74
6.32
50
46
40
40
31
25
I4
I5
16
22.12
23.70
25.28
22
22
21
5
7.90
34
22
I8
28.44
21
6
7
8
9.48
II.06
12.64
30
28
26
20
20
22
24
31.60
34.76
37.92
20
..,
. .
9
IO
II
I2
14.22
15.80
17.38
18.%
25
25
24
23
26
28
30
32
41.08
44.24
47.40
50.56
.__
4027: Gas Carburizing.
Results of 50 tests that represent variation in cation concentration for continuous carburizing. Results
were obtained over a 3 to 4 year period of operation using an automatic dew point controller
4927: Cooling Curve. Half cooling timeSource:
Datasheet
l-91, Climax Molybdenum
Company
284 / Heat Treater’s
Guide
4027RH: Hardenabilitv
Austenitize:
Hardness
Purposes
J distance,
916 in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1.5
16
18
20
22
24
26
28
30
32
Hardness
Purposes
J distance.
mm
1.5
3
5
I
9
11
13
15
20
25
30
35
40
45
50
Curves. Heat-treating
870 “C (16bO “F)
Limits for Specification
Eardness,
hleximum
HRC
hlinimum
51
48
43
31
32
28
26
24
23
22
22
21
21
20
.
46
42
34
28
24
22
20
...
.
...
...
...
...
...
...
...
...
...
...
.
.
“..
.
Limits for Specification
Hardness, ARC
Maximum
hlinimum
51
48
42
35
29
26
24
23
21
.
46
42
33
26
23
20
.
recommedned
by SAE. Normalized
(for forged or rolled specimens
only: 900 “C (1650 “F).
1
Alloy Steels (1300 through
alloy steel. Chemical composition: 0.28 C, 0.25 Si, 0.86 Mn, 0.020 P, 0.028 S, 0.062 Cr, 0.026 Ni,,0.23
heat; bar stock austenitized at 870 “C (1600 “F) 20 min
4027: CCT Diagram. Constructional
MO, 0 .11 Cu. Acommercial
9700 Series) / 285
Alloy Steels (1300 through
9700 Series) / 285
4028,4028H
Chemical
Composition.
4028. AISI and UNS: 0.3 to 0.30 C. 0.70
too.90 hZn.0.15 to0.30Si.0.035
Pmax.0.035
toO.OSOS.0.20 too.30 Mo.
UNS H10280 and SAE/AISI 4028H: 0.24 to 0.30 C. 0.60 to I .OO Mn.
0.035 to 0.050 S. 0.15 to 0.35 Si. 0.X to 0.30 hlo
Similar
ASTM
ASTM
1JNS
G-tO280:
Steels (U.S. and/or Foreign). 4028.
A333. A33 I. AS 19: SAE J-IO-I. 1113. J770.1028H.
LINS H-10280:
A304 SAE J-t07
Direct Hardening.
quenched hardness,
suitable process
Tempering.
Heat tn I245 “C (2275 “F). Do not forge after temperature
forging stock drops belo\\ approxtmately
870 ‘C ( 1600 “F)
Recommended
Heat Treating
of
Practice
Heat to 900 “C (l6SO “F). Cool in air
tempering
l
l
Annealing.
For a predominately
pearlitic structure. heat to 855 “C t IS70
“F). cool rapidI) to 750 “C (I 380 “F). then to 870 “C ( 1600 “F) at a rate not
to exceed I I “C (20 “F) per h: or heat to 870 “C ( 1600 “F). cool rapidly to
660 “C (I 220 “F), and hold for 5 h. For a predominateI>
spheroidized
structure. heat to 775 “C ( I-415 “FL cool from 7-U “C (I 370 “F) to 640 “C
procedures
Recommended
l
l
l
l
l
l
Heat to 85s “C ( IS70 “F) and quench in oil. ASappro\imatelq
12 to 48 HRC. Mat-tempering
is a
Reheat to obtain the desired hardness
Case Hardening.
Forging.
Normalizing.
t I I85 ‘F) at a rate not to exceed 6 “C t IO “F) per h: or heat to 775 “C (1425
“F). cool rapidly to 660 “C t I220 “F). and hold for 8 h
See recommended carbutizing.
described for -I I I8H
Processing
Forge
Normalize
Anneal
Rough machine
Austenitize or case harden
Quench
Temper
Finish machine
Sequence
carbonitriding.
and
288 / Heat Treater’s
1
2
3
4
5
6
7
8
9
10
II
12
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
l8.%
Guide
52
SO
46
40
34
30
28
26
2s
2s
24
23
45
40
31
25
22
20
__.
_._
.
13
14
IS
I6
I8
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
41.40
50.56
23
22
22
21
21
20
. .
4028: Liquid Carburizing. 1'l/32 in. outside diameter by 6 3/4in.
Oil quenched. Carburized at the temperatures indicated
4028, 4028H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
288 / Heat Treater’s Guide
4032,4032H
Chemical Composition.
4032. AISI: 0.30 to 0.35 c, 0.70 to 0.90
Mn.0.20to0.35Si,0.035Pmax,0.040Smax,0.20to0.30hlo.UNS:0.30
to0.35C. 0.70to0.90Mn.0.035
Pmax.0.040S
max.0.15 to0.30Si.0.20
to 0.30 MO. UNS H40320 and SAE/AISI 40328: Nominal. 0.29 to 0.35
C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si. 0.20 to 0.30 Mo
Similar Steels (U.S. and/or Foreign). 4032.
ASTM A322; FED QQ-S-00629 (FS4032);
UNS H40320: ASTM A304; SAE J I268
UNS
G40320;
SAE J404,J412. J770.4032H.
tions carbonitriding
is excellent
has been applied
to 4032H. Forgeability
of this grade
Forging.
forging
Heat to 1235 “C (2275 “F). Do not forge after temperature
stock drops below approximately
870 “C (1600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 900 “C (I 650 “F). Cool in air
Annealing.
Characteristics. With a carbon content that slightly overlaps 4027H
and with an otherwise identical composition,
the general characteristics of
4032H and 4027H are the same. The hardenability
pattern for 4032H
resembles that of4027H. although the curves for 4032H are moved slightly
upward compared with those for 4027H because of a higher nominal
carbon content. Fully hardened 4032H wiU provide a surface hardness of
approximately
48 HRC or slightly higher.
Grade 4032H is less weldable and has a slightly lower machinability
than 4027H because of a higher nominal carbon content. Direct hardening
rather than case hardening is used for 4032H. although for special applica-
of
For a predominately
pearlitic structure. heat to 855 “C (1570
“F). cool rapidly to 750 “C (I 380 “F), then to 640 “C (I I85 “F) at a rate not
to exceed I I “C (20 “F) per h; or heat to 870 “C (I 600 OF), cool rapidly to
660 “C (1220 “F), and hold for 5 h. For a predominately
spheroidized
structure, heat to 775 “C (1425 “F). cool from 745 “C ( 1370 “F) to 640 “C
(I I85 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 775 “C (1425
“F’), cool rapidly to 660 “C ( I220 “F), and hold for 8 h
Hardening. Heat to 855 “C (I 570 OF). and quench in oil. Carbonitriding
is a suitable process
Tempering.
Reheat to obtain the desired hardness
Alloy Steels (1300 through 9700 Series) / 287
Recommended
Forge
l
Normalize
. t%‘uE.d
l
Rough machine
l
Austenitize
l
Quench
l
Temper
l
Finish machine
l
Processing
Sequence
4032, 4032H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4032: Continuous Cooling Transformation Diagram. Composition: 0.32 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.28 MO. Austenitized at
1
288 / Heat Treater’s
4032H: Hardenability
(1650 “F). Austenitize:
Hardness
Purposes
I distance,
mm
1.5
3
i
7
2
I1
13
I.5
!O
15
$0
15
ul
15
50
Hardness
Purposes
I distance,
V,6 in.
5
5
>
IO
I1
I2
I3
I4
15
I6
18
!O
!2
!4
!6
!8
10
Guide
Curves. Heat-treating
870 “C (1600 “F)
Limits for Specification
Hardness,
Maximum
HRC
Minimum
51
55
51
44
36
32
29
21
24
23
23
22
21
20
50
46
34
21
24
22
20
.
.
Limits for Specification
Hardness, HRC
Maximum
Minimum
57
54
51
46
39
34
31
29
28
26
26
25
24
24
23
23
23
22
22
21
21
20
50
45
36
29
25
23
22
21
20
.
.
..”
.
.
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
1
Alloy Steels (1300 through 9700 Series) / 289
4032H: End-Quench
Distance from
quenched
surface
916in.
I
2
3
-I
5
6
1
8
9
IO
II
I3
Hardenability
Distance from
quenched
surface
Hardness,
ERC
Hardness,
mm
max
min
!$6 in.
mm
HRC
mas
1.58
3.16
57
5-l
SO
1s
36
19
15
23
22
21
20
13
I-1
IS
I6
I8
20
22
20.51
22.11
23.10
25.28
28.44
31.60
21
2-l
23
23
'3
2
31.16
22
1-l
31.9).
1108
44.21
21
21
20
1.11
51
6.37
46
39
31
31
29
28
26
26
25
1.90
9-18
Il.06
12.64
11.22
IS.80
1138
I8.%
::'
26
28
30
11.40
32
50.56
Alloy Steels (1300 through
9700 Series) / 289
4037,4037H
Chemical Composition.
4037. AISI and UNS: 0.35 10 0.40 C. 0.70
to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.20 to 0.30 hlo.
UNS H40370 and SAE/AISI 4037H: 0.34 to O.-l I C. 0.60 to I .OO hln. 0. IS
to 0.35 Si. 0.70 to 0.30 hlo
Hardening. Heat to 845 “C ( IS55 “F). and quench in oil. Carbonitriding
is a hardening process. In aerospace practice. parts are austenitized at 815
“C t IS55 “F). and quenched in oil or hater
Similar
Tempering.
Steels (U.S. and/or
Foreign).
ASTM A322. A33 I. AS 19, AS-+7: WE
H40370: ASTM A30-I: SAE J 1368
UNS
G-10370:
4037.
J-KM. J-Ill. 5770. 1037H. UNS
Characteristics.
A medium-carbon.
IOU-alloy steel that can be hardened to approximately
SO HRC or slightly higher, provided it is properl!
quenched. and the carbon is on the high side of the allouable range. The
hardenabilib
pattern is similar to that of other carbon-molybdenum
steels
(4077H and 103ZH) except that the curves move up\\ard hecause of the
higher carbon content. Has excellent forgeability,
but neldahility
(princepall? m terms of susceptibility
to weld cracking) decreases as carbon
content mcrcasrs
Rehsat to the temperature
hardness. See table
Recommended
l
l
l
l
l
l
l
Forging.
forging
Heat to I?30 “C ( X-IS “FL Do not forge after temperature
stock drops beIon approrimately
85.5 “C ( IS70 OF)
Recommended
Heat Treating
of
Practice
Normalizing.
Heat to 870 “C (1600 ‘FL Cool in air.
In aerospace practice, parts &arenormalized at 900 “C ( 1650 “F)
Annealing.
For a predominately
pearlitic structure, heat to 845 “C ( IS55
“F). cool rapidly to 745 “C ( I370 “FJ. then to 630 ‘C ( I I70 “F) at a mte not
to exceed I I “C (20 “F) per h; or heat to 845 “C ( IS55 “F), cool rapidI> to
660 “C ( IX0 “F). and hold for 5 h. For a predominately
spheroidired
structure. heat to 760 “C ( I100 “F). cool from 7X “C ( 1370 “F) to 630 “C
t I I70 “F) at a rate not to esceed 6 “C ( IO “F) per h: or heat to 760 “C ( I400
“F). cool rapidly to 660 “C (I 220 “F). and hold for 8 h.
ln aerospace practice. pans are annealed at 815 “C ( IS55 OF). Pans are
cooled to below -WI ‘% (750 “F) at a rate not to exceed I IO “C i200 OF) per h
l
Processing
required
to provide
the desired
Sequence
Forge
Normalize
Annsal
Rough machine
Austenitize
Quench
Temper
Finish machine
4037: Suggested
practice)
Tempering
Temperatures
(Aerospace
Tensile Strength Ranges
86010
1035 to
1175 to
1240 to
1035 MPa
1175 MPa
1240 hlPa
1380 blPa
620 to 860 MPa
(90to 125ksi) (125to 15Ok.G) (150to 17Ok.G) (170 to 180 ksi) (180 to200 ksi)
595 ‘Cl II
I IIOO”F,
65O”Cfh)
(1200°F)
s-lo ‘C
(lCMXI’;FI
595 ‘C
IIIOO”Fl
(a) Quench m oil or pol!nw
195 ‘C
r92S ‘:‘F)
5-u) “C
I IOW’F,
440 “C
(825 “I=)
-170“C
(875 “F)
Ib) @ench in ~awr. Source: AMS 275911
370 “C
1700°F)
3x5 “C
(725 “FJ
290 / Heat Treater’s
Guide
4037H: End-Quench Hardenability
Distance hm
quenched
Diktancefrom
ERC
surface
v,l/lain.
I
2
3
4
5
6
7
8
9
10
II
I2
mm
I .58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.%
max
Earducss,
quenched
Bardn-9
ERC
surface
min
‘/la
in.
mm
max
59
52
13
20.54
26
57
54
51
45
38
34
32
30
29
28
27
49
42
35
30
26
23
22
21
20
14
15
I6
18
20
22
24
26
28
30
32
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
4.2-l
47.40
50.56
26
26
35
25
25
2.5
24
24
24
23
23
4037: Cooling Curve. Source: Datasheet
l-21 6. Climax Molybdenum
Company
Alloy Steels (1300 through
4037: Isothermal Transformation
Diagram. Composition:
0.35 C, 0.80 Mn, 0.25 MO. Austenitized
4037: Hardness vs Tempering Temperature. Normalized at 870
“C (1600 “F). Quenched from 845 “C (1555 “F) and tempered in
56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in
12.827 mm (0.505 in.)
9700 Series) / 291
at 855 “C (1570 “F). Grain size: 7
4037: Hardness vs Tempering Time and Tempering Temperature. Tempered at temperatures indicated
292 / Heat Treater’s
4037H: Hardenability
(1800 “F). Austenitiz&
Hardness
Purposes
I distance,
nm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
rlardness
Purposes
I distance,
46in.
1
3
>
10
I1
12
13
14
15
16
18
,O
12
24
16
23
30
32
Guide
Curves. Heat-treating temperatures
845 “C (1555 “F)
-
Limits for Specification
Hardness, HRC
hlaximum
hliuimum
59
57
54
49
41
35
32
30
21
26
25
25
25
24
23
52
50
42
32
27
24
21
20
.
Limits for Specification
Eardness, HRC
Maximum
hlinimum
59
51
54
51
45
38
34
32
30
29
28
21
26
26
26
25
25
25
25
24
24
24
23
23
52
49
42
35
30
26
23
22
21
20
.
..
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
Steels (1300 through
9700 Series) / 293
4037: CCT Diagram. Constructional alloy steel composition: 0.41 C, 0.74 Mn, 0.008 P, 0.032 S, 0.28 Si, 0.014 Ni, 0.034 Cr, 0.21 MO, 0.065
Cu. Acommercial heat; barstock steel was austenitized for20 min at 845 “C (1555 “F). Source: Datasheet l-21 6. Climax Molybdenum Company
Alloy
Steels (1300 through
9700 Series) / 293
4042,4042H
Chemical
Composition.
1042. AISI: 0.40 to 0.15 C. 0.70 to 0.90
Mn.0.20 too.35 Si.O.040 Pmax.0.040S
max.0.20 too.30 hlo. UNS: 0.40
to0.3.S C. 0.70 to 0.90 hln. 0.035 Pmax. 0.010 S max. 0. IS too.30 Si. 0.30
to 0.30 MO. UNS H40420 and SAE/AISI
JOJZH: 0.39 to 0.46 C. 0.60 to
1.00 Mn. 0.15 to 0.3s Si. 0.20 to 0.30 hlo
Similar
ASTM
ASTM
Steels (U.S. and/or Foreign). 1042.
A322, A33 I, A5 19: SAE J-10-1. J312.J770.1042H.
A3O-l; SAE J I368
UNS
G-10-110:
LINS H-tO-tX
Characteristics.
Has characteristics
that closeI) parallel those of the
other medium-carbon.
molybdenum-alloy
steels (see -1027H and -1037H).
As the carbon content increases. the as-quenched hardrwss mcreases. Depending to some extent upon the precise carhon content. fully hardened
-1012H has a surface hardness of approsimatel>
55 HRC. Forgeobilit> of
this grade is escellent. but welding is difficult bscause of the difticult)
in
producing crack-free welds
Forging.
Heat to 1230 ‘-‘C (2245 “FL Do not forge after temperature
forging stock drops helow approximately
855 “C (IS70 “F)
Recommended
Heat Treating
Practice
of
Annealing.
For a predominately
pwlitic
structure. heat to 845 “C (1555
“FL cool rapidI\ to 745 “C (I 370 “F). then to 630 “C (I 170 “F) at a rate not
to exceed I I ‘C t 20 “F) per h: or hcu to 8-15 “C ( I555 “F), cool rapidly to
660 ‘C. (I220 OF). and hold for S h. For a predominately
spheroidized
structure. heat to 760 “C I 1400 “F). cool from 735 “C ( I370 “F) to 630 “C
(I 170 “F) at a r;ltc not to eucred 6 “C (IO “F) per h; or heat to 760 “C (I400
“F), cool rapidI> to 660 “C ( I220 “F). and hold for 8 h
Hardening. Heat to 845 “C ( I555 OF), and quench in oil. Carbonitriding
is a suitable process
Tempering.
Recommended
l
l
l
l
l
l
l
Normalizing.
Heat to 870 “C I 1600 “F). Cool in air
Reheat to the temperature
required
to provide
h,udrwss
l
Forge
Nomlalizc
Anneal
Rough machine
Austrnitirz
Quench
Tsmpcr
Finish machins
Processing
Sequence
the desired
294 / Heat Treater’s
4042: Continuous
Guide
Cooling Transformation
Diagram. Composition:
0.40 C, 0.80 Mn, 0.025 P, 0.020 S, 0.30 Si, 0.26 MO. Austenitized
at
810 “C (1490 “F)
4042: Isothermal Transformation
Diagram. Composition:
0.42 C, 0.20 Mn, 0.21 MO. Austenitized
at 870 “C (1600 OF). Grain size: 5 to 6
Alloy Steels (1300 through
I
2
3
4
5
6
7
8
9
IO
II
I2
I .58
3.16
4.14
6.32
7.90
9.48
II.06
12.64
14.22
15.80
17.38
l8.%
62
60
58
55
50
45
39
36
34
33
32
31
5.5
52
48
40
33
29
27
26
25
24
24
23
I3
I4
I5
I6
I8
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
30
30
29
29
28
28
28
27
27
27
26
26
9700 Series) / 295
23
23
22
22
22
21
20
20
4042: Hardness vs Tempering Temperature. Normalized at 870
“C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds.
Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel
296 / Heat Treater’s
4042H: Hardenability
(1600 “F). Austenitize:
Hardness
Purposes
I distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
Purposes
I distance,
V,6 in.
i
3
IO
11
12
13
14
15
I6
18
!O
!2
!4
!6
!8
10
$2
Guide
Curves. Heat-treating
845 “C (1555 “F)
Limits for Specification
Eardness,
Maximum
HRC
hlinimum
55
53
47
36
30
27
25
24
23
22
21
20
62
61
58
54
48
40
36
33
31
29
28
28
27
27
26
Limits for Specification
Hardness, HRC
Maximum
hlinimum
62
60
58
55
50
45
39
36
34
33
32
31
30
30
29
29
28
28
28
27
27
27
26
26
55
52
48
40
33
29
27
26
25
24
24
23
23
23
22
22
22
21
20
20
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
Steels (1300 through
9700 Series) / 297
4047,4047H
Chemical Composition.
4047. AISI and UN% O.-IS to 0.50 C. 0.70
to 0.90 Mn, 0.15 to 0.30 Si, 0.035 P max. O.O-iO S max. 0.20 to 0.30 Mo.
UNSH40470and SAE/AISI4047H:0.1-1toO.S1
C.O.60to l.OOMn.O.lS
to 0.35 Si. 0.20 lo 0.30 MO
Similar
ASThl
ASTM
Steels (U.S. and/or
Foreign).
4047.
A322. A33 I. AS 19: SAE J-W. JA II. J770.4047H.
A30-k SAE J I268
UNS
G10-170;
UNS H-lO-I70:
Characteristics.
W7H.
which ma) have a carbon content of up to
0.51. borders on u hat may be considered high-carbon steel and is sometimes used in applications that require spring grades. The hardenability
of
11U7H exhibits a pattern veq similar to the lower or medium-carbon
grades of the -lOXX series. although both the minimum and masimum
tunes are shifted further upward on the hardenability
chart because of the
higher carbon content of -IO-L7H. As-quenched hardness of fully hardened
-W7H should be near S5 HRC or slightI) higher. depending upon the
precise carbon content. Readily forged. but not r&omm;nded
fir \;*elding.
In addition to direct hardening and tempering. 10-17H is well adapted to
heat treating bq the nustempering process
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (IS25
“F). cool fairlq rapidlv to 730 “C ( 1350 “Fj. then to 630 “C ( I I70 “F) at a
rate not to exceed I I ;C (20 “F) per h: or cool fairly rapidly from 830 “C
(IS25 “Fj to 660 “C ( I220 “F). and hold for 5 h. For a predominately
spheroidized structure, heat to 760 “C ( 1400 “F). cool fairly rapidly to 730
“C t I350 “F), then to 630 “C ( I I70 “F). at a rate not to exceed 6 “C (IO “F)
per h; or heat to 760 “C ( 1100 “F). cool Fairly rapidly to 650 “C ( I200 “F).
and hold for 9 h
Hardening. Austenitize at 830 “C ( I525 OF). and quench in oil. Austempering and cwbonitridinp
are suitable processes
Tempering.
forging
Heat to I220 “C (2325 “F). Do not forge after temperature
stock drops belo\+ approsimntel)
8-lS YI ( 1555 “F)
of
Heat Treating
Practice
Recommended
l
l
l
l
l
Normalizing.
Heat to 870 “C (1600 “FL Cool in air
4047: Isothermal Transformation
Diagram. Composition:
to provide
the desired
Austenitize at 845 “C (I555 OF), quench in agitated
molten salt at 315 “C (655 “F). hold for 2 h and cool in air. Resulting
hardness should be 15 to SO HRC. No tempermg is required
l
Recommended
required
Austempering.
l
Forging.
Reheat to the temperature
hardness
l
Processing
Sequence
Forge
Normalize
Anneal
Rouph machine
Austenitize (or austemper)
Quench (or austemper)
Temper (or austemper)
Finish machine
0.48 C. 0.94 Mn. 0.25 MO. Austenitized
at 815 “C (1500 “F). Grain size: 6 to 7
298 / Heat Treater’s
4047: Continuous
Guide
Cooling Transformation
Diagram. Composition:
810 “C 11490 “Fb
4047H: End-Quench Hardenability
Diitance from
quenched
surface
i6 in.
mm
Eardoess,
RRC
max
min
Distance from
quenched
surface
‘/16h.
mm
Hardness,
ERC
max
min
1
2
3
4
5
6
7
8
9
10
11
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
64
62
60
58
55
52
47
43
40
38
37
51
55
50
42
35
32
30
28
28
27
26
13
14
15
16
18
20
22
24
26
28
30
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
34
33
33
32
31
30
30
30
30
29
29
2.5
25
25
25
24
24
23
23
22
22
21
12
18.96
35
26
32
50.56
29
21
0.48 C, 0.80 Mn, 0.025 P, 0.020 S, 0.25 Si, 0.26 MO. Austenitized
at
Alloy
Steels (1300 through
9700 Series) / 299
4047: Cooling Transformation
Diagram. Composition: 0.51 C, 0.81 Mn. 0.25 Si, 0.26 MO. Austenitized at 845 “C (1555 “F). Grain size: 8.
AC,, 790 “C (1455 “F); AC,, 745 “C (1370 “F). A: austenite, G: ferrite. P: pearlite, B: bainite, M: martensite. Source: Bethlehem Steel
4047: Hardness vs Tempering Time and Tempering Tempsrature. Tempering temperatures indicated
300 / Heat Treater’s
Guide
4047: Variations in Depth of Hardening. Tempered 1 h at indicated temperatures. (a) 12.7 mm
(l/2 in.) diam cylinders; (b) 25.4 mm (1 in.) diam
cylinders: (c) 38.1 mm (1’12 in.) diam cylinders
4047: Microstructures.
(a) 2% nital. 110x. Hot rolled steel bar. 28.6 mm (15s in.) diam with a mill defect (a sliver of metal) at the surface,
folded over oxide (dark gray). Primarily ferrite, resulting from decarburization, with patches of fine pearlite (dark). (b) 2% nital. 550x. Cold
drawn steel bar, 23 mm (29/32 in.), mill annealed; longitudinal section. Somewhat segregated ferrite (white) and fine pearlite (dark) caused
difficulty in machining (drilling) (continued)
Alloy
Steels (1300 through
9700 Series) / 301
4047: Microstructures
(continued).
(c) 2% nital, 550x. Hot rolled steel 26.2 mm (1 l/32 in.) diam: longitudinal section taken at midradius.
Acicular ferrite and upper bainite. resulting from rapid cooling from rolling temperature. Large dark areas are pearlite. (d) 2% nital, 550x.
Steel forging, 12.7 mm (‘12 in.) thickness, air cooled from forging temperature of 1205 “C (2200 “F); longitudinal section. Plates of ferrite
(white) and fine pearlite (dark). (e) 2% nital, 500x. Steel forging. Longitudinal section, 15.9 mm (5/8 in.). Austenitized at 830 “C (1525 “F),
cooled to 665 “C (1230 “F) and held 6 h. furnace cooled to 540 “C (1000 “F). air cooled. Ferrite (white) and lamellar pearlite (dark)
4047: Cooling
Curve. Half cooling time. Source: Datasheet
l-21 9. Climax Molybdenum
Company
302 / Heat Treater’s
Guide
4047H: Hardenabilitv Curves. Heat-treatina temperatures recommended by SAE. Normalize (for forged or roiled specimens only): 870 “C
(1600 “F). Austenitizk 845 “C (1555 “F)
Hardness
Purposes
1 distance.
mm
1.5
3
5
7
3
11
13
15
20
25
30
35
40
15
50
Hardness
Purposes
J distance,
‘$6 in.
1
2
3
1
5
5
7
3
3
10
11
12
13
14
15
16
18
20
!2
14
!6
!8
30
52
Limits for Specification
Flardness, mc
MilliDlUIU
Maximum
64
63
60
57
53
48
43
39
34
33
31
30
30
29
29
57
55
49
39
33
30
28
21
25
24
24
23
23
22
21
Limits for Specification
Eardnes, ERC
Maximum
Minimum
64
62
60
58
55
52
41
43
40
38
31
35
34
33
33
32
31
30
30
30
30
29
29
29
57
55
50
42
35
32
30
28
28
27
26
26
25
25
25
25
24
24
23
23
22
22
21
21
Alloy Steels (1300 through
4047: CCT Diagram. Constructional
9700 Series) / 303
alloy steel. Chemical composition: 0.48 C, 0.23 Si, 0.78 Mn, 0.005 P: 0.020 St 0.06 Cr, 0.012 Ni, 0.25
MO, 0.015 Cu. Bar stock from commercial heat was used in study. Steel was austenitized at 845 “C (1555 “F) 20 min. Source: Datasheet
l-219, Climax Molybdenum Company
Alloy Steels (1300 through 9700 Series) / 303
4118,4118H,
Chemical Composition.
4118RH
4118. AISI and UNS: 0. I8 to 0.23 C. 0.70
to 0.90 Mn. 0.15 to 0.30 Si. 0.035 P max. 0.040 S max. 0.40 to 0.6OCr. 0.08
to 0. I5 MO. UNS If41180 and SAE/AISI 4118H: 0. I7 to 0.23 C. 0.60 to
1.00 Mn, 0.15 to 0.35 Si. 0.30 to 0.70 Cr. 0.08 to 0.15 MO. SAE 4118RI-I:
0.18 to 0.23 C, 0.70 to 0.90 Mn. 0.15 to 0.35 Si. 0.10 to 0.60 Cr. 0.08 to
0.15 MO
Similar Steels (U.S. and/or Foreign). 4118.
UNS
G-l I 180:
SAE 5404. J412. J770. 4118H. UNS
ASTM A322, A33l. A505, ASl9;
H-II 180: ASTM A304: SAE Jl268.51868;
Characteristics.
ASTM
A913
Low-ahoy
steel which is used extensively
for case
hardening applications. conventional
carhurizing as well as carhonitriding.
As can be observed in the hardenability
data for -II ISH, the hardenability
differs little from that of a comparable 1000 series steel. The chromium
addition in 41 ISH little more than offsets the decrease in molybdenum
content. Depending somewhat upon the precise carbon content of 41 IgH.
the as-quenched surface hardness will be approximately
38 HRC or slightly
higher. Forgeahility
is excellent, but machinability
is only fair. 41 I8H can
be readily welded. although before any welding is attempted the carbon
equivalent
observed
should
Forging.
Heat to I?-!5 “C (2275 “F) maximum.
Do not forge after
of forging stock drops below approximately
870 “C (1600 “F)
temperature
be determined.
Recommended
Normalizing.
and recommended
Heat Treating
Heat to 925 “‘C (I695
welding
practices
Practice
“F). Cool in air
Annealing. Not usually required for this grade. Structures that are well
suited to machining are generally obtained by normalizing or by isothermal
annealing after rolling or forging. Isothermal annealing may be accomplished hy heating to 700 “C ( 1290 “F) and holding for 8 h
Direct Hardening. While applications for 41 l8H seldom require direct hardening. it can be accomplished by austenitizing at 900 “C (1650 “F)
and quenching in oil. Ion nitriding, gas nitriding, carbonitriding.
and gas or
liquid salt bath carburizing are suitable processes
Carburizing. II l8H responds readily to any gas or liquid salt bath
carburizing processes. The most widely used gas carburizing procedure is
described helow:
304 / Heat Treater’s Guide
l
l
l
l
Heat to 925 “C ( I695 “F) in a gaseous atmosphere with a carbon potential
of approximately
0.90%, for the required time. About 4 h at temperature
is required to attain a case depth of 1.37 mm (0.050 in.)
Decrease temperature to 845 “C ( 1555 “F). decrease carbon potential
slightly, and hold for a I h diffusion cycle
Quench in oil
Temper at I SO to I75 “C (300 to 335 “F). Higher tempering temperatures
may be used if some case hardness can be sacrificed
Other carburizing
cycles may be used. One cycle consists of slo\r
cooling from the carburizing temperature, then reheatmg to 845 “C ( IS55
“F) and oil quenching. However. this cycle is used less FrequentI) because
it hastes energy and takes too much ttme. Double treatments Hhich Mere
extensively used at one time are all but obsolete.
Depth of carburized cases depends upon time and temperature. The
rate of carburization
can be increased exponentially
by increasing the
carburizing temperature from 925 “C (I695 “F) to 1040 “C t 1905 “F) or
even higher. However, the economics must be considered. As a rule. the rate
of deterioration
of conventional
carburizing
furnaces becomes intolerable
as temperatures exceed 925 “C (1695 “F). Using a vacuum furnace has
proved to be the most practical answer to carburizing
at temperatures as
high as 1095 “C (2005 “F).
Carbonitriding.
3 I I8H is widely used in applications involt ing small
hardware items where only a thin. file hard case is required. In carbonitriding. the parts &are heated in a carburiring
atmosphere I$ ith an addition of
approximately
IO vol % anhydrous ammonia. Carbonitriding
temperatures
are most often within the range of 790 to 815 “C (I-155 to IS55 “F)
A common carbonitriding
cycle for lou-carbon
alloy steels. such as
3 I I8H, is to carbonitride at 8 IS “C ( IS00 “F) for 45 nun and quench in oil.
This results in a tile hard case approximately
0. I27 mm (0.005 in. j in depth.
Somewhat deeper cases may be obtained by increasing the temperature. the
4118H: End-Quench
Distance from
quenched
surface
916 in.
mm
I
1
3
-I
5
6
7
8
9
IO
II
I2
Hardenability
Aardoess,
ERC
max
min
IS8
48
3.16
4.7-I
6.32
7.90
9.48
II.06
12.64
l-l.32
IS.80
17.38
I8.%
46
II
3s
31
28
27
26
2-t
13
22
21
II
36
27
2.3
10
Distance from
quenched
surface
I&j in.
mm
I3
i-l
I5
I6
I8
20
22
2-t
26
‘8
30
32
Rardness
HRC
max
time. or both. Houever. this process is designed especially for developing
thin cases on small parts which \vill not be subjected to such finishing
operations as grinding.
Tempering of carbonitrided
parts is recommended ( IS0 to 260 “C, or
300 to 500 “F), because it decreases the tendency for brittleness, although
the vast majority of carbonitrided
parts are placed in service without
tempering
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
AMC~
(optional)
Rough and semilinish machine
Case harden or direct harden
Temper
Finish machine tcarbunzed parts only)
4118: Diametral Dimensions of a Pinion Before and After Carburizing and Hardening.
Carburlzed at 885 “C (1625 “F), oil
quenched
from 830 “C (1525
“F), tempered
at 185 “C (365 “F).
Depth of case, 1.016 to 1.270 mm (0.040 to 0.050 in.). 60 HRC
minimum. (a) Before treatment. (b) Aftertreatment.
(c) Differential
drive pinion gear
Alloy Steels (1300 through 9700 Series) / 305
4118, 4118H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4118H:
As-Quenched
Specimens
were quenched
Hardness
in oil
Size round
in.
mm
Surface
Aardness
‘12 radius
Center
33 HRC
12 HRC
33 HRC
20 HRC
33 HRC
20 HRC
87
88 HRB
87
88 HRB
85
87 HRB
4118H: Microstructures. (a) 4% nital, 250x. Steel bar, gas carburized for 8 h at 925 “C (1695 “F), quenched in oil, heated to 845 “C (1555
“F) and held for 15 min, quenched in oil, tempered for 1 h at 170 “C (340 “F). Completely decarburized surface layer (white). Structure identified in (b). (b) 4% nital, 500x. Same as (a), but a higher magnification. Shows surface oxidation (dark at top), decarburized surface layer
(ferrite), transition zone consisting of ferrite plus low-carbon martensite. and matrix of tempered martensite and retained austenite. (c) 4%
nital, 100x. Carburized, hardened, and tempered same as (a), but shows only partial decarburization near surface because specimen previously contained precipitated intergranular carbide particles. Case matrix same as (b). (d) 4% nital, 250x. Steel tubing, gas carburized 5 h
at 925 “C (1695 “F) and oil quenched, then hardened and tempered same as (a). Specimen shows the effect of localized overheating (burning) of the carburized surface during grinding. See (e) and (f). (e) 4% nital. 100x. Same as (d), but with less severe grinding burn. As in (d),
the light-etching surface layer is untempered martensite and retained austenite (not distinguishable here), and adjacent dark-etching zone
is self-tempered martensite. See (f). (f) 4% nital, 500x. Same as (d) and (e), except grinding burn is extremely slight. White surface layer
(untempered martensite) is barely perceptible, and the underlying layer of self-tempered martenslte is shallow. As in (d) and (e), matrix is
tempered martensite
306 / Heat Treater’s
Guide
4118H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness
hrposes
I distance,
urn
iardness
‘urposes
distance,
$6 in.
Limits for Specification
Eardness, ERC
Maximum
Minimum
Limits for Specification
Eiardnes, ERC
Maximum
Minimum
48
46
41
35
31
28
21
0
I
2
3
4
5
2s
24
23
22
21
21
20
41
36
27
23
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steels (1300 through 9700 Series) / 307
4118:
Carburizing, Single Heat Results
Specimens contained 0.21 C, 0.80 Mn, 0.008 P, 0.007 S, 0.27 Si, 0.16 Ni, 0.52 Cr, 0.08 MO; grain size was 6 to 8; critical points included AC,,
750°C (1380°F); Ac3, 825°C (1520°F); Ar,, 775°C (1430°F); Ar,, 680°C (1260 “F); 14.4-mm (0.565-in.) rounds were treated; 12.8-mm (0.505in.) rounds were tested
Recommended
For maximum
practice
hsile
ksi
streagtb
MPa
61
62
62
0.063
o.tN7
0.047
1.600
1.19-l
1.19-l
177.5
I-13.0
126.0
1223.8
985.6
868.7
131.0
93.5
63.5
903.2
644.7
437.8
9.0
17.5
21.0
42.3
41.3
42.4
352
293
241
57
56
56
0.063
0.047
0.047
1.600
1.19-l
1.19-l
177.0
138.0
120.0
1220.4
961.5
827.4
130.0
89.5
63.0
8%.3
617.1
-13-t.4
13.0
17.5
22.0
48.0
41.9
48.9
341
277
229
Eardness,
EIB
case hardness
Direct quench from pot(a)
Single quench and temper(b)
Double quench and temprk)
For maximum
mm
Eardness,
ERC
Yield strength
0.2 % offset
bi
hIPa
Core properties
Elongation
in2in.
Reduction
@mm),
9% ofarea, 5%
case properties
Depth
in.
core toughness
Direct quench from pot(d)
Single quench and tempede)
Double quench and temper(f)
(a) Carburized at 1700 “F(925 “C) for 8 h. quenched in agitated oil, tempered at 300 “F( IS0 “C). (b) Carhurized at I700 “F (925 “C) for 8 h, pot cooled reheated to 1525 “F (830
“0. quenched in agitated oil. tempered at 300 “F (150 “CJ. Good case and core properties. (c) Carburized at I700 “F (925 “C) for 8 h, pot cooled, reheated to IS25 “F (830°C).
quenched in agitated oil. tempered at 300 “F ( I SO “C). Maximum refinement of case and core. (d) Carburized at I700 “F (925 “C) for 8 h. quenched in agitated oil, tempered at 450
“F(230”C).(e)Carburizedat
1700”F(925”C)for8h,potcooled,reheatedto
lS2SoF(830”C).quenchedinagitatedoil,tempe~dat~S0”F(230”C).Goodcaseandcoreproperties.
(f)Carburizedat
17OO”F(925 “0 for 8 h, pot cooled. reheated to I.525 “F(830”C).
quenchedin agitatedoil.
tempered iit lSO”F(230
“C). Maximum refinement ofcaseandcore.
Source: Bethlehem Steel
Alloy Steels (1300 through 9700 Series) / 307
4120H,
4120RH
Chemical Composition. 4120H. AISI and UNS H41200: 0.18 IO
0.23 C. 0.90 to 1.20 Mn. 0.15 to 0.35 Si. O.-IO to 0.60 Cr. 0.13 to 0.20 MO.
SAE4120~:0.18to0.23C.0.90to1.20Mn,0.15to0.35Si.0.~0to0.60
Cr. 0. I3 to 0.20 MO
Similar Steels (U.S. and/or Foreign).
added to SAE J I268 and J I868 and to ASTM
standard H-steel
Characteristics.
its, but is carefully
8630
Both steels were recently
A9l-I. There is no existing
The RH grade is made to narrower composition
controlled
to provide restricted hardenability.
steels are equivalent to 8620H and 862ORH in hardenability,
but have
higher manganese content. no nickel, slightly
higher chromium,
and
slightly less molybdenum.
Jn application.
these steels are alternatives for
Recommended
Hardening. Ion
processes
limBoth
Heat Treating
nitriding.
gas nitriding,
Practice
and carbonitriding
are suitable
308 / Heat Treater’s
Guide
4120RH: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitiie:
Hardness
Purposes
.I distance,
‘/,#j in.
1
2
3
4
5
6
I
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
Hardness
Purposes
1 distance,
mm
1.5
3
5
7
?
I1
13
15
10
?5
30
35
to
15
$0
925 “C (1700 “F)
Limits for Specification
Hardness, HRC
Madmum
Minimum
47
45
41
38
34
31
29
28
26
25
24
23
23
22
22
21
20
42
39
35
30
26
24
22
21
20
.. .
.
..
.
.
.
Limits for Specification
Hardness, HRC
Maximum
Minimum
41
45
41
36
32
29
28
26
23
21
.
..
.
42
39
34
28
25
22
21
20
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steels (1300 through
9700 Series) / 309
4130,413OH
Chemical
Composition.
4130. AISI and UNS: 0.28 to 0.33 C. 0.40
toO.60~ln.0.lSto0.30Si.0.03SPn~a~.0.0~0Smax.0.80to
Recommended
to 0.25 MO. UNS HJ1300 and SAE/AISI J130H: 0.27 to 0.33 C. 0.30 to
0.70 hln. 0.035 P max. 0.010 S max. 0. I5 to 0.30 Si. 0.75 to I.20 Cr. 0. IS
Normalizing.
to 0.3
Annealing.
hlo
Similar Steels (U.S. and/or Foreign). 113O.l~NSG41300;AbIS
6350. 6356. 6360. 636 I. 636’. 6370. 637 I. 6373; ASTM A322. A33 I.
A505. ASl3. ASl9, A6-lh: hlfL SPEC MLS-16971:
SAE J-IO-I, J-112.
5770; (Ger.) DIN I .7118: (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 25 Crhlo
1.25 Crhlol
KB: (Jap.) JIS SChl 2. SCCM
I; (Swed.) SS)-) 3325; (U.K.)
B.S. CDS I IO. 41308. UNS H-l 1300; ASThI A.304; SAE J-107: (Ger.) DIN
I .72 18; (Fr.) AFNOR 25 CD -t(S); (Ital.) UNI 35 Crhlo -I. 25 Crhlo -I KB;
(Jap.) JIS SCM 2. SCCrbl I; (Sned.) SSIJ 3335: (U.K.) B.S. CDS I IO
Heat to 900 “C ( I650 “FL Cool in air
For a predominateI> pearlitic structure. heat to 855 “C ( IS70
“F). cool fairly rapidly to 760 “C (I400 ‘F). then to 665 “C (1730 “F) at a
rate not to exceed I8 “C (35 “F) per h; or heat to 85.5 “C ( I575 “F), cool
rapidly to 675 “C ( I245 “F). and hold for -I h. For a predominately
spheroidized structure. heat to 750 “C i I380 “F), cool from 750 “C (I 380
“F) to 665 “C (1230 “F) at a mte not to exceed 6 “C (IO “F) per h: cool
ranidlv
. - from 750 ‘C ( 1380 “F) to 675 “C ( I ?-I5 OF). and hold for 8 h
Hardening.
A medium-carbon
alloy steel which can he oil
quenched to attain a maximum as-quenched hardness of approximately
48
HRC. Its hardenahilitl
is significantly
higher than that of the carbon-molybdenum (40xX) grades.
3130H is produced in a number of product forms including tubing.
-l I3OH has been used extensively
for structures such as airframes that are
fabricated from tubing. -1130H is ueldahlc. hut because of its fairlj high
hardenahility. preheating and postheating must he used
l
Forging.
l
Austenittre
at 870 “C ( 1600 “FL and quench in oil
Reheat to the temperature
Recommended
l
l
l
l
Heat to 1230 “C (2245 OF) maximum. Do not forge after
temperature of forging stock drops below approximateI)
870 “C (I 600 “F)
4130: Continuous Cooling Transformation
Practice
Tempering.
Characteristics.
tized at 850 “C (1560 “F)
Heat Treating
l.lOCr,O.lS
Diagram. Composition:
l
u hich itill
Processing
result in the required
hardness
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize and quench
Temper
Finish machine
0.30 C, 0.50 Mn. 0.020 P, 0.020 S, 0.25 Si, 1 .OOCr, 0.20 MO. Austeni-
310 / Heat Treater’s
Guide
4130: Isothermal Transformation
4130H:
Diagram. Composition:
0.33 C, 0.53 Mn, 0.90 Cr, 0.18 MO. Austenitized
End-Quench Hardenability
Dice
from
quenched
surface
‘116 In.
mm
Esrdness,
ERC
max
min
Distance from
queocbed
surface
‘/la in.
mm
Eardness,
ERC
max
min
I
2
3
1.58
3.16
4.14
56
55
53
49
46
42
13
14
15
20.53
22.12
2370
34
34
33
24
23
23
4
5
6.32
7.90
51
49
38
34
16
18
25.28
28.44
33
32
23
22
6
7
8
9.48
11.06
12.64
41
44
42
31
29
27
20
22
24
31.60
34.76
31.92
32
32
31
21
20
9
IO
14.23
15.80
40
38
26
26
26
28
41.08
11.24
31
30
II
12
17.38
IS.%
36
35
25
25
30
32
47.40
SO.56
30
29
at 845 “C (1555 “F). Grain size:
Alloy
4130:
As-Quenched
Specimens
Hardness
mm
Surface
Eardnes,
ARC
l/r radius
Center
‘/z
I
2
4
I3
25
51
I02
51
51
4-l
45.5
50
50
32
25
SO
44
31
24.5
round
Source: Bethlehem
9700 Series) / 311
4139: Cooling Curves. Steel tubing. 31.75 mm (1.25 in.) outside
diameter by 1.651 mm (0.065 in.) wall
were quenched in water
in.
Si
Steels (1300 through
Steel
4130: Hardness vs Tempering Temperature. Normalized at 900
4130H: End-Quench Hardenability. 48 heats of 14835 contain-
“C (1650 “F). Quenched from 870 “C (1600 “F) in water and tempered at 56 “C (100 OF) intervals in 13.7 mm (0.540 in.) rounds.
Source: Republic Steel
ing0.35to0.39C,0.65to1.10Mn,0.13Nimax,0.05Crmax,0.03
MO max and boron treated; compared with 4130H
312 / Heat Treater’s
Guide
Microstructures. (a) 2% nital. 500x. Normalized by austenitizing at 870 “C (1600 “F) and air cooling to room temperature. Ferrite
(white areas) and lamellar pearlite (dark areas). Specimen shows slight banding. (b) 20/o nital. 750x. Hot rolled steel bar, 25.4 mm (1 in.)
diam, annealed by austenitizing at 845 “C (1555 “F) and cooling slowly in the furnace. Coarse lamellar pearlite (dark areas) in a matrix of
ferrite (white). (c) 2% nital, 750x. Hot rolled steel bar 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) for 1 h, cooled to 675 “C (1245
“F) and held for 2 h, and air cooled. Partly spheroidized pearlite (dark) in a matnx of ferrite (white). (d) 29b nital. 750x. Same as (c), except
the time at 675 “C (1245 “F) was increased to 4 h. Structure essentially the same as (c), except the degree of spheroidization of the pearlite
is greater. (e) 2% nital. 750x. Same as (c) and (d), except the time at 675 “C (1245 “F) was increased to 8 h. Structure is similar to those
shown in (c) and (d), except the degree of spheroidization of the pearlite has increased further. (f) 2% nital, 750x. Same as (c), (d), and (e),
except that the time at 675 “C (1245 “F) was increased to 16 h. The degree of spheroidization is greater than in (e). (g) 2% nital. 750x. Hot
rolled steel bar, 25.4 mm (1 in.) diam, austenitized at 870 “C (1600 “F) for 1 h and water quenched. Untempered martensite. (h) 5% picric
acid, 2 !/20/b HNO,, in ethanol; 11 000x. Same as (g), except an electron micrograph of a platinum-carbon-shadowed
two-stage carbon replica. Untempered martensite. (j) Not polished, not etched: 8600x. Annealed. Replica electron fractograph. Note fatigue striations, resolved
only at high magnification
4130:
Alloy Steels (1300 through
4130H: Hardenability Curves. Heat-treating
(1650 “F). Austenitize:
870 “C (1600 “F)
iardness Limits for Specification
Durposes
distance,
om
.5
t
1
3
5
!O
!5
IO
I5
lo
I5
i0
Hardness, HRC
Maximum
Minimum
56
55
53
51
48
44
41
39
34
33
33
32
31
31
30
49
46
40
36
32
28
26
25
24
23
22
20
.
iardness Limits for Specification
Burposes
1distance,
46h.
IO
11
12
13
14
I5
16
18
!O
!2
!4
!6
!8
10
52
Hardness. HRC
hlaximum
Minimum
56
55
53
51
49
47
44
42
40
38
36
35
34
34
33
33
32
32
32
31
31
30
30
29
49
46
42
38
34
31
29
27
26
26
25
25
24
24
23
23
22
21
20
temperatures
recommended
9700 Series) / 313
by SAE. Normalize (for forged or roiled specimens
only): 900 “C
314 / Heat Treater’s
Guide
4135,413SH
Chemical
Composition.
Similar
In aerospace practice.
4135. AISI: 0.33 to 0.38 C. 0.70 to 0.90
Mn. 0.80 to 1.10 Cr. 0.035 P max. 0.040 S max. 0.15 to 0.25 MO. UNS:
0.33toO.38C.O.70too.90 Mn.0.035 Pmax.0.04OS max.0.15 to0.30Si.
0.80 to l.lOCr, 0.70 to 0.90 Mo.UNS H41350and SAE/AISI 41358:
0.32 to 0.38 C. 0.60 to 1.00 Mn. 0.15 to 0.35 Si, 0.75 to 1.20 Cr. 0. I5 to
0.25MO
Steels (U.S. and/or
Foreign). 4135. UNS ~41350; AMS
ASTM A274. A355. A519; MlL SPEC MU-S-16974,
MLS-18733;
SAE J404.54 12.5770; (Ger.) DIN I .7220; (Fr.) AFNOR 35
CD 4.35 CD 4 TS; (Ital.) UNI 35 CrMo 4.35 CrMo 4 F, 34 CrMo 4 KB;
(Jap.) JIS SCM I. SCCrM 3; (Swed.) SSla 2234; (U.K.) B.S. 708 A 37.
41358. UNSH41350; ASTM A304: SAE Jl268; (Ger.) DIN 1.7220; (Fr.)
AFNOR 35 CD 4,35 CD 4 TS; (Ital.) UNI 35 CrMo 4. 35 CrMo 3 F, 34
CrMo 4 KB; (Jap.) JIS SCM I, SCCrM 3; (Swed.) SSld 2234; (U.K.) B.S.
708A 37
6365C. 6372C;
For a predominately
pearlitic structure. heat to 855 “C (I 570
“F), cool fairly rapidly to 760 “C ( I300 “F). then to 665 “C ( I230 “F) at a
rate not to exceed I9 “C (35 “F) per h: or heat to 855 “C (1570 “F). cool
rapidly to 675 “C (I245 “F). and hold for 4 h. For a predominately
spheroidized structure. heat to 750 “C ( I380 “F). cool from 750 “C (I 380
“F) to 665 “C (I 230 “F) at a rate not to exceed 6 “C ( IO OF) per h; or cool
rapidly from 750 “C ( 1380 “F) to 675 “C ( 1245 “F), and hold for 8 h. Anneal
at 845 “C (I 555 “F); cool to belou 540 “C ( IO00 “F) at a rate not to exceed
I IO “C (200 “F) per h
Hardening. Austenitize at 870 “C (1600 “F), and quench in oil or
polymer. Flame hardening, ion nitriding, gas niuiding, and carbonitriding
are suitable processes.
In aerospace practice. austenitize at 855 “C (1570 “F). Quench in oil
or polymer
Tempering.
Forging.
l
Forge
Normalize
l
Armed
l
Rough machine
Austenitize and quench
Temper
Finish machine
Heat to 1230 “C (2245 “F) maximum.
Do not forge after
of forging stock drops below approximately
X70 “C ( I600 “F)
Recommended
Heat Treating
Practice
Reheat to the temperature which will result in the required
hardness.
ln aerospace practice. see table for suggested tempering temperatures
per different tensile strengths. Quenchants include oil and polymers
Recommended
l
l
l
Normalizing.
Heat 10 900 “C ( I650 “F). Cool in air.
at 900 “C ( 1650 “F)
Annealing.
Characteristics.
4 l35H has generally
the same characteristics
as
4130H. except the higher mean carbon content results in a slightly higher
as-quenched hardness, about 50 to 52 HRC for 4135H. ln addition. the
higher mean manganese content of 3 I35H results in higher hardenahility.
CornDare hardenabilitv
data for 4130H with 4135H. Also, as the hardenability increases, the suitability
for welding decreases. Forgeability
of
4135H is very good
temperature
normalize
l
Processing
Sequence
4135H: End-Quench Hardenability
Diitancefrom
queocbed
surface
916 in.
mm
Eardness,
ERC
max
min
Distance fern
quenched
surface
‘116in.
mm
Ei3HllleSS,
ERC
max
min
I
2
1.58
3.16
58
58
51
50
13
1-I
20.54
22.1’
48
47
32
31
3
4
5
6
7
8
9
IO
II
II
4.74
6.32
7.90
9.48
II.06
12.64
14.22
15.80
17.38
18.%
57
56
56
55
54
53
52
51
SO
31
49
48
47
45
42
40
38
36
34
33
IS
I6
I8
20
22
24
26
28
30
32
23.70
25.28
28.4-l
31.60
34.76
37.92
41.08
44.24
47.40
50.56
46
45
4-l
42
41
40
39
38
38
37
30
30
29
28
27
27
27
26
26
26
4135, 4135H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
Alloy Steels (1300 through
4135H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
Hardness
Purposes
I distance,
mm
1.5
3
5
7
?
11
13
15
20
25
30
35
$0
15
50
Hardness
Purposes
I distaace,
$6 in.
1
2
3
1
5
5
7
B
9
10
11
12
13
14
15
6
8
:0
12
!4
:6
:8
IO
I2
845 “C (1555 “F)
Limits for Specification
Eardoess, HRC
Masimum
Minimum
58
58
57
56
56
55
53
52
49
45
43
41
40
39
37
51
50
49
48
46
42
39
37
32
30
28
27
27
26
26
Limits for Specification
Hardness, ERC
Maximum
Minimum
58
58
57
56
56
55
54
53
52
51
50
49
48
47
46
45
44
42
41
40
39
38
38
37
51
50
49
48
47
45
42
40
38
36
34
33
32
31
30
30
29
28
27
27
27
26
26
26
temperatures
recommended
9700 Series) / 315
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
316 / Heat Treater’s
4135: Suggested
Practice)(a)
620-860 hlPa
(W-125 ksi)
850 “C
(1550°F)
Guide
Tempering
Temperatures
Tensile strength ranges
860-1035 hlPa 1035-1175 MPa 11751210
(IZS-1SOksi)
(150-170hi)
(170-180
675 “C
(1250 “F)
(a) Quench in oil or polymer.
600 T
(1125°F)
Source: AbfS 27.5911
(Aerospace
MPa
ksi)
480 “C
1900 “F)
1240-1380 MPa
(180-2OOksi)
-I25 “C
(800 “F)
4135: Suggested Tempering Temperatures
Based on
As-Quenched
Hardness (Aerospace Practice)
Tensile strength
range
860 IO 1035 hlPa
I I25 to I50 ksl)
365 to I IO5 hlPa
I I40 IO 160 ksl,
1035t01175hlPn
(ISOto 170ksi)
ll75tol3l0hlPa
(170~~ 19Oksi)
I240 to I380 hlPu
(I80 to 200 ksi)
Sourer: AhlS 2759/l
RC 47-49
As-Quenched
Aardness
RC 50-52
RC 53-55
550 “C
(1025 “F)
5lO”C
(950 ‘F)
170 ‘T
1875 OF)
-12s ‘T
t8OO”FI
ml “C
r750”F,
595 “C
~1100°F~
550 “C
(1025°F)
SlO”C
t9SO “F)
180 “C
(900 “Fb
1.55 “C
t85O”F)
650 “C
t 12OOT)
595 “C
(1100°F)
550 “C
(1025 “F)
-5’5
-_ “C
(975 “F)
19s “C
(925 “I=)
316 / Heat Treater’s
Guide
4137,4137H
Chemical
Composition.
4137. AISI and UNS: 0.3s LO0.40 C. 0.70
to0.90Mn.0.15to0.30Si.0.80to1.10Cr.0.035Pmax.0.010Smax.0.15
to 0.25 MO. UNS H41370 and SAE/AISI J137I-I: 0.34 to 0.31 C. 0.60 to
1.00 Mn. 0. IS to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 MO
Similar
Steels (U.S. and/or Foreign). 5137. LINS G41370:
ASTM A322, A33 I, AS05, A5 19. AS17; SAE J-IO4 Jll2, J770; (Ger.) DIN
I .7225; (Fr.) AFNOR 40 CD 4.42 CD 4; (Id.) UNI G -IO CrMo 1.38 C&lo
4 KB. 40 CrMo 1; (Jap.) JIS SCM -I H. SChl3: (Swed.) SS1.t 2344; (U.K.)
B.S. 708 A 32.708 M 10.709 M 10.1137H.
LJNS H41370; ASTM ,430-I;
SAEJI268;(Ger.)DfN
1.722S;(Fr.)AFNOR40CDJ.42CD-l;(Ital.)LJNl
G 10 C&lo 4.40 CrMo 4. 38 CrMo 4 KB; fJap.) JIS SCM 4 H. SCM 4;
(Swed.) SS1-t 2244; (U.K.) B.S. 708 A 42.708 A 40.709 A 10
Characteristics.
A typical
medium-carbon.
moderately
high hardenability steel. Often referred to as a shaft steel, -I I37H is frequently used
for a variety of shaft applications in the quenched and tempered condition.
Depending upon the precise carbon content. the as-quenched hardness of
fully hardened 4137H is generally about 52 HRC or slightly higher. usualI>
a little higher than 413SH. but not as high as for ll40H.
The hardenability
pattern is essentially the same for 3137H as shown for 3135H: the only
difference is that the band is moved upward for 4137H because of the
higher carbon content. Forgeability of1137H is very good, but machinability is only fair and welding. although possible. is seldom recommended
Forging. Heat to 1230 “C (22-U “F). Do not forge after temperature
forging stock drops below approximately
870 “C ( I600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 870 “C f I600 “Fj. Cool in air
For a predominately
pearlitic structure. heat to 835 “C ( I555
“F). cool fairly rapidly to 755 “C ( I390 “Fj. then cool from 755 “C ( I390
“F) to 665 “C ( 1230 “F) at a rate not to exceed I1 “C (25 “F) per h; or heat
to 845 “C (I 555 “F). cool rapidly to 675 “C ( IX5 “F). and hold for 5 h. For
a predominately
spheroidized structure. heat to 750 “C ( 1380 “F), cool to
665 “C (I230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750
“C ( I380 “F), cool fairly rapidly to 675 “C ( I245 “F). and hold for 9 h
Hardening.
Austenitize at 855 “C (I570 “F), and quench in oil. Carbonisalt bath and gas nitriding, and ion nitriding are suitable processes
Tempering.
Recommended
l
l
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Nitride (optional)
of
Annealing.
triding.
Nitriding. If nitriding is considered. the steel must be treated (hardened
and tempered), and nitriding must be done on finished parts because any
finishing operation will remove the most useful portion of the case. First.
use a typical processing cycle consisting of: rough machining, austenitizing
at 845 “C I I555 “FI. oil quenching. tempering at 620 “C (I I50 “F). and
finish machining. Then, nitride in ammonia gas at 525 “C (975 “F) for 21
h. using an ammonia dissociation of 30%: or nitride at 525 “C (975 “F) for
5 h with an ammonia dissociation of 25%. then at 565 “C ( 1050 “F) for 20
h nith an ammonia dissociation of 75 to 805. Certain proprietary salt bath
nitriding processes are also applicable for surface hardening
Reheat after quenching to the temperature shown by the
hardness-tempering
temperature curve to obtain the required hardness for
these specific steels
4137, 4137H:
sents an average
Hardness
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
Alloy
Steels (1300 through
9700 Series) / 317
4137H: End-Quench Hardenability
Distance from
quenched
surface
‘&jin.
mm
I
2
3
-I
5
6
7
8
9
IO
II
I’
1.58
3.16
Eardness,
ERC
mar
min
6.31
7.90
9.4
II.06
12.64
59
59
58
58
57
57
56
55
14.22
55
I5 80
17.38
18.96
54
53
52
1.71
52
51
SO
49
49
18
-Is
1.3
-IO
39
37
36
Distance from
quenched
surface
‘&in.
mm
13
I-1
IS
16
18
10
x!
2-l
26
28
30
32
4137: Continuous Cooling Transformation
tized at 860 “C (1580 “F)
20.5-i
22.12
23.70
2528
28.4-I
31 60
31.76
37.92
-I I Ax3
44.24
47.40
SO.56
Rardness.
ARC
mas
min
51
50
49
48
46
45
44
43
4’
-I1
41
II
35
34
31
31
3’
31
30
30
30
29
‘9
29
Diagram. Composition:
0.36 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si. 1 .OOCr, 0.20 MO. Austeni-
318 / Heat Treater’s
4137H:
Hardenability
(1600 “F). Austenitize:
Hardness
Purposes
J distance,
mm
1.5
3
5
7
3
I1
13
15
20
25
30
35
$0
15
50
Hardness
Purposes
I distance,
1/16in.
I
2
3
1
5
5
7
3
3
IO
I1
12
13
14
I5
16
I8
20
!2
!4
!6
!8
!O
52
Guide
Curves. Heat-treating
845 “C (1555 “F)
Limits for Specification
Eardness, ERC
MaximlUll
Minimum
59
59
58
58
57
56
55
55
52
48
46
44
43
42
41
52
51
50
49
48
45
42
39
35
33
31
30
29
29
29
Limits for Specification
Eardoess. ARC
Maximum
Minimum
59
59
58
58
57
57
56
55
55
54
53
52
51
50
49
48
46
45
44
43
42
42
41
41
52
51
50
49
49
48
45
43
40
39
37
36
35
34
33
33
32
31
30
30
30
29
29
29
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 319
4140,414OH
Chemical Composition. 4140. AISI and UNS: 0.38 to 0.43 C, 0.75
to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.80to1.10Cr,0.15
to 0.25 MO. 414OH.AISIandUNS: 0.37 to 0.44 C, 0.65 to l.lOMn, 0.035
Pmax.0.040 S max,0.15 too.30 Si.O.75 to 1.2OCr,O.15to 0.25 MO
Similar Steels (U.S. and/or Foreign). 4140. UNS ~41400;
AMS
6381.6382,6390,6395; ASTM A322, A331, A505, A519, A547, A646;
MlL SPEC M&S-16974; SAE J404, J412.5770; (Ger.) DIN 1.7225; f,Fr.)
AFNOR 40 CD 4.42 CD 4; (Ital.) UN1 40 CrMo 4, G 40 CrMo 4,38 CrMo
4 KB; (Jap.)JIS SCM 4 H, SCM 4; (Swed.) SSt4 2244; (U.K.) B.S. 708 A
42,708 M 40,709 M 40.4140H. UNS H41400; ASTM A304; SAE 5407;
(Ger.)DIN 1.7225;(Fr.) AFNOR 40 CD 4,42 CD 4; (Ital.) UN1 G 40 CrMo
4,40 CrMo 4,38 CrMo 4 KB; (Jap.) JIS SCM 4 H, SCM 4; (Swed.) SS14
2244; (U.K.) B.S. 708 A 42,708 M 40,709 M 40
Characteristics.
Among the most widely used medium-carbon alloy
steels.Relatively inexpensive considering the relatively high hardenability
4140H offers. Fully hardened 4140H ranges from about 54 to 59 HRC,
depending upon the exact carbon content. Forgeability is very good, but
machinability is only fair and weldability is poor, becauseof susceptibility
to weld cracking
Tempering. Reheatafter quenching to obtain the required hardness
Nitriding. 4140H respondsto the ammonia gasnitriding process,resulting in a thin, file hard case, the outer portion of which is composedof
epsilon nitride. This constituent not only provides an abrasion-resistant
surface,but also increasesfatigue strength of componentssuch as shaftsby
as much as 30%. However, if nitriding is considered, the steel must be
pretreated(hardenedand tempered),and nitriding must be done on finished
parts becauseany finishing operation will remove the most useful portion
of the case.A typical processingcycle that includes nitridmg is:
l
l
l
l
l
l
Rough machine
Austenitize at 845 “C (1555 “F)
Oil quench
Temper at 620 “C (1150 “F)
Finish machine
Nitride at 525 “C (975 “F) for 24 h, using an ammonia dissociation of
30%; or nitride at 525 “C (975 “F) for 5 h with an ammoniadissociation
of 25%. then at 565 “C (1050 “F) for 20 h with an ammoniadissociation
of 75 to 80%
Forging. Heat to 1230 “C (2250 “F). Do not forge after temperatureof
forging stock drops below approximately 870 “C (1600 “F)
Certainproprietarysalt bath nitriding processesarealso applicablefor surface
hardeningof414OH
Recommended
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 “C (1600 “F). Cool in air
Annealing. For a predominately pearlitic structure, heatto 845 “C (1555
“F), cool fairly rapidly to 755 “C (1390 “F), then cool from 755 “C (1390
“F) to 665 “C (1230 “F), at a rate not to exceed 14 ‘C (25 “F) per h; or heat
to 845 “C (1555 “F), cool rapidly to 675 “C (1245 “F), and hold for 5 h. For
a predominately spheroidized structure, heat to 750 “C (1380 “F), cool to
665 “C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 750
“C (1380 “F), cool fairly rapidly to 675 “C (1245 “F), and hold for 9 h
l
l
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Nitride (optional)
Hardening. Austenitize at 855 “C (1570 “F), and quench in oil
1140: Isothermal Transformation
7 to 8
Diagram. Composition:
0.37 C, 0.77 Mn, 0.98 Cr, 0.21 MO. Austenitized
at 845 “C (1555 “F) Grain size:
320 / Heat Treater’s
Guide
4140H: End-Quench Hardenability
Distance from
quenched
surface
&jh.
1
2
3
4
5
6
7
8
9
10
11
12
mm
1.58
3.16
4.14
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardness,
ARC
max
min
60
60
60
59
59
58
58
57
57
56
56
55
53
53
52
51
51
50
48
41
44
42
40
39
4140: Cooling Transformation
Distance from
quenched
surface
‘/x6h
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.10
25.28
28.44
31.60
34.16
31.92
41.08
44.24
41.40
50.56
Hardness,
ARC
max
min
55
54
54
53
52
51
49
48
41
46
45
44
38
37
36
35
34
33
33
32
32
31
31
30
Diagram. Composition: 0.44 C, 1.04 Mn, 0.29 Si, 1 .13 Cr, 0.15 MO. Austenitized
size: 9. AC,, 795 “C (1460 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite.
at 845 “C (1555 “F). Grain
Source: Bethlehem Steel
Alloy Steel / 321
4140:
Effect of Microstructure
on Tool Life
Feed was 0.010 in./rev (0.25 mm/rev) for all specimens;
depth of cut was 0.100 in. (2.5 mm).
Microstructure
Steel condition
Hardness, HB
Pearlite
Ferrite
192
180
300
90
65
10
35
Normalized
Annealed
Quenched tempered
4140:
As-Quenched
Specimens
‘h
1
2
4
Tempered
martensite
Hardness
13
25
51
102
ft/miu
mm/s
300
360
300
1520
1830
1520
4140: Hardness vs Tempering Temperature. Normalized at 870
quenched in oil
mm
cutting speed
100
Size round
in.
constituent, %
“C (1600 “F). Quenched from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds.
Tested in 12.827 mm (0.505 in.) rounds. Source: Republic Steel
Surface
Hardness, HRC
t/z radius
Center
57
55
49
36
56
55
43
34.5
55
50
38
34
Source: Bethlehem Steel
4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO
Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr,
0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F);
AC,, 805°C (1480°F); Ar,, 745 “C (1370°F); Ar,, 680 “C (1255 “F).
Recommended thermal treatment: forge at 1205 “C (2200 “F)
maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to
1650 “F) for an approximate hardness of 311 HB; quench from
830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from
845 “C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000
“F), tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm
(1.5 in.) diam bars and over are taken at half radius position.
Source: Republic Steel
4140: Gas Nitriding. Oil quenched from 845 “C (1555 “F), tempered at 595 “C (1105 “F), and nitrided at 550 “C (1020 “F)
I
I
4140: Depth of Hardness.
31.75 mm (1.25 in.) diam bars,
through hardened by induction
0
20
Duration
40
of nitriding,
60
hr
60
322 / Heat Treater’s
Guide
4140: Effect of Mass. Composition: 0.38 to 0.43 C, 0.75 to 1 .OO
Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.80 to 1.10 Cr,
0.15 to 0.25 MO. Approximate critical points: AC,, 730 “C (1350 “F);
AC,, 805 “C (1480°F); Ar,, 745 “C (1370 “F); Ar,, 680 “C (1255 “F).
Recommended thermal treatment: forge at 1205 “C (2200 “F)
maximum, anneal at 815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 197 HB, normalize at 845 to 900 “C (1555 to
1650 “F) for an approximate hardness of 311 HB; quench from
830 to 855 “C (1525 to 1570 “F) in oil. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from
845 “C (1555 “F) in sizes shown, tempered at 650 “C (1200 “F),
tested on 12.827 mm (0.505 in.) rounds. Tests from 38.1 mm (1.5
in.) diam bars and over are taken at half radius position. Source:
Republic Steel
4140: Variations in Hardness after Production Tempering. (a)
76.2 mm (3 in.) diam valve bonnets. Steel from one mill heat. Parts
heated at 870 “C (1600 “F), oil quenched, and tempered at 605 “C
(1125 “F) to a hardness of 255 to 302 HB. (b) Valve segments,
12.7 to 25.4 mm (0.5 to 1 in.) section thickness. Steel from one mill
heat. Parts heated at 870 “C (1600 “F), oil quenched, and tempered at 580 “C (1075 “F) to a hardness of 321 to 363 HB
4140: Depth of Case vs Duration of Nitriding. Double stage nibided at 525 “C (975 “F). Numbers indicate hours of nitriding at 15
to 25% dissociation. Remainder of cycle at 83 to 85% dissociation
4140: Effect of Microstructure
on Tool Life
Heat Treater’s
Guide: Practices
and Procedures
for Irons and Steels
Copyright@ ASM International@ 1995
Alloy Steel I323
4140: Gas Nitriding. (a) 7 h, 2 suppliers, 20 to 30% dissociation;
dissociation; (d) 40 h, 5 heats, 25 to 30% dissociation;
to 30% dissociation; (h) 50 h, 20 to 30% dissociation.
core hardness
(b) 9 h, 2 heats, 25 to 30% dissociation; (c) 24 h, 2 suppliers, 20 to 30%
(e) 90 h, 9 heats, 25 to 35% dissociation; (f) 25 h, 20 to 30% dissociation; (g) 35 h, 20
For (f), (g), (h), 1: 21 to 23 HRC; 2: 26 to 28 HRC; 3: 33 to 35 HRC; 4: 36 to 37 HRC
324 / Heat Treater’s
4140: Microstructures.
Guide
(a) 2% nital, 825x. Resulfurized forging normalized by austenitizing at 900 “C (1650 “F) Ii2 h. air cooling; annealed
by heating at 815 “C (1500 “F) 1 h. furnace cooling to 540 “C (1000 “F), air cooling. Blocky ferrite and fine-to-coarse lamellar pearlite. Black
dots are sulfide. (b) Nital, 500x. 25.4 mm (1 in.) diam. austenitized at 845 “C (1555 “F) 1 h. cooled to 650 “C (1200 “F). and held 1 h for isothermal transformation, then aircooled to room temperature. White areas, ferrite; gray and black areas, pearlite with fine and coarse lamellar
spacing. (c) 2% nital, 500x. Hot rolled steel round bar. 25.4 mm (1 in.) diam, austenitized at 845 “C (1555 “F) for 1 h and water quenched.
Fine, homogeneous. untempered martensite. Tempering at 150 “C (300 “F) would result in a darker etching structure. (d) 2% nital, 500x.
Same as (c), except the steel was quenched in oil rather than water, resulting in the presence of bainite (black constituent) along with the
martensite (light). (e) 2% nital, 750x. Steel bar austenitized at 845 “C (1555 “F). oil quenched to 66 “C (150 “F), and tempered 2 h at 620 “C
(1150 “F). Martensite-ferrite-carbide
aggregate. (f) As polished (not etched), 200x. Oxide Inclusions (stringers) in a steel bar, 25.4 mm (1 in.)
diam. Stringers parallel to the direction of rolling on the as-polished surface of the bar. (g) Not polished, not etched, 8600x. Replica electron
fractograph showing the dimpled structure typical of the overstress mode of failure. (h) 2% nital, 400x. Oil quenched from 845 “C (1555 “F),
tempered for 2 h at 620 “C (1150 “F), surface activated in manganese phosphate, gas nitrided for 24 h at 525 “C (975 “F), 20 to 30% dissociation. 0.0050 to 0.0076 mm (0.0002 to 0.0003 in.) white surface layer Fe,N, iron nitride, and tempered martensite. (j) 2% nital. 400x. Same
steel and prenitriding conditions as (h). except double stage gas nitrided: 5 h at 525 “C (975 “F), 20 to 30% dissociation: 20 h at 565 “C (1050
“F), 75 to 80% dissociation. High second-stage dissociation caused absence of white layer. Diffused nitride layer and a matnx of tempered
martensite
Alloy Steel I325
4140H: Hardenability
Curves. Heat-treating temperatures
845 “C (1555 “F)
-
(1600 “F). Austenitizk
Hardness
purposes
I
limits for specification
I
I distsnce,
mm
I
1.5
1
4
;
!
a
I1
13
II.5
2!O
: !.5
)O
)5
L10
L15
I
I
io
z
I
I
Hardness
purposes
I distance,
II,l(i”.
.
I
I
2
3
1
5
f5
7
I3
,3
10
11
12
13
14
15
16
18
!O
,2
24
26
i ‘8
30
32
Hardness, HRC
hlaximum
hfiuimum
60
60
60
59
59
58
51
51
5.5
53
51
49
48
46
45
53
52
52
51
50
48
46
43
38
35
33
32
32
31
30
limits for specification
Hardness, HRC
Maximum
hfinimum
60
60
60
59
59
58
58
51
57
56
56
55
55
54
54
53
52
51
49
48
47
46
45
44
53
53
52
51
51
50
48
47
44
42
40
39
38
37
36
35
34
33
33
32
32
31
31
30
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
326 / Heat Treater’s
Guide
4142,4142H
Chemical Composition.
4142. AISI and UN.% 0.40 to 0.45 C, 0.75
to1.00Mn,0.035Pmax,0.040Smax.0.15to0.30Si.0.80to1.10Cr.0.15
to 0.25 MO. UNS 841420 and SAE/AISI 4142H: 0.39 to 0.46 C, 0.65 to
I. IO Mn. 0. I5 to 0.35 Si, 0.75 to 1.20 Cr. 0.15 to 0.35 MO
Tempering.
required
Reheat after quenching
hardness
to the temperature
to obtain
the
Steels (U.S. and/or Foreign). 4142. UNS G41420;
ASTM A322. A33 I. A505. A5 19, A 547; SAE 5404.5412. J770.41428.
Nitriding. If nitriding is considered. the steel must be pretreated (hardened and tempered), and nitriding must be done on finished parts because
any finishing operation will remove the most useful portion of the case. A
typical processing cycle that includes nitriding is
UNS H41420; ASTM
CrMo 4
l
Similar
A304; SAE J 1268: (Ger.) DfN I .7223; (Ital.) UNI 38
Characteristics.
A slightly higher carbon version of 4140H. Characteristics are essentially the same as those described for 4140H. Depending
on the precise carbon content within the allowable
range, as-quenched
hardness of fully hardened 4142H should be at least 54 HRC and may be
as high as 60 HRC. 4142H is also a high hardenability
steel. Can be readily
forged, but as carbon increases, the susceptibility
to cracking in heat
treating or welding also increases, while machinability
decreases
Forging.
Heat to 1230 “C (2250 “F). Do not forge after temperature
forging stock drops below approximately
870 “C (I600 “F)
Recommended
Normalizing.
Heat Treating
l
l
l
l
l
of
Practice
Heat to 870 “C (1600 “F). Cool in air
Certain proprietaty
hardening
For a predominately
pearlitic structure. heat to 845 “C ( 1555
“F), cool fairly rapidly to 755 “C ( I390 “F). then cool from 755 “C ( I390
“F) to 665 “C ( I230 “F) at a rate not to exceed I4 “C (25 “F) per h; or heat
to 845 “C (I 555 “F). cool rapidly to 675 “C ( I245 “F). and hold for 5 h. For
a predominately
spheroidized structure, heat to 750 “C (I 380 “F), cool to
665 “C ( 1230 “F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 750
“C (I380 “F’), cool fairly rapidly to 675 “C (I 245 “F), and hold for 9 h
Austenitize at 855 “C (I570 OF). and quench in oil. Flame
hardening, ion nitriding, gas nitriding, and carbonitriding are suitable processes
salt bath nitriding
Recommended
l
Annealing.
Hardening.
Rough machine
Austenitize at 845 “C (1555 “F)
Oil quench
Temper at 620 “C ( I I50 “F)
Finish machine
Nitride at 525 “C (975 “F) for 24 h. using an ammonia dissociation of
30% or nitride at 525 “C (975 “F) for 5 h with an ammonia dissociation
of 25%. then at 565 “C (1050 “F) for 20 h with an ammonia dissociation
of 75 to 80%
l
l
l
l
l
l
l
l
processes are also applicable for surface
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize
Quench
Temper
Finish machine
Nitride (optional)
4142: Increase in Lead Change with Depth of Nitrided Case.
13-tooth five-pitch helical pinion gear, hardened and tempered at
565 “C (1050 “F)and nitrided in two stages at 525 “C (975 “F) using ammonia dissociation rates of 15 to 25% for the first stage and
63 to 65% for the second stage
4142, 4142H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
Repre-
Alloy Steel / 327
4142H: Continuous
Austenitized
Cooling Transformation
Diagram. Composition:
0.42 C, 0.85 Mn, 0.020 P, 0.020 S, 0.25 Si, 1 .15 Cr, 0.20 MO.
at 880 “C (1580 “F)
4142H: End-Quench Hardenability
Distance born
quenched
surface
‘/lb in. mm
I
-l
;
-I
5
6
7
8
9
IO
II
I2
Eardness,
ERC
max
min
I x3
62
5.5
4.73
3.16
6.32
7.90
9.18
Il.06
12.64
11.22
IS.80
17.38
18.96
62
61
61
61
60
60
60
59
59
58
!bl
55
53
53
52
51
50
49
47
46
4.4
4142: isothermal Transformation
Distance from
quenched
surface
&in.
mm
I3
I-l
IS
16
18
20
22
24
26
28
30
32
20.51
22.12
23.70
25 28
28.-M
31.60
34.76
37.92
11.08
44.24
47.40
SO.S6
Diagram. Composition: 0.42
C. 0.89 Mn, 0.018 P, 0.028 S, 0.23 Si, 0.05 Ni, 0.94 Cr, 0.18 MO,
0.025 Al. 0: austenitized at 870 “C (1800 “F); 0: austenitized at
980 “C (1795 “F); A: austenitized at 1095 “C (2005 “F)
Eardoess.
ERC
min
max
58
57
57
56
55
54
53
53
52
51
51
so
42
41
-+o
39
37
36
35
34
3-I
3-l
33
33
I
328 / Heat Treater’s
Guide
4142H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
J distuuce,
mm
Curves. Heat-treating
845 “C (1550 “F)
limits for specification
Rardness,
Maximum
ARC
hlinimum
I .5
3
5
7
Y
II
I3
IS
20
2s
67
62
62
62
61
61
60
60
58
56
55
s-l
s-l
53
52
51
-19
-la
13
BY
30
35
55
53
36
3s
40
15
so
52
51
SO
3-l
33
33
Hardness
purposes
I distauce,
!/,6 in.
I
,
1
5
1
s
)
IO
II
I2
13
I-1
IS
16
18
!O
!2
!-I
!6
!8
10
12
limits for specification
Eat-does,
Maximum
62
62
62
61
61
61
60
60
60
59
99
58
58
57
57
56
55
51
53
53
92
51
Sl
50
q RC
Minimum
55
55
51
53
53
52
51
50
-19
-17
-I6
-l-l
12
-II
40
39
37
36
35
31
34
3-l
33
33
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy
4145,4145H,
Steel I329
4145RH
Chemical
Composition.
4145. AISI and CJNS: O.-l3 to 0.18 C. 0.75
to l.00hln.0.03SPmax.0.010Sniax.0.1Sto0.30Si.0.80toI.IOCr.0.lS
to 0.3 MO. UNS H41450 and SAE/AISI
4145H: 0.42 to 0.49 C. 0.65 to
I.10 Mn. 0.15 to 0.35 Si. 0.75 to I.20 Cr. 0.15 to 0.1-S hlo. SAEJIJSRH:
O.-l3 to 0.48 C. 0.75 to 1.00 Mt. 0.80 to I. IO Cr. 0. I5 to 0.35 hlo
Similar Steels (U.S. and/or Foreign). 41~5. 11~s
G11150:
ASThl A322 A33l. AS05. ASl9: hllL SPEC hIIL-S-16974;
SAE J-104.
J-112. J770.4145H.
1JNS H1I4SO; ASTM A3O-l. A9l-l: SAE 51’68. Jl868
Characteristics.
4145H. along with 1147H and -1lSOH. is commonly
known tts a high-strength steel. All are capable ofbetn~g heat treated to high
strengths. As-quenched -I l4SH M ill have hardness values ranging generally
from approximately
55 to 62 HRC. In hardenability. 4l-tSH ranks as one of
the highest of the AISI alloy steels. ForSeability
is good. but because of
high carbon content and high hnrdenahility. restricted cooling rate from the
ftnish forging temperature is generally recommended. This can he accomplished hy cooling in a furnace or by co\ering with on insulating mnterial.
Rapid cooling from the forginp temperature can result in cracking, especially for ForSings of complex contigurntton.
hlachinahility
is penerally
regarded as poor. although 414SH is machined try all of the conventional
processes. Strongly susceptible to \\eld cracking, and the entire \\elding
process must be closely controlled. Often \selded usmg more sophisttcated
processes such as plasma orc and electron beam. partly because of the
applications for which it is most often used
Recommended
Normalizing.
Heat to I220 “C (2225 “F). Do not forge after temperature of
forging stock drops below approxmlately
870 ‘C t 1600 “Fj. Slow coolinp
is recommended
Practice
Heat to 870 “C t 1600 “F). Cool in air
Annealing.
For a prsdominstely
pcnrlitic structure. heat to 830 “C ( IS25
“Fj. cool fairly rapidly to 7-tS “C i 1370 “Fj. then to 670 “C ( I?-tO “Fj at a
rate not to exceed 8 “C t IS W per h: or heat to 830 “C (IS25 “Pj. cool
rapidly to 675 C t l2-lS “F). and hold for 6 h. For a predominately
ferritic
and spheroidired
carhide structure. heat to 750 “C (I 380 ‘F’j. cool to 670
“C t 1240 “Fj at a rote not to esceed 6 ‘C t IO “Fj per h; or cool fairly rapidly
from 750 “C t I380 “Fj to 660 “C t I230 OF). and hold for IO h
Hardening. Heat to 845 “C t IS55 “Fj, and quench in oil or polymer.
Flame hardening. ion nitriding. gas nitridinp. and carbonitriding
are suitable processes
Tempering.
After quenching, reheat immediately to the tempering
perature that will provide the required strength and/or hardness
Recommended
l
l
l
l
Forging.
Heat Treating
l
l
l
Processing
tem-
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitire
and quench
Temper
Finish mnchins
4145H: End-Quench Hardenability
Distance from
quenched
surface
&in.
mm
Hardness,
HRC
mar
min
Distance from
quenched
su tface
l/l6 in.
mm
Hardness,
q RC
max
min
I
I..58
63
56
I?
‘0 5-I
59
-Lb
2
3
4
z
3.16
4.74
6.32
9.18
7.90
63
62
62
61
62
55
55
5-l
53
I-l
IS
I6
‘018
22.12
23.70
3.18
3 I .60
28.4-I
59
58
S8
57
-I5
4.1
12
10
38
7
8
II 06
12.6-l
61
61
51
52
21
11
34.76
37.9’
Sh
55
37
36
9
IO
14.22
IS.80
60
h0
51
SO
26
28
-11.08
55
55
35
II
I2
17.38
18.96
60
59
49
18
30
32
-17.10
50.56
5s
54
3-1
3-l
44.2-I
35
4145, 4145H: Hardness vs Tempering Temperature.
sents an average
based
on a fully quenched
structure
Repre-
330 / Heat Treater’s
Guide
4145H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
3
5
7
?
11
13
15
20
25
30
35
40
15
50
Hardness
purposes
I distance,
Y,6 ill.
1
I
,
,
I
1
I
0
1
2
3
4
5
6
8
10
12
14
16
18
i0
i2
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Ehrdness, ERC
llleximum
Minimum
63
63
63
62
62
61
61
60
59
58
51
56
55
55
55
limits for
56
55
55
54
53
52
51
50
47
42
39
31
35
34
34
specification
Hardness, HRC
Maximum
Minimum
63
63
62
62
62
61
61
61
60
60
60
59
59
59
58
58
51
57
56
55
55
55
55
54
56
55
55
54
53
53
52
52
51
50
49
48
46
45
43
42
40
38
31
36
35
35
34
34
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 331
4145RH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness
purposes
J distance,
‘/,6 in.
I
2
3
4
5
6
1
8
9
IO
II
I?
I3
I-l
IS
16
I8
20
22
24
26
28
30
32
Hardness
purposes
1 distance,
mm
IS
3
5
limits for specification
Hardness, HRC
hfaximum
hfiuimum
62
62
61
61
60
60
59
59
58
58
58
57
51
56
56
55
54
53
52
57
51
56
56
55
55
5-l
53
52
52
51
SO
49
48
41
46
4-I
43
42
51
40
51
SO
SO
49
40
39
38
31
limits for specification
Eardness, HRC
hlaximum
Minimum
7
3
II
I3
62
62
61
61
60
59
59
I5
10
58
51
Pi
30
ss
lo
1s
50
55
5-I
52
Sl
SO
49
51
51
56
56
55
s-i
53
52
19
-16
44
42
-IO
39
31
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
332 / Heat Treater’s
Guide
4147,4147H
Chemical
COITIpOSitiOn.
4147. AISI and UNS: 0.45 to 0.50 C. 0.75
to 1.00 Mn.0.035 Pmax, O.O-lOS niax.0. I5 to 0.30 Si.O.80 to l.lOCr.0.
IS
to 0.25 MO. UNS H41470 and SAE/AISI 4147H: 0.U to 0.5 I C. 0.65 to
I.10 Mn. 0.15 to 0.35 Si. 0.75 to 1.20 Cr. 0.15 to 0.25 Mo
Similar
Steels (U.S. and/or
Foreign).
4147.
UNS
~31470;
ASTM A322, A331, AS05. A519; WE J-W, Ul?, 5770: tGer.) DIN
1.7228; (Jap.) JIS SCM 5 H. SCM 5.4147H. UNS H11170: ASTM A30-I:
SAE J 1268: (Ger.) DIN I .7228: (Jap.) JIS SCM 5 H. SCM 5
Characteristics.
The characteristics
are much the same as those outlined for 111SH. Because of increased carbon content. the maximum
as-quenched hardness is slightly higher. approximately
56 to 63 HRC.
depending on the precise carbon content. Hardenability
is high. and the
band shows about the same pattern as that for 313SH. except for a shift
slightly upward. Susceptibility
to craching because of rapid cooling after
forging. welding. or heat treating is greater than that for 111SH because of
the higher carbon content
Annealing. For a predominately pearlitic structure. heat to 830 “C (I 52s
OF). cool fairly rapidly to 745 “C ( I370 “FJ, then to 670 “C ( I240 “F) at a
rate not to exceed 8 “C ( IS “F) per h: or heat to 830 “C ( IS25 “F), cool
rapidly to 675 “C t 1245 “F). and hold for 6 h. For a predominately
ferritic
and spheroidized carbide structure, heat to 750 “C ( I380 “F), cool to 670
“C t 12-10 “F) at a rate not to exceed 6 “C ( IO “F) per h; or cool fairly rapidly
from 750 “C ( I380 “F) to 660 ‘C t I220 “F). and hold for IO h
Hardening.
ing. ion &riding,
Tempering.
perature that !iill
Heat to 1220 “C (2225 “F). Do not forge after temperature of
forging stock drops below approsimately
870 “C t 1600 “F). Slow cooling
is recommended
Recommended
Normalizing.
Heat Treating
Forge
Normalize
l
AL\nnlal
l
Rough machine
Austenitize and quench
Temper
Finish machine
l
Heat to 870 “C t I600 “FL Cool in air
Processing
l
l
Practice
After quenching. reheat immediately to the tempering
provide the required strength and/or hardness
Recommended
l
Forging.
Heat to 8-U “C t 1555 “F). and quench in oil. Flame hardengas nitriding. and carbonitriding
are suitable processes
l
Sequence
4147, 4147H: Hardness vs Tempering Temperature.
sents an average based on a fully quenched structure
4147H: End-Quench Hardenability
Distance from
quenched
surface
l/16 in.
mm
I
Hardness,
ARC
max
mia
Distance from
quenched
surface
l/16 in.
mm
Hardness,
HRC
max
min
;7
I.58
4.71
3.16
64
64
57
56
57
IS
I-l
IS
'054
22.12
23.70
61
61
60
49
43
46
-I
5
6.32
7.90
64
63
56
55
16
18
25.28
28.4-I
60
59
4s
12
6
7
8
9.18
I I.06
12.64
63
63
63
55
5s
51
20
22
34
31.60
34.76
37.92
59
St?
57
40
39
38
9
IO
11.22
IS.80
63
62
s-l
53
26
28
-l I .08
44.24
57
57
37
Sl
II
I2
17.38
18.96
62
62
52
51
30
32
47.40
SO.56
56
56
37
36
tem-
Repre-
Alloy Steel I333
4147H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
Hardness
purposes
I distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
to
15
50
iardn ess
wrposes
I distance.
46in.
0
1
2
3
4
5
6
8
!O
12
!4
!6
18
IO
I2
845 “C (1555 “F)
limits for specification
Eardness,ERC
Maximum
hlinimum
64
64
64
64
63
63
63
63
62
60
59
58
57
57
56
57
57
56
55
55
55
54
53
50
45
42
39
37
36
36
limits for specification
Eardness,
Maximum
64
64
64
64
63
63
63
63
63
62
62
62
61
61
60
60
59
59
58
57
57
57
56
56
HRC
hlinimum
57
57
56
56
55
55
55
54
54
53
52
51
49
48
46
45
42
40
39
38
37
37
37
36
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
334 / Heat Treater’s
Guide
4147: Isothermal Transformation
Diagram. Composition:
0.46 C, 0.77 Mn, 0.016 P, 0.025 S, 0.28 Si, 0.15 Ni. 1.06 Cr, 0.22 MO
334 / Heat Treater’s Guide
4150,415OH
Chemical Composition.
4150. AISI and UNS: 0.18
to
0.53
c.
0.75
Recommended
to 1.00 Mn.0.035 Pmax, 0.04OS max. 0.15 100.30 Si.0.8010 I. IOCr.0.1.5
to 0.25 MO. UNS 641500 and SAE/AISI 4150A: 0.47 to 0.53 C. 0.65 to
I.10 Mn. 0.15 to 0.35 Si, 0.75 to I.20 Cr. 0.15 to 0.25 MO
Normalizing.
Similar Steels (U.S. and/or Foreign). 4150.
Annealing.
UNS
G-~I~OO:
ASTM A322. A331, ASOS. ASl9; MfL SPEC MLL-S-I I595 (ORD-IISO);
SAE J404, J412, J770; (Ger.) DIN 1.7228: (Jap.) JJS SCM 5 H, SChl 5.
4150H. UNS H41500; ASTM A304; SAE Jl268; (Ger.) DIN I .7228; (Jap.)
JIS SCM 5 H. SCM 5
Characteristics. High-hardenability
steel. capable of being heat
treated to high levels of strength. When the carbon content is on the higher
side of the allowable range (0.53%). as-quenched hardness can approach
65 HRC. Characteristics
are generally the same as those given for 314SH
and 4147H. Minor differences because of higher carbon content include
higher as-quenched hardness, an upward shift of the hardenability
band.
and an even greater tendency to cracking during heat processing
Forging. Heat to 1220 “C (2275 “F). Do not forge after temperature of
forging stock drops below approximately
870 “C (1600 “F). Slow cooling
is recommended
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air.
Jn aerospace practice.
normalize
at 870 “C (I 600 “F)
For a predominately
pearlitic structure, heat to 830 “C (I 525
“F), cool fairly rapidly to 71.5 C (I370 “F). then to 670 “C (1240 “F’) at a
rate not to exceed 8 “C ( I5 “F) per h; or heat to 830 “C ( I525 “F), cool
rapidly to 675 YY ( I245 “F). and hold for 6 h. For a predominately
ferritic
and spheroidized carbide structure. heat to 750 “C (1380 “F). cool to 670
“C ( I210 “F) at a rate not to exceed 6 “C ( IO “F) per h: or cool fairly rapidly
from 750 “C ( I380 “F) to 660 “C ( 1220 “FL and hold for IO h.
In aerospace practice. anneal at 830 “C ( I525 “F). Cool below 540 “C
( 1000 “F) at a rate not to exceed I IO “C (200 “F) per h
Hardening. Heat to 8-15 “C ( IS55 “F). and quench in oil or polymer.
Flame hardening, boriding, ion nitriding.
gas nitriding. carbonitriding.
austempering
and martempering
are candidate processes. In aerospace
practice, parts are austenitized at 830 “C ( IS25 “F). and are quenched with
oil or polymer
Tempering.
After quenching, reheat immediately to the tempering temperature that will provide the required strength and/or hardness. See table
Alloy Steel / 335
Recommended
l
Forge
Normalize
l
Anneal
l
l
l
l
l
Processing
Sequence
4150:
As-Quenched
Specimens
Hardness
quenched in oil
Size round
Rough machine
Austenitize and quench
Temper
Finish machine
In.
‘/z
I
2
4
mm
13
25
91
102
Surface
Eardness, ERC
% radrus
Ceoler
64
62
58
47
64
62
57
43
63
62
56
42
Source: Bethlehem Steel
4150: Continuous Cooling Transformation
Diagram. Composition:
0.50 C, 0.85 Mn, 0.020 P. 0.020 S, 0.25 Si, 1 .OOCr, 0.22 MO. Austeni-
tized at 850 “C (1560 “F)
4150: End-Quench Hardenability.
Use of successively higher
austenitizing temperatures. Composition: 0.55 C, 0.84 Mn. 0.30
Si, 0.13 Ni, 0.92 Cr, 0.21 MO
336 / Heat Treater’s
Guide
4150H: Hardenability
Curves. Heat-treating
845 “C (1555 “F)
(1600 “F). Austenitize:
Hardness
purposes
limits for specification
J distance,
mm
Hardness, HRC
Maximum
hlinimum
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
J distance,
I46 in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
65
65
65
65
65
65
65
64
63
62
61
60
59
58
58
limits
59
59
58
58
57
57
56
55
51
47
44
41
39
38
38
for specification
Hardness, ARC
Maximum
hlinimum
65
65
65
65
65
65
65
64
64
64
64
63
63
62
62
62
61
60
59
59
58
58
58
58
59
59
59
58
58
57
57
56
56
55
54
53
51
50
48
47
45
43
41
40
39
38
38
38
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel I337
4150H: End-Quench Hardenability
Distance from
quenched
surface
&in.
mm
Hardness.
HRC
mah
min
Distance from
quenched
surface
‘/16h.
mm
Hardness.
HRC
ma\:
min
7I
;
I .S8
69
59
I?
10.5-l
63
51
1.74
3 lb
6S
bS
59
15
I-1
23 70
21.1:
b2
62
18
50
.I
s
6
6 32
I 90
9.48
65
65
6.5
58
S8
Sl
I6
I8
20
25.3
28.44
3 I .hO
b2
61
47
4s
bO
-I3
8
9
I0
1
II.06
12.6-l
l-1.2’
IS.80
6S
6-I
61
64
57
S6
22
21
lb
31.16
Sb
37.9:
4l.08
59
59
58
-II
10
39
38
II
I2
17.38
18.96
6-l
63
s-l
53
30
31
47.40
58
SO.Sb
SY
38
38
S5
28
44.2-l
58
4150, 4150H: Hardness vs Tempering Temperature. Repre-
4150: Hardness vs Tempering Temperature. Normalized at 870
sents an average based on a fully quenched structure
“C (1600 “F), quenched from 845 “C (1555 “F), and tempered in
56 “C (100 “F) intervals in 13.716 mm (0.540 in.) rounds. Tested in
12.827 mm (0.505 in.) rounds. Source: Republic Steel
4150: Suggested Tempering Temperatures (Aerospace
Practice)(a)
860-1035 hlPa
(125l50bi)
Tensile strength ranges
1035-1175 hlPa
1175-1240 MPa
(150-170 ksi)
(170-180 ksi)
650 “C
(IXIO’F,
~a)Qurnch
59s “C
(I lOO”F,
~iioilorpol~mrr.
53 “C
(975 “F)
Source: .~hlS ?7S9/l
1240-1380 hlPa
(180-200 hi)
41s “C
lXOO”F,
Alloy Steel I337
4161,4161H,
Chemical
4161RH
Composition.
4161. AISIand UNS: 0.56 to 0.64 C, 0.75 to
1.00 Mn, 0.035 P max, 0.040 S max. 0.15 to 0.30 Si, 0.70 to 0.90 Cr, 0.25 to
0.35 MO. UNS H41610 and SAE/AISI 4161H: 0.55 to 0.65 C, 0.65 to 1.10
Mn, 0.15 to 0.35 Si, 0.65 to 0.95 Cr. 0.25 to 0.35 M O. SAE 4161RI-I: 0.56 to
0.64 C, 0.75 to 1.00 Mn, 0.15 to 0.35 Si, 0.70 to 0.90 Cr, 0.25 to 0.35 MO
Similar Steels (U.S. and/or Foreign). 4161. UNS
ASTM A322, A33 1; SAE J404,54 12,5770.4161H. UNS H4 1610; ASTM
A304, A914; SAE 51268
Characteristics.
A high-carbon steel, with a mean carbon content of
0.60%, has the highest carbon content of the 4100 steels. Chromium
content is lower and the molybdenum content is higher than that of 4150H
and other steels in the 4100 series. As a result. hardenability is higher. The
band shows clearly that when all elements affecting hardenability are on the
high side, the upper line of the band approaches that of an air-hardening
steel, nearly a straight line. Depending on the precise carbon content,
as-quenched hardness for 4161 H ranges From 60 to 65 HRC. Often used for
various tool, die, and spring applications. Well suited for heat treating by
338 / Heat Treater’s
Guide
the austempcring process. MUSI he mated CiUCfully in all hcitt prowssing
iIpplications lo avoid cracking
g;lS nilriding.
austcmpcring.
Forging. ~~cat IO 120~ “C (2200 “t:). DO not I’ogc alicr tcmpcraturc of
Ibr@ng stock drops hclow approximntcly
X70 “C (IMX) “F). Forgings
should Aways IX COOM SIOWIY IO itvoid critcking
Tempering.
Recommended
Normalizing.
Heat Treating
iulslcmpcring,
iilld c;whonilriding
urc Slliliiblc
quenching is in iI molten salt bath
proccsscs.
Bcforc parts rc;rh room tcmpcritturc. tcmpcr immcdiatcly.
38 10 SO “C (IO0 to I20 “F) is idcitl. ‘I’hc tcmpcring tcmpcraturc depends
upon
the dcsircd h;rrdncss or combination of’ propcrtics
Austempering.
Austcnitize ai X30 “C ( IS25 “I:), quench into a wcllilpiti~tcd I~ICII SCIIIhilth ill 3 I5 ‘7’ (000 “F). hdtl Ibr 2 h, imd COOI in ;Gr.
No tcmpcring is rcquirctl
Practice
Hcai IO X55 “C: (IS70 “I:). C:ool in air
Annealing.
For subscqucnt milchinine or opcmtinns involved in I;lhricw
ing P;UIS. B prcdominatcly
sphcroidizcd micmstmcturc is usually prcliirrcd.
This cun hc uchievcd hy hwing IO 760 “C (IWO “F), cooling to 705 “C’ (IBOO
‘19 81 iI riitc not IO cxcccd 6 “C: ( IO “l;) per h; or by heating IO 760 “C‘ ( I4W “F).
cooling f;iirly ntpidly to (,(A) “CT ( I220 “19, imd holding Ihr IO h
Hardening.
I lcilt to X30 “c’ ( IS25 “I’), itlId quench in oil. Thin sections
may be I’ully hardcncd hy ;tir cooling liom XBO “C ( IS25 “F). Ion nitriding.
Recommended
Processing
l
IGgc
Normali/.c
l
,\lllKxil
l
KOUgh
l
iId
quench (or ;tustcmpcr)
Tcmpcr (or ilustcmpcr)
Finish m;rchinc (or illlStClllpCr)
l
l
l
Sequence
lllilChillC
Au~~cl~i~izc
4161H: End-Quench Hardenability
Distance frum
quenched
surface
916 in.
mm
I
2
3
4
s
6
7
x
0
IO
II
12
I.58
3.10
4.14
6.32
7.90
9.18
I I .ofl
12.64
14.22
IS.XO
17.38
I x.96
Hnrdness,
HWC
IIIPX
min
0.5
OS
05
65
OS
6.5
h5
OS
65
65
65
6-l
60
bo
ho
60
60
OfI
h0
b0
SJ
59
59
so
Iktnncc
liw~~~
quenched
surface
l/16 in.
mm
13
I3
IS
I0
IX
20
22
2-l
26
2x
30
32
20.5-I
22.12
23.70
2.5.28
2x.44
3 I .60
31.76
37.92
41.0x
4J.ZJ
17.40
5050
Iii
Hardness,
HHC
mnx
min
04
64
03
61
6-t
03
(13
63
h3
03
0.3
0.3
5X
5x
57
so
5s
53
SO
3x
45
43
42
.II
4161, 4161H: Hardness vs Tempering Temperature.
sents an average
based
on a fully quenched
structure
Repre-
Alloy Steel / 339
4161 H: Hardenability
Curves. Heat-treating temperatures
(1600 “F). Austenitize:
845 “C (1555 “F)
iardness
wrposes
distance,
Im
.5
1
3
5
0
5
0
5
0
5
0
lardness
iurposes
distance.
16h.
0
1
2
3
4
5
6
8
0
2
4
6
8
0
7
limits for specification
Earduess,
Maximum
ERC
Minimum
65
65
65
65
65
65
65
65
65
64
63
63
63
63
63
60
60
60
60
60
60
60
60
58
56
53
50
46
43
41
limits for specification
Eardness,
Maximum
65
65
65
65
65
65
65
65
65
65
65
64
64
64
64
64
64
63
63
63
63
63
63
63
HRC
hliuimum
60
60
60
60
60
60
60
60
59
59
59
59
58
58
57
56
55
53
50
48
45
43
42
41
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
340 / Heat T
reater’s
4161RH: Hardenability
“C (1800 “F). Austenitize:
Hardness
purposes
J distance,
%6 in.
1
2
3
4
5
5
7
B
3
10
11
12
13
14
15
16
18
20
22
z4
26
28
30
32
Hardness
purposes
J distance,
‘/I6in.
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Guide
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Eardness.
Maximum
HRC
Minimum
60
60
60
60
60
60
60
60
60
60
60
59
59
59
58
57
56
54
53
51
49
47
46
45
65
65
65
65
65
65
65
65
65
65
65
64
64
64
63
63
62
62
61
60
59
58
57
57
limits for specification
Hardness,
Maximum
65
65
65
65
65
65
65
65
64
63
62
61
59
58
57
HRC
Minimum
60
60
60
60
60
60
60
60
59
51
55
53
50
4-l
45
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
Alloy Steel / 341
4320,4320H,
4320RH
Chemical Composition. 4320. AISI and UNS: 0.17 to 0.11 C. O.-Is
too.65 h~n.0.035Pmax.0.O-l0Smax.0.15to0.30Si.
1.65to7.00Ni.0.-10
to 0.60 Cr. 0.20 to 0.30 MO. IJNS H43200 and SAE/AISI
4320H: 0. I7 to
0.23 C. 0.10 to 0.70 Mn. 0.15 IO 0.35 Si, 1.55 to 2.00 Ni. 0.35 to 0.65 Cr.
0.20 to 0.30 MO. SAE 4320RH: 0. I7 to 0.21 C. O.-IS to 0.65 hln. 0.15 to
0.35 Si, 1.65 to 2.00 Ni, O.-l0 to 0.60 Cr. 0.20 to 0.30 hlo
Similar Steels (U.S. and/or Foreign).
4320.
UNS
G~3200:
ASThl A322. A33 I, A505, ASl9. A535; SAE J1O-k. J-II?. J770.43208.
UNS H13200; ASTM A30-L A9l-l; SAE J 1268. J IX68
Annealing. Not usually annealed for a pearlitic structure because machinahility
is better \i hen the predominate structure is spheroidal carbide.
This is best obtained by heating after normalizing
(following
forging or
rolling). to 775 “C ( IQ5 “Fj. cooling rapidly to 650 “C (I300 “F). then
holding for 8 h
Tempering. Tempering of carburized or carhonitrided parts made from
1320H is always recommended. Tempering temperature should be at least
I SO “C (300 “F). Somen hat higher tempering temperatures may be used if
some hardness can be traded off for increased toughness
Case Hardening.
Characteristics.
Used almost exclusively
for carhurizing applications,
notably heavy-duty. heavy-section
pears. pi-tions. and related machinery
components. Can be directlq hardened to 10 HRC or higher through
relativeI)
thick sections hecause of hiph hardenability.
Use of -l330H.
hoiiever. is far less errtensiLe \h hen compared with most other allo> carburizing steels because it costs more. and hecause its properties (relating
mainly to hardenability)
are not required for a maJority of applications.
Forgeable and ueldable. but has relatively poor machinahilir).
Carburizing procedures are the same as those given
for 31 I XH. -13XH can be carbonitrided,
although this process is infrequently applied. Parts made from 1320H are not. as a rule. well suited to
the carbonitriding
process. If used. see carbonitriding
procedure described
for grade -II l8H. Gas carhuriring.
ion nitriding,
austempering.
and
martemperin~ are altematke processes
Recommended
l
l
Forging.
Heat to 17-15 “C. (2275 “F) maxmium.
Do not forge after
temperature of forging stock drops below approsimately
870 “C ( 1600 OF)
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
4320:
Heat to 925 “C ( 1695 “FL Cool in air
Carburizing,
Processing
Sequence
Forge
Normalize
Anneal
Rough and semifinish machine
Carburizc and harden
Temper
Finish machine (usually grinding. removing
total case per side from critical areas)
no more than IO% of the
Single Heat Results
Specimens
contained
0.20 C. 0.59 Mn, 0.021 P, 0.018 S, 0.25 Si, 1.77 Ni, 0.47 Cr, 0.23 MO; grain size was 6 to 8; critical
1350 “F (730 “C); AC,, 1485 “F (805 “C); Ar,, 1330 “F (720 “C); Ar,, 840 “F (450 “C); 0.565-in. (14.4-mm)
round treated,
round tested
Elongation
case
Recommended practice
Hardness,
ERC
in.
mm
60.5
62.5
62
0.060
0.075
0.075
I.52
1.91
1.91
217
218.3
151.75
I-196
I505
lo46
159.S
I78
97
I loo
12’7
669
5X 5
59
59
0.060
0.07S
O.07S
I .s2
I.91
I.91
215.5
211,s
115.75
I186
I-158
IOOS
158.75
173
91.S
1095
1193
652
Depth
Tensile strength
ksi
MPa
Yield point
ksi
hiPa
in2in.
(50mm),
points Included AC,,
0.505-in. (12.8-mm)
Reduction
ofarea,
I&lldlll?SS,
*
EB
13.0
13.5
19.5
so. I
48.2
49.-l
429
429
302
12.5
l2.S
21.8
19.J
so.9
56.3
415
115
293
Q
For maximum case hardness
Direct quench from pot(a)
Single quench and rempert bl
Double quench and tempertc~
For maximum core toughness
Direct quench from pot(d)
Smplr quench and temper(e)
Double quench and tempert fl
(a~ Carburizcd at 1700 “F t925 “C) for 8 h. quenched in agitated oil. tempered at 300 “F ( I SO ‘T I. I b, Carburircd at I700 “F t92S “C I for 8 h. pot cooled. reheated to I500 OF (8 I5
“CL quenched in agitated oil. tempered at 300 “F t I50 T). Good case and core properties. ic) Carbunred at I700 “F t92.i “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C),
quenched inagitatedoil,
reheated to 142YFt77S
“C).qucnchrd
inagitatrdoil.
tempered at 3tW)“Fl ISOTI
hlavirnum refinement ofcaseandcore.
td)Carburizedat
17OO”F(925
‘T) for 8 h. quenched in agitated oil. tempered at 1SO “F (130 “C). tr) Carburirrd
at I700 ‘F (925 “C, ior 8 h. pot cooled. reheated to IS00 “F 18lS “C). quenched in agitated oil.
tcmperedat150°Ft23t)“C~.
Good cujemd core properties of) Carbutized at 17OO”Ft925 “CT) for8 h. pot cooled. reheated to lSOWFt8lS
“C). quenched inagitatedoil.
reheated
to 1425 “F(775 “Ckquenchrd
in agttatrd oil. temperedat -lSO”Ftl30”C~.
hlaximum refinement ofcaseandcore.
tsourcc: Bethlehem Steel)
4320: Surface Carbon Content after Carburizing. 25.4 mm
(1
tn.) diam bar, 26 tests. Carburized
at 925 “C (1695 “F)using a diffusion cycle, quenched
from 815 “C (1500 “F) in oil at 60 “C (140
“F), tempered
at 650 “C (1200 “F). Dew point, -1 “C (30 “F) at discharge end. Desired carbon concentration,
0.85 0.05%
342 / Heat Treater’s Guide
4320H: End-Quench Hardenability
Diitmce
from
quenched
surface
‘/,6 in.
Eardness,
ERC
mm
man
min
Dice
Prom
quenched
surface
‘/la in.
mm
Eardoess,
ERC
maw
I
2
I .58
3.16
48
47
?I
38
13
I-1
20.54
22.12
28
27
3
4.74
6.32
7.90
9.48
II.06
12.64
14.22
15.80
17.38
I&%
45
13
41
38
36
34
33
31
30
29
35
32
29
27
25
23
22
21
20
20
IS
I6
18
20
22
2-l
26
28
30
32
23.70
25.28
28.4-l
31.60
34.76
37.92
41.08
44.2-l
-+7.40
SO.56
27
26
25
25
24
2-t
2-l
2-l
24
24
4
5
6
7
8
9
IO
II
I2
4320: Effect of Prior Microstructure on Hardness after Tempering. Specimens tempered 2 h
4320, 4320H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
4320:
As-Quenched Hardness
Specimens
were quenched
in oil.
Size round
in.
mm
‘/2
I3
25
51
102
I
2
4
Source: Bethlehem
Steel
Surface
44.5
39
35
25
Eardness, HRC
L/zradius
44.5
37
30
2-l
Center
44.5
36
27
23
Alloy Steel / 343
4320H: Hardenability Curves. Heat-treating
(1700 “F). Austenitize:
hardness
wrposes
I distance,
nm
.5
1
3
5
!O
!5
LO
15
lo
15
in
925 “C (1700 “F)
limits for specification
Earduess, ERC
Maximum
Minimum
48
47
45
42
39
36
34
32
28
26
41
39
35
30
21
25
23
22
. ..
25
25
24
24
24
.
...
..
hardness limits for specification
wrposes
distance.
‘16io.
Eardness, HRC
Mxximum
Minimum
48
41
45
43
41
38
36
34
33
31
30
29
28
21
21
26
25
25
24
24
24
24
24
41
38
35
32
29
21
25
23
22
21
20
20
.
..
..
.
.
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
344 / Heat Treater’s Guide
4320: CCT Diagram. Carburizing composition: 0.20 C, 0.28 Si, 0.57 Mn, 0.0113P. 0.022 S, 0.50 Cr, 1.83 Ni. 0.26 MO. Alaboratory, induction
air melted heat; ingot was forged to 12.7 mm (0.5 in.) square bar stock heated at 925 “C (1700 “F) for 1 h and air cooled. Steel was austenitized for 20 min at 925 “C (1700 “F). Source: Datasheet l-57. Climax Molybdenum Company
Alloy Steel / 345
4320: Cooling Curve. Half cooling time. Source: Datasheet
l-57. Climax Molybdenum
Company
346 / Heat Treater’s Guide
4320RH: Hardenability Curves. Heat-treating temperatures
“C (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification
purposes
J distance,
916in.
1
2
3
4
5
6
7
8
9
10
II
12
13
14
IS
16
18
20
22
24
26
28
30
32
Ehrdoess, ERC
Maximum
Minimum
47
46
44
41
39
36
34
32
31
29
28
26
25
24
24
23
22
22
II
21
21
21
21
21
42
40
37
34
31
29
27
25
23
23
22
21
20
Hardness limits for specification
purposes
J distance,
null
1.5
3
5
1
9
II
I3
IS
20
25
30
35
-lo
35
SO
Hardness, ERC
Maximum
Minimum
41
46
44
40
31
34
31
30
25
23
22
21
21
21
II
42
40
31
33
30
21
25
23
20
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 347
4330v
Chemical
COIIIpOSitiOn:
AISI
4330V. 0.30 C. I.80 Ni. 0.80 Cr. 0.30
MO. 0.07 V steel
Austenitizing.
Characteristics.
An aerospace grade steel (AMS 2759/l)
Recommended
Normalizing.
Annealing.
Heat Treating Practice
Heat to 900 ‘22 (1650 “F)
Heat to 855 “c ( I 575 OF)
Temperature is 870 “C (1600 “F). Hardening quenchants are oils or polymers
Alloy Steel I347
4335v
Chemical
Composition.
AISI 433SV.0.35C. I .80Ni.
MO. 0.2 V steel
Characteristics.
An aerospace grade steel (AMS
Recommended
Normalizing.
Heat Treating
Heat to 900 “C ( I 650 “F)
2759/l)
Practice
0.72 Cr. 0.35
Annealing.
Heat to 845 “C ( 1555 ‘W
Austenitizing.
Temperature
chants are oils or polymers
is 870 “C (1600
“F),
Hardening
quen-
Alloy Steel I347
4340,434OH
Chemical Composition.
4340. AISI and UNS:
to0.80Mn.0.035
Pmax,0.040Smax.0.15to0.30Si,
to 0.90 Cr. 0.20 to 0.30 MO. 4340H. AISI and UN!?
too.95 Mn.0.025 Pmax.0.025S
max.0.15 too.35 Si.
to 0.95 Cr. 0.20 to 0.30 MO
0.38 to 0.43 C. 0.60
1.65to2.00Ni.0.70
0.37 to 0.44 C. 0.60
I.55 to2.00Ni.0.65
Similar
Steels (U.S. and/or Foreign). 4340. UNSG43-100: AMS
533 I, 6359.6413.64lS;
ASTM A322. A33 I. A505, A5 19, A5-t7. A646:
MJLSPEC hUL-S-16971; SAEJIO-L J-412. J770;(Ger.) DIN 1.656S:(Jap.)
JIS SNCM 8; (U.K.) B.S. 817 M 40.31 I I Type 6.2 S 119.3 S 95. UJOH:
UNS H43100; ASTM A3M; SAE 5407; (Ger.) DIN 1.6565: (Jap.) JIS
SNCM 8; (U.K.) B.S. 817 M GO.31 I I Type 6.2 S 119.3 S 95
Characteristics.
A high-hardenability
steel, higher in hardenability
than any other standard AlSl grade. When the elements that contribute to
hardenability are on the high side of their allowable ranges, the upper curve
of the hardenability
band is virtually a straight line. thus indicating that
4340H would be ah-hardening
in thin sections. Depending on the precise
carbon content, as-quenched hardness ranges from 54 to 59 HRC. Because
of high hardenability.
4340H is not considered suitable for welding by
conventional
means. although it can be welded by sophisticated processes
such as electron beam welding. 434OH can be forged \rithout difftculty,
although its hot strength is considerably
higher than that of carbon or loher
alloy grades, requiring more powerful forging machines. Machinability
is
relatively poor
Annealing.
For a predominately
pearlitic structure (not usuaUy preferred for this grade). heat to 830 “C ( I525 “F), cool rapidly to 705 “C (I 300
“F), then to 565 “C ( 1050 “F) at a rate not to exceed 8 “C ( 15 “F) per h: or
heat to 830 “C ( I525 “F), cool rapidly to 650 “C ( I200 “F). and hold for 8
h. For a predominately
spheroidized
structure. heat to 750 “C (1380 “F).
cool rapidly to 705 “C ( I300 “F) then cool to 565 “C ( I050 “F) at a rate not
to exceed 3 “C (5 “F) per h: or heat to 750 “C (I 380 “F). cool rapidly to 650
“C ( I200 “F). and hold for 12 h. A spheroidized
structure is usually
preferred for both machining and heat treating
Hardening. Austenitize at 815 “C (1555 “F). and quench in oil. Thin
sections may be fully hardened by air cooling
Tempering.
In common with all
susceptible to quench cracking. Before
to 50 “C. 100 to 120 “F), they should
Tempering temperature depends upon
of mechanical properties
Nitriding. Can be nitrided to produce high surface hardness and for
increased fatigue strength. See processing procedure given for 414OH
Recommended
l
Forging.
Heat to I230 “C (2250 “F). Do not forge after temperature of
forging stock drops below approximately
900 “C (1650 “F). Slow cooling
from forging is recommended to prevent the possibility of cracking
Recommended
Normalizing.
Heat Treating
Practice
Heat to 870 “C ( 1600 “F). Cool in air
high-hardenability
steels, 4340H is
parts reach ambient temperature (38
be placed in the tempering furnace.
the desired hardness or combination
l
l
l
l
l
l
Processing
Forge
Normalize
Anneal
Rough machine
Austenitize, quench. and temper
Finish machine
Nitride (optional)
Sequence
348 / Heat Treater’s
Guide
4340: Isothermal Transformation
Grain size: 7 to 8
Diagram.
Composition:
0.42 C. 0.78 Mn, 1.79 Ni, 0.80 Cr. 0.33 MO. Austenitized
at 845 “C (1555 “F).
4340: Cooling Transformation
Diagram. Composition: 0.41 C. 0.87 Mn, 0.28 Si, 1.83 Ni, 0.72 Cr, 0.20 MO. Austenitized at 845 “C (1555
“F). Grain size: 7. AC,, 755 “C (1390 “F); AC,, 720 “C (1330 “F). A: austenite, F: ferrite, 8: bainite, M: martensite. Source: Bethlehem Steel
Alloy
Steel / 349
4340 + Si: End-Quench
Hardenability. Composition: 0.42 C,
0.83 Mn, 1.5 Si, 1.85 Ni, 0.90 Cr, 0.41 MO. Quenched from 845 “C
(1555 “F). Source: Bethlehem Steel
4340: Tempered Hardness Versus Austenitizing
Temperature and Section Size
Specimens
Austenitizing
temperature
“F(“C)
1500(815)
were quenched
Section
Size
ill.
mm
%
12.7
31.8
54
12.7
31.8
54
12.7
31.8
54
1 L/4
21/s
1550(845)
%
1 vi.4
21/8
1600 (870)
‘h
1%
2%
in oil.
Aardness, ARC
Tempered for 2 h at
400°F
6OO’F
8OO’F 1000°F 1200°F
(205OC) (315OC) (125’C) (S-lO°C) (65OOC)
53.5
53.5
51.0
53.5
53.0
52.0
53.5
53.5
52.5
50.0
50.0
49.0
49.5
50.0
48.0
50.0
50.0
48.5
44.5
45.5
44.0
44.0
45.0
43.0
45.0
45.5
44.0
39.0
40.0
37.5
39.0
39.5
38.0
40.0
39.5
39.0
29.5
28.5
28.0
29.0
27.0
27.5
29.5
29.0
28.0
4340 + Si: Cooling Transformation Diagram. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84 Ni, 0.91 Cr, 0.40 MO, 0.12 V, 0.083 Al. Austenitized at 845 “C (1555 “F). Grain size: 8. AC,, 805 “C (1480 “F); AC,, 760 “C (1400 “F). A: austenite, F: ferrite, B: bainite, M: martensite. Source:
Bethlehem Steel
350 / Heat Treater’s
Guide
4340H: End-Quench Hardenability
Distance from
quenched
surface
&in.
mm
I
2
3
4
5
6
7
8
9
10
II
I?
1.58
3.16
4.74
6.32
7.90
9.48
Ii.06
12.64
14.22
15.80
17.38
IS.96
Ehrdoess,
ERC
max
min
60
60
60
60
60
60
60
60
60
60
59
59
53
53
53
53
53
53
53
52
52
52
51
51
4340: End-Quench Hardenability.
Distance from
quenched
surface
‘116in.
mm
13
14
15
16
18
20
22
21
26
28
30
32
20.5-i
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
SO.56
Hardness.
ERC
max
min
59
58
58
58
58
57
57
57
57
56
56
56
SO
49
49
48
37
46
45
4-I
43
42
41
40
Influence of initial structure
and time at 845 “C (1555 “F). HR: hot rolled, N: normalized, A: annealed, S: spheroidized. (a) 0 min; (b) 10 min; (c) 40 min; (d) 4 h
4340: Hardness vs Tempering Temperature. Normalized at 870
“C (1800 “F), quenched from 845 “C (1555 “F), and tempered in
56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in
12.8 mm (0.505 in.) rounds. Source: Republic Steel
Alloy Steel / 351
4340: Hardness vs Diameter. 0.38 to 0.43 C, 0.80 to 0.80 Mn,
0.040Pmax,0.040Smax,0.20to0.35Si,
1.65to2.00Ni,0.70to
0.90 Cr. 0.20 to 0.30 MO. Approximate critical points: AC,, 725 “C
(1335 “F); AC,. 775 “C (1425 “F); Ar,, 710°C (1310 “F); Ar,, 655 “C
(1210 “F). Forge at 1230 “C (2250 “F) maximum; anneal at 595 to
660 “C (1105 to 1220 “F) for a maximum hardness of 223 HB; normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB; quench in oil from 830 to 855 “C (1525 to 1570
“F). Test specimens normalized at 870 “C (1600 “F) in over-sized
rounds, quenched from 845 “C (1555 “F) in oil, tempered at 540
“C (1000 “F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38
mm (1.5 in.) diam bars and over are taken at half radius position.
Source: Republic Steel
4340: Nitriding. 20 to 30% dissociation.
(a) 7 h. (b) 24 h. (c) 48 h
4340 + Si: Tensile Strength, Yield Strength Elongation, and
Reduction in Area. Composition: 0.43 C, 0.83 Mn, 1.55 Si, 1.84
Ni. 0.91 Cr, 0.40 MO, 0.12 V. 0.083 Al. Normalized at 900 “C (1650
“F), austenitized at 855 “C (1570 “F), quenched in agitated oil,
tempered for 1 h. Source: Bethlehem Steel
352 / Heat Treater’s
Guide
4340: Gas Nitriding. Two tests. Nitrided at 550 “C (1020 “F) for 20 h, 20 to 509’0 dissociation
4340: Hardness vs Diameter. Composition:
0.38 to 0.43 C, 0.60
to0.80Mn,0.040Pmax,0.040Smax,0.20to0.35Si,
1.65t02.00
Ni, 0.70 to 0.90 Cr, 0.20 to 0.30 MO. Approximate critical points:
Ac,,725”C(1335”F);Ac,,775”C(1425”F);Ar,,710”C(1310”F);
Ar,, 655 “C (1210 “F). Recommended thermal treatment: forge at
1230 “C (2250 “F) maximum; anneal at 595 to 660 “C (1105 to
1220 “F) for a maximum hardness of 223 HB; normalize at 845 to
900 “C (1555 to 1650 “F) for an approximate hardness of 415 HB;
quench in oil from 830 to 855 “C (1525 to 1570 “F). Test specimens normalized at 870 “C (1600 “F) in over-sized rounds,
quenched from 845 “C (1555 “F) in oil, tempered at 650 “C (1200
“F). Tested in 12.8 mm (0.505 in.) rounds. Tests from 38 mm (1
l/z in.) diam bars and over are taken at half radius position.
Source: Republic Steel
4340: Effect of Nitriding and Shot Peening on Fatigue Behavior. Comparison between fatigue limits of crankshafts (S-N
bands) and fatigue limits for separate test bars, indicated by plotted points at right
4340: Microstructure.
2% nital, 500x. Quenched in oil from 845
“C (1555 “F) and tempered at 315 “C (600 “F). Tempered martensite
Alloy Steel / 353
E4340,
E4340H
Chemical Composition.
E-4340.AISI and ZJNS:0.38 to
O.-i3
c.
0.65 to 0.85 Mn. 0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I.65 to ?.OO
Ni,
0.70to 0.9OCr.O.20
100.30
MO.E434OH.AlSIaod UNS:0.37IOO.-U
C. 0.60 to 0.95 Mn. 0.025 Pmax. 0.035 S max. 0. IS to 0.30 Si. I.55 to X0
Ni. 0.65 to 0.95 Cr. 0.20 to 0.30 MO
Similar Steels (U.S. and/or Foreign). U340.
ASThl A33l. A5OS. ASl9: MIL SPEC
(Ger.) DIN I .6563: tJap.) JIS 40 NiCrMo
Type 8. S 139. EXMOH.UNS H43406;
DIN 1.6563: (Ital.) UNI 10 NiCrhlo 7,40
UNS
Gw06;
hlfL-S-5000;
SAE J-W. 5770;
7. -tO NiCrMo 7 KB; (11.K.) B.S.
ASThl 430-k SAE 5407: (Ger.)
NiCrhlo 7 KB: (U.K.) B.S. Type
8. S 139
Characteristics. Basically a prenuum grade of 4330H. Prescribed
composition
carries lower maximums
for hoth phosphorus and sulfur.
Manganese range IS slightly higher. but this IS of little practical sipnificance. Hardennhility
and other properties are the same as for conventtonal
4310H. Weldability
and machinability
are poor; forgeability
is good. Asquenched hardness. 5-l to 59 HRC
Forging.
Heat to 1230 “C t 1750 “FL Do not forge after temperature of
forging stock drops helo\.r approximately
900 “C ( 1650 ‘F). Slou cooling
from forging is recommended to prevent the possibility of crnching
“F). then to 565 “C t 1050 “F) at a rate not to exceed 8 “C (15 “F) per h; or
heat to 830 “C ( I525 “F). cool rapidly to 650 “C ( 1300 “F), and hold for 8
h. For a predominately
sphcroidized
structure, heat to 7.50 “C (I 380 “F).
cool rapidly to 705 ‘C (I300 “F), then to 565 “C (1050 “F) at a rate not to
exceed 3 “C (5 “F) per h; or heat to 750 “C (I 380 “F), cool rapidly to 650
“C ( I200 ;F). and hold for I:! h. A spheroidized
structure is usually
preferred. for hoth machining and heat treating
Hardening. Austenitire at 835 “C ( IS55 “F), and quench in oil. Thin
sections may be fully hardened hy air cooling
Tempering.
These steels. in common with all high-hardenahility
steels,
are susceptible to quench crackin_e. Before parts reach ambient temperature
(38 to 19 “C. or 100 to I20 OF). they should be placed in the tempering
furnace. Tempering temperature depends upon the desired hardness or
comhinatton of mechanical properties
Nitriding. Can he nitrided to produce high surface hardness and to
increase fatigue strength. See processing procedure given for 1140H
Recommended
l
l
Recommended
Heat Treating Practice
Normalizing. Heat to 870 “C (I600 “F). Cool in air
Annealing. For a predominately pearlittc structure
(not usually preferred for this grade). heat to 830 “C t IS75 “F). cool rapidly to 705 “C ( I300
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize. quench. and temper
Finish machine
Nitride (optional)
E4340, E434OH: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
354 / Heat Treater’s
Guide
E434OH: Hardenability
Curves. Heat-treating
870°C (1800 “F). Austenitize:
Hardness
wrposes
I distance,
nnl
1.5
i
3
II
13
15
!O
!5
IO
15
lo
IS
i0
iardness
wrposes
I distance,
46h.
limits for specification
Hardness, HRC
MtlXhllUll
Minimum
60
60
60
60
60
60
60
60
60
59
58
58
57
57
57
1
0
I
2
3
4
5
6
8
!O
!2
!3
16
18
IO
2
53
53
53
53
53
53
53
53
52
51
SO
49
47
46
44
limits for specification
Hardness, HRC
Maximum
Minimum
60
60
i
845 “C (1555 “F)
60
60
60
60
60
60
60
60
60
60
60
59
59
59
58
58
58
57
51
51
51
51
53
53
53
53
53
53
53
53
53
53
53
52
52
52
5’
i;
51
SO
49
18
47
46
4s
4-t
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only):
Alloy Steel I355
4615
Chemical Composition.
4615.AISI and UNS: 0. I 3 IO 0.18 c. 0.45
to0.65Mn.0.035Pmax.0.040Smax.0.15
to 0.30 MO
to0.30Si.
1.65 to2.00Ni.0.20
Similar Steels (U.S. and/or Foreign). 4142. UNS G16150; AMS
6290; ASTM A322, A331, A505: MIL SPEC MU-S-7493;
SAE J404,
13 12, J770. This steel is no longer in SAE 5-W or J 4 12, but does appear
in SAE J770. which is now J1397
Characteristics.
Used extensively
for making parts that will be case
hardened by carburizing or carbonitriding.
Over a period of years, however,
use has declined in favor of carburizing
grades that have slightly higher
carbon (for better core properties),
lower nickel content. or both. Asquenched surface hardness (not carburized) can be expected to be approximately 35 to 40 HRC. and the hardenability
band should be nearly the same
general pattern as the one for 4620H. No AISI hardenability
band for 4615.
The slight difference in range of nickel content for 4615 and 4620H is not
signiticant. Grade 4615 forges easily and is weldable. although alloy steel
practice, in terms of preheating and postheating, should be used
Recommended
Normalizing.
Heat to 1245 “C (2275 “F) maximum. Do not forge after
temperature of forging stock drops below approximately
900 “C ( I650 “F)
4615: Carbon Gradients
4615 mod (cast),
slight differences
same carburizing
Produced
by Liquid Carburizing.
carburized
at 925 “C (1695 “F) for 7 h. Indicates
in gradients
obtained
in two furnaces
using the
conditions
4615: Hardness vs Tempering Temperature.
average
based
on a fully quenched
structure
Heat to 925 “C (1695 OF). Cool in air
Case Hardening. See recommended carburizing, carbonitriding, and
tempering procedures described for 4 I I8H. Flame hardening, liquid carburizing, austempering and martempering
are alternative treatment processes
Recommended
l
l
l
l
l
l
Processing
an
Sequence
Forge
Normalize
Anneal (optional)
Rough and semifinish machine
Case harden
Temper
Finish machine (carburized parts only)
4615: End-Quench
Hardenability.
Mn, 1.90 Ni, 0.24 MO. Austenitized
4615: Liquid Carburizing.
Represents
Practice
Annealing. Not usually required for this grade. Structures that are well
suited to machining are generally obtained by normalizing or by isothermal
annealing after rolling or forging. Isothermal annealing may be accomplished by heating to 700 “C ( 1290 “F) and holding for 8 h
l
Forging.
Heat Treating
tests
Composition:
0.15 C, 0.63
at 925 “C (1695 “F). Grain size: 6
Case
hardness
gradients
after
10
356 / Heat Treater’s
Guide
4615: Carbon Gradients After Carburizing.
(a) Carburized for 4
h at 870 “C (1600 “F); (b) Carburized for 4 h at 925 “C (1695 “F)
4615: Depth of Case vs Time and Temperature.
25 mm (1 in.)
round bars, carburized at 925 “C (1695 “F), oil quenched
4615: isothermal Transformation
Diagram. Composition: 0.15
C. 0.63 Mn. 1.90 Ni, 0.24 MO. Austenitized at 925 “C (1695 “F).
Grain size: 8
356 / Heat Treater’s
Guide
4620,4620H,
4620RH
Chemical COIIIpOSitiOn.
1620. AIS1 and UN% 0.17 to 0.22 C. 0.15
too.65 Mn.0.035 Pmax.0.040Smax,0.15
ro0.30Si.
1.65 to3.00Ni.0.20
to 0.30 Mo. UNS A46200 and SAE/AISI 4620H: 0.17 to 0.23 C. 0.35 to
0.75 Mn. 0.15 to 0.35 Si, I.55 to 2.00 Ni. 0.20 to 0.30 hlo. SAE 4620RH:
0.17 to 0.22 C. 0.45 to 0.65 hln. 0. IS to 0.35 Si, I.65 to 2.00 Ni. 0.20 to
0.30 MO
Similar
Steels (U.S. and/or
Foreign).
294; ASTM A322, A33 I, ASOS, AS35; hlfLSPEC
J4 12. J770.4620H.
UNS H46200; ASTM
A304
4620. UNS G46WO; AhlS
MU-S-7493;
SAEJ10-I.
A9 I-l; SAE J 1268. J I868
Characteristics.
lrsed eswnsivel) for carburiring.
Because of relativelj high nickel content. it has hern replaced in some areas with lower
nickel alloys that have been developed and have hardenability
and other
properties equal to those of 462OH. Depending on the precise carbon
content within the allouabls
range. as-quenched hardness without carburizinp ranges betueen approsimately
40 to 35 HFX. Has a reasonably
high hardenabilit!.
Because of the relatwely high nickel content. 4620H is
srronglq susceptible to retention of austenite. While retained auslenite is
usually considered as an undesirahls constituent. some specific applications exist 1%here retained austenire has proved to be an advantage
Alloy Steel / 357
Forging.
forging
Heat to 1245 “C (X75 “F). Do not forge after temperature
stock drops helow approximateI>
815 “C (IS55 “F)
Recommended
Normalizing.
Heat Treating
of
tempering procedures described
pering are alternative processes
Recommended
Practice
l
Heat to 915 “C ( 1695 “F). Cool in air
l
Annealing.
Structures with best machinabilib
are de\elopsd
by normalizing or by isothermal transformation
after rolling or forginp. Commonly used isothermal practice consists of heating to 775 ‘C (1415 “F).
cooling rapidly to 650 ‘C ( I300 “F). and holding for 6 h
l
Hardening.
l
Seldom subjected to hardening treatments except carburizing and carbonitriding.
See recommended carburizing. carboniu-iding.
and
4620:
Carburizing,
l
l
l
for 41 l8H. Flame hardening
Processing
and martem-
Sequence
Forge
Nomlalize
Anneal (optional)
Rough and semifinish machine
Case harden
Temper
Finish machine (carburized parts only)
Single Heat Results
Specimens
contained
0.17 C, 0.52 Mn, 0.017 P, 0.016 S, 0.26 Si, 1.81 Ni, 0.10 Cr, 0.21 MO; grain size 6 to 8; critical points included AC,, 1300
“F (705 “C); AC,, 1490 “F (810 “C); Ar,, 1335 “F (725 “C); Ar,, 1220 “F (660 “C); 0.565-in. (14.4-mm) round treated, 0.505-in. (12.8-mm)
round
tested
Core properties
Case
Recommended practice
Elongation
Depth
Tensile strength
ksi
hlPa
Ill.
6’ S
62
0.07.5
0.060
.91
52
119.25
I22
822.2
811
83.5
77.25
576
532.6
19.5
72.0
59.1
55.7
277
248
58 5
59
59
0.060
0.065
0 MO
57
.6S
.65
147.5
I IS.5
I IS.25
1017
796.3
794.63
I IS.75
80.75
77
798.07
556.8
531
16.8
70.5
22.5
57.9
63.6
62.1
302
318
235
mm
b’ield point
ksi
hIPa
Reduction
Ofare&
(SOmm), %
5%
Hardness,
HRC
in2in.
Hardness,
EIB
For maximum case hardness
Direct ouench from rot(u)
Single &ench and &per(b)
Double quench and temper(c)
For maximum core toughness
Direct quench fmm pot(d)
Single quench and temper(r)
Double quench and temper(f)
(a) Carburizzd at 1700°F (925 TI for 8 h, quenched in agitated oil, tempered at 300 “F I I SO “C) 1.b) Carburized at 1700 “F (925 “C I for 8 h pot cooled. reheated to IS00 “F (815
“CJ. quenched in agitated oil, tempered at 300 “F ( 150 “CL Good case and core properties. tc) Carburizcd at I700 ‘,F 1925 “C) for 8 h. pal cooled, reheated IO IS25 “F (830 “C).
quenchrdinagitatedoil.rehestedto
1175”Fi800”C).quenchcdinagiraredoil.
temperedat
“Ft 150°C) hlsaimumrefinemcntofcclseandcore.(d)Carburizcdat
17OO”F(925
“C). quenched in agitatedoil.
tempered at -IS0 “Ft230”C)
Ir) Carburircdat
1700 “Ft925 “C). pot cooled. reheated to IS00 “F18lS ‘CL quenched in agitatedoil,
temperedatJS0
“F(23O”C).
Goodcasesndcore
propenies. (fl Carburircd at 1700 “Fi92S “C) for 8 h. pot cooled, reheated to IS25 “Ft830 “CL quenched in agitatedoil,
reheated to 1175 “F(800
T). quenched in agitated oil. tempered at -IS0 “F (230 “C ). (Source: Bethlehem Steel 1
4620H: End-Quench Hardenability
Distance loom
quenched
surface
‘/,b in.
mm
Hardness,
HRC
min
max
Distance from
quenched
surface
&in.
mm
Hardness,
HRC
may
I
I.58
48
-II
I3
20.54
12
1
-I
5
6
7
3.16
4.74
6.32
7.90
9.48
ll.c6
J5
-II
39
3-I
31
29
3s
27
2-l
21
I4
IS
I6
I8
20
2’
21.12
23.70
‘5 ‘8
5s:;
3160
31.76
22
22
‘I
21
20
8
9
IO
II
I2
12.6-I
I-l.22
15.80
17.38
18.96
27
26
2s
2-l
23
24
26
33
30
32
37.92
41 08
44.21
47.40
SO.56
3
358 / Heat Treater’s
Guide
4620H: Effects of Carburizing
63 HRC
and Quenching
Methods
on Dimensions.
Gears, carburized
0.762 to 1.02 mm (0.030 to 0.040 in.), 58 to
Specimens 19 mm
4620: Liquid Carburizing.
(.75 in.) diam by 51 mm (2 in.), carburized, air
cooled, reheated in neutral salt at 845 “C (1555
“F), quenched in salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) Carburized at 900
“C (1650 “F); (c) Carburized at 925 “C (1695 “F)
4620: Range of Surface Carbon vs Position in Furnace. Bearing races, carburized in a pit furnace 762 mm (30 in.) in diameter
by 914 mm (36 in.) deep. Open load of races was carburized for 7
h in natural gas atmosphere; 3 92 h diffusion cycle followed. Surface carbon aim was 1 .OO%. Each bar represents 14 heats of steel
Alloy
4630:
As-Quenched
Specimens
Hardness
4620, 4620H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
quenched in oil
Repre-
HWdIlt?SS
Size round
in.
mm
Surface
‘/* radius
Center
‘/:
13
25
Sl
102
40 HRC
21 HRC
23 HRC
% HRB
32 HRC
99 HRB
91 HRB
91 HRB
31 HRC
97 HRB
9ZHRB
88 HRB
I
2
-l
Steel / 359
Source: Bethlehem Steel
4620: CCT Diagram. Chemical composition: 0.20 C, 0.49 Mn, 0.016 P. 0.022 S, 0.23 Si, 1.76 Ni. 0.25 MO, 0.076 Al. A laboratory induction
air melted heat. Specimens 4 mm (0.16 in.) in diameter were through-carburtzed
to various carbon levels by holding in a carburizing atmosphere at 1150 “C (2100 “F) for 16 to 20 h. Machined dilatometer specimens [3 mm (0.116 in. )] in diameter were austenitized and cooled at
three different rates to define the partial CCT diagram at each carbon level. Cooling rates ranged from 357 to 3280 “C (675 to 5900 “F) per
min. The cooling curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture
specimens (gear tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil [66
“C (150 “F)] or in hot oil [170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to
obtain partial kinetic data on continuous-cooling
transformation at various carbon levels in the carburized case. Hardness values (in circles
on the diagram) were exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram.
Source: Datasheet l-262, Climax Molybdenum Company
360 / Heat Treater’s
Guide
4620: Microstructures. (a) Nital, 1000x. Gas carburized at 1.000/b carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820
“C (1510 “F), oil quenched, tempered 1 h at 180 “C (355 “F), retempered 2 h at 260 “C (500 “F). Composition: 0.95 C. Retained austenite
(by x-ray), tempered martensite, lower bainite. carbide. (b) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 230 “C (450 “F). 10% retained austenite (by x-ray), tempered
martensite, lower bainite. dispersed carbide particles. (c) Nital, 1000x. Gas carburized and heat treated before tempering under same conditions as (a) and (b), but tempered 1 h at 180 “C (355 “F) and retempered 2 h at 220 “C (425 “F). Composition: 0.95 C. 20% retained
austenite (by x-ray), tempered martensite, lower bainite, carbide. (d) Nital, 1000x. Gas carburized at 1 .OO% carbon potential for 4 h at 940
“C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355 “F). Composition: 0.90 C. 35% retained austenite (by x-ray), and tempered
martensite. (e) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, heated to 820 “C (1510 “F)
for 30 min. oil quenched, tempered 20 min at 94 “C (200 “F). Composition: 0.95 C. 40% retained austenite (by x-ray), and tempered martensite. (f) Nital, 1000x. Gas carburized at 1.00% carbon potential for 8 h at 940 “C (1725 “F), oil quenched, and tempered for 1 h at 180 “C (355
“F). Composition: 0.95 C. 45% retained austenite (by x-ray), and tempered martensite.
Alloy Steel / 361
4620H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness
w-poses
I distance,
nm
1.5
3
5
7
1
11
13
15
20
25
30
35
Hardness
purposes
I distance,
V,6 ill.
1
2
3
4
5
6
I
8
9
10
11
12
13
14
15
16
18
20
22
limits for specification
Hardness,
hlanimum
HRC
hlinimum
48
46
42
37
33
30
27
26
23
22
21
41
31
28
23
.
..
..
limits for specification
Hardness,
MaGmum
48
45
42
39
34
31
29
27
26
25
24
23
22
22
22
21
21
20
ARC
hlinimum
41
35
27
24
21
...
.
.
.
temperatures
recommended
by SAE. Normalize (for forged or roiled specimens
only): 925 “C
1
362 / Heat Treater’s
Guide
4626,4626H
Chemical COIIIpOSitiOn.
4626. AISI and UN!%: 0.2-l to 0.29 C. 0.45
to0.65Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.70to
l.00Ni.0.15
to0.25Mo.4626E.AISIaodUNS:0.23to0.29C,0.40to0.70Mn,0.035
P max. 0.040 S max. 0.15 to 0.30 Si. 0.65 to I .05 Ni. 0.15 to 0.25 MO
G46260;
UNS
Steels (U.S. and/or Foreign). 4626.
ASTM A322. A33 I; SAE 5404.5412. J770.46268.
UNS H-16260; ASTM
A304 This steel is no longer in SAE 5404 or J3 12. but does appear in SAE
5770. which is now J I397
Annealing.
Best structures for machining are obtained either by normalizing or by isothermal treatment after rolling or forging. Isothermal treatment is accomplished by heating to 815 “C (1500 “F). cooling rapidly to
675 “C ( I235 “F). and holding for 8 h
Similar
Characteristics.
Usually used for carburizing or carbonitriding
applications, although because of the as-quenched hardness of approximately
43
to 48 HRC that can be developed, it is sometimes used for parts that require
strength and toughness without case hardening. To save energy. 4626H is
sometimes used rather than lower carbon steels for carburizing. because the
harder cores provided by 4626H often permit thinner cases. decreasing the
required carburizing
time. The hardenability
of 4626H is slightly lower
than shown for 4620H. because of the lower alloy content of 4626H. Can
be welded, but alloy steel practice must be used
Direct Hardening.
Tempering.
Temper to at least 205 “C (100 OF) and preferably
some loss of hardness can be tolerated
Case Hardening.
tempering
Forging.
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
of forging stock drops below approximately
870 “C ( 1600 “F)
Recommended
Normalizing.
Heat Treating
l
I
2
3
4
5
6
7
8
9
IO
II
I2
I S8
3.16
4.74
6.32
7.90
9.48
II.06
12.6-I
I-t.22
15.80
Il.38
18.96
l
See recommended carburizing,
described for 41 l8H
Processing
higher if
carbonitriding.
Sequence
Forge
Normalize
Anneal (optional)
Rough and semifinish machine
Case harden or direct harden
Temper
Finish machine (carburized parts only)
Hardenability
Distance from
quenched
surface
&III.
mm
l
l
Heat to 900 “C (1650 “F). Cool in air
4626H: End-Quench
l
l
Practice
procedures
Recommended
l
temperature
Heat to 870 “C (1600 “F) and quench in oil. Caris a suitable hardening process
bonitriding
Eardness,
ERC
min
max
51
38
41
33
29
27
25
24
23
22
22
21
4s
36
29
24
II
Distance from
quenched
surface
‘/,a in.
mm
I3
IJ
IS
I6
I8
20
22
‘4
26
20.5-l
22.12
23.10
25.28
28.44
31.60
3-1.16
31.92
AI.08
Ehl-dlleSS,
HRC
max
21
20
.._
.._
4626, 4626H:
sents an average
Hardness
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
and
Alloy
4626H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
iardness
wrposes
I distance,
om
._5
/
,
I
b
I
3
5
!O
!5
iardness
wrposes
I distance,
116i”.
I
,
I
I
i
i
I
I
)
IO
II
12
13
l-1
IS
limits for specification
Eardness, ERC
Maximum
Minimum
51
45
48
38
31
27
25
2-l
23
21
36
29
23
20
limits for specification
Aardness, ERC
Maximum
Minimum
51
48
41
33
29
27
‘5
24
23
22
22
21
21
20
4s
36
29
24
21
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel I363
only): 925 “C
364 / Heat Treater’s
Guide
4718H
Chemical COI?IpOSitiOn.
UNS H47180 and SAE/AISI 47188: 0. IS
to 0.21 C. 0.60 to 0.95 MN, 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60
Cr. 0.30 to 0.40 Mo
4718H: Hardenability
Curves. Heat-treating
925 “C (1700 “F)
(1700 “F). Austenitize:
temperatures
Similar
Steels (U.S. and/or
Foreign).
to SAE J I268 and will appear in ASTM
recommended
This steel has heen added
A301
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Hardness limits for specification
3urposes
I distance,
q m
.5
Hardness, HRC
hlinlmum
Maximum
47
47
46
43
39
36
34
32
29
27
26
26
2s
25
24
40
40
38
31
28
25
23
22
21
20
(continued)
Alloy Steel I365
4718H: Hardenability
Curves. (continued) Heat-treating
only): 925 “C (1700 “F). Austenitize:
Hardness
purposes
J distance,
%6 ill.
I
2
3
4
5
6
7
8
9
10
II
12
13
14
15
16
18
20
22
24
26
28
30
32
925 “C (1700 “F)
limits for specification
Hardness, HRC
Maximum
blinimum
47
47
45
43
40
37
35
33
32
31
30
29
29
28
27
27
27
26
26
25
25
24
24
24
40
40
38
33
29
27
25
24
23
22
22
21
21
21
20
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
366 / Heat Treater’s Guide
4720,472OH
Chemical Composition.
4720.
AI!31
and UNS: 0.17 IO 0.22 C. 0.50
to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si.0.90to
l.10Ni.0.35
to 0.55 Cr. 0.15 to 0.25 MO. UNS 847200 and SAE/AISI 47208: 0. I7 to
0.23 C. 0.45 to 0.75 Mn. 0.15 to 0.35 Si. 0.85 to 1.25 Ni. 0.30 to 0.60 Cr,
0.15 too.25 MO
Similar Steels (U.S. and/or Foreign). 4720.
UNS
ASTM A274. A322. A331. A5 19, A535; SAE J404, J412,5770.
UNS H47200; ASTM A304; SAE J I268
G472OO;
4720H.
Characteristics. Essentially the same as those for 4620H. The lesser
nickel content of 4720H is compensated for by a chromium addition. As a
result, hardenability
for the two steels is nearly the same. As-quenched
hardness of approximately
40 to 45 HRC is also the same. Because of the
lower nickel content and the chromium addition, the tendency of 4720H to
retain austenite in carburized cases is less than for 4620H. In many instances, 4720H has replaced 4620H as a carburizing steel
Recommended
Normalizing.
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
temperature of forging stock drops below approximately
845 “C ( I555 “F)
Practice
Heat to 925 “C ( 1695 “F). Cool in air
Annealing.
Best structures for machining are obtained either by normalizing or by isothermal treatment consisting of heating to 815 “C (1500 “F),
cooling rapidly to 650 “C ( I300 “F). and holding for 8 h
Case Hardening.
tempering
procedures
Recommended
l
l
l
l
l
Forging.
Heat Treating
l
l
See recommended carburizing,
described for 4 I I8H
Processing
carbonitriding,
Sequence
Forge
Normalize
Anneal (optional)
Rough and semifinish machine
Case harden
Temper
Finish machine (carburized parts only)
4720H: End-Quench Hardenability
Diicefrom
quenched
surface
l/,/16in.
mm
I
2
3
4
5
6
7
8
9
IO
II
I2
I .58
3.16
4.14
6.32
7.90
9.48
II.06
12.6-l
14.22
IS.80
17.38
18.96
Flardoess,
ERC
max
min
48
41
33
39
35
33
29
28
27
26
25
24
41
39
31
37
23
21
:::
Distance from
quenched
surface
‘/,a in.
mm
13
I-l
IS
I6
18
20
22
2-l
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
33.76
31.92
41.08
44.24
47.40
SO.S6
Eardness,
ARC
max
2-l
23
23
22
21
21
21
20
4720, 4720H: Hardness vs Tempering Temperature. Represents an average
based
on a fully quenched
structure
and
Alloy Steel / 367
4720H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
925 “C (1700 “F)
Hardness
wrposes
I distance,
nm
1.5
limits for specification
Aardness, HRC
Maximum
Minimum
48
47
43
38
33
30
28
27
2-l
23
22
21
20
41
39
32
75
22
20
..
Hardness limits for specification
xuposes
I distance,
116in.
I
3
IQ
II
I2
13
1-I
IS
16
18
!O
!?
!1
!6
Elardness, ERC
Maximum
Minimum
48
4-I
43
39
35
32
29
28
27
26
25
2-l
2-I
23
23
22
21
‘I
?-I
20
41
39
31
27
23
21
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
366 / Heat Treater’s
Guide
4815,4815H
Chemical
Composition.
4815. AIM and UNS: 0. I3 to 0. I8 C. 0.40
Annealing.
to0.60Mn,0.03SPmax.0.~0Smax.0.lSto0.30Si.3.35to3.7SNi.0.20
to 0.30 MO. UNS H-t8150 and SAE/AISI 4815H: 0. I2 to 0. I8 C. 0.30 to
0.70 hln. 0.15 to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 MO
After normalizing, heat to 650 ‘C (1200 “F), hold for I h per
inch of section thickness. Cooling rate from this temperature is not critical.
hlay also be isothermally annealed by heating to 745 “C (1370 “Fj. cooling
rapidly to 605 “C (I I25 “F), and holding for 8 h
Similar
Tempering.
ASThl
ASThl
Steels (U.S. and/or
Foreign).
4815.
A322. A33 I. ASOS: SAE J-IO-I. J-t I2.J770.4815I-l.
A304 SAE J 1268
G48 I SO;
UNS
UNS H-18 I SO:
Characteristics.
Represents a relatively high alloy carburizing grade
intended for use where sections are thick and relatively
hard. and tough
cores are mandatory.
Depending
on the precise carbon content. asquenched hardness should be approximately:
35 to 42 HRC. Hardenability
is relatively
high. As is true for other htgh-nickel
carburizing
steels.
austenite may be retained in the carburized case. Amenable to welding. but
alloy steel practice of preheating and postheating must be used
Forging.
forging
Heat to 1245 “C 12275 “Ft. Do not forge after temperature
stock drops below approxtmately
815 “C (15% “Ft
Recommended
Heat Treating
Practice
of
All parts made from this grade should he tempered at I50
“C (300 “F) or higher if some loss of hardness can be tolerated. Tempering
~bill help in transforming retained austenite
case
Hardening. See carburizing process described for 31 l8H. This
grade is rarely subjected to carbonmiding.
Liquid carburizing.
gas carburizing, and martempering are suitable processes
Recommended
l
l
Anneal
l
Rough and semifinish machine
Case harden
Temper
Finish machine ccarburized parts only)
l
Heat to 925 “C (I695 “Fj. Cool in air
l
Sequence
Forge
Normalize
l
l
Normalizing.
Processing
4815: Continuous Cooling Curves. Composition: 0.14 C. 0.45
Mn, 0.22 Si, 3.42 Ni, 0.21 MO. Austenitized at 925 “C (1695 “F).
Grain size: 9. AC,, 800 “C (1475 “F); AC,, 730 “C (1350 “F). A:
austenite, F: ferrite, B: bainite, M: martensite. Source: Bethlehem
Steel
4815: Liquid Carburizing.
Pinion liquid carburized at 900 “C
(1650 “F) for 2.5 h. quenched in still oil, tempered at 205 “C (400
“F) for 0.5 h. Hardness, 58 to 60 HRC. 12 tests done to measure
runout
Alloy Steel I369
4815:
ZOIllZ
Carbon Gradients
Temperature
“F
OC
4815: Isothermal Transformation
Atmosphere
Tiiein
zone, h
Carbon
potential, %,C
Cycle l(a)
1
2
3
1690
1690
1670
920
920
910
Methane
Methane
Carrier gas, air
8
14
13
1.25
1.25
0.80(b), 0.55(c)
Cycle 2(d)
1
2
3
1690
1690
1670
920
920
910
Methane
Methane
Carrier gas. air
6
10
9
1.25
1.25
0.80(b), 0.60(c)
Cycle 3(e)
1
2
3
1690
1690
1670
920
920
910
Methane
Methane
Carrier gas, air
4
7
6
1.25
1.25
0.80(b), 0.75(c)
Diagram. Carburized, 1 .O%
carbon. Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at 980 “C (1795 “F). Grain size: 7
(a) Target, 0.1 IO-in. (2.79-mm) case at 0.25% C. (b) At center of fone. (c) At discharge.
(d) Target, 0.~in.
(2.29-mm) at 0.25% C. (e) Target. 0.070-m. (1.78-mm) case at
0.25% C
4815: Carbon Gradients. From three-zone
continuous pushertype carburizing furnace. Carbon potential was controlled manually. A: Cycle 1, 35 h; 0: Cycle 2, 25 h; 0: Cycle 3, 17 h
4815: End-Quench
Hardenability.
Mn, 3.36 Ni. 0.19 MO. Austenitized
8 to 9
Composition: 0.16 C, 0.52
at 900 “C (1650 “F). Grain size:
4815: End-Quench
Hardenability. Carburized, 1 .O% carbon.
Composition: 0.97 C, 0.52 Mn, 3.36 Ni, 0.19 MO. Austenitized at
980 “C (1795 “F). Grain size: 7
4815, 4815H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
370 / Heat Treater’s
I
2
3
4
5
6
7
8
9
IO
II
I2
I .xX
3.16
4.74
6.32
7.90
9.48
I I .06
12.64
14.22
15.80
17.38
18.%
Guide
45
4-l
44
42
41
39
37
35
33
31
30
29
38
37
31
30
27
24
22
21
20
I3
l-l
IS
I6
I8
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
31.92
41.08
44.2-l
47.40
50.56
28
28
27
27
26
25
24
24
2-l
23
23
23
4815: Depth of Case vs lime and Temperature.
13 mm (0.5 in.)
round bars, carburized at 900 “C (1650 “F), and oil quenched
4815: Variation in Carbon Concentration.
Steel rock bit cutters
carburized at 925 “C (1695 “F). Pit-type furnace, 314 mm (36 in.)
in diameter by 1829 mm (72 in.) deep, used a carburizing-diffusion
cycle. Dew point controlled at the generator only. Each test represents one load of 1361 kg (3000 lb). (a) 40 tests. Carbon at 1.8 mm
(0.070 in.) below surface; (b) 50 tests. Carbon at 2.42 mm (0.095
in.) below surface
4815: Isothermal Transformation
Diagram. Composition: 0.16
C, 0.52 Mn. 3.36 Ni, 0.19 MO. Austenitized at 900 “C (1650 “F).
Grain size: 8 to 9
4815: Variation of Surface Carbon Content. 50 tests of rock bit
cutters carburized in two pit-type furnaces to an aim of 0.75% C.
Furnaces were operated simultaneously,
using the same gas
generator. Each furnace was 914 mm (36 in.) in diameter by 1829
mm (72 in.) deep and contained a load of about 1361 kg (3000 lb).
A carburize-diffuse cycle was used. An automatic dew point controller was employed on the generator, but not on the furnace
Alloy Steel / 371
4815H: CCT Diagram. Composition
for commercial SAE 4815 carburizing steel: 0.16 C, 0.63 Mn, 0.010 P, 0.012 S, 0.24 Si, 3.35 Ni, 0.21
Cr, 0.24 MO. 0.19 Cu. In this study, slabs from commercial billet 76 mm (3 in.) square were normalized at 925 “C (1695 “F) for 1 h. Specimens
were austenitized at 870 “C (1600 “F) for 20 min. The purpose of the study was to characterize a standard grade of carburizing steel for
comparison with recently developed grades. Source: Datasheet l-257. Climax Molybdenum Company
372 / Heat Treater’s
Guide
4815H: Hardenability
(1700 “F). Austenitize:
Hardness
purposes
J distance,
IUDI
1.5
II
13
.5
!O
Y
IO
i5
lo
15
;0
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Eardness, HRC
Maximum
Minimum
45
45
44
42
40
31
35
32
29
27
26
25
24
24
23
38
36
33
28
25
22
20
.
.
.. .
iardness
wrposes
limits for specification
I distance,
116in.
Eardnes,
Maximum
I
,
1
IO
I1
12
13
14
15
I6
8
!O
!2
!4
!6
!8
IO
I2
45
44
44
42
41
39
37
35
33
31
30
29
28
28
21
27
26
25
24
24
24
23
23
23
ARC
hlinimum
38
31
34
30
27
24
22
21
20
..”
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 373
4817,4817H
Chemical
Composition.
4817. AISI and UNS: 0. IS to 0.20 C. 0.40
Annealing.
to0.60hln.0.03SPmax.0.~0Smax.0.lSto0.30Si.3.1Sto3.7SNi.0.20
to 0.30 MO. UNS A18170 and SAE/AISI 4817H: 0. II to 0.20 C. 0.30 to
0.70 hln. 0.1s to 0.35 Si. 3.20 to 3.80 Ni. 0.20 to 0.30 hlo
After normnlizinp. heat IO 650 “C (I100 “F), hold for I h per
inch of section thickness. Cooling rnte from this temperature is not critical.
hIa> also be isothermall> annealed b> heating to 715 “C (I 370 “F), cooling
rapidly to 605 “C ( I I25 “F). and holding for 8 h
Similar
Tempering.
ASTM
ASTM
Steels (U.S. and/or
A3X.
A304
Foreign).
4817.
A33 I. AS 19; SAE J-104. J-l I?. 5770.4817H.
SAE Jl368
UNS
G-18170:
UNS H-I8 170:
Characteristics.
U’ith the exception of a slightly higher carbon content, steels 18lSH and 1817H we identical. and thiir characteristics
me
essentially
identical. As-quenched
hardness (core hardness) should be
slightI> higher for 1817H (approximately
36 to 43 HRC). Hardcnahilit!,
patterns are nearly identical. Welding is possible. but preheating and postheating must be used
Forging.
Heat to 12-15 “C (2175 OF) mnsimum. Do not forge after
temperature of forging stock drops belo\{ approxunatel>
8-U “C ( IS55 “F)
Recommended
Normalizing.
Case Hardening.
See cttrhurizinp process described
grade is rareI> subjected to carhonitriding
Recommended
l
l
l
l
Practice
l
“FL Cool in air
l
Heat Treating
Heat to 925 “C (16%
All pans made from this grade should he tempered at IS0
“C (300 “F) or higher if some loss of hrudness GUI be talented. Tempering
\\ill help in transtormma retnmed wstenite
l
Processing
for 41 l8H. This
Sequence
Forge
Normalize
Anneal
Rough md semifinish machine
Case harden
Temper
Finish machine (cluburized parts only)
4817H: End-Quench Hardenability
Distance from
quenched
surface
I/lb in.
mm
Hardness,
HRC
min
max
Distance from
quenched
surface
‘lib in.
mm
Hardness,
HRC
mas
I
7
I 58
46
39
13
20.5-i
30
;
-I
5
6
7
8
9
10
II
I2
-1.7-l
3.16
6.32
7.90
9.18
I I.06
I2.M
I-I.72
IS.80
17.38
18.96
45
46
44
12
-II
39
37
35
33
3’
Iii
3x
35
32.
‘9
27
1.5
23
22
21
20
‘0
I-l
15
16
18
70
22
24
‘6
‘8
30
32
22.12
13.70
25.x3
‘8.44
31.60
34.76
37.91
41.08
44.2-l
47.40
SO.56
‘9
‘8
78
17
26
3
25
25
2.5
2-l
21
4817, 4817H: Hardness vs Tempering Temperature. Represents an average
based
on a fully quenched
structure
374 / Heat Treater’s
Guide
4817: Carburizing
and Hardening vs Diametral Dimensions. Bevel drive pinion gear (a), carburized at 925 “C (1695 “F), tempered at
160 “C (320 “F). Depth of case, 1.27 to 1.65 mm (0.050 to 0.065 in.). Major spline diameter of twenty-five 4 kg (8 lb) gears (b) before treatment, (c) after treatment
4817: Cooling Curve. Half cooling time. Source: Datasheet
I-50. Climax Molybdenum
Company
Alloy Steel / 375
4817: CCT Diagram. Chemical composition:
0.17 C, 0.54 Mn, 0.015 P, 0.025 S, 0.33 Si, 0.087 Al. Alaboratory induction air melted heat.
Specimens 4 mm (0.16 in.) in diameter were through-catburized
to various carbon levels by holding in a carburizing atmosphere at 1150 “C
(2100 “F) for 16 to 20 h. Machined dilatometer specimens 3 mm ((0.118 in.) in diameter were austenitized and cooled at three different rates to
define the partial CCT diagram at each carbon level. The cooling rates ranged from 375 to 3280 “C (675 to 5900 “F) per min. The cooling
curves used to define the diagrams are not shown. Instead, the cooling curves shown were measured on impact-fracture specimens (gear
tooth simulation) at locations corresponding to the surface and the case-core interface during quenching in warm oil 66 “C (150 “F) or in hot
oil 170 “C (340 “F). Specimens were austenitized at 900 “C (1650 “F) for 20 min. The objectives of the study were to obtain partial kinetic
data on continuous-cooling transformation at various carbon levels in the carburized case. Hardness values (in circles on the diagram) were
exhibited by specimens of each carbon level subjected to the fastest cooling rate used to define each CCT diagram. Source: Datasheet 1279.
Climax Molybdenum Company
(continued)
376 / Heat Treater’s
Guide
4617: CCT Diagram. (continued)
Alloy Steel / 377
4817H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
iardness
wrposes
I distance,
nm
1.5
3
I1
13
I5
!O
5
30
3.5
lo
15
50
iardness
wrposes
distance,
:I6 in.
I
2
3
1
5
5
7
9
1
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
limits for specification
Eardness,
Maximum
HRC
hlinimum
39
38
35
31
28
25
23
21
46
46
45
44
42
39
37
34
31
28
21
26
25
25
25
...
.
limits for specification
Hardness,
Maximum
46
46
45
44
42
41
39
37
35
33
32
31
30
29
28
28
27
26
25
25
25
25
24
24
HRC
hfinimum
39
38
35
32
29
27
25
23
22
21
20
20
.
.
.
.
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
378 / Heat Treater’s
Guide
4820,4820H,
4820RH
Chemical COIIIpOSitiOn.
4820. AISI and UNS: 0.18 to 0.23 C. 0.50
to0.70Mn.0.035Pmax.0.040Smax.0.15to0.30Si,3.25to3.75Ni.0.20
to 0.30 MO. UNS H48200 and SAE/AISI
48208: 0. I7 to 0.23 C. 0.40 to
0.80 Mn. 0.15 to 0.35 Si, 3.20 to 3.80 Ni. 0.20 to 0.30 MO. SAE IZORH:
0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.15 to 0.35 Si. 3.25 to 3.75 Ni, 0.20 to
Recommended
Normalizing.
Heat Treating
Practice
Heat to 925 “C (I 695 “F). Cool in air
Annealing.
0.30 MO
After normalizing, heat to 650 “C (I 200 “F). hold for I h per
inch of section thickness. Cooling rate from this temperature is not critical.
hlay also be isothermally annealed by heating to 745 “C ( I370 “F). cooling
rapidly to 605 “C ( I I25 “F), and holding for 8 h
Similar
Tempering.
Characteristics.
Case Hardening. See carburizing process described
grade is rarely subjected to carbonitriding.
Austempering
process
G-18200;
Steels (U.S. and/or Foreign). 4820. UNS
ASTM A322, A33 1, A505. AS 19, A535; SAE JW. 5412. J770. 4820H.
UNS H48200; ASTM A304, A9 14; SAE J I 268. J8668
In general. the characteristics of 4820H are similar to
those described for 48 I SH and 48 17H. Because of higher carbon content.
as-quenched hardness of 4820H ranges from approximately
40 to 45 HRC.
The hardenability
band is shifted upward when compared with the bands
for 4815H and 4817H. As is true for other high-nickel carburizing steels.
there is a strong tendency for retention of austenite in the carburized cases
of 4820 and 4820H. Amenable to welding, but alloy steel practice of
preheating and postheating must be used
Forging.
temperature
Heat to 1245 “C (2275 “Fj maximum.
Do not forge after
of forging stock drops below approximately
845 “C (I 555 “F)
Carburizing,
4820:
All parts made from this grade should be tempered at 150
“C (300 “F) or higher if some loss of hardness can be tolerated. Tempering
will help in transforming retained austenite
Recommended
Processing
for 4118H. This
is an alternative
Sequence
Forge
Normalize
. Anneal
l
Rough and semifinish machine
l
Case harden
l
Temper
l
Finish machine (carburized parts only)
l
l
Single Heat Results
Specimens
contained
0.21 C, 0.51 Mn, 0.021 P, 0.018 S, 0.21 Si, 3.49 Ni, 0.18 Cr. 0.24 MO; critical points
1440 “F (780 “C); Ar,, 1215 “F (855 “C); Ar,, 780 “F (415 “C); grain size was 6 to 8; 0.565-in. (14.4-mm)
round tested
Yield strength
0.2% offset
ksi
hU’a
Ctl.92
Recommended practice
Eardness,
ARC
Depth
in.
mm
..,
For maximum case hardness
Direct quench 6om pot(a)
Single quench and temper(h)
Double quench and temper(c)
60
61
60
0.039
0.047
0.047
For maximum core toughness
Direct quench from pot(d)
Single quench and temper(e)
Double quench and tempertf)
56
57.5
56.5
0.039
0.047
0.047
included AC,, 1310 “F (710 “C); AC,,
round treated. 0.505-in. (12.8-mm)
Tensile strength
hIPa
ksi
Elongation
Reduction
in2ill.
Ofare&
(50mm), %
%
Hardness,
EB
205
2075
204.5
l-11)
1431
1110
165.5
167
I65 5
II-II
II51
II-11
13.3
I38
13.8
53.3
52.2
52.4
41.5
415
415
200.5
205
196.5
I382
1113
I355
170
184.5
171.5
II72
1272
I I82
12.8
13.0
13.0
53.0
53.3
53.4
4QI
41s
401
(a)Carburized at 1700 “F(92S “C) for 8 h, quenched in agitated oil. tempered at 3OO”F( IS0 “C, (h) Catknzed at 17OO”Ft925 “CI for 8 h. pot cooled. reheated to 1475 “F(800
“C). quenched in agitated oil. tempered at 300 “F (IS0 “C). Good case and core properties. (5) Carburized at I700 “F t92S “C) for 8 h. pot cooled. reheated to IS00 “F (815 “C).
quenched inagitatedoil. reheated to IJSO”F(79O”C). quenched inagitatedoil. temperedat 3OO”F(lSO”C). For maximum refinement ofcaseandcore. (d)Carburizedat 1700°F
(925”C)forS h.quenched inagitatedoil, temperedat450”F(230°C).
te)Carhurizedat 1700”F(92S°C) for8 h. potcooled. reheated to lJ7S”F(800°C).quenched
inagitatedoil.
tempered at 450”F(230”C). Goodcaseandcore properties. (nCarburizedat 17OO”F(925 “0 for8 h. pot cooled. reheated IO 1500°F~81S “C).quenched in agitatedoil. reheated
to 1~50”F~7’H)“C~,quenchedinagitatedoil.temperedat~50”F~230”C).(Source:
BethlehemSteel)
4820:
As-Quenched
Hardness
(Oil)
4820: Hardness vs Tempering Temperature.
Grade: 0.18 to 0.23 C, 0.50 to 0.70 Mn. 0.20 to 0.35 Si, 3.25 to 3.75
Ni.0.20to0.30Mo;ladle:0.20C,0.61
Mn,0.027P,0.016S,0.29Si,
3.47 Ni, 0.07 Cr, 0.22 MO; grain size: 6 to 8
Si
round
in.
mm
Surface
Rardness, HRC
‘12radius
Cenler
‘/I
I3
15
51
102
45
4s
36
27
4.5
39
31
21
4-l
37
27
24
I
2
4
Source: Bethlehem Steel
average
based
on a fully quenched
structure
Represents
an
Alloy Steel I379
4820: Variation of Surface Carbon Content after Carburizing.
Surface carbon concentration [first 0.076 mm (0.003 in.) depth of
cut] in nineteen 25.4 mm (1 in.) diam bars carburized with production parts in a two-row continuous furnace. Desired carbon content,
0.75 to 0.80%. Specimens were carburized at 925 “C (1695 “F)
using a diffusion cycle, quenched from 815 “C (1500 “F) in oil at 60
“C (140 “F), tempered in lead at 620 “C (1150 “F) for 5 min, wire
brushed, and liquid-abrasive cleaned. Atmosphere at the charge
end of the furnace was automatically controlled at a dew point of
-15 “C (5 “F) and at the discharge end at 3 “C (35 “F). Endothermic gas enriched with straight natural gas was used as the carbunking medium; air was added at the discharge end
4820H: End-Quench Hardenability
Distance from
quenched
surface
‘/,b in.
mm
Eardness,
ERC
max
min
Distance 6om
quenched
surface
‘46in.
,IM,l
2
3
1.58
3.16
4.74
48
48
47
41
40
39
13
I4
1s
-I
5
6
7
6.32
7.90
9.48
I I.06
46
45
43
32
38
3-l
31
‘9
16
18
20
22
20.54
22.12
23.70
2S.28
28.44
31.60
34.76
8
9
IO
II
I2
12.64
14.22
IS.80
17.38
18.96
-IO
39
37
36
35
27
26
25
2-l
23
24
26
28
30
32
37.92
41.08
44.24
47.40
50.56
I
Rardoess,
ERC
max
min
34
33
32
31
29
28
28
27
27
26
26
25
22
22
?I
‘I
20
20
..,
.._
.._
.__
380 / Heat Treater’s
4820: Continuous
Austenitized
Guide
Cooling Transformation
0.18 C, 0.47 Mn, 0.009 P, 0.010 S, 0.27 Si, 3.33 Ni, 0.18 Cr, 0.23 MO.
at 900 to 920 “C (1650 to 1690 “F) for 4 h
Diagram. Composition:
at 780 “C (1435 “F). Blank carburized
Alloy Steel I381
4820H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
Hardness
purposes
J distance,
mm
1.5
3
5
I
9
11
13
15
20
25
30
35
40
4.5
50
Hardness
purposes
I distance,
k,b in.
1
2
3
1
5
5
7
B
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
limits for specification
Hardness,
hlaximum
HRC
hlinimum
41
40
39
36
32
29
27
25
22
21
20
.
48
48
48
46
45
43
40
39
3.5
32
29
28
21
26
26
limits for specification
Hardness,
hlarimum
48
48
41
46
45
43
42
40
39
37
36
35
34
33
32
31
29
28
28
21
21
26
26
25
HRC
hlinimum
41
40
39
38
34
31
29
21
26
25
24
23
22
22
21
21
20
20
.
. ..
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
1
382 / Heat Treater’s
Guide
4820RH: Hardenability
“C (1700 “F). Austenitize:
Hardness
purposes
J distance,
‘46io.
I
2
3
4
5
6
7
B
9
IO
II
12
13
II
IS
I6
I8
?O
12
2-l
16
18
30
32
Hardness
purposes
J distance,
mm
I .5
3
s
7
9
II
13
IS
20
!5
30
35
40
85
SO
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Eardoes,
Maximum
ARC
Minimum
17
47
46
45
33
41
40
38
36
35
34
33
32
31
30
29
28
27
26
25
25
25
24
23
42
32
-II
xl
36
33
32
30
28
27
26
25
24
24
23
33
22
22
21
20
20
limits for specification
Hardness, HRC
Minimum
Maximum
37
47
46
44
42
40
38
3.5
32
29
27
26
25
24
23
12
42
31
38
3-l
32
30
27
2-l
23
22
21
20
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
1
Alloy Steel / 383
50940,50940H,
50940RH
Chemical Composition. 5OB40. AISI: 0.38 to 0.43 C, 0.75 to I .oo
Mn, 0.035 P max. 0.040 S max. 0.40 to 0.60 Cr. 0.0005 B min. UNS: 0.38
to 0.42 C, 0.75 to I .OO Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.10
to 0.60 Cr. 0.0005 B min. UNS A50401 and SAE/AISI
50B40H: 0.37 to
0.1WC.0.65to1.10Mn.0.15to0.35Si.0.30to0.70Cr.B(c~beexpected
to be 0.0005 to 0.003 percent). SAE SOB4ORH: 0.38 to 0.43 C. 0.75 to I .OO
Mn. 0.15 to 0.35 Si, 0.40 to 0.60 Cr. B (can be expected to be 0.0005 to
0.003 percent)
Similar Steels (U.S. and/or Foreign).
50B40.
UNS
G5w01;
ASTM A5 19; SAEJ404.5412,
J770; (Ger.) DIN 1.7007; (Ital.) UN1 38 CrB
I KB. 50B40H. UNS H50401; ASTM A304, A914: SAE Jl268. Jl868;
(Ger.) DW I .7007: (Ital.) UN1 38 CrB I KB
Characteristics. A medium-carbon gade with an as-quenched surface
hardness in the range of approximately
52 to 58 HRC. depending on
whether the carbon is low or high on the allowable range. The hardenability
band for SOB-IOH is nearly equal to that of 8630H. a higher alloy and more
expensive steel. Is easily foged and responds readily to heat treatments that
are used for other low-alloy steels of similar carbon content
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (1525
“F), cool rapidly to 740 “C ( I365 “F), then to 670 “C ( 1240 “F) at a rate not
to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F). cool rapidly to
675 “C (1245 “R. and hold for 6 h. For a predominately
spheroidized
structure. heat to 760 “C (I 300 “F), cool to 665 “C ( I230 “F) at a rate not
to exceed 6 “C ( IO “F) per h; or heat to 760 “C ( 1400 “F), cool rapidly to
665 “C (1230 “F). and hold for 8 h. For most subsequent operations such
as machining and hardening, a predominately
spheroidized
structure is
preferred
Hardening.
Tempering.
Heat to 1230 “C (3250 “FI maximum.
Do not forge after
temperature of forging stock drops below approximately
925 “C ( I695 “F)
Recommended
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 870 “C ( I600 “F). Cool in air
5084OH: End-Quench
Distance from
quenched
surface
l/16 in.
mm
I
2
3
4
5
6
7
8
9
IO
II
I?
I .58
3.16
1.7-l
6.32
790
9.48
I I.06
12.64
14.22
15.80
17.38
18.96
Eardness,
ARC
mar
min
60
60
59
59
58
58
57
57
56
55
53
51
l
Hardenability
53
53
52
51
50
48
4-l
39
31
31
29
28
Distance from
quenched
surface
‘/la in.
mm
13
1-l
15
I6
ia
20
22
2-l
26
28
30
32
20.51
22.12
23.70
25.28
28.4-I
31.60
31.76
31.92
41.08
44.2-l
47.40
50.56
Aardness.
HRC
min
max
19
47
4-l
31
38
36
35
34
33
32
30
29
27
26
25
25
23
II
at 845 “C (1555 “F). and quench in oil
Parts made from SOB-tOH should be tempered immediately
after they have been uniformly quenched to near ambient temperature. Best
practice is to place workpieces into the tempering furnace just before they
have reached room temperature. ideally when they are in the range of 38 to
50 “C (100 to I20 “F). Tempering temperature must be selected based upon
the tinal desired hardness
l
Forging.
Austenitize
Processing
Sequence
Forge
Normalize
Anneal
Rough and semifinish machine
Austenitize and quench in oil
Temper
Finish machine
50840,50B40H:
Hardness
sents an average
based
vs Tempering
on a fully quenched
Temperature.
structure
Repre-
384 / Heat Treater’s
Guide
50940H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1555 “F)
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
J distance,
‘/,6 in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
limits for specification
Eardness,
Maximum
ARC
Minimum
60
60
60
59
59
58
57
56
50
43
37
35
34
32
30
53
53
52
51
49
44
38
33
27
24
22
limits for specification
Eardness,
Maximum
60
60
59
59
58
58
57
57
56
55
53
51
49
47
44
41
38
36
35
34
33
32
30
29
RRC
blinimum
53
53
52
51
50
48
44
39
34
31
29
28
27
26
25
25
23
21
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
Alloy Steel / 385
50B40RH: Hardenability Curves. Heat-treating temperatures
“C (1600 “F). Austenitize:
845 “C (1555 “F)
iardness limits for specification
wrposes
I distance,
/lfJ in.
0
Hardness, ARC
Maximum
Minimum
59
59
58
58
57
56
55
5-l
52.
so
-t9
47
-is
4.4
-II
38
36
3-t
33
37
31
30
5-l
5-I
S?
S3
52
SO
-17
13
38
35
33
3’
ii
30
‘9
28
26
2-l
23
21
21
20
19
28
iardness limits for specification
wrposes
distance,
mm
.s
Rardness, EIRC
hlinimum
Maximum
S-l
5-l
53
s3
3
59
59
58
98
56
55
5-l
5
51
0
46
5
5
39
35
33
36
31
‘8
3
23
0
31
?I
5
29
28
20
I
(I
0
51
47
42
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
386 / Heat Treater’s Guide
50844,50B44H
Chemical Composition.
5OB44. AIM: 0.43 to O.-i8 C. 0.75 to 1.OO
Mn. 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.40 to 0.60 Cr. 0.0005 to
0.003 B. IJNS: 0.43 to 0.48 C. 0.75 to 1.00 Mn, 0.035 Pmax. 0.040 S max,
0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS ES0441 and
SAE/AISI 50B44H: 0.42 to 0.49 C. 0.65 to I. IO Mn. 0. I5 to 0.35 Si. 0.30
to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar Steels (U.S. and/or Foreign). SoB44.
ASTM A5 19; SAE 5404, 5412. 5770. 50B44H.
A304; SAE J I268
UNS
Gs04-1 I ;
UNS H50441; ASTM
Characteristics. Has the same general characteristics as 50B40H. Because of slightly higher carbon content, the as-quenched hardness of
SOB44H will be higher. although the carbon ranges of the two steels
overlap. The asquenched hardness will range from approximately
54 to 60
HRC. Hardenability
bands for the two grades are similar. the band for
SOB44H shifted slightly upward. Is easily forged and responds readily to
heat treatments that are used for other low-alloy
steels of similar carbon
content
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (I 525
“F), cool rapidly to 740 “C (I 365 OF). then to 670 “C ( 1240 “F) at a rate not
to exceed I I “C (20 “F) per h: or heat to 830 “C (I 525 “F), cool rapidly to
675 “C (I235 “F). and hold for 6 h. For a predominately
spheroidized
structure. heat to 760 ‘C ( 1300 “F), cool to 665 “C ( I230 OF) at a rate not
to exceed 6 “C (IO “F) per h: or heat to 760 “C (1400 “F), cool rapidly to
665 “C ( 1230 “F). and hold for 8 h. For most subsequent operations such
as machining and hardening, a predominately
spheroidized
structure is
preferred
Hardening.
Tempering.
Heat to 1230 “C (2250 “F) maximum. Do not forge after
temperature of forging stock drops below approximately
925 “C (1695 “F)
Recommended
Heat Treating
Practice
Recommended
l
Anneal
Rough and semifinish machine
Austenitire and quench in oil
Temper
Finish machine
l
Sequence
Forge
Normalize
l
l
Heat to 870 “C (1600 “Fj. Cool in air
Processing
l
l
Normalizing.
at 845 “C (IS55 “F), and quench in oil
Parts made from SOB34H should be tempered immediately
after they have been uniformly quenched to near ambient temperature. Best
practice IS to place workpieces into the tempering furnace just before they
have reached room temperature, ideally when they are in the range of 38 to
50 “C ( IO0 to I20 “F). Tempering temperature must be selected based upon
the final desired hardness
l
Forging.
Austenitize
50844,50844H:
Hardness vs Tempering Temperature. Repre-
sents an average based on a fully quenched structure
50844H: End-Quench Hardenability
Distancefrom
Eardoess,
ERC
min
max
I
2
3
4
5
6
7
8
Y
IO
II
12
I.58
3.16
4.74
6.32
7.90
9.48
Il.06
12.64
I-I.22
IS.80
17.38
I a.96
63
63
62
62
61
61
60
60
59
58
57
56
56
56
55
55
54
52
48
43
38
34
31
30
Distance from
quenched
surface
Vi6 in.
mm
I3
I-2
IS
I6
IX
20
‘2
24
26
28
30
32
20.54
22. I2
23.70
25.28
28.4-I
31.60
34.76
37.92
11.08
44.2-l
47.-Kl
50.56
EZUdlleSS,
ERC
max
min
5-l
52
SO
48
44
-lo
38
37
36
35
3-l
33
29
29
28
27
26
2-l
23
21
20
Alloy Steel / 387
50844H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitiie:
845 “C (1555 “F)
iardness
wrposes
I distance.
qm
1.5
3
5
7
?
I1
13
15
20
25
30
35
10
15
50
iardness
wrposes
distance,
‘16in.
1
3
IO
I1
12
13
I4
I5
I6
I8
!O
!2
!4
!6
!8
SO
i2
limits for specification
Hardness, ERC
Maximum
Minimum
63
63
63
62
61
61
60
59
55
49
42
38
31
35
34
56
56
55
54
52
49
42
36
30
21
25
23
21
.
limits for specification
Eardness, HRC
Maximum
Minimum
63
63
62
62
61
61
60
60
59
58
51
56
54
52
50
48
44
40
38
37
36
35
34
33
56
56
55
55
54
52
48
43
38
34
31
30
29
29
28
27
26
24
23
21
20
.
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
1
388 / Heat Treater’s Guide
5046,5046H
Chemical Composition.
Annealing. For a predominately pearlitic structure, heat to 830 “C (1525
Similar Steels (U.S.
OF), cool rapidly to 755 “C (1390 “F), then cool from 755 “C (1390 “F) to
655 “C (1220 “P) at a rate not to exceed 11 “C (20 “F) per h; or heat to 830
“C (1525 “F), cool rapidly to 665 “C (1230 OF), and hold for 4 qz h. For a
predominately spheroidized structure, heat to 760 “C (1400 OF),cool to 665
“C (1230 “F) at a rate not to exceed 6 “C (10 “F) per h; or heat to 760 “C
(1400 “F), cool rapidly to 660 “C (1220 “F), and hold for 8 h
5046. AISI: 0.43 to 0.50 C, 0.75 to 1.00
Mn,0.040Pmax,O.O40S
max.0.20to0.35 Si,O.20 too.35 Cr. UNS: 0.43
to0.50C,0.75to1.00Mn,0.035Pmax,0.040Smax,0.15to0.30Si,0.20
to 0.35 Cr. UNS I-I50460and SAE/AISI 5046lk0.43 to 0.5OC,O.65 to
1.10 Mn, 0.15 to 0.35 Si, 0.13 to 0.43 Cr
and/Or
Foreign). 5046.
ASTM A519; SAE J404,J412,J770.5046H.
SAE J 1268
UNS
G50460;
UNS H50460; ASTM A304:
Characteristics.
A typical medium-carbon, very low-alloy steel.
When both manganese and chromium are on the high side of their allowable ranges, 5046H has sufficient hardenability so that full hardness can be
obtained in thin sections by oil quenching. As-quenched hardness typically
ranges from approximately 53 to 58 HRC, depending on whether the
carbon is on the low or the high side of the range
Hardening. Austenitize at 845 “C (1555 “F), and quench in oil for thin
sections. Thicker sections wih require a water or brine quench for full
hardness
Tempering. After quenching, reheat to the temperature required to
achieve the final desired hardness
Recommended
Processing
Sequence
Forge
l Normalize
l Anneal (preferably spheroidize)
l Rough machine
l Harden
Q Temper
l Finish machine
l
Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after
temperature of forging stock drops below approximately 870 “C (1600 “F)
Recommended
Heat Treating
Practice
Normalizing. Heat to 870 “C (1600 “F). Cool in air
5046: Hardness vs Tempering Temperature. Normalized at 870
5046H: End-Quench Hardenability
“C (1600 “F), quenched from 845 “C (1555 “F), tempered in 56 “C
(100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8
mm (0.505 in.) rounds. Source:.Republic.Steel
Distance from
quenched
surface
&h.
mm
1
1.58
3.16
4.15
6.32
7.90
9.48
1.06
12.64
14.22
15.80
17.38
18.96
2
3
4
5
6
I
8
9
10
11
12
Hardness,
HRC
max
min
63
62
60
56
52
46
39
35
34
33
33
32
56
55
45
32
28
27
26
25
24
24
23
23
Distance from
quenched
surface
?,&h.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
max
min
32
31
31
30
29
28
27
26
25
24
23
23
22
22
21
21
20
Alloy
5046H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
J distance.
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
Hardness
purposes
I distance,
%6 in.
0
1
2
3
4
5
6
8
0
2
4
6
8
0
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
flardness, HRC
Maximum
hIinimum
63
62
59
54
48
39
35
34
32
30
29
27
26
24
56
54
40
30
27
26
25
25
22
20
.
limits for specification
Hardness, HRC
Maximum
hlinimum
63
62
60
56
52
46
39
35
34
33
33
32
32
31
31
30
29
28
21
26
25
24
23
56
55
45
32
28
21
26
25
24
24
23
23
22
22
21
21
20
..”
...
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 389
only): 870 “C
390 / Heat Treater’s Guide
50B46,50B46H
Chemical Composition.
SOB46. AISI: 0.44 to 0.49 C, 0.75 to 1.OO
Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si, 0.20 to 0.35 Cr. 0.0005 to
0.003 B. UNS: 0.44 to 0.49 C, 0.75 to 1.00 Mn. 0.035 Pmax. 0.040 S max.
0.15 to 0.30 Si. 0.20 to 0.35 Cr. 0.0005 B min. UNS II50461 and
SAE/AISI SOB46H: 0.43 to 0.50 C. 0.65 to I. 10 Mn, 0.15 to 0.35 Si. 0.13
to 0.43 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar Steels (U.S. and/or Foreign).
SOB46.
IJNS
G5046I ;
ASTM
ASTM A519; SAE J404. 5412, J770. 50B46H. UNS H5046I:
A304; SAE J I268
Characteristics. Boron influences 50B36H much the same as it affects
50B4OH and 50B44H. 50B46H has a lower chromium content. When the
chromium is low. approaching 0.13. the hardenability
without the boron
would be little more than that of a plain carbon steel. Hardenability
is lower
when compared with 50BUH.
As-quenched surface hardness for 50B46H
can be expected to be about the same as for 50B44H. 54 to 60 HRC
Forging.
temperature
Annealing.
For a predominately
pearlitic structure. heat to 830 “C (1525
“F), cool rapidly to 740 “C ( I365 OF). then cool to 670 “C (1240 “F) at a
rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (I 525 “F), cool
rapidly to 675 “C (I 245 “F), and hold for 6 h. For a predominately
spheroidized structure, heat to 760 “C ( 1400 “F’), cool to 665 “C ( 1230 “F)
at a rate not to exceed 6 “C (IO “F) per h: or heat to 760 “C ( 1400 “F), cool
rapidly to 665 “C (I230 “F), and hold for 8 h
Hardening.
Tempering.
Recommended
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 870 “C (1600 “F). Cool in air
50646: Hardness vs Tempering Temperature. Normalized
l
at
870 “C (1600 “F), quenched
from 845 “C (1555 “F) in oil and tempered in 56 “C (100 “F) intervals
in 13.7 mm (0.540 in.) rounds.
Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
at 845 “C (I 555 “F), and quench in oil
Parts made from 50B44H should be tempered immediately
after they have been uniformly quenched to near ambient temperature. Best
practice is to place workpieces into the tempering furnace just before they
have reached room temperature. ideally when they are in the range of 38 to
50 “C ( 100 to I20 “F). Tempering temperature must be selected based upon
the final desired hardness
l
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
of forging stock drops below approximately
925 “C (1695 “F)
Austenitize
Processing
Sequence
Forge
Normalize
Anneal
Rough and semifinish machine
Austenitize and quench in oil
Temper
Finish machine
50846H: End-Quench Hardenability
Distance from
quenched
surface
V,6 in.
mm
I
2
3
.I
5
6
7
8
9
IO
II
I2
1.58
3.16
1.74
6.32
7.90
9.48
II.06
12.6-l
14.21
15.80
17.38
18.96
Hardness.
BRC
min
may
63
62
61
60
59
58
57
56
54
51
17
13
56
5-l
52
so
-II
32
31
30
29
28
27
26
Distance from
quenched
surface
916in.
mm
13
I-I
IS
16
I8
‘0
22
2-l
26
28
30
32
20.54
22.12
23.70
25.28
28.4-I
31.60
34.76
37.92
II .08
44.2-l
47.40
50.56
Eardoess,
ERC
msx
min
40
38
37
36
35
34
33
32
31
30
29
28
26
25
25
23
23
22
21
20
_..
Alloy Steel / 391
50B46H: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only):
870°C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness limits for specification
wrposes
I distance,
nm
Eardness, ERC
luaximum
Minimum
63
62
61
56
60
47
59
58
56
53
12
37
35
35
31
29
‘8
76
34
55
53
24
22
21
32
31
29
iardness limits for specification
wrposes
I distance,
46i”.
,
I
,
I
I
0
I
2
3
4
5
6
8
II
‘2
4
6
8
‘0
‘2
Eardoess, ERC
Maximum
Minimum
63
62
61
60
59
58
51
56
54
51
47
43
40
38
31
36
35
34
33
32
31
30
29
28
56
54
52
50
41
32
31
30
29
28
27
26
26
25
25
2-l
23
22
II
20
392 / Heat Treater’s
Guide
50B50,50B50H
Chemical
COIIIpOSitiOn.
50B50.AISI:
0.48 to 0.53 C. 0.75 to 1.00
Mn. 0.035 P max. O.MO S max. 0. IS to 0.30 Si, O.-IO to 0.60 Cr. 0.0005 to
0.003 B. UNS: 0.18 to 0.53 C. 0.75 to I .OO Mn. 0.035 P max. O.O-lO S max.
0.15 to 0.30 Si. 0.40 to 0.60 Cr. O.OOOS B min. UNS H50501 and
SAE/AISI
50B50H: 0.47 to 0.5-l C. 0.65 to I. IO Mn. 0. IS to 0.35 Si, 0.30
to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or
Annealing. For a predominately spheroidized structure. heat to 750 “C
t I380 “F). cool rapidI> to 705 “C ( I300 “F). then cool to 650 “C ( I200 “F).
at a rate not to exceed 6 “C I IO “F) per h: or heat to 750 “C ( I380 OF). cool
rapidly to 675 “C ( I Z-IS ‘W. and hold for I2 h
Hardening.
SOBSO. LINS G50501;
ASTM AS 19; SAE J-IO-I. 5412.5770; t&r.) DIN I .7 138; (Jap.) JIS SUP I I.
50B50H. UNS HSOSOI; ASThl ,430-k SAE Jll68;
(Ger.) DIN 1.7138;
(lap.) JIS SUP I I
Characteristics.
Borders between what is usually considered as a
medium-carbon
and a high-carbon steel. depending on the precise carbon
content. n hich also controls the as-quenched surface hardness. A range of
approximately
56 to 62 HRC can be expected. The 0.30 to 0.70% chromium and the boron treatment produce a relativeI> high hardenability.
Lksd
for a variety of applications. u here its hardenability
is ad\ antageous. such
as heavy-duty springs
Forging.
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
of foging stock drops below approximateI>
925 “C (I 695 “F)
Parts made from SOBSOH should be tempered immediately
after they have been uniformly quenched to near ambient temperature. Best
practice is to place uorkpieces into the tempering furnace just before they
have reached room temperature. ideally when the) are in the range of 38 to
50 “C (I 00 to I20 ‘Fj. Tempering temperature must be selected based upon
the final desired hardness
Recommended
l
Normalizing.
I
2
3
1
5
6
7
8
Y
IO
II
I:!
I.%
3.16
1.74
6.32
7.90
9.48
Il.06
12.6-t
I-i.12
15.80
17.38
I8.%
l
l
Heat to 870 “C ( 1600 “FI. Cool in air
l
Heat Treating
5085OH: End-Quench
Distance from
quenched
surface
916in.
mm
l
Practice
Recommended
65
65
6-t
6-l
63
63
62
62
61
60
60
59
l
Hardenability
Bardness,
HRC
min
max
59
59
58
57
56
55
52
41
-I2
37
3s
33
at 845 ‘C ( 1555 “F), and quench in oil
Tempering.
l
temperature
Austsnitize
Foreign).
Distance from
quenched
surface
916 in.
mm
13
I-l
15
I6
18
20
22
3-l
26
28
30
31
20.S-l
‘1.12
23.70
25.28
28.4-t
31.60
31.76
37.92
-Il.08
44.2-i
-17.40
SO.56
Aardness,
BRC
max
58
57
56
5-l
50
-17
4-l
II
39
38
37
36
21
20
Processing
Sequence
Forge
Normalize
AMY
Rough and semifinish machine
Austcnitire
and quench in oil
Temper
Finish machine
50950,50950H:
Hardness
sents an average
based
vs Tempering
on a fully quenched
Temperature.
structure
Repre-
Alloy Steel I393
50B50H: Hardenability
“C (1600 “F). Austenitize:
iardness
>urposes
I distance,
q m
1.s
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
I distance,
I,/,fj in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Hardness, HRC
Maximum
Minimum
6.5
65
65
64
63
63
62
62
59
54
49
44
40
38
37
59
59
59
51
55
52
46
39
32
29
27
26
24
22
20
limits for specification
Hardness, HRC
hlavimum
Minimum
65
65
64
64
63
63
62
62
61
60
60
59
58
51
56
54
50
47
44
41
39
38
31
36
59
59
58
57
56
55
52
41
42
37
35
33
32
31
30
29
28
27
26
25
24
22
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
394 / Heat Treater’s
Guide
50860,50B60H
Recommended
Chemical
COIIIpOSitiOn.
50860. AIM: 0.56 to 0.64 C. 0.75 to I .OO
Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 to
0.003 B. UNS: 0.56 to 0.64 C. 0.75 10 1.00 Mn. 0.035 Pmax. 0.040 S max.
0.15 to 0.30 Si. 0.40 to 0.60 Cr. 0.0005 B min. UNS I-I50601 and
SAE/AISI
50B6OH: 0.55 10 0.65 C. 0.65 to I. IO Mn. 0.15 to 0.35 Si. 0.30
to 0.70 Cr. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign). 5OB60. UNS GS0601;
ASTM A5 19; SAE 5404. J412, J770. 50B6OR. UNS H50601; ASTM
A304; SAE Jl268
Characteristics.
Has the same general characteristics
as other boroncontaining steels. With the higher carbon content, an as-quenched hardness
in the range of approximately
58 to 63 HRC can be expected. The hardenability of this grade is quite high. Both the top and the bottom boundaries of the hardenability
band are straight lines for significant
distances
from the quenched end. Used for parts lhat demand high hardenability.
especially where economy is a factor. This steel. similar to other boron-containing steels. represents a cost-effective
way of achieving high hardenability
Forging.
Heat LO I205 “C (2200 “F) maximum.
Do not forge after
temperature of forging stock drops below approximately
925 “C ( I695 “F).
Because of high hardenability,
forgings. especially complex shapes. should
be cooled slowly from the forging operation to minimize the possibility of
cracking. Forgings may be slow cooled by either placing them in a furnace
or burying them in an insulating compound
50B60l-l: End-Quench
Distance from
quenched
surface
l/16 in.
mm
I
2
3
1
5
6
7
8
9
IO
II
I?-
1.58
3.16
4.75
6.32
7.90
9.48
11.06
12.6-I
14.22
IS.80
17.38
I a.96
Hardenability
Eardness,
ERC
max
min
60
__.
65
6.5
64
64
64
60
60
60
60
59
57
53
47
42
39
37
Distance from
quenched
surface
‘&j in.
mm
I3
II
15
I6
I8
20
22
2-l
26
28
30
32
20.54
22.12
23.70
25.28
28.4-t
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Eardlless.
ARC
miw
min
63
63
63
62
60
58
55
53
51
49
-17
44
36
35
3-l
41
33
31
30
29
28
21
26
25
Normalizing.
Heat Treating
Practice
Heal LO870 “C ( 1600 “F). Cool in air
Annealing.
For a predominately
spheroidized
structure. which is usually favored for this grade, heat to 750 “C (I 380 “F), cool rapidly to 700 “C
( I290 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C (IO
“F) per h: or heat 10 750 “C (I 380 “F). cool rapidly to 650 “C ( 1200 “F),
and hold for I2 h
Hardening.
Austenitize
at 845 “C (I 555 “F). and quench in oil
Tempering.
Selection of tempering temperature depends on the fmal
properties desired. To prevent cracking, make sure parts have reached a
uniform temperature throughout each section, and then place them in a
tempering furnace before ambient temperature is reached. 38 to 50 “C (100
to I20 “F) is considered ideal
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough and semitinish machine
Austenitize and quench
Temper
Finish machine
50860: Hardness vs Tempering Temperature.
Normalized at
870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds.
Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
Alloy Steel / 395
50B60H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness
purposes
I distance,
nm
limits for specification
Eardness, HRC
Maximum
Minimum
.s
I
3
5
!O
!S
10
15
10
IS
i0
iardness
wrposes
distance.
‘16b.
65
65
65
62
59
56
52
18
1.5
60
60
60
60
59
57
Sl
44
36
34
32
30
78
27
25
limits for specification
Aardness, ARC
Maximum
Miuimum
65
65
6-l
6-l
6-l
63
63
63
62
60
58
55
53
51
49
37
44
60
60
60
60
60
59
57
53
17
12
39
37
36
35
34
34
33
31
30
29
28
37
26
2s
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
396 / Heat Treater’s
Guide
5117
Chemical
Composition.
5117. AISI and UNS: 0.15 100.20 C. 0.70
to 0.90 hln. 0.035 P max. 0.040 S max. 0. IS to 0.30 Si. 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or Foreign).
UNS
Gs I I 70
Characteristics.
A slightly modified
version of 5 IX. The carbon
range is lower, hut the ranges for the two steels overlap. Although there is
no H version of 5 I 17. hardenability
is expected to he very close to that of
S I2OH. As-quenched hardness for 51 I7 (no case) usually ranges from 36
to -II HRC.’ Readily forgeable and weldable with alloy steel welding
practice. Definitely a case hardening grade and is used for parts that require
kther carburizing or carbonitriding~
For further details see 5 l20H
Forging.
temperature
Heat to 12-15 “C (2275 “F) maulmum. Do not forge after
of forging stock drops beIon approximately
870 “C t 1600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 935 “C t 1695 “FL Cool in air
Annealing.
Not usually requtred for this grade. Structures that are well
suited to machining are generally ohtained hy normalizing or hy isothermal
annealing after rolling or forgins. Isothermal annealing is accomplished by
heating to 700 “C t 12570 “FJ, and holding for 8 h
Case Hardening. See recommended carhurizing, carhonitriding. and
tempering procedures described for 4 I I SH. Ion nitriding and gas nitriding
are alternative processes
Recommended
l
l
l
l
l
l
l
Forge
Normalize
Anneal (optional)
Rough and senitinijh
Case harden
Temper
Finish machine
Processing
Sequence
machine
5117: Hardness vs Tempering Temperature.
erage based on a fully quenched structure
Represents
an av-
396 / Heat Treater’s
Guide
5120,512OH
Chemical
Composition.
5120. AISI and UNS: 0. I7 to 0.22 C. 0.70
to 0.90 hln, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr.
IJNS H512OOand SAE/AISI 5120H: 0.17 to 0.23 C. 0.60 to I .OOhln. 0. IS
to 0.35 Si. 0.60 to 1.00 Cr
Similar Steels (U.S. and/or
Foreign).
5120.
ASTM A322. A33l. ASl9: SAE J-101. 5770: (Ger.)
.AFNOR 20 MC 5.5120H. UNS HS 1200: ASThf A304
DIN I .7147; (Fr.) AFNOR 20 hfC 5
UNS
GS 1200:
DIN 1.7147: (Fr.)
SAE J 1268: (Ger.)
Characteristics.
A low-alloy carburizing grade. An as-quenched hardness of approximately
38 to 4-I HRC can normally be expected. This range
represents the core hardness of carhurized 5 I20H. Would not be considered
it high hardenability
steel. but it is similar to II IXH in hardenahility
Forging.
Heat to I245 “C (2275 ‘F) maximum.
Do not forge after
temperature of forging stock drops below approximately
870 ‘C I I600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 925 “C t I695 “F). Cool in air
Annealing.
Best machining structures lue obtained hy hesting to 800 “C
t 1475 “FL cooling rnpidly to 675 Y f 1215 “F). and holding for IO h
Tempering.
tempered
tolerated
PHIIS that hove been crtrburized or carbonitrided
should be
at 150 ‘C (300 “FL or higher if some loss of h‘ardness can be
Case Hardening.
tempering
process
procedures
Recommended
l
Forge
Normalize
.
AnIlZd
l
See recommended carhurizing.
carbonitriding,
and
described for -! I I8H. Ion mtriding IS an alternative
Processing
Sequence
Rough and semitinish machine
Carhurize. diffuse and quench. or carhonitride
. Temper
l
Finish muchine if required
l
l
and quench
Alloy Steel 1397
5120, 5120H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
5120H: End-Quench Hardenability
Distance from
Hardness,
HRC
min
max
I
2
3
1
5
6
7
8
9
I0
II
I?
I.58
3.16
4.7-l
b.32
7.90
9.18
I I .M
Ix4
l-l.22
IS.80
17.38
18.96
48
46
-II
36
33
30
18
'7
25
2-l
23
'2
-IQ
34
28
23
20
Distance frum
quenched
surface
‘&in.
mm
I3
l-l
I5
I6
18
20
22
2-l
26
18
30
31
20.54
'2.12
23.70
'5.28
78.4-l
31.60
34.76
37.91
41.08
4-4.2-I
17.40
50.56
Hardness.
HRC
ma\
21
'I
20
398 / Heat Treater’s
Guide
5120H: Hardenability
(1700 “F). Austenitize:
Curves. Heat-treating
925 “C (1700 “F)
iardness
wrposes
limits for specification
I distance,
lull
Eardnes,
Maximum
I.5
I
i
I
I
1
3
5
!O
!S
iardness
wrposes
I distance,
116in.
1
I
i
i
,
I
I
)
10
I
,2
3
-I
5
6
ERC
Minimum
48
46
-II
3-l
31
29
27
25
22
40
3-l
27
22
20
limits for specification
Eardnesr, BRC
Minimum
Maximum
48
46
II
36
33
30
28
27
25
2-l
23
22
21
21
20
40
31
28
23
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 399
5130,5130H,
5130RH
CheITIiCSl
COIIIpOSitiOn.
5130. AISI and UNS: 0.28 to 0.33 C. 0.70
to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to 1.10 Cr.
UNS H51300 and SAE/AlSI 5130H: 0.27 to 0.33 C, 0.60 to I .OO Mn, 0. I5
to 0.35 Si. 0.75 to I .20 Cr. SAE5130RH: 0.28 to 0.33 C, 0.70 to 0.90 Mn,
0. IS to 0.35 Si. 0.80 to I. IO Cr
Similar Steels (U.S. and/or Foreign). 5130. UNS G5 1300: SAE
5304. J412. 1770; (Ger.) DIN 1.7030; (U.K.) B.S. 530 A 30. 530 H 30.
513OH.llNS H51300; ASTM A304,A914;SAEJl268.
Jl868;(Ger.)
DIN
1.7033: (Fr.) AFNOR 32 C 3: (Ital.) UN1 31 Cr 4 KB: (Jap.) JIS SCr 2 H.
SCr 2; (U.K.) B.S. 530 A 32.530 H 32
Characteristics.
A medium-carbon
alloy steel. Chromium is the sole
alloying element; manganese in the range of 5 l30H is not considered an
alloy. Hardenability
is considered fairly high. Depending on the specific
carbon content. as-quenched hardness in the range of approximately
16 to
53 HRC can be expected. Can be welded. but alloy steel welding practice
is mandatory
Annealing.
For a predominately
pearlitic structure, heat to 845 “C (1555
“F), cool rapidly to 755 “C ( 1390 “F), then cool to 670 “C ( 1240 OF). at a
rate not to exceed I I “C (20 “F) per h; or heat to 845 “C (1555 “F). cool
rapidly IO 675 “C (1245 “F), and hold for 6 h. For a largely spheroidized
structure, heat to 790 “C (1155 “F). cool rapidly to 690 “C (I275 “F), and
hold for 8 h
Hardening. Austenitize at 855 “C (IS70 “F), and quench in oil. Ion
nitriding, gas nitriding. liquid carburizing. and gas carburizing are suitable
processes
Tempering.
Reheat after quenching
the desired hardness
Recommended
l
l
Forging.
temperature
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
of forging stock drops beIon! approximately
870 “C ( I600 “F)
Recommended
Normalizing.
Heat Treating
Heat to 900 “C (I650
Practice
“FL Cool in air
l
l
l
l
l
Processing
to the temperature
that will result in
Sequence
Forge
Normalize
Anneal (preferably spheroidize)
Rough machine
Austenitize and quench
Temper
Finish machine
5130: Hardness vs Tempering Temperature. Normalized at 900
“C (1650 “F), quenched
from 870 “C (1600 “F) in water.
tempered
in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in
12.8 mm (0.505 in.) rounds. Source: Republic Steel
400 / Heat Treater’s
Guide
5130H: End-Quench Hardenability
Distance from
quenched
surface
!j6iu.
mm
Eardnes.
ERC
min
max
Distance from
quenched
surface
Qhin.
mm
Hardness.
HRC
man
min
5130: Depth of Case vs Time and Temperature. 57.2 mm (2.25
in.) outside diameter by 165 mm (6.5 in.), oil quenched.
ized at temperatures indicated
Carbur-
Alloy Steel / 401
5130H: Hardenability
(1650 “F). Austenitize:
Hardness
purposes
I distance,
nm
I .5
iardness
3urposes
I distance,
/ifI in.
0
I
7
;
-I
s
6
8
!O
12
!-I
!6
!8
0
P
Curves. Heat-treating
870 “C (1600 “F)
limits for specification
Elardness, HRC
Maximum
Minimum
56
55
s3
51
48
45
-I’
39
35
33
31
30
28
26
2-l
49
46
12
37
33
30
21
2.5
21
limits for specification
Hardness, HRC
Maximum
Minimum
56
ss
53
51
49
17
IS
-12
40
38
37
36
3s
34
34
33
32
31
30
29
27
26
2s
2-l
49
46
43
39
35
32
30
18
26
2s
23
‘2
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
402 / Heat Treater’s
Guide
5130RH: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitiie:
870 “C (1600 “F)
Hardness
purposes
limits for specification
I distance.
Elardness,
Maximum
‘/,6 in.
I
2
3
1
5
5
7
B
3
10
II
II
13
I4
IS
16
I8
20
22
2-l
26
28
30
32
Hardness
purposes
J distance,
mm
I.5
3
5
7
9
II
I3
I5
20
IS
30
35
40
xi
50
EIRC
Minimum
50
47
44
41
37
35
33
31
29
27
1-6
25
24
23
32
21
20
55
53
51
49
46
44
42
39
31
35
34
33
32
31
30
29
28
27
26
2s
24
23
22
‘I
limits for specification
Elardoess,
Maximum
55
53
51
48
45
42
39
36
32
29
28
26
74
23
21
BRC
Minimum
50
47
4-l
39
36
33
31
28
2-I
21
‘0
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
Alloy Steel / 403
5132,5132H
Chemical
Composition.
5132. AISI and UNS: 0.30 to 0.35 C. 0.60
IO 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to 1.00 Cr.
UNS A51320 and SAE/AISI 51328: 0.7-9to 0.35 C. 0.50 to 0.90 hln. 0. IS
to 0.35 Si. 0.65 to I. IO Cr
Similar
Steels (U.S. and/or Foreign).
5132.
UNS
GS 1320;
ASTM A322, A331, A505, ASl9: SAE J404. J-412, 5770; (Ger.) DIN
I .7033; (Fr.) AFNOR 32 C 4; (Ital.) UN1 34 Cr 4 KB; (Jap.) JIS SCr 2 H.
SCr 2: (U.K.) B.S. 530 A 32, 530 H 32. 51328. LINS HSl320: ASTM
A304: SAE J1268; (Ger.) DfN 1.7034: (Fr.) AFNOR 38 C 4; (Ital.) 1lNI 38
Cr -I KB; (Jap.) JIS SCr 3 H; (U.K.) B.S. 530 A 36.530 H 36, Type 3
Characteristics.
Varies only slightly
in composition
from Sl30H.
General characteristics
are essentially the same as those for 5130H. The
slightly higher carbon range of 5 l32H raises the maximum as-quenched
hardness to approximately
48 to 55 HRC. although the hardenability
of
5 l32H can be slightly less than that of 5 I30H because of the possibility of
a lower chromium content. This grade can be welded. but alloy steel
welding practice is mandatory
rate not to exceed I I “C (20 “F) per h: or heat to 845 “C (1555 “F), cool
rapidly to 675 “C (I245 “F), and hold for 6 h. For a largely spheroidized
structure. heat to 790 “C ( 1455 “F). cool rapidly to 690 “C (I 275 “F), and
hold for 8 h
Hardening.
nitriding
Austenitize
and gas nitriding
at 855 “C (IS70 “F), and quench
are suitable processes
Tempering.
Reheat after quenching
the desired hardness
Recommended
l
l
l
l
l
l
l
Processing
to the temperature
in oil. Ion
that will result in
Sequence
Forge
Normalize
Anneal (preferably spheroidize)
Rough machine
Austenitize and quench
Temper
Finish machine
Forging.
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
temperature of forging stock drops below approximately
870 “C (I600 “F)
Recommended
Normalizing.
Annealing.
‘F). cool rapidly
Heat Treating
Practice
5132: Microstructure.
Heat to 900 “C ( I650 “F). Cool in air
For a predominately
pearlitic structure. heat to 815 “C (I 555
to 755 “C ( I390 “F), then cool to 670 “C ( I230 “F), at a
5132, 5132H: Hardness vs Tempering Temperature.
Repre-
sents an average based on a fully quenched structure
5132H: End-Quench Hardenability
Distance from
quenched
surface
V~6in.
mm
I
7
i
4
5
6
7
8
9
10
II
I2
I.58
3.16
4.74
6.32
7.90
9.48
Il.06
12.64
14.22
IS.80
17.38
18.96
Eardoess,
HRC
max
mia
57
56
5-l
52
SO
-la
1s
42
40
38
37
36
SO
-17
-I3
40
35
32
29
27
25
24
‘3
22
Distance from
quenched
surface
‘116in.
mm
I3
II
I5
I6
I8
20
‘2
21
26
‘8
30
32
20 s-t
72.11
23 70
25.28
28.44
31.60
34.76
37.92
-Il.08
44.2-l
-17.10
50.56
Hardness,
HRC
max
min
35
3-1
31
33
32
31
30
29
38
27
26
25
21
20
.._
.._
.
Nital, 1650x. Steel forging, austenitized at
645 “C (1555 “F) and water quenched. Some blocky ferrite (light
areas) and bainite (dark, feathery constituent) in a matrix of
marlensite
404 / Heat Treater’s
Guide
5132H: Hardenability
(1650 “F). Austenitize:
Curves. Heat-treating
845 “C (1555 “F)
Hardness limits for specification
wrposes
I distance.
nm
Hardness, HRC
hlinimum
Maximum
I.5
57
50
II
13
IS
!O
!5
10
15
U)
15
i0
56
51
5’
49
45
4’
39
35
33
.-1’
31
29
27
25
47
43
38
33
29
‘6
35
II
iardness
wrposes
I distance,
116io.
0
I
7
;
-I
5
6
8
!O
I2
I4
16
18
10
i?
limits for specification
Eardness, HRC
hlinimum
Maximum
51
56
s-1
52
50
48
46
42
40
38
37
36
3s
3-I
3-1
33
32
31
30
29
28
27
26
‘S
50
-17
43
-IO
3s
32.
29
27
3
2-l
23
22
21
20
temperatures
recommended
by SAE. Normalize (forforged
or rolled specimens
only): 900 “C
Alloy Steel / 405
5135,5135H
Chemical Composition. 5135. AISI and UNS: 0.33 IO 0.38 C. 0.60
10 0.80 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.80 to I.05 Cr.
UNSH513SOand
SAE/AISI513SH:0.32
to0.3XC.0.50to0.90Mn.0.15
to 0.35 Si. 0.70 to I. I5 Cr
Similar Steels (U.S. and/or Foreign).
5135.
l!NS
GS 1350;
ASThI .43X. A33l. ASIY: SAE J4O-l. 5412.1770; Ger.) DIN I.7034 (Fr.)
AFNOR 38 C 1: (Ital.) LlNl 38 Cr 4 KB: (Jap.~ JIS SCr 3 H: (U.K.) B.S.
530 A 36.530 H 3.51358. LlNS HS 1350; ASTM A30-k SAE J 1268; (Ger.)
DIN 1.7035; (Fr.j AFNOR -I2 C -1: (Ital.) UN1 -II Cr -I KB, 40 Cr -I: (Jap.~
JIS SCr -1 H; (U.K.) B.S. 530 A 10,530 H -IO. 530 hl10.2
S I I7
Characteristics.
A low-allo)
version of the carbon steels 1035 and
1038H. Because of the chromium addition. hardenahility
of 513SH is
considerably greater than for 1038H. When fully quenched. an as-quenched
hardness of approsimatelq
SO to 56 HRC can he expected. Can he welded.
hut is susceptible to Lteld cracliing
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (I525
“F). cool rapidly to 740 “C ( 136s “F). then cool to 670 “C ( I140 “F), at a
rate not to exceed I I “C (20 “F) per h: or heat to 830 “C ( I525 “F), cool
rapidly to 675 “C ( IX
“F). and hold for 6 h. For a predominately
spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 690 “C
(1275 OF). and hold for 8 h
Hardening.
nitriding
Tempering.
Forging.
Heat to 1230 “C (3750 “FI maximum. Do not forge after
of forging stock drops helow approximateI)
870 ‘C ( 1600 “F)
Recommended
l
l
l
l
l
Recommended
Heat Treating Practice
Normalizing. Heat to 870 “C ( I600 “F). Cool in air
After
at 815 “C (I555 “F). and quench
are suitable processes
quenching.
reheat to the temperarure
in oil. Ion
required
obtaining the desired hardness
l
temperature
Austenitize
and gas nitridinp
l
Processing
Sequence
Forge
Normalize
Anneal (,preferahly spheroidize,
Rough machine
Austenitize and quench
Temper
Finish machine
5135, 5135H: Hardness vs Tempering Temperature. Represents an average
5135H: End-Quench Hardenability
Distance from
‘/16in.
mm
Hardness,
HRC
min
ma\
I
1.58
3.16
4.14
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
57
56
55
54
52
50
47
45
43
41
40
quenched
surface
2
3
4
5
6
7
8
9
10
11
12
58
51
-VI
47
43
38
35
32
30
28
27
25
24
Distance from
quenched
surface
l/16 in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
max
min
39
38
37
37
36
35
3-l
33
23
22
21
21
20
32
32
31
30
based
on a fully quenched
structure
for
406 / Heat Treater’s Guide
5135H: Hardenability Curves. Heat-treating temperatures
(1800 OF). Austenitize:
845 “C (1555 “F)
Hardness limits for specification
purposes
J distance,
mm
1.5
3
5
I
9
11
13
1.5
20
25
30
35
40
45
50
Eardness. ERC
Maximum
Minimum
58
58
56
54
53
50
47
44
40
37
35
3-l
33
32
31
51
19
46
41
36
32
30
27
2.3
21
Hardness limits for specification
purposes
I distance,
I116in.
I
1
3
IO
I1
12
13
14
15
16
I8
!O
!2
!4
!6
!8
IO
12
Eardnes.
MZIXhWfl
58
57
56
55
54
52
50
47
45
43
41
40
39
38
37
37
36
35
34
33
32
32
31
30
EIRC
Minimum
51
49
47
-I3
38
3s
32
30
‘8
27
25
24
23
22
21
21
20
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 407
5140,5140H,
Chemical
5140RH
Composition.
5140. AISI and UNS: 0.38 to 0.43 C, 0.70
to 0.90 Mn, 0.035 P max. 0.040 S max. 0. I5 to 0.30 Si. 0.70 to 0.90 Cr.
UNS H51400 and SAE/AISI 5140H: 0.37 to 0.44 C. 0.60 to I .OO Mn. 0. I5
to 0.35 Si, 0.60 to 1.00 Cr. SAE 514ORH: 0.38 to 0.43 C. 0.70 to 0.90 Mn.
0. I5 to 0.35 Si. 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or Foreign). 5140.
UNS
~51400;
ASTM A322. A33 I, A505. A5 19; SAE J404, J-il2. J770; (Ger.) DIN
I .7035; (Fr.) AFNOR 42 C 4; (Ital.) UNI 40 Cr 3. II Cr 4 KB; (Jap.) JIS
SCr-1H;(U.K.)B.S.530A40.530H~,530M40,2Sll7.51~0R.UNS
H5 1400; ASTM A304. A914; SAE J 1268, J 1868; (Ger.) DIN I .7006; (Fr.)
AFNOR42C2.45CZ
Characteristics.
The characteristics
described for 5 I35H generally
apply for 5140H. Because the carbon range is higher, slightly higher
as-quenched hardness of approximately
5 I to 57 HRC can be expected. The
possibility
of a slightly lower chromium content for 5lJOH makes no
significant difference in hardenability.
This grade can be welded. but is
susceptible to weld cracking
Forging.
temperature
Heat to 1230 “C (2250 “F) maximum.
Do not forge after
of forging stock drops below approximately
870 “C (I 600 “F)
Recommended
Normalizing.
Heat Treating
Practice
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (1525
“F), cool rapidly to 740 “C ( I365 “F). then cool to 670 “C ( I240 “F), at a
rate not to exceed I I “C (20 OF) per h; or heat to 830 “C (I 525 “F). cool
rapidly to 675 “C (I 245 “F), and hold for 6 h. For a spheroidized structure.
heat to 750 “C (I 380 “F), cool rapidly to 690 “C (I 275 “F). and hold for 8 h
Hardening. Austenitize at 8-0 “C (1555 “F), and quench in oil. Ion
nitriding, gas nitriding, carbonitriding,
austempering and mat-tempering are
alternative processes
Tempering.
obtaining
After quenching,
the desired hardness
Recommended
l
l
l
l
l
l
l
reheat to the temperature
Processing
required
for
Sequence
Forge
Normalize
Anneal (preferably spheroidize)
Rough machine
Austenitize and quench
Temper
Finish machine
Heat to 870 “C ( I600 “F). Cool in air
5140: Isothermal Transformation
C. 0.68 Mn, 0.93 Cr. Austenitized
6 to 7
Diagram. Composition: 0.42
at 845 “C (1555 “F). Grain size:
5140: Hardness vs Tempering Temperature. Normalized at 870
“C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in
56 “C (100 “F) intervals in 13.8 mm (0.545 in.) rounds. Tested in
12.8 mm (0.505 in.) rounds. Source: Republic Steel
408 / Heat Treater’s
1
2
3
4
5
6
7
8
9
IO
II
12
I .58
3.16
4.74
6.32
7.90
9.48
II.06
12.64
11.22
15.80
17.38
18.96
60
59
58
57
56
5-l
52
SO
48
-16
45
43
Guide
53
52
50
48
-I3
38
35
33
31
30
29
28
I3
II
I5
I6
I8
20
22
‘4
26
28
30
32
20.5-I
22.12
23.70
25.28
28.U
31.60
31.76
37.92
-11.08
44.24
-17.-w
50.56
32
40
39
38
37
36
35
3-l
3-l
33
33
32
27
‘7
35
25
24
23
21
20
5140: End-Quench Hardenability. Composition: 0.43 C, 0.80 Mn, 0.010 P 0.050 S, 0.26 Si, 0.02 Ni, 0.84 Cr, 0.02 MO. Grain size: 7 to 8.
Austenitized
5140:
at 955 “C (1750 “F) as in production and austenitized
As-Quenched
Hardness
at 845 “C (1555 “F) in accordance
(Oil)
Single heat results; grade: 0.38 to 0.43 C, 0.70 to 0.90 Mn, 0.20 to
0.35 Si, 0.70 to 0.90 Cr; ladle: 0.43 C, 0.78 Mn, 0.020 P, 0.033 S, 0.22
Si, 0.06 Ni. 0.74 Cr, 0.01 MO; grain size 6 to 8
Surface
Eurdness, ERC
‘/2 radius
57
53
46
35
57
48
38
29
Size round
in.
f.4
i
2
.I
mm
I3
‘5
51
102
Source: Bethlehem Steel
Center
56
-15
35
20
with hardenability
specifications
Alloy
5140: Continuous
Cooling Curves. Composition: 0.42 C, 0.87
Mn. 0.25 Si, 0.89 Cr. Austenitized at 845 “C (1555 “F). Grain size:
8. AC,, 805 “C (1480 “F); AC,, 750 “C (1380 “F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem
Steel
Steel / 409
5140: Tempering Temperature vs Furnace Cooling and Water
Quenching. Tempered at 620 “C (1150 “F) for2 h. Source: Climax
Molybdenum
5140: Distribution
of Case Depth after Carbonitriding. Carbonitrided at 775 “C (1425 OF) for 8 h and quenched in oil at 77 “C
(170 “F). 25 tests on a steel pinion shaft
410 / Heat Treater’s
Guide
5140H: Hardenability
(1800 “F). Austenitize:
Hardness
purposes
J distance,
mm
limits for specification
q ardness, ERC
Maximum
Minimum
1.5
60
3
5
7
9
II
13
I5
20
‘5
30
35
-lo
45
50
59
58
51
55
53
50
47
42
39
36
35
34
33
32
Hardness
purposes
J distance,
916in.
I
1
s
i
5
5
7
3
3
IO
II
II
13
I4
15
I6
18
!O
!2
!-I
!6
!8
lo
12
Curves. Heat-treating
845 “C (1555 “F)
53
52
50
35
40
35
32
30
28
25
23
21
limits for specification
Eardness, ARC
Maximum
Minimum
60
59
58
57
56
5-l
52
50
48
46
45
43
42
40
39
38
37
36
35
31
34
33
33
32
53
52
SO
48
43
38
35
33
31
30
29
28
27
27
26
25
2-l
23
‘I
‘0
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 411
5140RH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
Hardness
purposes
I distance,
‘/,6 in.
I
5
1
3
2
IO
II
I?
I3
I4
I5
lb
I8
10
22
14
16
18
30
32
Hardness
purposes
J distance,
mm
I.5
3
5
7
9
II
13
I5
20
25
30
3s
40
-Is
50
845 “C (1555 “F)
limits for specification
Eardness, EIRC
Maximum
Minimum
59
58
57
55
53
51
18
-I6
4-l
13
II
40
39
37
36
35
34
33
32
31
30
30
29
29
54
53
51
49
45
?I
38
36
34
33
32
31
30
29
28
27
26
25
34
23
22
21
20
limits for specification
Eardness, BRC
Minimum
Mximum
59
58
57
55
52
18
46
4-l
39
35
33
32
31
30
29
5-l
53
51
-I7
42
38
36
3-l
30
27
3
2-l
22
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
412 / Heat Treater’s
Guide
5147H
Chemical
to 0.57
Similar
SAE
UN.3 HSlJ70and
COIIIpOSitiOn.
C. 0.60 to I .05 Mn.
J-W
0. IS IO 0.35
Steels (U.S. and/or
or J-l 13. but does appeu
.SAE/AISI 5147H: 0.4.5
Si. 0.80
Foreign).
in SAE
5770.
to 1.3
This steel is no longer
which is nou J I397
5147H: Hardenability
Curves. Heat-treating
(1600 “F). Austenitize:
845 “C (1555 “F)
Hardness
purposes
J distaace.
mm
I.S
3
5
1
9
II
13
1s
20
3
30
35
+o
-Is
50
Recommended
Heat Treating
Practice
Cr
temperatures
in
Hardening.
recommended
Gas niukiing
and ion nitriding
are suitable
by SAE. Normalize (for forged or rolled specimens
processes
only): 870 “C
limits for specification
Eardoess,
Maximum
61
61
64
63
62
61
60
60
58
57
ss
53
52
SO
19
H RC
Minimum
57
56
55
53
5’
i;
u
39
33
31
29
27
25
23
21
(continued)
Alloy Steel / 413
5147H: Hardenability
Curves. (continued) Heat-treating
only): 870 “C (1600 “F). Austenitize:
Hardness
purposes
J distance,
1.. .
/16m.
1
2
3
4
5
6
I
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
845 “C (1555 OF)
limits for specification
Hardness, HRC
Maximum
Minimum
64
64
63
62
62
61
61
60
60
59
59
58
58
57
51
56
55
54
53
52
51
50
49
48
57
56
55
54
53
52
49
45
40
37
35
34
33
32
32
31
30
29
21
26
25
24
22
21
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
414 / Heat Treater’s
Guide
5150,515OH
Chemical
Composition.
5150. AISI and UN% 0.4 IO 0.53 C. 0.70
to 0.90 Mn. 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr.
UNS EI515OOand SAE/AISI 515OH: 0.47 to 0.54 C. 0.60 to I .OO Mn. 0. I5
to 0.35 Si. 0.60 to 1.00 Cr
Similar
Steels (U.S. and/or
ASTM A322. A33l.
I .7006: (Fr.) AFNOR
Foreign). 5150. UNS
G5 1500;
A505, ASl9; SAE J-W, JJl2. 5770: (Ger.) DIN
42 C 2,45 C 2.5150H. UNS H5 1500: ASTM A30-k
SAE Jl268
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (I 525
“F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C (I 200 “F), at a
rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool
rapidly to 675 “C ( 1245 “F). and hold for 6 h. For a predominately
spheroidized structure, heat to 750 ‘C (I380 “F), cool rapidly to 705 “C
( I300 “F). then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C (IO
“F) per h: or heat to 750 “C ( 1380 “F). cool rapidly to 675 “C ( I245 “F),
and hold for IO h
Hardening.
Characteristics.
Has a borderline carbon content. between a mediumcarbon and a high-carbon
steel. When fully hardened, an as-quenched
hardness of approximately
55 to 60 HRC is normal, slightly higher when
the carbon is near the maximum of the allowable range. Hardenability
is
also considered as relatively high. Because of the high carbon content and
the high hardenability, does not have good weldability
nitriding,
Tempering.
After quenching.
vide the desired hardness
Recommended
l
Forging.
temperature
Heat to 1220 “C (2225 “F) maximum.
Do not forge after
of forging stock drops below approximately
870 “C ( 1600 “F)
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 870 “C (1600 “F). Cool in air
Austenitize at 830 “C (IS25 “F), and quench in oil. Gas
fluidized bed nhriding. and ion nitriding are suitable processes
l
reheat to the temperature
Processing
required
to pro-
Sequence
Forge
Normalize
Anneal (preferably spheroidire)
Rough machine
Austenitize and quench
Temper
Finish machine
5150: Isothermal Transformation
Diagram. Composition: 0.48
C, 0.86 Mn, 0.023 P, 0.021 S, 0.25 Si, 0.18 Ni, 0.98 Cr, 0.04 MO.
0.09 Cu. Austenitized at 860 “C (1580 “F). Grain size 5 to 6
5150, 5150H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
Repre-
Alloy Steel / 415
5150: Hardness vs Tempering Temperature. Normalized at 870
“C (1800 “F), quenched from 845 “C (1555 “F), tempered in 56 “C
(100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in 12.8
mm (0.505 in.) rounds. Source: Republic Steel
5150H: End-Quench Hardenability
Distance from
Distance from
quenched
surface
‘&jin.
mm
Hardness,
ERC
max
min
1.58
3.16
-4.71
6.32
7.90
9.18
I I.06
12.64
IA.22
IS.80
17.38
18.96
2
3
.I
5
h
7
8
9
IO
II
12
65
65
64
63
62
61
60
59
58
56
55
53
5150: As-Quenched
59
S8
57
56
53
49
42
38
36
31
33
33
13
I-l
1s
16
I8
20
22
21
26
28
30
32
Hardness
20.54
22.12
23.70
25.28
28.4-l
31.60
31.76
37.92
11.08
44.21
47.40
50.56
Eardoess,
ERC
min
max
51
SO
48
-17
15
13
42
-II
40
39
39
38
31
31
30
30
29
28
27
26
2s
24
23
22
(Oil)
Single heat results; grade: 0.48 to 0.53 C, 0.70 to 0.90 Mn, 0.20 to
0.35Si,0.70to0.90Cr,ladle:0.49C,0.75Mn,0.018P,0.018S,0.25
Si, 0.11 Ni, 0.80 Cr, 0.05 MO; grain size 7 to 8
in.
Size round
mm
Surface
Hardness, HRC
‘/: radius
Center
‘/>
I
2
4
I3
25
51
I02
60
59
55
37
60
52
-l-l
31
59
50
40
29
Source: Bethlehem Steel
416 / Heat Treater’s
Guide
5150H: Hardenability
Curves. Heat-treating
845 “C (1555 “F)
(1600 “F). Austenitize:
iardness
wrposes
limits for specification
I distance,
Rardnes,
Maximum
q m
1.5
1
3
II
13
15
!O
!5
10
I5
lo
15
i0
iardness
wrposes
I distance,
46 in.
1
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
RRC
Minimum
65
65
64
63
62
60
58
51
52
47
44
42
40
39
38
59
58
57
54
50
43
37
35
31
29
28
27
26
24
22
limits for specification
Eardness, ARC
hlioimum
Maximum
65
65
64
63
62
61
60
59
58
56
55
53
51
50
48
47
45
43
42
41
40
39
39
38
59
58
57
56
53
49
42
38
36
34
33
32
31
31
30
30
29
28
27
26
25
24
23
22
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel I417
5155,5155H
Chemical
Composition.
5155. AISI and UNS: 0.5 1 to 0.59 C, 0.70
0.040 S max. 0.1s to 0.30 Si. 0.70 to 0.90 Cr.
UNS H51550and SAE/AISI 51558: 0.50 to 0.6OC. 0.60 to I .OO Mn. 0. IS
to 0.90 Mn. 0.035 P
max.
to 0.30 Si. 0.60 to I .OO Cr
Similar
Steels (U.S. and/or Foreign). 5155. UNS GSISSO:
ASTM A322, A33 I. AS 19: SAE J4O-l. J-II 2. J770; (Ger.) DUV I .7 176: (Fr.)
AFNOR SS C 3. 51558. UNS HS 1550; ASThl A30-l: SAE J 1268; (Ger.)
DIN I .7 176: (Fr.) AFNOR 55 C 3
Characteristics.
In general. the characteristics
of 5 ISSH are the same
as those discussed for 5 ISOH. However. the slightI> higher carbon range of
SISSH makes a higher as-quenched hardness possible. 57 to 63 HRC is
normal for fully quenched 5 I SSH. Although the hardenability
patterns of
5 ISOH and 5 ISSH are similar. the entire band is slightI> higher for 5 ISSH.
Because of the high carbon content and the high hardenabilitj,
this grade
does not have good weldability
Forging.
Heat to I 220 “C (2%
“F) maximum. Do not forge after
temperature of forging stock drops bslok+ approximateI>
870 “C t I600 “F)
Annealing.
For a predominately
pearlitic structure, heat to 830 “C (I 525
“F). cool rapidly to 705 “C ( I300 “FL then cool to 650 “C ( 1200 “F). at a
rate not to exceed I I “C (20 “F) per h; or heat to 830 “C (IS25 “F), cool
rapidly to 675 “C t I315 “F), and hold for 6 h. For a predominately
spheroidized structure. heat to 750 “C ( I380 “F), cool rapidly to 705 “C
i I300 “F). then cool to 650 “C ( I200 “F), at a rate not to exceed 6 “C (IO
“F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (I 245 “F).
and hold for IO h
Hardening.
nitriding
Heat Treating
Practice
After quenching.
vide the desired hardness
Recommended
l
l
l
l
l
Normalizing.
Heat to 870 “C i 1600 “F). Cool in air
at 830 “C (IS25 “F), and quench in oil. Gas
are suitable processes
Tempering.
l
Recommended
Austenitire
and ion nitriding
l
Processing
5155, 5155H: Hardness
Dicmnce from
quenched
surface
‘/,6 in.
mm
I
Hardness.
ARC
max
min
Distance from
quenched
surface
%6 in.
mm
Hardness,
ARC
min
max
1.58
4.74
3.16
64
65
h0
58
59
13
I-l
IS
20.54
22. II
23.70
1
6.32
6-l
57
16
25.28
31
5
7.90
9.48
II.06
12.6-I
l-I.31
1580
17.38
18.96
63
63
62
62
61
60
59
57
55
52
-17
II
37
36
35
3-l
18
20
22
7-I
16
28
30
32
28.4-l
3 I .6O
31.76
37.92
41 08
44.2-l
17.10
50.56
31
31
30
29
28
27
xl
25
7
x
9
IO
II
ss
51
52
3-l
33
;-3
h
II
Hardenability
required to pro-
Sequence
Forge
Normalize
Anneal (preferably spheroidire)
Rough machine
Austenitize and quench
Temper
Finish machine
sents an average
5155H: End-Quench
reheat to the temperature
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
418 / Heat Treater’s
Guide
5155H: Hardenability
Curves. Heat-treating temperatures
845 “C (1555 “F)
-
(1600 “F). Austenik
Hardness
purposes
J distance,
mm
1.5
3
5
7
9
11
13
15
20
25
30
35
40
45
50
Hardness
purposes
J distance,
%6in.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
limits for specification
Eardness, EIRC
Maximum
MillhllUll
..
65
65
64
64
63
61
60
56
50
46
44
43
42
41
60
60
59
56
53
48
40
37
34
32
30
29
28
27
25
limits for specification
Hardness, ARC
MSlXimlUU
Minimum
.
60
65
64
64
63
63
62
62
61
60
59
51
55
52
51
49
47
45
44
43
42
41
41
40
59
58
51
55
52
47
41
31
36
35
34
34
33
33
32
31
31
30
29
28
27
26
25
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
Alloy Steel / 419
5160,5160H,
5160RH
Chemical
Composition.
5160. AISI and UNS: 0.56 to 0.63 C. 0.75
to I .OOMn, 0.035 P max. 0.040 S max. 0.15 to 0.30 Si. 0.70 to 0.90 Cr.
UNS H51600 and SAE/AISI 516OH: 0.55 to 0.65 C. 0.65 to I .OO Mn, 0. I5
to 0.35 Si, 0.60 to I.00 Cr. SAE 516ORH: 0.56 to 0.6-t C, 0.75 to I .OO Mn.
0. IS to 0.35 Si, 0.70 to 0.90 Cr
Similar
Steels (U.S. and/or
Foreign).
ASTM A322 A33l. A505. ASl9; SAE J-W
H51600:ASThlA30&A914:SAE51268,J1868
5160.
UNS
G51600;
5412. 5770. 5160H. UNS
Characteristics.
Detinitely
considered a high-carbon alloy steel. Asquenched hardness of 58 to 63 HRC is considered normal. Sometimes
values higher than this range are obtained, depending on the precise carbon
content. Hardenability
is slightly higher than that of 5lSSH. Used for a
variety of spring- applications.
notably flat springs. Often uses austempering
..
as a method of heat treating
Forging.
temperature
Heat to 1205 “C t2300 “F) maximum.
Do not forge after
of forging stock drops below approximately
870 “C (1600 “F)
rapidly to 675 “C (I215 “F). and hold for 6 h. For a predominately
spheroidized structure, heat to 750 “C (I 380 “F). cool rapidly to 705 “C
(1300 “F). then cool to 650 “C (I 200 “F). at a rate not to exceed 6 “C (IO
“F) per h: or heat to 750 “C ( I380 “F). cool rapidly to 675 “C (1245 “F),
and hold for IO h
Hardening.
polymer.
Tempering.
After quenching,
vide the desired hardness
Recommended
Annealing.
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air
For a predominately
pearlitic structure. heat to 830 “C ( I525
“F). cool rapidly to 705 “C ( I300 “F). then cool to 650 “C ( 1200 “F). at a
rate not to exceed I I “C (20 “F) per h; or heat to 830 “C ( IS25 “F). cool
reheat to the temperature
in oil or
required to pro-
Austempering.
Austenitize at 845 “C (I 555 “F), quench in molten salt
at 315 “C (600 “F), and hold for I h. Parts are cooled in air from 315 “C
(600 “F) and need no tempering. A spring temper hardness within the range
of approximately
16 to 52 HRC is obtained
Recommended
l
Normalizing.
Austenitize
at 830 “C (IS25 “F), and quench
Gas nitriding and ion nitriding are suitable processes
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (preferably spheroidize)
Rough machine
Austenitize and quench (or austemper)
Temper (or austemper)
Finish machine
5160: Isothermal Transformation
Diagram. Composition:
C, 0.94 Mn, 0.88 Cr, 0.22 MO. Austenitized
Grain size 7
0.61
at 845 “C (1555 “F).
420 / Heat Treater’s
Guide
5160: Correlation of Annealing Practice with Surface Finish
andTool Life in Subsequent Machining. (a) Annealed (pearlitic)
microstructure, 241 HB, and surface finish of flange after machining eight pieces. (b) Partially spheroidized microstructure, 180
HB, and surface finish of flange after machining 123 pieces
5160: Hardness vs Tempering Temperature. Normalized at 870
“C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in
56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in
12.8 mm (0.505 in.) rounds. Source: Republic Steel
5160:
As-Quenched
Hardness
(Oil)
Single heat results; grade: 0.56 to 0.64 C. 0.75 to 1 .OO Mn, 0.20 to
0.30Si,0.70to0.90Cr;ladle:0.62C.0.84Mn,0.010P,0.034S,0.24
Si, 0.04 Ni. 0.74 Cr, 0.01 MO; grain size: 6 to 8
Size round
in.
mm
Surface
63
62
53
40
Aardness, ERC
‘/z radius
62
61
46
32
Center
62
60
43
29
Alloy Steel / 421
5160H: End-Quench Hardenability
Distance from
quenched
surface
&in.
mm
Hardness,
ERC
max
min
Distance from
quenched
surface
‘/lb in.
mm
Hardness,
ERC
mas
min
I
;')
I.58
4.74
3.16
.::
60
60
I3
IS
I-I
20.51
23.70
22.11
58
5-l
56
3s
3-l
35
-I
5
6
6.5
65
6-l
61
63
62
61
60
99
58
56
5'
37
-I-'
39
37
16
I8
20
2'
2-l
30
26
28
2.5 28
18.U
3 I .60
34.76
37.91
4-4.2-l
47.40
-I I .0x
52
48
47
46
-IS
-I?
u
-43
34
33
32
8
III90
6.31
7.90
9.48
Il.06
12.6-l
l-l
I7
IS 3x
80
22
;Lj
I2
I896
59
36
32
SO26
-I2
27
7
5160: Continuous
Cooling Curves. Composition: 0.63 C, 0.86
Mn, 0.23 Si, 0.83 Cr. Austenitized at 845 “C (1555 “F). Grain size:
7 ‘Is. AC,, 780 “C (1435 “F); AC,, 755 “C (1390 “F). A: austenite, F:
ferrite, P: pearlite, B: bainite, M: martensite. Source: Bethlehem
Steel
5160:
Section
Thickness
vs
Austempered
Hardness.
Quenched in agitated salt containing some water. Rockwell C
hardness values converted from microhardness readings taken
with a 100 g (3.53 oz) load. Low values of surface hardness result
from decarburization.
(a) 24.6 mm (0.967 in.) diam. Austenitized
at 900 “C (1650 “F) and quenched in salt at 300 “C (570 “F) for 15
min. High hardness at center because of segregation. (b) 26.29
mm (1.035 in.) diam. Austenitized
at 940 “C (1725 “F) and
quenched in salt at 315 “C (600 “F) for 15 min
422 / Heat Treater’s
5160: Microstructures.
Guide
(a) 4% picral with 0.05% HCI. 500x. Hot rolled coil-spring steel, austenitized at 870 “C (1600 “F) for 30 min and oil
quenched. Untempered martensite (dark, needlelike constituent) and retained austenite (light constituent). (b) 4% nital. 4% picral, mixed 1
to 1: 1000x. Same steel and heat treatment as (a), except at a higher magnification. Untempered martensite (dark gray constituent) and the
retained austenite (light constituent are now more clearly resolved). (c) 4% nital. 4% picral, mixed 1 to 1; 1000x. Same steel as (a), except
tempered at 205 “C (400 “F) after austenitizing and quenching. Predominantly tempered martensite (dark), with small particles of ferrite
(white). (d) 2% nital. 11Ox. Spring steel, 16.1 mm (0.632 in.) diam, austenitized at 870 “C (1600 “F) for 5 min, hot coiled, oil quenched at 60
“C (140 “F), tempered at 425 “C (795 “F) for 40 min. Note tempered martensite and decarburization.
(e) 2% nital, 275x. Same steel and
treatment as(d). except at a higher magnification. Surface decarburization (white area near top of micrograph) occurred in the bar mill, while
the steel was at about 1150 “C (2100 “F). ( f) 4% nital, 4% picral, mixed 1 to 1; 1000x. Hot rolled steel. austenitized at 870 “C (1600 “F) for
30 min, oil quenched, tempered at 540 “C (1000 “F) for 1 h. Predominantly tempered martensite (dark). with some ferrite (white)
Alloy Steel I423
516OH: Hardenability Curves. Heat-treating temperatures recommended by SAE. Normalize (for forged or rolled specimens only): 870 “C
(1800 “F). Austenitize: 845 “C (1555 “F)
iardness
wposes
I distance,
lull
limits for specification
Earducss, ERC
Maximum
Minimum
3
.
I
3
5
0
s
0
5
0
5
0
iardness
wrposes
distance,
$6io.
1
0
I
2
3
4
5
6
8
0
2
4
6
8
0
2
65
64
64
62
58
53
49
46
44
42
41
60
60
60
59
57
52
46
40
36
34
32
30
28
27
27
limits for specification
Hardness, ERC
Maximum
Minimum
65
65
64
64
63
62
61
60
59
58
56
54
52
48
47
46
45
44
33
43
42
60
60
60
59
58
56
s2
47
42
39
37
36
35
35
34
34
33
32
31
30
29
28
28
27
424 / Heat Treater’s
Guide
5160RH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize:
845 “C (1555 “F)
Hardness
purposes
J distance.
!I,6in.
limits for specification
Eardness,
Maximum
I
2
3
4
5
6
7
8
9
IO
II
I2
65
6.5
6.i,
65
6-l
63
6Z
60
58
S6
55
s3
I3
51
I-l
SO
IS
?2
18
17
4-l
-13
-II
?-I
II
16
18
30
32
40
I6
I8
10
Hardness
purposes
J distance,
mm
I .s
3
5
7
Y
II
I3
IS
20
75
30
3s
60
60
60
59
58
57
5-l
SO
4s
32
40
39
38
37
36
36
3s
3-I
33
32
31
30
29
T!9
39
39
38
limits for specification
Eardoess,
Maximum
65
6.c
65
65
63
62
60
57
52
17
-I3
II
-lo
40
IS
39
38
so
BRC
Minimum
ARC
Minimum
MI
60
60
59
57
5-t
-I9
13
38
36
31
32
31
30
‘9
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 870
Alloy Steel / 425
51 B60,51
Chemical
B60H
Composition.
51~60. AM: 0.56 to 0.6-1C. 0.75 to 1.00
hln. 0.035 P max. O.MO S mas. 0. IS to 0.30 Si. 0.70 to O.YO Cr. 0.0005 to
0.003 B. UNS: 0.56 too.64 C, 0.75 to 1.00 hln, 0.035 Pmax, O.O-lO S max.
0.15 to 0.30 Si, 0.70 to 0.90 Cr. 0.0005 B min. UNS H51601 and
SAE/AISl51B60H:
0.55 to O.hS C. 0.65 to I. IO hln. 0. IS to 0.35 Si. 0.60
to I .OO Cr. B (can he expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or
Foreign).
51B60. UNS GSI 601:
.+,STILl ASl9: SAE J3O-i. 5112. 5770. 51B60H.
A3o-t: SAE J I268
UNS HSl601:
ASTM
Characteristics.
With the exception of a slightly higher chromium
content. 5 I B6OH has practicalI!
the same characteristics
as SOB60H. .bquenched hardness of 58 to 63 HRC can he expected. Hardenability
of
51 BhOH is slightl) higher. because of the increase in chromrum
Forging. Heat to IlOS ‘C I 2300 “F) maximum. Do not forge after
temperature of forging stock drops below approximutel!
925 “C (1695 “FL
Because of high hardenability,
forgmgs. especialI>; comples shapes. should
he cooled slow I> from ths forging operation to mminize the possihilit}
of
crackinp. Forgings ma! he slob cooled by either placing them in a furnace
or huqing them in an Insulating compound
For a prsdoninatel)
spheroidized structure which is usually
favored for this grade of steel. heat to 750 “C ( 1380 “F). cool rapidly to 700
‘C ( 1190 “F). then cool to 655 “C ( I2 IO “F). at a rate not to exceed 6 “C
t IO “F, per h: or heat to 750 ;‘C I 13X0 “F). cool rapidI) to 650 “C ( 1200 OF),
and hold for 12 h
Hardening.
nitridinp
Selection of tempering temperarure depends on the final
properties desired. To prevent cracking, make sure parts have reached a
uniform temperature throughout each section. and then place them in I
tempering furnace hefore nmhient temperature is reached. 38 to SO “C (100
to I20 “F, is considered ideal
Recommended
l
l
l
l
l
Heat to 870 “C I 1600 ‘FL Cool in air
l
Heat Treating
Austenitize at 815 “C ( IS55 “FL and quench in oil. Gas
and ion niuidinp are suitnhle processes
Tempering.
Practice
Recommended
Normalizing.
Annealing.
l
Processing
Sequence
Forge
Normalize
Anneal
Rough and semitinish machine
Austenitize and quench
Temper
Finish machine
51 B60: Isothermal
Transformation
0.64 C. 0.88 Mn, 0.83 Cr. 0.0006
“F). Grain size 6 to 7
51 B60: End-Quench Hardenability.
Mn, 0.83 Cr. 0.0006
6 to 7
B. Austenitized
Diagram. Composition:
B. Austenitized
at 845 “C (1555
Composition:
0.64 C, 0.88
at 845 “C (1555°F). Grain size
426 / Heat Treater’s
Guide
51 B60: Hardness vs Tempering Temperature.
Normalized at
870 “C (1600 “F), quenched from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds.
Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
51 B60H: End-Quench
Distance from
quenched
surface
&h.
1
2
3
4
5
6
7
8
9
10
11
12
mm
1.58
3.16
4.75
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardenability
Hardness,
ARC
max
min
_..
.__
.
.
_..
65
60
60
60
60
60
59
58
57
54
50
44
41
Distance from
quenched
surface
l/h5in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
max
min
65
64
64
63
61
59
57
55
53
51
49
47
40
39
38
37
28
27
25
51860: Microstructures.
(a) Picral. 1000x. Hot rolled steel bar,
31.8 mm (1 l/4 in.) diam, austenitized at 870 “C (1600 “F), air
cooled (normalized); austenitized at 815 “C (1500 “F), water
quenched. Untempered
martensite, some retained austenite
(white), fine spheroidal carbide. (b) Nital, 1000x. Hot rolled steel
bar, 13.8 mm (1 l/4 in.) diam, austenitized and quenched to obtain
a martensitic structure, then heated to 675 “C (1245 “F) for 15 h.
Spheroidal carbide particles in a matrix of ferrite
Alloy Steel / 427
51 B6OH: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness
purposes
I distance.
am
limits for specification
Eardness, HRC
Minimum
Maximum
I .s
60
1
3
II
13
IS
!O
!S
10
1s
lo
IS
50
60
60
60
59
58
55
51
-IO
37
35
32
30
28
25
Hardness
purposes
I distance,
&$in.
65
63
61
57
s-l
51
-17
limits for specification
Eat-does, ERC
Minimum
hlaximum
3
)
IO
II
I2
I3
I-t
I5
I6
18
31
!2
!-I
?6
!8
10
12
65
65
6-l
64
63
61
59
57
55
53
51
49
47
60
60
60
60
60
59
58
57
5-l
50
4-l
II
40
39
38
37
36
31
33
31
30
28
27
'S
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
428 / Heat Treater’s
Guide
E51100
Chemical Composition.
AISI and UNS: 0.98 to 1.10 C. 0.25 to
0.45 hln. 0.025 P max. 0.025 S max. 0. IS to 0.30 Si. 0.90 to I .I5 Cr
Similar Steels (U.S. and/or Foreign). 1lNS Gs 1986; AhlS 6443.
6446.6449: ASTM A295 A322, A505. A519:SAEJ4045412.J770: (Ger.)
DIN I.3503
Characteristics.
One of only two alloy steels listed bj NISI \\hich
contain carbon of near 1.0% or higher. The E prefix in the designation
indicates that it is manufactured only by the electric furnace process. which
is further indicated by the IO\V contents of phosphorus and sulfur. This gade
and its companion. E52 100, are sometimes called tool steels because their
composition
is nearly identical with L2 grade of tool steel. However.
neither ES II00 or ES2 100 is made by what is commonly considered as tool
steel practice; they are both made in relativelq large quantities.
Although ES I 100 does sene many commercial applications. it is used
most extensively
as a material for ball and ball race rolling element
bearings. for which extremely high hardness is needed.
There is no H version of this steel because the end-quench test is not
often used to evaluate hardenabilitj
of the VS~ high-carbon grades. It is.
ho\rever. generally considered an oil-hardemng steel. so that its hardenability is considered as fairly high. As-quenched
hardness generally ranges
from 62 to 66 HRC. depending on the cooling power of the quenchant
Forging.
temperature
Heat to II50 “C (2100 “F) masimum.
of forging stock drops below approximately
Annealing.
For a predominantl!
spheroidized structure. which is generally desired for machining as \\ell as heat treating. heat to 795 “C (1460°F).
cool rapid11 to 750 “C t I380 “F). then cool to 675 “C. ( I345 “FL at a rate
not to exceed 6 “C (IO “F) per h: or heat to 795 “C (I460 “Fj. cool rapidly
to 690 “C ( I175 “F), and hold for I6 h
Hardening. Austenitize at 845 “C ( 15% “F) in a neutral salt bath or in a
gaseous atmosphere I\ ith a carbon potential of near I .08. and quench in oil
Tempering.
After quenching, parts should be tempered as soon as they
have uniformly reached near ambient temperature. 38 to 50 “C ( 100 to I20
“F) is ideal. Because of the high carbon content, parts must be tempered to
at least I20 “C (250 “F) to convert the tetragonal martensite to cubic
martensite. Most commercial practice calls for tempering at IS0 “C (300
“F). H hich does not reduce the as-quenched hardness to any significant
amount. Li’hen a reduction in hardness from the as-quenched value of
approximatcl)
two points HRC can be tolerated. a tempering temperature
of I75 “C (3-15 “F) is recommended.
Sometimes subjected to higher
tempering temperatures. 1%ith an accompan) ing loss of hardness
Recommended
l
l
Do not forge after
l
915 “C t 1695 “F)
l
l
Recommended
Normalizing.
Heat Treating
Practice
l
l
Heat to 885 “C (1625 “FL Cool in air
Processing
Sequence
Forge
Normalize
Anneal t spheroidize 1
hlachine. including rouph grinding
Austenitize and quench
Temper
Finish grind
E51100: Hardness vs Tempering Temperature. Represents
average
lsased on a fully quenched
structure
an
428 / Heat Treater’s
Guide
E52100
Chemical Composition.
AM: 0.98 to 1.10 C. 0.25 to O.-IS Mn.
0.025 P max. 0.025 S max. 0.15 to 0.30 Si. I .30 to 1.60 Cr. UNS: 0.98 to
I.10 C. 0.15 to 0.X Mn. 0.015 P max. 0.025 S max. 0.70 to 0.30 Si. 1.30
to I .60 Cr
Similar
6-W.
SPEC
(Ger.)
53-t A
Steels (U.S. and/or Foreign). UNS GS2986:
6U7; ASTM A27-l. A322. A331. A505. ASl9. A535.
MlL-S-980.
MJL-S-7120.
hllL-S-Zl-t I;
SAE J-IO-I.
DIN 1.3505; (Fr.) AFNOR IOOC 6: (Ital.) UN1 lOOCr6:
99.535 A 99
AMS 6-WO.
44636: MUJ-II’. 5770:
(U.K.) B.S.
Characteristics.
Because E52 100 has the same composition
as 5 I IO
escept for a modest Increase m chromtum. the characteristics and commercoal applications are similar. The as-quenched hardnesses for the tmo steels
can be the same (62 to 66 HRCJ. depending mainly on section thickness.
Because of higher chromium
content. the hardenability
of ES2100 is
someLt hat higher. Sometimes an attempt is made to evaluate hardness by
the end-quench method. ES2100 is selected when greater section sizes and
the increased hardenability
are needed
Forging.
temperature
Heat to I IS0 “C (1100 “FJ maximum.
Do not forge after
of ForSinS stoch drops below approxtmately
915 “C (I 695 “F)
Alloy
Recommended
Heat Treating
Tempering.
Practice
Normalizing.
Heat to 885 “C (1625 “FL Cool
practice this alloy is nomtalized at 900 “C ( 1650 “F)
in air
Steel / 429
In aerospace
Annealing.
For a predominantly
spheroidired
structure which is generally desired for machining as dell as heat treating. heat to 795 “C t l-160 “F).
cool rapidly to 750 “C ( I380 “F). then cool to 675 “C ( 12-15 “Ft. at a rate
not to exceed 6 “C I IO “F) per h; or heat to 795 “C ( I460 “FL cool rapidly
to 690 “C ( I275 “F). and hold for I6 h. Parts are annealed at 775 “C ( 1125
“F) for 20 min. cooled to 740 “C (I 365 “F) at a rate not to exceed IO “C (20
“F) per h. and air cooled to ambient temperature
Hardening. iwstenitize at 845 “C (IS55 “Ft in a neutral salt bath or in a
gaseous atmosphere with a carbon potential of near I .OCr. and quench in
oil.
In aerospace practice, this alloy is austenitized at S-15 “C (IS55 “Ft.
Ho\+ever. 815 “C (1500 “F) is pemissible
for parts requiring distortion
control. Parts are hardened from the spheroidize annealed condition or
normalized condition. Parts are quenched in oil or polymer. Immediately
after quenching, parts are refrigerated at -70 “C (-95 “F) or lomet-. held for
I h minimum. then air barnled to room temperature. If parts have high
propensity
for cracking during refrigeratton.
a snap temper IS recommended
After quenching. parts should be tempered as soon as they
have uniformly reached near ambient temperature, 38 to 50 “C (100 to I20
‘FJ is ideal. Because of the high carbon content, parts must be tempered to
at least 120 “C (250 “F) to convert the tetragonal martensite to cubic
martensite. Most commercial practice calls for tempering at 150 “C (300
“F). which does not reduce the as-quenched hardness to any significant
amount. When a reduction in hardness from the asquenched
value of
approsimately
two points HRC can be tolerated, a tempering temperature
of I75 “C (3-0 “F) is recommended.
Sometimes subjected to higher
tempering temperatures. u ith an accompanying
loss of hardness. In aerospace practice. at least t\<o tempering operations are required. For hardness
in the range of 58 to 65 HRC. parts are tempered at 170 to 230 “C (310 to
450 “F)
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (spheroidire)
Machine. including rough grinding
Xustenitize and quench
Temper
Finish grind
E52100: Isothermal
Transformation
Diagram. Composition:
1.02 C, 0.36 Mn, 0.20 Ni. 1.41 Cr. Austenitized
at 845 “C (1555
“F). Grain size: 9
E52100: Hardness vs Tempering Temperature. Represents an
average based on a fully quenched structure
430 / Heat Treater’s
E52100: End-Quench
(1555 “F). Insufficient
austenite
Guide
E52100: Continuous Cooling Curves. Composition: 1.06 C,
0.33 Mn, 0.32 Si, 1.44 Cr. Austenitized at 845 “C (1555 “F). Grain
size: 9. AC,, 780 “C (1440 “F); AC,, 755 “C (1390 “F). A: austenite,
F: ferrite, P: peartite, B: bainite, M: martensite. Source: Bethlehem
Steel
Hardenability. Austenitized at 845 “C
time to permit full carbide solubility in
E52100: End-Quench Hardenability. 13 mm (0.5 in.) diam bar.
Composition: 1.02 C. 0.36 Mn, 0.20 Ni, 1.41 Cr. Austenitized at
845 “C (1555 “F). Grain size: 9
E52100: Influence of Agitation of Surface Hardness. Various
section thicknesses,
martempered
in hot salt
E52100: Hardness Distribution. Steel rings, 100 heats. Heated
at 790 “C (1455 “F) for 3 h. cooled rapidly to 725 “C (1335 “F), then
cooled to 695 “C (1280 “F) at 8 “C (15 “F) per h, and air cooled.
Hardness measurements were made on rings located at extreme
positions in furnace load. Treatment resulted in spheroidized
structure. Composition: 0.90 to 1.05 C, 0.95 to 1.25 Mn, 0.50 to
0.70 Si, 0.90 to 1.15 Cr
E52100: Variation of Brine11 Hardness Measurements on Annealed Plain Carbon and Low-Alloy Steels. 52100 seamless
tubes were austenitized at 790 “C (1445 “F), rapid furnace cooled
to 750 “C (1380 “F), then cooled to 695 “C (1280 “F) at 6 “C (10
“F) per h, and air cooled
I
I
I
Alloy Steel / 431
E52100: Austenitizing
Temperature
vs Grain Size and M,Temperature.
(a) Grain size; (b) MS temperature
E52100: Microstructures.
(a) 4% picral with 0.05% HCI, 1000x. Steel bar, 123.8 mm (4.875 in.) diam, heated to 770 “C (1420 “F) for 10 h,
held for 5 h, cooled to 650 “C (1200 “F) at 11 “C (20 “F) per h. furnace cooled to 28 “C (80 “F). Fine dispersion of spheroidal carbide in a
matrix of ferrite. Prior structure for(b) to (k). (b) 4% nital. 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 790 “C (1455 “F) for t/2 h. oil
quenched, tempered at 175 “C (345 “F) for 1 h. Black areas are bainite, gray areas tempered martensite, white dots are carbide particles
that did not dissolve during austenitizing. (c) 4% nital, 4% picral, mixed 1 to 1: 500x. See (a), austenitized l/2 h at 845 “C (1555 “F) and oil
quenched, then tempered same as (b). Tempered martensite and carbide particles (white) undissolved during austenitizing. Ghost lines are
because of inhomogeneous distribution of carbon and chromium. (d) 4% nital, 4% picral, mixed 1 to 1; 500x. See (a), austenitized at 855 “C
(1570 “F) for l/2 h, oil quenched, tempered at 260 “C (500 “F) for 1 h. Tempered martensite and undissolved carbide particles. Ghost lines
less prominent because of higher austenitizing and tempering temperatures. See (c). (e) 4?0 nital, 4% picral, mixed 1 to 1; 500x. See (a).
Austenitized at 845 “C (1550 “F) for % h, oil quenched, tempered at 400 “C (750 “F) for 1 h. Tempered martensite and a dispersion of carbide
particles not dissolved during austenitizing. Ghost lines have nearly disappeared. Compare with (c) and (d). (f) 4% nital. 4% picral, mixed 1
to 1; 500x. See (a). Austenitized at 925 “C (1695 “F) for l/2 h, oil quenched, tempered at 175 “C (345 “F) for 1 h. Mainly tempered martensite.
High austenitizing temperature resulted in some retained austenite (angular white areas) and a few carbide particles. Compare to (c) and
(e).
(continued)
432 / Heat Treater’s
Guide
E52100: Microstructures
(continued).
(g) 4% nital. 4% picral, mixed 1 to 1; 1000x. Same specimen as (f) shown at higher magnification.
Dark areas are tempered martensite. Retained austenite (angular light gray areas) is well resolved. A few undissolved carbide particles remain from the original structure (a). (h) 4% nital, 4% picral, 1000x. See (a). Austenitized at 980 “C (1795 “F) for ‘12 h. oil quenched, tempered
at 175 “C (345 OF) for 1 h. Coarse plates (needles) of tempered martensite and retained austenite (white). Carbide particles are almost
wholly dissolved. (j) 4% nital, 4% picral, mixed 1 to 1; 500x. See (a). Austenitized at 855 “C (1570 “F) for ‘,‘2 h, quenched in a salt bath at 260
“C (500 “F), held for l/s h, air cooled to room temperature. Spheroidal carbide particles in lower bainite, some retained austenite. (k) 4% nital,
4% picral, mixed 1 to 1; 1000x. See (a). Austenitized at 955 “C (1750 “F) for 2 h, cooled slowly to 705 “C (1300 “F), oil quenched. Note dark
gray needles of martensite, carbide rejected to grain boundaries (light gray), bainite (black), and retained austenite (small light areas). (m)
4% nital, 500x. Steel rod austenitized at 900 “C (1650 “F) for20 min and slack quenched in oil to room temperature. Dark areas (etched) are
a mixture of fine pearlite and bainite. Light areas (almost unetched) are untempered martensite. (n) 4% nrtal. 10 000x. Steel rod, austenitized
at 1125 “C (2060 “F) for 15 min, oil quenched. Electron micrograph of a replica rotary-shadowed
with chromium. Coarse, untempered
martensite. Note cracks in martensite platelets (upper left, upper right). (p) 4?h nital, 5000x. Steel rod, austenitized at 980 “C (1795 “F) for 1
h, quenched in a lead bath at 357 “C (675 “F), held for 2 h. air cooled. Electron micrograph of a replica rotary-shadowed with chromium.
Bainite, probably upper bainite. (q) 4% nital, 10 000x. Steel wrre, austenitized at 900 “C (1650 “F) for 30 set, quenched in a lead bath at 530
“C (990 “F), held for 30 set, air cooled. Electron micrograph of a replica rotary-shadowed with chromium. Lamellar pearlite and bainite. (r)
4% nital. 10 000x. Steel rod, austenitized at 1150 “C (2100 “F) for 3 min, quenched in a lead bath at 575 “C (1065 “F), held for 5 min, air
cooled. Electron micrograph of a replica static-shadowed with chromium. Fine lamellar pearlite.
Alloy Steel / 433
6118,6118H
Chemical Composition.
6118. AK1 and UNS: 0. I6 to 0.2 I C. 0.50
to0.70Mn.O.035
Pma~0.030Smaa.0.15
to0.30Si.0.50to0.70Cr.0.10
too.15 V. UNS H61180and
SAE/AISI
6118H: 0.15 too.21 C.O.40 10 0.80
hln. 0. IS to 0.35 Si. 0.40 to 0.80 Cr. 0.10 to 0. IS V
Similar
Steels (U.S. and/or
Foreign).
110-l. 5770: (Cer.) DIN I .7S I I. 6118H.
1268: (Ger.) DIN I .75 I I
6118. LINS Ghll80:
UNS H6lI80:
ASTh1430-l:
WE
SAE
Recommended
Normalizing.
A chromium-vanadium
carhurizing-c~honitriding
steel. Its characteristics
‘are approximately
the same as thoss for -!I l8H.
Because of the slightI> lo\\er clvbon range of 61 l8H. the as-qusnchcd
hardness is likely to be lower. spproxmiatel!
36 to 42 HRC. The chromium
contents of these tbo steels are nearly the same. and their hardennbilitj
hands are nearly the same. The small amount of vanadium contained in
61 l8H acts as a grain refiner and does not increase hardenahility.
Is rendilj
forgeable and weldable (using allo) steel practice). hlachines reasonaLA>
ttell
Heat to I245 T (217s “F) maslmum. Do not fwgs after
of forging stock drops Mow approximately
900 ‘C ( 1650 ‘F)
6118H: End-Quench
Distance from
quenched
su t-face
I‘16 in.
mm
Practice
“F). Cool in air
Annealing.
Structures ha\ ine best machinability
are normally obtained
hy normalizing orb! isothermal treatment which consists of heating to 885
“C ( 1625 “FL cooling rapid11 to 690 “C ( 1775 “F). and holding for 4 h
tempering
process
See recommended carhurizing.
carbonitriding.
and
described for -II l8H. Ion nitriding is an alternative
procedures
Recommended
l
l
l
l
l
Forging.
Heat to 925 “C (I695
Case Hardening.
Characteristics.
temperature
Heat Treating
l
l
Processing
Forge
Normalize
Anneal (optional)
Rough and semifinish
Case harden
Temper
Finish machine
Sequence
machine
Hardenability
Hardness,
ARC
may
min
I
;7
I 58
4.71
3 16
46
u38
39
28
36
-I
5
6
7
8
Y
I0
II
12
6.32
7.90
Y.-l8
Il.06
12.6-I
l-l.11
15.80
17.38
18.96
33
30
28
27
16
26
2s
2s
2-I
2-l
22
‘0
Distance from
quenched
surface
I‘16 in.
mm
Hardness,
ERC
mas
10.5-l
12.12
23 70
3.28
33 u
31 60
3-l 76
37 92
41.08
4-l 74
-+7.40
50.56
6118, 6118H: Hardness
sents an average
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
434 / Heat Treater’s
Guide
6150,615OH
Chemical
Composition.
6150.AlSIandUNS:0.48to0.53C.0.70
to0.90Mn,0.035Pmax,0.030Sma~.0.15to0.30Si,0.80to1.10Cr.0.15
V min. 6150H.AISland UN& 0.47 to 0.54 C.O.60 to 1.00 Mn.0.035
max. 0.040 S max. 0.15 to 0.30 Si. 0.75 to I.20 Cr. 0. IS V min.
Annealing.
For a predominantly
pearlitic structure. heat to 830 “C (I 515
“FJ. cool rapidly to 760 “C ( 1100 “F), then cool to 675 “C (I 235 “F). at a
rate not to exceed 8 “C (IS “Fj per h: or heat to 830 “C (1515 “F). cool
rapidly to 675 “C (1%
“FL and hold for 6 h. For a predominantly
spheroidized structure, heat to 760 “C t I100 “F), and cool to 675 “C ( I245
“F) at a rate not to exceed 6 “C (IO “F) per h; or heat to 760 “C (1300 “F),
cool rapidly to 650 “C ( I200 “F). and hold for IO h
P
Similar Steels (U.S. and/or Foreign). 6150. UNS G61500; AhlS
6448. 6450, 6455: ASTM A322. A33l: MIL SPEC hlIL-S-8503;
SAE
J4O-l. J4lL 5770;
CrV -I: (Jap.) JIS
47. 6150H. UNS
(Fr.) AFNOR 50
SSIJ 2230; (U.K.)
(Ger.) DIN 1.8159; (Fr.) AFNOR 50CV-1: (Ital.) UNI SO
SUP IO: (Shed.) SSIJ 2230: (U.K.) B.S. 735 A SO. En.
H61500: ASThl A30-I; SAE 5407; (Ger.) DlN I .8159:
CV -I; (Ital.) UNI 50 CrV 3; (Jap.) JIS SUP IO: (Swed.)
B.S. 735 A SO. En. 37
Characteristics.
A medium high-carbon
chromium-vanadium
allo)
steel which has been used for numerous applications
including premium
quality springs. Its as-quenched hardness is generally 55 to 60 HRC.
depending on the precise carbon content. Hardenahilit)
is relativeI)
high.
approximately
the same as for -IllOH. The chromium content is main11
responsible for the hardenability.
The vanadium serves as a grain refiner
and has no significant
effect on hardenability.
Is forgeable. but is not
recommended for helding
Hardening.
Tempering.
Reheat immediately after quenching [preferably before the
temperature of the parts drops below the range of 38 to 50 “C (100 to I20
“F)] to the temperature required to obtain the desire combination
of mechanical properties
Austempering.
For many spring applications. this steel is austempered
bq austenitizing at 870 “C t 1600 “F), quenching in an agitated molten salt
bath at 3 IS “C (600 “F). holding for I h. and air cooling No tempering is
required. Hardness after this treatment generally ranges from approximatslq 16 to 5 I HRC
Recommended
l
Forging.
temperature
Heat to 1230 “C (2X0 “F) maximum.
Do not forge after
of forging stock drops below approximately
900 YI. ( 1650 “F)
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 900 “C (I650 “F). Cool in air
6150: Isothermal Transformation
C, 0.67 Mn, 0.93 Cr, 0.18
Grain size: 9
Diagram. Composition:
V. Austenitized
at 845 “C (1555
l
0.53
“F).
Heat to 870 “C (1600 OF). and quench in oil
Processing
Sequence
Forge
Normalize
Anneal
Rough machine
Austenitize and quench (or austemper)
Temper (or austemperj
Finish machine
6150:
gears
Equipment
requirements
Production requirements
H’eight of eclch piece
Pieces per furnace load
Producuon per hourcaj:
Number of pieces
Net work load
Gross furnace losdr b )
Equipment requirements
hlanempering furnace
Size of salt pot
Capxit) of salt pal
-r)peofsdr
Quenching sapacrty of ball pot
Operating rcmpenture
Agitation
for salt mat-tempering
0.9kp(llb,
32
128
116kg(256lb)
152kgt336lb)
tmmrnion-heated salt pot(c)
6lOb) 381 by838nun1Xbq
lSby33in.)
272kgl6OOlb)
Nitrate-nitrite(X
acueradded)
I81 kg/ht-IGOIb/h)
205 ‘T (400 “R
Air-operated stirrer
la1 Clsle ume. IS min. Ib) Work and fikwrrs. Each IYkturz welghed 9.1 kg (20 lb)
rmpr) and <ontamed right gears. (5 I Salr pot mred ai 2 I kV A (3 phase. 60 cycle, 220
to UO VI for heating IO temperature rdnee of I7S to WO “C (350 to 790 “FL Blower
I ‘,? hp. 3 phaje.60c>clzs. 220 c’) used forcooling b> dri\ingroom-rempratureairbewren \rall of pot and exterior shell of furnace
Alloy Steel / 435
6150: Hardness vs Tempering Temperature. Normalized at 900
“C (1650 “F), quenched from 870 “C (1600 “F) in oil, tempered in
56 “C (100 “F) intervals in 13.7 mm (0.540 in.) rounds. Tested in
12.8 mm (0.505 in.) rounds. Source: Republic Steel
6150H: End-Quench Hardenability
Distance frum
quenched
surface
916in. mm
1
2
3
4
5
6
I
8
9
10
11
12
6150:
As-Quenched
Hardness
(Oil)
Single heat results; grade: 0.48 to 0.53 C. 0.70 to 0.90 Mn, 0.20 to
0.35 Si, 0.80 to 1.10 Cr, 0.15 V minimum; ladle: 0.51 C, 0.80 Mn,
0.014P,0.015S.0.35Si,0.11Ni.0.95Cr.0.01Mo,0.18V;grainsize:
5 to 6 for 70%, 2 to 4 for 30%
Size round
in.
mm
Surface
Hardness, HRC
?(zradius
Center
‘h
13
25
51
102
61
60
54
42
60
58
47
36
60
57
44
35
1
2
4
Source: Bethlehem Steel
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardness,
HRC
max
min
6.5
65
64
64
63
63
62
61
61
60
59
58
59
58
51
56
55
53
50
41
43
41
39
38
Distance &urn
quenched
surface
916in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
HaIdIlesS,
HRC
max
min
51
55
54
52
50
48
47
46
45
44
43
42
31
36
35
35
34
32
31
30
29
27
26
25
436 / Heat Treater’s
6150: Microstructures.
Guide
(a) 2% nital, 550x. Steel wire, austenitized at 900 “C (1650 “F) for 20 mm and slack quenched in oil to room temperature. Lower bainite (dark) and untempered martensite (light). (b) Picral, 550x. Austenitized at 880 “C (1620 “F) for l/z h, cooled to 730
“C (1350 “F) held 5 h, cooled to 650 “C (1200 “F) at 28 “C (50 “F) per h, held 1 h, air cooled. Pearlite and ferrite. (c) 4% nital, 500x. Steel
wire, austenitized at 885 “C (1625 “F) for 20 min, quenched to 675 “C (1245 “F) for 20 min, oil quenched to room temperature. Structure
mainly pearlite. (d) 4% nital, 5000x. Steel wire, austenitized at 845 “C (1555 “F) for r/p h, oil quenched, tempered at 150 “C (300 “F). An electron micrograph of a replica rotary-shadowed
with chromium. Tempered martensite and some spheroidal carbide particles. (e) 4% nital,
10,000x. Steel wire, austenitized at 870 “C (1600 “F), held for 2 h, quenched in lead to 650 “C (1200 “F), held for 2 h, water quenched. An
electron micrograph of a replica rotary-shadowed with chromium. Partly spheroidized carbide in a ferrite matrix. (f) 4% nital, 10,000x. Steel
wire, austenitized at 870 “C (1600 “F) for 2 h, quenched in lead to 720 “C (1330 “F), held 2 h, water quenched. An electron micrograph of a
replica rotary-shadowed with chromium. Partly spheroidized and partly lamellar pearlite in ferrite. (g) Nital, 535x. Steel rod, 13 mm (l/2 in.)
diam, austenitized at 845 “C (1555 “F) for 1 h, quenched to 315 “C (600 “F), held 16 min, air cooled. Mostly bainite, probably lower bainite.
(h) Nital, 1000x. Same steel, rod diameter, and heat treatment as (g), except at higher magnification. Austempering was the heat treatment used
Alloy Steel / 437
81 B45,81
B45H
Chemical
Composition.
N&15. AISI: 0.43 IO (J.-U C, 0.75 to I .OO
hln.0.035 Pmax.O.O-!OSmax.O.lS
to0.30Si.0.20to0.10Ni.0.351o0.55
Cr. 0.08 to 0. IS MO. 0.0005 to 0.003 B. UNS: 0.43 to O.-l8 C. 0.75 to 1.00
hIn.0.035 Pmax.O.WOS
max.0.15 to0.30Si.0.20
toO.-lONi.0.35
100.55
81BGH:
Cr. 0.08 to 0.15 Mo. 0.0005 B min. UNS HSlJSl and SAE/AISI
O.-P to 0.19 C. 0.70 to 1.05 Mn. 0.15 to 0.35 Si. 0.15 to O.-IS Ni. 0.30 to
0.60 Cr. 0.08 to 0. IS hlo. B (can be expected to he 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or
ASThl ASl9: SAE J-W.
A3O-k SAE J 1268
Foreign).
JAI?. 1770. 81BJ5H.
MB35
UNS
LINS G8l-lS I :
H813Sl: ASTM
Annealing.
Forapredominantl\
pearlitic structure. heat to 830°C (IS25
“FJ. cool rapidI) IO 725 “C ( I33S-‘F). then cool to 6-10 “C (I I85 “F). at a
rate not to exceed I I ‘C (20 “F) per h; or heat to 830 “C (IS25 “F), cool
rapidly to 660 “C t 1220 ‘F). and hold for 7 h. For a predominantly
spheroidizsd structure. heat to 750 “C t I380 OF). and cool rapidly to 725
“C t I.335 “F). then continue cooling to 610 “C t I I85 “F) at a rate not to
csceed 6 “C (IO “F); or heat to 750 “C ( I380 “F). cool rapidly to 660 “C
t I230 “F). and hold for IO h
Hardening.
Tempering.
Characteristics.
A slightI> modified version of 86B-iSH. Ni. Cr. and
MO are slightly louer. The as-quenched hardnesses of the IWO steels are
essentially the same, approaunatel> S-l to 60 HRC. Hardenabilitb
of the t\to
grades is nearly the same
After quenching. parts should be tempered immediately.
Selection of tempering temperature depends upon the desired mechanical
propertizs
Recommended
l
Forging.
temperature
Heat to 1230 ‘C (2250 “F) maxmium.
Do not forge after
of forging stock drops below approximately
925 “C ( 1695 “F)
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 815 “C t IS55 “F), and quench in oil
Heat to 870 “C t 1600 “FL Cool in mr
81845: Hardness vs Tempering Temperature. Normalized
at
870 “C (1600 “F), quenched
from 845 “C (1555 “F) in oil, tempered in 56 “C (100 “F) intervals
in 13.7 mm (0.540 in.) rounds.
Tested in 12.8 mm (0.505 in.) rounds. Source: Republic Steel
l
Processing
Sequence
Forge
Normalize
Anneal
Rough and ssmifmish machine
Austenitizs and quench
Temper
Finish machine
81 B45H: End-Quench Hardenability
Distance from
quenched
surface
!&in.
mm
I
2
3
-I
3
6
7
8
9
I0
II
I2
I 58
3.16
4.7-l
6.32
7.90
9.48
I I 06
12.6-l
I-I.22
IS.80
17.33
I X.96
Hardness,
HRC
Olin
nlax
63
63
63
63
63
63
62
62
61
60
60
59
56
56
56
56
s5
5-l
53
51
1s
44
II
39
Distance l’rom
quenched
surface
916 in.
mm
13
I-I
IS
I6
18
20
22
2-I
‘6
18
30
3’
20.5-l
22.12
23.70
3.28
x3.44
31.60
31.76
37.91
41.08
44.2-l
47.40
50.56
Hardness,
ElRC
max
min
58
57
57
56
55
53
52
50
49
-17
45
43
38
37
36
35
34
32
31
30
29
28
28
17
438 / Heat Treater’s
Guide
8615
Chemical
Composition.
8615. AISI and UNS: 0.13 KI 0. I8 C. 0.70
to0.90Mn,0.035Pmrut.0.~0Smax.0.15to0.30Si,0.30to0.70Ni,0.~0
to 0.60 Cr. 0. I5 to 0.25 MO
Similar Steels (U.S. and/or Foreign). LINS G86150;
5333; ASTM A322; ML SPEC MIL-S-866; SAE J4O-%,J770
Tempering.
AMS
Characteristics.
Similar to 8617H and 8620H. except with a lower
carbon range. Extensively
used for parts processed by carburizing
and
carbonitriding.
Although there is no published AISI hardenability
band for
8615. the hardenability
pattern for 8615 should be very similar to that for
8617H. adjusted down slightly because 8615 has a lower carbon range.
As-quenched surface hardness for 86 I5 usually ranges from 35 to 30 HRC.
Fogeable and weldable: machinability
is fairly good
Forging.
temperature
OF). then holding for 4 h. Another technique is to heat to 790 “C (1455 “F).
cool rapidly to 660 “C ( 1220 ‘F). and hold for 8 h
Heat to 1245 “C (2275 “F) maximum.
Do not forge after
of forging stock drops below approximately
900 “C (1650 “F)
Temper all carburized or carbonitrided
parts at I50 “C (300
“F). and no case hardness will be lost as a result. If some decrease in
hardness can be tolerated. toughness can be increased by tempering at
somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening.
scribed for 8620H.
processes
Recommended
l
l
l
l
Recommended
Normalizing.
Heat Treating Practice
Heat to 935 “C ( I695 OF). Cool in air
Annealing.
Structures nith best machinability
malizing or by heating to 885 “C ( 1625 “F). cooling
are developed by norrapidly to 660 “C ( I220
8615: Case Depth of Liquid Carburized Steel vs Time and
Temperature. 19 mm (0.75 in.) outside diam by 121 mm (4.75 in.),
oil quenched.
l
Carburized
at indicated
temperatures
l
l
See carburizing
flame hardening
Processing
and carbonitriding
and ion nitriding
practices deare alternative
Sequence
Forge
Normalize
AMY
(if required)
Rough machine
Semitinish machine allowing only grinding stock. no more than IO% of
the case depth per side for cart&red
parts. In most instances. carboniuided parts are completely finished in this step
Carburize or cmbonitride and quench
Temper
8615: Liquid
Carburizing. Specimens
19 mm (0.75 in.) by
121 mm (4.75 in.), carburized
at 925 “C (1695 “F) for 15 h, air
cooled, reheated in neutral salt at 845 o C (1555 “F), quenched
in
salt at 180 ’ C (355 “F)
8615: Hardness vs Tempering Temperature.
average
based
on a fully quenched
structure
Represents
an
Alloy Steel I439
8617,8617H
Chemical
Composition.
8617. AISI and UNS: 0. IS to 0.10 C, 0.70
too.90
Mn. 0.035 Pmax. 0.04OS max. 0. I5 too.30 Si.O.10 to0.70Ni.0.40
to 0.60 Cr. 0. IS to 0.25 Mo. UNS H86170
and SAE/AISI
86178:
0. II to
0.20 C, 0.60 to 0.95 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr.
0.15 too.25
Mo
Similar
Steels (U.S. and/or Foreign). 6617. UNS G86170; AMS
SAE J-IO-I. 5770; (Ger.) DIN I .6523; (Fr.) AFNOR 20 NCD 2.22 NCD
3: (Ital.) UNI 20 NiCrMo 2; (Jap.j JIS SNCM 21 H. SNCM 21: (U.K.) B.S.
805 H 20.805 M 20.8617H. l[NS H86 170; ASIXI A304 SAE J 1268; (Ger.)
DIN 1.6523; (Fr.) AFNOR 20 NCD 3, 22 NCD 2; (Ital.) UN1 20 NiCrhlo 3:
(Jap.) JIS SNCM 21 H. SNCM 21; (U.K.) B.S. 805 H 20.805 M 20
6272:
Characteristics.
A carburizing prade of the multiple alloy series. NiCr-Mo. Not as widely used for case hardening as 8620H and 8622H. An
as-quenched hardness of approximately
35 to 40 HRC can be expected
without carhurizinp. Hardenability
is reasonahl) high. Has excellent forgeahility. can he welded using allo) steel practice, and has fair11 good
machinability
Forging.
Heat to 1245 “C (2375 “F) malimum.
Do not forge after
temperature of forging stock drops below approsimately
900 “C ( 1650 “F)
Recommended
Normalizing.
Heat Treating
can he tolerated, toughness can he increased
higher temperatures. up to 260 “C (SO0 “F)
Heat to 925 “C ( 1695 “F). Cool in air
Annealing.
Structures with hest machinability
are developed hj normalizing or hq heating to 885 “C ( I625 “FL cooling rapidly to 660 “C ( I320
“FL and holding for 1 h: or heat to 790 ‘C (l-IS.5 “F). cool rapid11 to 660
“C (I 220 “F), and hold for 8 h.
Tempering.
Temper all carhurized or carbonitrided
parts at I SO “C (300
OF) and no loss of case hardness will result. If some dscrease in hardness
at somewhat
Case Hardening. See carburizing and carbonitriding
practices described for 8620H. Flame hardemng. ion nitriding.
gas nitriding.
gas
carhurizing, austempering and martempering are alternative processes
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (if required)
Rough machine
Semifinish machine allowinp only 8rinding stock. no more than 10% of
the case depth per side for carhunzed parts. Ln most instances. carhonitrided parts are completely finished in this step
Carburize or carhonitride and quench
Temper
8617: Equipment
carburized parts
requirements
Production
requirements
Weight of load
Weight ofeach prece
Number of pieces treated per hour
Practice
hy tempering
Equipment
for oil mat-tempering
1S3.6kg(lOOOlbnet)
I .S kg f 3.3 lb)
75
requirements
Capacib of quench tank
Type of oil
7511 L(2oGOgal)
hIineraloil\rithaddjti~est~iscosi~,~SOSUS)
lkmpenturr
I SO “C ( 300 “F)
Direct tlow(a,
of oil
Agitation
(a) Agitation pro\ idrd bj I\GO S-hp motors drivmg 457.mm (IS-in.)
‘pm. causing lhc oil to flow at a rate of911 mm/set (36 in./sec)
propellers at 370
8617, 8617H: Hardness vs Tempering Temperature. Represents an average
8617H: End-Quench Hardenability
Distance from
quenched
swtface
l/16 in.
mm
Hardness,
HRC
min
max
I
I.58
46
2
3.16
4-l
39
33
3
1.11
-II
17
-l
6.32
7.90
9.18
38
3-l
31
28
24
20
5
6
7
Il.06
8
1264
l-l.22
IS.80
17.38
IS.96
9
IO
II
I2
___
27
26
2s
2-l
23
1::
Distance from
quenched
surface
‘/lb in.
mm
I3
I-I
IS
I6
I8
20
21
21
26
2o.s-l
22.1’
23.70
25.18
28.4-l
31.60
34.76
37 92
28
41.08
5-1.2-l
30
32
17.40
50.56
Hardness.
HRC
max
23
22
‘2
21
II
20
..:
based
on a fully quenched
structure
440 / Heat Treater’s
Guide
8617H: Hardenability
Curves. Heat-treating
925 “C (1700 “F)
(1700 “F). Austenitize:
Hardness
purposes
I distance,
nm
1.5
i
)
Ll
13
I5
‘0
!5
10
$5
limits for specification
Hardness, HRC
Maximum
Minimum
46
44
42
37
32
29
27
25
23
22
20
39
33
27
23
20
.
Hardness limits for specification
wrposes
I distance,
/16mm
,
1;
1
IO
I1
12
13
I4
I5
I6
I8
!O
!2
Hardness, HRC
Maximum
Minimum
46
44
41
38
34
31
28
27
26
25
24
23
23
22
22
21
21
20
39
33
27
24
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 441
8617: Microstructures.
(a) 1% nital, 500x. 8617H, gas carburized for 3 74 h at 925 “C (1695 “F), cooled in the furnace to 540 “C (1000 “F), air
cooled, heated to 840 “C (1545 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F), quenched in oil, tempered for 2 h at 150 “C (300 “F).
Numerous microcracks (small black streaks), are present both at the boundaries and across martensite plates. (b) 39/onital. 200x. 8617, carbonitrtded 4 h at 845 “C (1555 “F) in 8% ammonia, 8% propane, remainder endothermic gas, oil quenched, tempered 1 !‘z h at 150 “C (300 “F). Tempered martensite (dark) and retained austenite. (c) 3?L nital, 200x. 8617 steel bar, carbonitrided and tempered same as (b), except held at -73 “C
(-100 “F) for 2 h between quenching and tempering to transform most of the retained austenite. Scattered carbide and small amounts of retained
austenite in a matrix of tempered martensite. (d) Picral, 200x. 8617 steel bar, annealed by being austenitized at 870 “C (1600 “F) for 2 h, furnace
cooled. Fine pearlite (dark) in ferrite matrix (light). Magnification too low for good resolution of structure
Alloy Steel / 441
8620,862OH
Chemical
Composition.
8620. AK3 and UNS: Nominal. 0.18
too.23 CO.70 to0.90Mn,0.035 Pmax,O.O40S
to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO.
Nominal. 0.17 to 0.23 C, 0.60 to 0.95 Mn, 0.035
to 0.30 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr, 0.15
max,0.15 toO.3OSi,O.40
862038. AISI and UNS:
P max, 0.040 S max, 0.15
to 0.25 MO
Similar Steels (U.S. and/or Foreign). 8620. UNS G86200, AMS
6274,6276,6277; ASTM A322, A33 1, A513, A914; MIL SPEC MIL-S16974; SAE 5126851868; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD
2,22 NCD 2; (Ital.) UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21;
(U.K.) B.S. 805 H 20,805 M 20.8620H. UNS H86200; ASTM A304; SAE
5407; (W. Ger.) DIN 1.6523; (Fr.) AFNOR 20 NCD 2, 22 NCD 2; (Ital.)
UN1 20 NiCrMo 2; (Jap.) JIS SNCM 21 H, SNCM 21; (U.K.) B.S. 805 H
20,805 M 20
Characteristics.
Used extensively as a case hardening steel for both
carburizing and carbonitriding. As-quenched surface hardness usually
ranges from approximately 37 to 43 HRC. Reasonably high hardenability.
Excellent forgeability and weldability, although alloy steel practice should
be used in welding to minimize susceptibility to weld cracking. Machinability is fairly good. Because 8620H and 8620 are high-tonnage steels,
some mills produce them with lead additions. This significantly improves
machinability without sacrificing heat treating response
Forging. Heat to 1245 “C (2275 “F) maximum, and do not forge after the
temperature of the forging stock has dropped below approximately 900 “C
(1650 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 925 “C (1700 OF) and cool in air
Annealing.
Structures with best machinability are developed by normalizing or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C (1225
OF), and holding for 4 h. Another technique is to heat to 790 “C (1450 “F),
cool rapidly to 660 “C (1225 “F), and hold for 8 h
Carburizing.
In general, carburizing practice for 86208 (and 8620) is
the same as for other low-carbon, plain carbon, and alloy steels. Because of
its inefficiency, the pack method is used only for highly specialized applications. Carburizing by immersion is often used, although mainly for
developing relatively thin cases. Any one of a number of proprietary molten
salt baths can be used, usually within the temperature range of 870 to 925
“C (1600 to 1700 “F). As a rule, workpieces are quenched directly from the
carburizing temperature. 8620H and other carbon and alloy steels are most
frequently gas carburized, a far more efficient method that is easier to
control
442 / Heat Treater’s
Guide
Gas Carburizing.
effectively
extensively:
l
l
l
l
Although a number of different cycles can be used
for 8620 and 8620H. the one listed below is a cycle used
Carburize at 925 Y? ( I700 ‘F) in a prepared carbonaceous atmosphere
u ith the dewed carbon potential (commonly about 0.90 carbon) for-l h
Reduce temperature to g-15 “C ( IS55 “F). reduce carbon potential to near
eutectoid. and diffuse for I h
Quench in oil
Temper for I h at I SC)“C (300 ‘F)
This cycle will result in a total case of approximatslj
I.3 mm (0.050 in.).
Deeper cases can be obtained with longer cycles. but this is a matter of
diminishing returns. Obtaining greater case depths by increasing time cycles IS
costly in terms of energy consumption. Case depth can be increased exponsntiallly by increasing the carburizing temperature. but this approach becomes a
matter ofeconomlcs as wAl, because the rate ofdeterioration
on furnace alloys
and refmctories above ahwt 925 “C ( 1700 ‘F) may become intolerable because
of the high cost of hmace maintenance. The most economical approach for
deep-case carbwizing LSthe use of the vacuum Furnace, which operates as high
as 1095 ‘C (2000 “F)
Carbonitriding.
For thin, file-hard cases, parts made of 8620 or 8620H
are often carbonitrided
at g-15 “C ( ISSO ‘F) in a carbonaceous atmosphere
with an addition of 10% anhydrous ammonia. Temperatures of 790 to 900
“C ( I-150 to I650 “F) have been used, but 84.5 “C t IS55 “F) seems to be the
most common. Parrs are oil quenched directly from the carbonitriding
temperature. Just as is true for carburizing.
the case depth increases hith
time at temperature. Using a carbonitriding
temperature of 845 “C (1555
‘F). it is possible to obtain a case depth of approximately
0.305 mm (0.012
in.) in about 45 min
Other PrOCeSSeS.
ion nitriding,
carburiring
Flame hardening.
austempering.
martempering,
gas nitriding ion carburizing.
vacuum carburizing.
liquid
Tempering.
Temper all carburized or carbonitrided
parts at IS0 “C (300
“F) and virtually
no loss of case hardness results. If some decrease in
hardness can be tolerated, toughness can be increased by tempering at
somewhat higher temperatures, up to 260 ‘C (SO0 “F)
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (if required)
Rough machine
Semitinish machine. allowing onl? grinding stock, no more than 10% of
the case depth per side for carbunzed parts. In most instances, carbonitridcd parts are completeI> tinished in this step
Carburize or carbonitride and quench
Temper
8820: Continuous
Cooling Curves. Composition: 0.17 C, 0.82
Mn, 0.31 Si, 0.52 Ni, 0.50 Cr, 0.20 MO. Austenitized at 925 “C
(1700 “F). Grain size: 9. AC,, 825 “C (1520 “F); AC,, 745 “C (1370
“F). A: austenite, F: ferrite, B: bainite, M: martensite
Alloy Steel / 443
8620: Isothermal Transformation
Diagram. Composition: 0.18
C, 0.79 Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C
(1650 “F). Grain size: 9 to 10
8620: End-Quench
8620: Austenitizing
8620: Cooling Time vs Depth of Hardness. Time to cool from
Temperature vs Depth of Hardness. Cast
Hardenability. Composition: 0.18 C, 0.79
Mn, 0.52 Ni, 0.56 Cr. 0.19 MO. Austenitized at 900 “C (1650 “F).
Grain size: 9 to 10
RL7911. Heat treatment: A: 900 “C (1650 “F), 15 min. lpsen Furnace; B: 1000 “C (1830 “F), 15 min, lpsen Furnace; C: 1100 “C
(2010 “F), 15 min, Muffle and Ipsen. Depth below surface: 1: 0.3
mm (0.012 in.); 2: 2.5 mm (0.1 in.)
730 “C (1350 “F) to temperatures of 540 to 260 “C (1000 to 500
“F), quenched from 845 “C (1555 “F)
8620: Gas Carburizing. Carburized
8620: Liquid Carburizing,
in a recirculating pit furnace.
7.5 h at temperature. 12% CH,. Core: 0.2296 C. 0: 925 “C (1700
“F); 0: 900 “C (1650 “F); A: 870 “C (1600 “F)
Case Hardness Gradients.
tests. Scatter resulting from normal variations
Nine
444 / Heat Treater’s
6620H:
End-Quench Hardenability
Distance from
qurnched
surface
I.‘,6 in.
mm
I
?
1
4
5
h
7
Y
9
I II
II
I2
Guide
Hardness.
HRC
mas
min
I .5x
3 Ih
4.7-l
h.32
7 90
Y.-IS
Il.ufl
12.64
II 12
I5 80
17.38
IX.%
-lx
17
4-l
-II
37
34
22
30
‘9
2x
27
26
6620: End-Quench
with theoretical
-II
37
31
27
23
21
_:
Hardenability.
Jominy
results compared
curve (constant H)
6620: Depth of Case vs 0.40% C and 59 HRC. Test specimens
25-mm (l-in.) diam were processed with production gears in a
two-row continuous gas carburizing furnace using a diffusion cycle and an atmosphere of endothermic gas enriched with natural
gas: air was added to the discharge end. Effective case depth to
50 HRC was measured on a microhardness traverse taken midway between the ends of a cross section of the gear tooth at the
junction of the involute profile and root fillet. (a) Depth of case to
0.40% C, 48 tests. 25-mm (l-in.) diam bar tempered in lead at 650
“C (1200 “F). (b) Depth of case to 50 HRC. 47 tests. Gears tempered at 160 “C (325 “F)
6620: Carbon Gradients Produced by Liquid Carburizing.
mm (0.75-in.) diam by 51 mm (2 in.), carburized
“F) for 8 h
19at 910 “C (1675
6620, 6620H: Hardness vs Tempering Temperature.
sents an average based on a fully quenched structure
Repre-
Alloy Steel / 445
8620: Carbon, Nitrogen, and Hardness Gradients. 8620 and
1018 carbonitrided at 845 “C (1555 “F) for 4 h in a batch radianttube furnace. Test data were obtained in a construction-equipment manufacturing plant under normal production conditions,
using a standard carbonitriding cycle. Test specimens were carbonitrided in production loads containing 23 kg (50 lb) of gears
and shafts. The carbonitriding atmosphere, which was controlled
by an infrared control unit, consisted of endothermic gas at 14.1
ma/h (500 fP/h), ammonia at 0.71 m3/h (25 ftVh), propane at 0.01 to
0.02 m3/h (0.25 to 0.75 Wh), and 0.32 to 0.34% CO,. Dew point of
the atmosphere was maintained at -7 to - 6 “C (19 to 21 “F)
throughout
the carbonitridinq
cycle. All specimens
were
quenched from the carbonitriding temperature (845 “C or 1555 “F)
in warm (54 “C or 130 “F) oil. (a) Carbon; (b) Nitrogen; (c) Hardness. Quenched in oil at 54 “C (130 “F). Hardness converted from
Tukon
8620H: Carbonitriding.
Load: gears, 342 kg (753 lb) net, 459 kg
(1011 lb) gross. Batch-type furnace with brick-lined heating chamber, heated by radiant tubes; vestibule-enclosed
quench. Dimensions of furnace chamber: 1422 mm wade, 1676 mm long, 1092
mm high (56 by 66 by 43 in.). Garner gas: endothermic gas at 21.2
mVh (750 ft Vh), including 63 min at temperature. Enriching gas:
additions of propane at 0.1 m3/h (5 fWh), and of ammonra at 1 .l
m3/h (38 ff/h), started after 33 mm at temperature. Generator dew
point: -15 to -14 “C (5 to 7 “F) throughout carbonitriding process
cycle. Heating chamber pressure: 1.5 to 2.0 mm (0.06 to 0.08 in.)
H,O. Carbonitriding temperature: 815 “C (1500 “F). Quenching
temperature: 815 “C (1500 “F). (a) Temperature and dew-point
variations. (b) resulting carbon gradient
Analysis
of Atmosphere
Near End of Cycle
Amount
furnace,
Conbtituent
8620:
Approximate
Critical
in
5
Amount
\es,tibule,
in
B
Points
Temperature
Critical
point
OF
T
446 / Heat Treater’s
Guide
8820: Depth of Case After Gas Carburizing.
Depth of case to 0.40% C. 0: Furnace A. 762 by 1219 by 457 mm (30 by 48 by 18 in.). Atmosphere control dew cell with manual reset. Rated gross load, 680 kg (1500 lb). 0: Furnace B, same as Furnace A. A: Furnace C. 914 by 1829
by 610 mm (36 by 72 by 24 in.). Atmosphere control infrared analyzer controlling carbon dioxide, automatic reset. Rated gross load, 1588
kg (3500 lb) (a) 25-mm (1 -in.) rounds carburized at 925 “C (1700 “F) for 1.75 h. Quenched in oil from 845 “C (1555 “F). Diffusion cycle used.
Dew points of -15 “C (5 “F) for first part of 925 “C (1700 “F) cycle, -12 “C (10 “F) for diffusion cycle at 925 “C (1700 “F), and -3 “C (27 OF)
for time at 845 “C (1555 “F) before quenching. Endothermic plus straight natural gas as enriching gas. Tempered in lead at 650 “C (1200
“F), wire brushed, and liquid abrasive cleaned. (b) 25-mm (l-in.) diam bar. Endothermic with straight natural gas as enriching gas. Carburized at 925 “C (1700 “F), using diffusion cycle. Dew point of -15 “C (5 “F) for 3 h at 925 “C (1700 “F), a dew point of -12 “C (10 “F) for the
difl usion portion, and -3 “C (27 “F) for 1 h at 845 “C (1555 “F). (c) 25-mm (1 -in.) diam bar. Total cycle at 925 “C (1700 “F) was 10.5 h, 5 h with
a -15 “C (5 “F) dew point, and 5.5 h with a -12 “C (10 OF) dew point. Equalizing time at 845 “C (1555 “F) was 1 h, with a dew point of -3 “C
(27 “F). (d) 25-mm (1 -in.) diam bar. Diffusion time with a -12 “C (10 “F) dew point was 6 h. (e) Gears, carburized at 925 “C (1700 “F) in a
continuous furnace. (f) 25-mm (1 -in.) diam by 38 mm (1.5 in.), batch-type carburizing
8620H: Gas Carburizing.
Shafts, 171 kg (376 lb), 440 kg (969 lb)
gross. Vestibule, enclosed-quench,
brick-lined heating chamber,
radiant-tube heated. Carrier gas: 21.8 ma/h (770 ff/h) endothermic gas for 5 h 53 min at temperature. Enriching gas: 0.28 m3/h (10
fP/h) propane, 3 h 59 min at temperature (66% of cycle). Generator dew point: 1 to 4 “C (33 to 39 “F). Heating chamber pressure:
2.5 to 3.6 mm (0.10 to 0.14 in.) water column. Carburized at 925
“C (1700 “F) and quenched from 845 “C (1555 “F). (a) Furnace
temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
Alloy Steel / 447
8620H: Gas Carburizing.
Load: ring gears, 231 kg (510 lb) net,
390 kg (860 lb) gross. Metallic-retort
pit furnace, electrically
heated. 0.34 m3/h (100 ff/h) endothermic gas throughout the cycle, including 5 h 59 min at temperature. Enriching gas: 0.34 m3/h
(12 W/h) natural gas for 2.5 h at temperature (42% of at-temperature cycle). Generator dew point: -6 to -4 “C (22 to 25 “F). Heating
chamber pressure: 5.1 to 7.9 mm (0.20 to 0.31 in.), water column.
Carburizing temperature: 925 “C (1700 “F). Slow cooled from 925
“C (1700 “F) in cooling pit. Atmosphere at the end of cycle: 20.8%
CO, 0.496 CO,, 34.0% H,, 0% O,, 0.8% CH,. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620H: Gas Carburizing.
Ring gears, 231 kg (510 lb) net, 390 kg
(860 lb) gross. Metallic-retort pit furnace, electrically heated. 2.83
m3/h (100 fP/h) endothermic gas for 5 h 15 min at temperature,
carrier gas. Enriching gas: 0.34 ma/h (12 ftYh) started at temperature and shut off after 3 h (57% of cycle). Generator dew point: -4
to -3 “C (24 to 26 “F). Heating chamber pressure: 8.6 to 11 mm
(0.34 to 0.44 in.) water column. Carburized at 925 “C (1700 “F)
and slow cooled in cooling pit. (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620: Depth of Case vs Time and Temperature. 12-mm (0.5-in.)
diam by 6.4 mm (0.25 in.). Carburized at 855 “C (1575 “F), oil
quenched, tempered at 150 “C (300 “F), treated at 49 “C (120 “F)
448 / Heat Treater’s
Guide
8620H: Gas Carburizing. Shafts, 145 kg (320 lb) net, 258 kg (569
lb) gross. Metallic-retort pit furnace, electrically heated. Carrier
gas: 2.83 mVh (100 fP/h) endothermic gas for 5 h 5 min at temperature. Enriching gas: 0.3 m3/h (9 ff/h) natural gas, for 2 h 50
min from start of cycle (56% of cycle). Generator dew point: 4 to
-3 “C (24 to27 “F). Heating chamber pressure: 9.9 to 12 mm (0.39
to 0.49 in.) water column. Carburized at 925 “C (1700 “F) and
quenched from 845 “C (1555 “F). (a) Furnace temperature and atmosphere conditions for carburizing. (b) Resulting carbon gradient
8620: Microstructures.
8620: Effect of Carburizing
Time and Temperature. Specimens 19-mm (0.75-in.) diam by 51 mm (2 in.), carburized, air
cooled, reheated in neutral salt at 845 “C (1555 “F), quenched in
salt at 180 “C (360 “F). (a) Carburized at 870 “C (1600 “F); (b) carburized at 900 “C (1650 “F); (c) carburized at 925 “C (1700 “F)
(a) Picral, 200x. Steel bar normalized by being austenitized at 900 “C (1650 “F) for2 h and cooled in still air. Mixture
of ferrite and carbide. Cooling too rapid to produce an annealed structure. (b) Nital, 100x. Steel bar carbonitrided for 4 h at 845 “C (1555 “F),
oil quenched, not tempered. and stabilized by subzero treatment. Conventional case structure with martensite, carbide particles, and a
small amount of retained austenite. (c) Picral, 1000x. Coarse grain steel, gas carburized 11 h at 925 “C (1700 “F), furnace cooled at 845 “C
(1555 “F), oil quenched, tempered 2 h at 195 “C (380 “F). Tempered martensite and retained austenite. A large martensite plate contains
several microcracks
Alloy
Steel
/ 449
8820: Microstructures
(continued). (d) Picral, 1000x. Same steel, carburizing and heat treatments, and structure as (c), but specimen was subjected to maximum compressive stress of 4137 MPa (600 ksi) for 11.4 million cycles in a contact fatigue test. Butterfly structural alterations developed at microcracks. (e) 4% picral, 500x. Steel gas carburized for 18 h at 925 “C (1700 “F), reheated to 830 “C (1540 “F) and held 40 min, oil
quenched, tempered 1 hat 175 “C (350 “F). Nearsurface are grain-boundary oxides and, less visible because of dark etching, bainite and peariite.
Remaining structure is carbide particles and retained austenite in a matrix of tempered martensite. (f) Not polished, not etched; 23x. Steel tubing,
gas carburized 8 h at 925 “C (1700 “F), hardened, and tempered. Scanning electron micrograph of fractured carburized case. See (g). (g) Not
polished, not etched, 1100x. Same as (f), but a higher magnification. Fractured carburized case consists of carbide, retained austenite, and tempered martensite. (h) Not polished, not etched; 23x. Same as (f), except a scanning electron mrcrograph of fractured uncarburized core material
(low-carbon martensite). Fracture surface is fibrous. (j) Not polished, not etched; 1100x. Same as (h), but at higher magnification, showing that
fractured uncarburized core material has elongated dimples formed dunng transgranular rupture
Alloy Steel / 449
8622,8622H,
862
2RH
Chemical
Composition.
8622. AISI and UNS: 0.20 to 0.25 C, 0.70
to 0.90 Mn, 0.035 Pmax, 0.040 S max, 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40
to 0.60 Cr, 0.15 to 0.25 MO. UNS H86220 and SAE/AISI 8622H: 0.19 to
0.25 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr,
0.15 to 0.25 MO. SAE 8622RH: 0.20 to 0.25 C, 0.70 to 0.90 Mn, 0.15 to
0.35 Si, 0.40 to 0.70 Ni, 0.40 to 0.60 Cr, 0.15 to 0.25 MO
Recommended
Tempering.
Characteristics.
Case Hardening.
Steels (U.S. and/Or
Foreign).
Except for a slightly higher carbon range, 8622H has
an identical composition to 8620H, and the characteristics for 86228 are
approximately the same as those for 8620H. Because of the higher carbon
range, as-quenched surface hardness is slightly higher for 8622H, approximately 39 to 45 HRC. The hardenability band for 8622H, is adjusted
upward just slightly when compared with 8620H. In some carburizing
applications, steels that are higher in carbon content have been used to
attain a higher core hardness which permits thinner cases. These steels use
shorter carburizing cycles and save energy
Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after
temperature of forging stock drops below approximately 900 “C (1650 “F)
Practice
malizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C
(1220 “F), and holding for 4 h; or by heating to 790 “C (1455 “F), cooling
rapidly to 660 “C (1220 “F), and holding for 8 h
8622. UNS G86220; SAE
5404.5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20.8622I-I. UNS H86220;
ASTM A304; SAE 5407; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20
Similar
Heat Treating
Normalizing.
Heat to 925 “C (1695 “F). Cool in air
Annealing.
Structures having best machinability are developed by nor-
Temper all carburtzed or carbonitrided parts at 150 “C (300
“F), and virtually no loss of case hardness will result. If some decrease in
hardness can be tolerated, toughness can be increased by tempering at
somewhat higher temperatures, up to 260 “C (500 “F)
See carburizing and carbonitriding practices described for 8620H. Gas nitriding and ion nitriding are alternative processes
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (if required)
Rough machine
Semifinish machine, allowing only grinding stock, no more than 10% or
the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step
Carburize or carbonitride and quench
Temper
450 / Heat Treaters
Guide
8822H: Hardenability
Curves. Heat-treating
925 “C (1700 “F)
(1700 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
3
5
7
?
I1
13
15
ZO
!5
30
35
$0
$5
50
Hardness
purposes
I distance,
VI6in.
,
$
3
IO
I1
12
13
14
15
16
18
20
22
24
26
28
30
32
limits for specification
Hardness, HRC
Minimum
Maximum
50
50
47
43
39
35
32
31
28
26
25
24
24
24
24
43
39
34
28
25
22
20
...
limits for specification
Hardness, HRC
Minimum
Maximum
50
49
47
44
40
37
34
32
31
30
29
28
27
26
26
25
25
24
24
24
24
24
24
24
43
39
34
30
26
24
22
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
Alloy Steel / 451
8822RH: Hardenability
“C (1700 “F). Austenitize:
Hardness
purposes
J distance,
‘/,6 in.
I
-l
3
1
5
b
7
B
9
IQ
II
12
IS
I-l
IS
16
I8
10
12
!-I
16
18
10
32
Hardness
purposes
I distance,
mm
I.5
>
II
13
I5
!O
!S
SO
$5
u)
15
i0
Curves. Heat-treating
925 “C (1700 “F).
limits for specification
Eardness, ARC
Maximum
Minimum
49
-17
45
II
38
35
32
30
29
28
17
26
25
21
21
23
‘3
22
22
2’
22
22
22
21
4-t
II
37
32
29
27
2-l
22
21
20
limits for specification
Eardness, HRC
hlinimum
Maximum
49
17
4-l
-lo
36
32
30
28
25
23
22
22
22
22
22
4-I
-II
36
31
28
2-l
22
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
452 / Heat Treaters
Guide
8822, 8622H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8622H: End-Quench Hardenability
Distance from
quenched
surface
'/,6 in.
mm
I
7
;
-1
5
6
7
8
Y
I0
II
12
Hardness,
HRC
max
min
Distance from
quenched
surface
l/l6 in.
mm
Hardness,
HRC
man
I.58
SO
13
I3
20.54
27
1.71
3.16
6.32
7 90
9.48
I I.06
126-l
I-1.22
15.80
17.38
18.96
17
49
4-l
10
37
3-l
32
31
30
29
‘8
3-l
39
30
26
21
21
20
I5
II
I6
I8
20
22
24
26
28
30
31
x.12
23 70
25 28
284-I
31.60
31.76
37.92
-I I .08
J-l.21
47.4)
50.56
26
25
25
2-l
2-l
2-l
2-l
2-l
2-l
‘-I
452 / Heat Treaters
Guide
8625,8625H
Chemical
COIIIpOSitiOn.
8625. AISI and UNS: 0.23 to 0.33 C. 0.70
toO.90 hln. 0.035 Pmas. O.O-!OS max.0.1.5 toO.3OSi. 0.30 too.70 Ni.O.10
to 0.40 Cr. 0. IS to 0.3 hfo. UNS H86250 and SAE/AISI 86258: 0.22 to
0.28 C. 0 60 to 0.95 hln. 0.15 to 0.35 Si. 0.35 to 0.7s Ni. 0.3s to 0.65 Cr.
0. IS to 0.3 hlo
Similar
Steels (U.S. and/or Foreign).
SPEC hllL-S-16974:
A304 SAE J I’68
SAE 1104. 1770. 86258.
8625.llNS 686250: hill
1rNS H842SO: ASTM
Characteristics.
Identical to 86ZOH swept for higher carbon range.
Hhich results in a higher as-quenched hardness (approsimately
-IO to 46
HRC). and some\\ hat higher hardenabilitl.
Case hardening by carburizinp
or carbonitriding
are the heat treatments most often used. Has come into
more extensive use to sa\e energy in carburirinp.
Weldable. but alloy steel
welding practice must be used
Annealing.
Structures ha\ ing best machinability
are developed by normalizing; or bl heating- to 885 “C ( 1625 “F). cooling rapidly to 660 “C
( I220 “FL and holding tor -I h: or by heating to 790 “C ( 1455 “F). cooling
rapidly to 660 jC t 1220 “F). and holding for 8 h
Tempering.
Temper all carburized or carbonitrided
parts at IS0 “C (300
“F). and virtualI) no loss of case hardness will result. If some decrease in
hardness can be tolerated, toughness can be increased by tempering at
someu hat higher temperatures. up to 260 “C (SO0 OF)
Case Hardening.
See carburizing
and carbonitriding
practices described for 862OH. Ion nttridinp and gas mtriding are alternative processes
Recommended
l
l
l
Forging.
Heat to 1315 “C (2775 “F) maslmum. Do not forge after
temperature of forging stock drops belot+ appro\imatel>
900 “C ( 1650 “F)
Recommended
Heat Treating
l
l
Practice
l
Normalizing.
Heat to 915 ‘C ( IhYS ;F). Cool in air
l
Processing
Sequence
Forge
Normalize
Anneal (ifrequired)
Rough machine
Ssmkinish machine. allo\\ing. only grinding stock. no more than IO% of
the case depth per side for carbuhzed parts. In most instances. carbonitrided p‘artutswe completely finished in this step
Carbunze or carbonitride and quench
Temper
Alloy Steel / 453
8625: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
iardness
w-poses
distance,
qm
.5
1
3
5
:0
:5
IO
I5
Kl
15
i0
iardness
wrposes
distance,
‘16in.
.O
1
2
3
4
5
6
8
!O
!2
!4
!6
!8
IO
12
870 “C (1600 “F)
limits for specification
Badness, HRC
Maximum
Minimum
52
51
48
45
41
38
35
33
29
28
21
26
26
26
25
45
40
35
31
28
25
23
21
limits for specification
Hardness, HRC
hlahum
hlinimum
52
51
48
46
43
40
31
35
33
32
31
30
29
28
28
27
27
26
26
26
26
25
25
25
45
41
36
32
29
21
25
23
22
21
20
.
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 900 “C
454 / Heat Treaters
Guide
8625, 8625H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8625H: End-Quench Hardenability
Distance From
quenched
surface
‘/,6 in.
mm
I
Hardness,
ERC
min
maw
Distance from
quenched
surface
‘/,6 in.
mm
HidlleSS,
HRC
max
IO
1.58
3.16
J.74
6.32
7.90
9.48
Il.06
12.64
14.22
15.80
52
51
18
46
43
10
37
3s
33
32
45
-II
36
37
29
27
2s
23
22
21
IS
I3
IS
lb
18
20
22
2-l
26
28
20.5-I
22.12
13 70
3.18
28.4-I
31.60
31.76
37.92
4108
44.2-I
29
38
28
27
27
26
26
26
26
2s
II
I2
17.38
18.96
31
30
20
30
32
47.10
50.56
2s
75
2
3
-I
5
6
7
8
9
454 / Heat Treaters Guide
8627,8627H
Chemical
COIIIpOSitiOn.
8627. AISI and UNS: 0.25 to 0.30 c. 0.70
to0.90Mn.0.03SPmax.0.030Smax,0.lSto0.30Si,0.~0to0.70Ni.0.~0
to 0.60 Cr. 0. I5 to 0.25 Mo. UNS A86270 and SAE/AISI 86278: 0.24 to
0.30 C. 0.60 to 0.95 Mn. 0.15 to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr.
0. IS to 0.25 MO
‘F) per h; or heat to 760 “C ( l-t00 “F). cool rapidly
and hold for 8 h
Direct Hardening.
Tempering.
Austenitize
to 665 “C (I 230 “F),
at 870 “C (1600 “F), and quench in oil
After direct hardening. After quenching.
to provide the desired hardness
reheat to the tem-
Similar Steels (U.S. and/or Foreign). 8627.llNS G86270; ShE
perature required
J-IO-L J770.86278.
and carbonitriding
practice deCase Hardening. See carburizing
scribed for 8620H. Ion nitriding and gas nitriding are suitable processes
LINS H86270:
ASTM
A3O-t; SAE J I268
Characteristics. Has a borderline composition. with a carbon content
near the maximum used for case hardening. but at ahout the minimum
suitable for direct hardening. Used for both as demanded. however. Asquenched surface hardness of approximately
12 to 38 HRC can be expected. Hardenability
band for 8627H is slightly higher than for 862SH
Forging. Heat to 1230 “C (2250 “F) maximum. Do not forge after
temperature of forging stocb drops below approximately
900 “C ( I650 “F).
For direct hardening, see tempering curve
Tempering.
After case hardening. Temper all carburized or carbonitridsd parts at I SO “C (300 “F). and Gtually
no loss of case hardness will
result. If some decrease in hardness can be tolerated, toughness can be
increased hy tempering at somen hat higher temperatures. up to 260 “C
(500 “F). For direct hardening, see tempering curve
Recommended
l
Recommended
Heat Treating Practice
Normalizing. Heat to 900 “C (I650 “FL Cool in air
Annealing. For a predominantly pearlitic structure. heat
to 8-0 “C (I 555
“F). cool rapidly to 730 “C ( I350 “F), then cool to 6-10 “C ( I I85 “F). at a
rate not to exceed I I “C (20 “F) per h: or heat to 815 “C (15% “F). cool
rapidly to 665 “C (I230 “F). and hold for 6 h. For a predominantly
spheroidized structure, heat to 760 “C ( l-t00 “F). cool rapidly to 730 “C
I I350 “Fj, then cool to 650 “C ( I200 “F). at a rate not to exceed 6 “C ( IO
l
l
l
l
l
l
l
Processing
Sequence
Forge
Nomralize
Anneal (if required)
Rough machine
Semitinish machine. allo~iing only grinding stock, no more than 10% of
the case depth per side for carburized parts. In most instances, carbonitrided parts are completely tinished in this step
Case harden or direct harden
Quench
Temper
Alloy Steel / 455
8627H: Hardenability
(1650 “F). Austenitize:
Hardness
purposes
J distance,
mm
1.5
2
I1
13
15
20
25
30
35
40
45
50
Hardness
purposes
I distance,
!iSill.
i
4
)
10
II
12
13
14
15
16
18
20
!2
24
26
28
30
32
Curves. Heat-treating
870 “C (1600 “F)
limits for specification
Aardness,
Maximum
ARC
hbimum
47
43
38
34
31
21
25
24
21
20
54
53
50
41
44
41
38
35
32
30
28
27
27
27
27
limits for specification
Hardness,
Maximum
54
52
50
48
45
43
40
38
36
34
33
32
31
30
30
29
28
28
28
21
27
27
21
21
q RC
hGtknum
47
43
38
35
32
29
27
26
24
24
23
22
21
21
20
20
.
.
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
456 / Heat Treaters
Guide
8627, 8627H: Hardness vs Tempering Temperature. Represents an average based on a fully quenched structure
8627H: End-Quench Hardenability
Distance From
quenched
‘surface
I 16in.
mm
Hardness.
HRC
mm
min
Distance From
quenched
iut-race
‘.&ill.
mm
Hardness.
HRC
nlas
min
456 / Heat Treaters
Guide
8630,863OH
Chemical Composition.
8630. MS1 and UNS: 0.28 to 0.33 C. 0.70
IO (J.90 hln. 0.035 P mxs. 0.010 S ma\. 0. IS to 0.30 Si. 0.10 to 0.70 Ni. 0.40
to 0.60 Cr. 0. IS to 0.15 hlo UNS H86.300 and SAE/AISI
86308: 0.27 to
0.33 C. 0.60 to 0.95 hln. 0.15 to 0.35 Si. 0.3.i to 0.75 Ni. 0.35 to 0.65 Cr.
0. IS to 0.25
Similar
hlo
Steels (U.S. and/or Foreign).
863O.llNS G86300: AhlS
6280. 6% I. 635s. 6530. 6550: ASThl ,432
A?? I : MlL SPEC hlIL-S1697-l; SAE J-IO-t. J-II?. 5770: tGsr.) DIN l.hS-lS: tltnl.) UNI 30 NiCrhlo
2 KB. 8630H. 1lNS H86300: ASThl A.301: S.4EJ 1268; tGer.) DIN I.6S-lS.
tltal.) 1lNl 30 NiCrhlo 2 KE3
Characteristics.
A medium-carbon
steel. Responds rendil> to direct
hardening. As-quenched
surfxe
hardness usunlly ranges from npproximateI, -t6 to S2 HRC Its hardennhilit>
band is s~milur IO other 86XXH
steels. Seldom used tor case hardening h> curburirinq
or carbomtridinp
hecause of its carbon content. Genernll~ a\ ailahle in various product forms
mcluding seamless tubing used in productne \\elded structures. Forges
ensil! rmd can he melded hy virtually an\ of the \rell-knwn
techniques.
Because of its relattvel~ high hardenahtltt~. allo) steel practtce must he
used in welding
Forging.
temperature
Hent to 1230 “C t22SO “F) maximum. Do not forge after
of forging stock drops MOM approximateI>
900 “‘C i I650 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 900 “C t IhSO ‘F). Cool in air.
In aerospace practice. parts are normalized 3: 000 ‘C I I650 “F)
Annealing.
For a prsdonunantl~
psxlitic structure. heat to 835 “C t IS55
“FI. cool rapidly to 730 “C t I3SO “F). then cool to 610 “C t I I80 “F). at a
rate not to exceed I I “C t 20 “F) per h: or heat to X-0 “C f IS55 “F). cool
rupidl> to 66s ‘C t I230 “FI. and hold for 6 h. For a predominantly
spheroidtzed \tructure. heat to 760 ‘C t l-IO0 ‘F). cool rapidly to 730 “C
I I350 “F). then cool to 650 “C t I200 “F). at a rate not to exceed 6 “C t IO
“FJ per h: or heat to 760 “C t l-IO0 “F). cool rapidly to 665 ‘C I I230 “F).
and hold for 8 h
In aerwpuce pmcoce. parts are unnsalsd at 84S jC t IS55 “F). then cooled
to below S-IO“C I I(NHI “F) at ~1mte not to exceed 95 ‘C (205 “F) per h
Hardening. Austenitire at 870 “‘C I 1600 “F). and quench in oil. Flame
hardeninp. _eas nitridinp. ion nitriding. carhonitriding.
and martemperinp
are alternattve
processes. Qusnchunts
include \\uter and polymers. In
aerospace practice. austsmtize at XSS ‘YY t IS70 “F). and quench in oil or
poll mer
Tempering.
providing
*After quenchtng. reheat to the temperature required
the desired hardness or other mechanical properties
Recommended
Processing
Forge
Nomlalize
>\MtXll
Rough and semifinish machine
Austenitize and quench
Temper
Finish machine
Sequence
for
Alloy Steel / 457
8630H: End-Quench Hardenability
Distance from
quenched
surface
‘/lb in.
mm
I
7
;
-I
s
6
7
8
9
I0
II
II
8630:
I..58
Distance from
quenched
surface
l/16 in.
mm
Eardness.
HRC
may
min
Hardness.
HRC
min
mas
43 71
16
S6
55
54
-19
46
-1.3
IS
I-l
15
20.5-l
22.12
23.70
33
33
3’
23
2).
77
6.31
7.90
9.48
II.06
12.64
I-l 22
15.80
17.38
18.96
52
50
47
4-l
II
39
37
3s
31
39
ss
32
29
28
17
26
‘9
2-l
16
18
20
‘2
‘-I
‘6
28
SO
32
25.28
2X.44
31 60
34.76
37 92
11.08
J-l.24
47 40
SO.56
;;
30
30
29
29
29
29
29
3
I;
21
20
20
Approximate
Critical
Points
8630: End-Quench
Temperature
Critical point
“C
OF
735
795
71s
660
I?SS
1460
1370
I220
Hardenability. Composition: 0.30 C, 0.80
Mn, 0.54 Ni. 0.55 Cr, 0.21 MO. Austenitized at 870 “C (1600 “F).
Grain size: 9
8630: Isothermal Transformation
Diagram. Composition: 0.30
C, 0.80 Mn, 0.54 Ni. 0.55 Cr. 0.21 MO. Austenitized at 870 “C
(1600 “F). Grain size: 9
458 / Heat Treaters
Guide
8630: Continuous Cooling Transformation
Austenitized
8630:
Diagram. Composition:
0.30 C, 0.80 Mn, 0.020 P, 0.020 S, 0.25 Si, 0.55 Ni, 0.50 Cr, 0.20 MO.
at 850 “C (1560 “F)
Effect of Heat Treatment
Hent treatment
H’ater quenched from 84.i ‘C I IS55
“FL rempered ~~180°C (900 “FI
\\aslerquenchrd from 84S ,‘C I ISSS
FL kmpered at 5-M) “C I IO(w) ‘FI
\Varer quenched from 845 ’ C I I SSS
“FL wmperedat 5% “Cc I IOO’F,
‘/z in.
(13 mm)
8630: Suggested
Practice)
on Hardness
Size round measured in
2in.
I In.
Jill.
(2Smm)
(51 mm) (IO2 mm)
201
302
IS6
I87
3.1
I87
269
I87
235
2Yi
269
23.5
217
269
211
227
I97
620-860 hlPa
(!JO-125ksi)
I I ) 650 C
I l~(N)‘l=~
1216fiO’C
~12iO”F1
I
ca~HeatrdwWS”C~
1555‘~F~.iuma~ecoolsda~
I I “C~2O”F~p~rhour1062S
“CI I ICS
,F). cooled in ar. fb) Hrnred to 870 “C ( I600 “FL cooled in air. Source: Rrpuhtic Sttxl
I ,Qusnsh
Tempering
Temperatures
(Aerospace
Tensile strength range
865-1035 hlPa 1035-1175 MPa 1175-1210 MPa IWO-1380 MPa
(12515Oksi)
(1%17Oksi)
(17048Oksi)
(MI-200
ksi)
sso ,‘C
I 103 ‘F,
5.50 “C
I 1025 “FI
In ml orpol!mrr.
185 “C
(905 “F1
510°C
1950 -FI
-l-lo
(825
-l-lo
(825
“C
“FJ
“C
“FJ
121 C)uench in skater Source: AhlS 2759/l
370 “C
(700°F)
370 “C
(700 “Fj
Alloy Steel / 459
8630H: Hardenability Curves. Heat-treatinq
(1650 “F). Austenitize:
iardness
wrposes
I distance,
nm
1.5
)
I1
13
15
!O
!5
!O
I5
K.l
6
i0
iardness
wrposes
distance,
‘16io.
0
1
2
3
4
5
6
8
0
2
4
6
8
0
2
870 “C (1600 “F)
limits for specification
Hardness,
Maximum
HRC
Minimum
49
46
42
38
33
29
27
26
23
21
20
.
56
55
54
51
48
44
41
38
34
31
30
29
29
29
29
limits for specification
Hardness, HRC
hlaximum
56
55
54
52
50
47
44
41
39
37
35
34
33
33
32
31
30
30
29
29
29
29
29
29
Minimum
49
46
43
39
35
32
29
28
21
26
25
24
23
22
22
21
21
20
20
temperatures
-
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
460 / Heat Treaters
Guide
8830: Hardness
vs Tempering
Temperature.
Composition:
0.28 to 0.33 C, 0.70 to 0.90 Mn. 0.20 to 0.35 Si, 0.40 to 0.70 Ni,
0.40 to 60 Cr. 0.15 to 0.25 MO. Forged at 1230 “C (2250 “F). Normalized at 900 “C (1650 “F). Furnace cooled from 815 to 870 “C
(1500 to 1600 “F). Tempered 2 h. Maximum annealed hardness,
179 HB. Hardness normalized in test size, 225 HB. Source: Republic Steel
460 / Heat Treaters
Guide
86B30H
Chemical
Composition.
SAE/AISI 86B30H:o27 KI 0.33 c.O.60
to0 95 hln.0.035 Pmas.O.040S
ma\.O.lS to0.30Si.O.3S
too.75 Ni.0.35
to 0.65 Cr. 0.1.5 to 0.5 MO. O.OOOS to 0.003 B. UNS H86301 and
SAE/AISE
86B30H: 0.27 to 0.33 C. 0.60 to 0.95 hln. 0. IS to 0.3s Si. 0.35
to 0.75 Ni. 0.35 too.65 Cr.0.15 to025 hlo. B (can beexpected to heO.OOOS
to 0.003 percent 1
Similar
Steels (U.S. and/or Foreign).
UNS
G863OI:
ASThl
.A?W; S,-IE J 1268
Annealing.
For a predominantly
pearlitic structure, heat to 8-15 “C (I 555
“F). cool &a I! to 730 “C t 1350°F~ then cool to 610 “C (I I85 “F). at a
rate not to exceed I I ‘C (20 ‘F) per h; or heat to 8-U “C (IS55 “F), cool
rapid11 to 66s “C t I230 “F). and hold for 7 h. For a predominantly
sph?roidized structure. heat to 760 “C t 1100 “F). cool rapidly to 730 “C
t I?0 “F). then cool to 650 ‘C ( I200 jF). at ;L rate not to exceed 6 “C ( IO
“‘FJ per h; or heat to 760 ‘C I 1400 ‘F). cool rapidly to 665 “C (I 230 “F),
and hold for IO h
Hardening.
Characteristics.
Identical in composition to 8630H \\ ith boron added.
The applications of 86830H are also 5inilx
to those for 8630H. 86B?OH
ib selected for ik+ increased hurdsnnbilit!.
1%hich IS a result of the horon
addition. As-quenched surfxe hardnecs of86B3OH generally ranges from
46 to S1_ HRC. about the same as for 8630H. Forging and heat trenting
prwedure3 for 86B30H are essential11 the same a\ those used for X630H
hardening.
processes
Tempering.
the tempemture
Forging.
Heat to I230 “C (2250 “FI maximum.
Do not forge after
of forging stock drops below approximateI>
92s ‘C t I695 “F,
l
l
l
Recommended
Heat Treating
Practice
l
l
Normalizing.
Heat to 900 “C t 16.50 “‘FL Cool in uir
l
at 870 “‘C t 1600 “F). and quench in oil. Flame
cxbonitriding.
and ion nitriding anz suitable
Parts should be tempered immediateI)
after quenching
which u ill pro\ ids the requued hardness
Recommended
l
tcmpersturc
Austenitire
pas nitridinp.
Processing
Sequence
Forge
Normalize
,kineal
Rough and semifinish machine
Austenitizr
and quench
Temper
Finish machine
86B30H: Hardness vs Tempering Temperature.
average based on a fully quenched structure
Represents
an
at
Alloy Steel / 461
88630H: Hardenability
Curves. Heat-treating
“C (1650 “F). Austenitiie:
870 “C (1600 “F)
iardness
wrposes
I distance,
nm
1.5
\
i
1
9
I1
13
15
20
z5
30
35
40
15
50
limits for specification
Eardness, HRC
hlaximum
hliuimum
56
56
55
55
54
54
53
53
52
50
48
46
43
41
40
49
49
48
48
48
47
46
44
39
35
33
30
28
27
25
iardness limits for specification
Burposes
distance,
\6 in.
0
1
2
3
4
5
6
8
.O
:2
!4
16
!8
IO
I2
Hardness. ERC
Maximum
hlinimum
56
55
55
55
54
54
53
53
52
52
52
51
51
50
50
49
48
41
45
44
43
41
40
39
49
49
48
48
48
48
48
47
46
44
42
40
39
38
36
35
34
32
31
29
28
21
26
25
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 900
462 / Heat Treaters
Guide
86B30H: End-Quench Hardenability
Distance from
quenched
surface
146h.
mm
1
1.58
2
3
4
5
6
3.16
4.14
6.32
7.90
9.48
7
11.06
8
9
12.64
14.22
15.80
10
11
12
17.38
18.96
Hardness,
HRC
max
min
56
55
55
55
54
54
53
53
52
52
52
51
49
49
48
48
48
48
48
41
46
44
42
40
Distance from
quenched
surface
‘/lb in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
mar
min
51
50
50
49
48
41
45
44
43
41
40
39
39
38
36
35
34
32
31
29
28
27
26
25
8637,8637H
Chemical COrTIpOSitiOn.
8637. AISI and UNS: 0.35 to 0.40 C, 0.75
to 1.00 Mn. 0.035 Pmax. 0.040 S max. 0.15 to 0.30 Si, 0.40 to 0.70 Ni, 0.40
to 0.60 Cr. 0.15 to 0.25 MO. IJNS II86370 and SAE/AISI 8637I-I: 0.34 to
0.41 C, 0.70 to 1.05 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr,
0.15 to 0.25 MO
Similar
Steels (U.S. and/or
J404,J412.J770.8637H.
Foreign). 8637. UNS G86370; SAE
UNS H86370; ASTM A304; SAE 51268
Characteristics.
A medium-carbon, low-alloy steel, which is widely
used for a variety of machinery components because of its ability to be heat
treated for high strength and toughness. Used for shafts requiring high
fatigue strength. Amenable to nitriding for resistance to surface wear and
for greater fatigue strength. As-quenched surface hardness ranges from 50
to 55 HRC. Its hardenability is considered fairly high. Is readily forged
“F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F),
and hold for 8 h
Direct Hardening.
Tempering.
After quenching, reheat immediately to the tempering temperature that will provide the desired combination of mechanical properties
Nitriding. Responds well to ammonia gas nitriding as well as to nitriding
in any one of several proprietary molten salt baths. The following is a
commonly used cycle for ammonia gas nitriding:
l
l
l
Forging.
Heat to 1230 “C (2250 “F) maximum. Do not forge after
temperature of forging stock drops below approximately 900 “C (1650 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 870 “C (1600 OF). Cool in air
For a predominantly pearlitic structure, heat to 830 “C (1525
“F), cool rapidly to 725 “C (1335 “F), then cool to 640 “C (1185 “F), at a
rate not to exceed 11 “C (20 “F) per h; or heat to 830 “C (1525 “F), cool
rapidly to 665 “C (1230 OF), and hold for 6 h. For a predominantly
spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C
(1335 “F), then cool to 640 “C (1185 “F), at a rate not to exceed 6 “C (10
Parts are austenitized, quenched, and tempered at 540 “C (1000 “F) or
higher. (Tempering temperature must always be higher than the nitriding
temperature)
Finish machine
Nitride in ammonia gas for 10 to 12 h with an ammonia gas dissociation
of 25 to 30%
See processing data for 4140H for other nitriding cycles
Recommended
l
l
Annealing.
Austenitize at 855 “C (1570 OF), and quench in oil
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal
Rough and semilinish machine
Austenitize and quench
Temper
Finish machine (grind if required)
Nitride (optional)
8637, 8637H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
Repre-
Alloy Steel / 463
8637H: Hardenability
Curves. Heat-treating temperatures
845 “C (1555 “F)
(1600 “F). Austenitize:
iardness
wrposes
I distance,
nm
.5
!
i
1
a
1
3
5
!O
!5
10
15
10
15
i0
Hardness
purposes
J distance,
%ain.
I
2
3
4
5
5
7
5
J
IO
I1
12
3
14
.5
‘6
.8
!O
!2
,4
!6
!8
50
12
limits for specification
Hardness, HRC
Minimum
Maximum
59
59
58
57
55
54
52
50
45
41
38
36
35
35
35
52
51
49
47
43
39
36
33
29
21
25
24
24
23
23
limits for specification
Hardness, HRC
Minimum
Maximum
59
58
58
51
56
55
54
53
51
49
47
46
44
43
41
40
39
37
36
36
35
35
35
35
52
51
50
48
45
42
39
36
34
32
31
30
29
28
21
26
25
25
24
24
24
24
23
23
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
464 / Heat Treaters
Guide
8637H: End-Quench Hardenability
Distance from
Hardness,
HRC
max
min
1
2
3
4
S
6
7
8
9
10
11
12
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
59
58
58
57
56
55
54
53
51
49
47
46
52
51
50
48
45
42
39
36
34
32
31
30
Distance from
quenched
surface
mm
516 in.
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
SO.56
Hardness,
HRC
max
min
44
43
41
40
39
37
36
36
35
35
35
35
29
28
27
26
25
25
24
24
24
24
23
23
464 / Heat Treaters
Guide
8640,864OH
Chemical Composition.
8640. MS1 and UN.9 0.38
to I .OO hln. 0.035 Pmw.. O.(J-lOS max. 0. IS to 0.30 Si. 0.40
to 0 60 Cr. 0. IS to 0.25 hlo. 86JOH. MS1 and LJNS: 0.37
IO I.05 hln.0.0.35 Pmw O.O-!OS max.O.lS to0.3OSi.0.35
to 0.65 Cr. 0. IS to 0.25 hlo
Similar
Steels (U.S. and/or Foreign).
to 0.43 C. 0.75
to 0.70 Ni.O.41
to 0.4-I C. 0.70
toO.7S Ni.0.35
l
l
l
1lNS
G864OO:
ASThl A3O-l. A32
hllL SPEC hllL-S-l6974
SAE 140-I. J412. 5770:
t&r.,
DIN 1.6546; (Ital.) LINI 40 NiCrhlo
2 KB: tL1.K.) B.S. Type 7.
g&OH.
1lNS H86-W: 4SThl MO-k SAE J-107: tGer. ) DIN I .6546; t Ital. I
LINI 40 NiCrMo 2 KB: tL1.K.) B.S. Type 7
8640.
Characteristics.
Probably the most u idsI! used medium-c&on.
IOH allo) steel. A~ailnhls tn various product fomls. Can be heat treated to high
values of strength and toughness and. if desired. can btt nitrided to achie\ e
wrfxe.;
that help to resist abrasion and furtha increase fatigue strength.
Depending on the precise carbon content. an as-quenched surface hardwss
of approximately
52 to 57 HRC can be expected. Hardrnnbilitj
is rslati\4>
high. Can he forged by an! one of thz various forging methods
of
2s
to 3oc
SW processuy
data for 4 I-IOH for other nitriding qcles
Recommended
l
l
l
l
l
l
l
l
Forging.
Parts xs austenitired.
qwnched. and tsmpered at S-IO “C (1000 “F) or
higher. (Tempering temperature must nl~aqs be higher than tht nitriding
tsmpsraturs t
Finish machine
Nitride in ammonia gas for IO to 12 h u ith an ammonia gas dissociation
Processing
Sequence
Forge
Normalize
Anneal
Rough and senitinish
machine
Auhtrnitiz? and qurnch
Ttmpcr
Finish machine cgnnd if rzqulred)
Nitride (optional)
Heat to 1230 “C cYS(J “F) m;Ixm~um. Do not forge after
temperature of forging stozh drops MOM sppro\imatsl>
900 “C ( I hS(J “F,
Recommended
Normalizing.
Heat Treating
Practice
Hzat to 870 “C t 1600 “FL Cool in air
Annealing. Far a predominantI! psnrlitlc struuctur~. heat to 830 “C t IS25
“FL cool rapidI) to 725 ‘C t I335 “FL then cool to 640 “C t I I85 ‘F). at a
rate not to exceed I I ‘C (20 “F) per h: or heat to 830 “C ( IS25 *FJ. cool
rapidly to 665 “C (I230 “FL and hold for 6 h. For a predominantI>
spheroidixd
structure. hat to 750 “C t 1380 “‘FI. cool rapid11 to 725 “C
t 133.5 “FL then cool to 640 YI ( I I85 “FL at a rate not to csceed 6 “C t IO
‘F) per h: or htat to 750 “C t 1380 ‘FL cool rapid11 to 665 “C I 1230 “F).
and hold for 8 h
Hardening.
Austenitlzc
at MS “C t IS70 ‘FL and quench in oil
Tempering.
pcrrltun
After quenchinp. reheat imnwdiatcl~
to th? tempenng trmthat will provide the deswd combination o~mschanicnl properttss
Nitriding. Responds HA to ammonia gas nitridinp as well as to nitriding
in any one of szvcral proprietary
molten salt baths. Ths following
is a
commonI) used cycle for ammonia gas nitriding:
8640: Hardness vs Diameter. Composition: 0.38 to 0.43 C, 0.75
to1.00Mn,0.040Pmax.0.040Smax,0.20to0.35Si,0.40to0.70
Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO. Test specimens were normalized at 870 “C (1600 “F) in over-sized rounds, quenched from 845
“C (1555 “F) in oil in sizes shown, tempered at 540 “C (1000 “F).
Tested in 12.8 mm (0.505 in.) rounds. Tested from bars 38 mm
(1.50 in.) diam taken at half radius position. Source: Republic
Steel
Alloy Steel / 465
8840: Continuous
C oling Curves. Composition: 0.37 C, 0.67
Mn, 0.25 Si, 0.56 Ni, 0.44 Cr, 0.18 MO. Austenitized at 845 “C
(1555 “F). Grain size: 7. AC,, 795 “C (1460 “F); AC,, 745 “C (1370
“F). A: austenite, F: ferrite, P: pearlite, B: bainite, M: martensite
8640H: End-Quench Hardena bility
Distance from
quenched
surface
‘&, in.
mm
1
2
3
4
5
6
7
8
9
10
11
12
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardness,
HRC
max
mio
60
60
60
59
59
58
57
55
54
52
50
49
53
53
52
51
49
46
42
39
36
34
32
31
Distance from
quenched
su t-face
916 in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness.
HRC
ma\
mill
47
45
44
42
41
39
38
38
37
37
37
37
30
29
28
28
26
26
25
25
24
24
24
24
8640: Hardness Gradients. Nitrided to 20 to 30°0 dissociation.
(a) Nitrided for 7 h: (b) nitrided for 24 h; (c) nitrided for 48 h
466 / Heat Treaters
Guide
8840H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
I distance,
mm
I1
3
.5
!O
!5
10
\5
lo
15
i0
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Hardness. HRC
Minimum
hlatimum
60
60
60
60
58
57
55
54
48
43
40
39
38
37
31
53
53
52
50
47
42
38
36
31
21
26
25
24
24
24
Hardness limits for specification
wrposes
I distance,
/I6 in.
J
IO
11
12
13
14
5
6
8
!O
!2
!4
!6
!8
10
12
Hardness, HRC
hlinimum
Maximum
60
60
60
59
59
58
51
55
54
52
50
49
41
45
44
42
41
39
38
38
37
37
31
31
53
53
52
51
49
46
42
39
36
34
32
31
30
29
28
28
26
26
25
25
24
24
24
24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 467
8640:
Approximate
Critical
Points
8640H: Variation of Brine11 Hardness Measurements.
Critical
point
Tests
done on annealed plain carbon and low-alloy steels
Temperature
T
AC,
AC,
Ar,
Ar,
Source: Republic
Svrl
8640: Cooling Curves. Composition:
(using interrupted Jominy method)
0.37 C. 0.87 Mn, 0.25 Si, 0.56 Ni. 0.44 Cr, 0.18 MO. Grain size: 7. Austenitized
at 845 “C (1555 GF)
Alloy Steel / 467
8642,8642H
Chemical Composition.
8642. AISI and UNS: 0.40 to 0.45 C. 0.75
to I .OO Mn, 0.035 Pmas. 0.040 S ma. 0. IS too.30 Si. 0.30 to 0.70 Ni. 0.40
to 0.60 Cr. 0. I5 to 0.3 hlo. Uh’S HS6420 and SAE/AISI 8642H: 0.39 to
0.46 C, 0.70 to 1.05 Mn. 0. IS to 0.35 Si, 0.35 to 0.75 Ni. 0.35 to 0.65 Cr.
0.15 to0.25 Mo
temperature
Similar
Recommended
Steels (U.S. and/or Foreign).
J4O-l. 1412.5770.8642H.
8642. UNS G86420: SAE
UNS H86.420: ASThl A304 SAE Jl268
Characteristics.
Change in composition
from 864OH is slight. Has
essentiall) the same characteristics
as described for 864OH. As-quenched
surface hardness for 8642H. because the c&on content is slightly higher.
is approximately
53 to 59 HRC. Hurdenabilib
band is shifted upirard
slightlq for 8647H.
methods
Forging.
by any one of the various
forging
Heat to 1230 ‘C (2250 “F) maximum. Do not forge after
of forging stock drops brlo~r approximately
900 “C (I 650 W
Normalizing.
Annealing.
Can be forged
Heat Treating
Practice
Heat to 870 “C t I600 “FL Cool in air
For a predominantly
pearlitic structure, heat IO 830 “C ( IS35
“F). cool rapidl! to 775 “C t 1335 “F). then cool to 610 ‘C (I I85 “F). at a
rate not to esceed I I “C t 20 “F) per h: or heat to 830 “C (I 525 “F), cool
rapidI!, to 665 “C (I230 “Fj. and hold for 6 h. For B predominantly
468 / Heat Treaters
Guide
spheroidized structure, heat to 750 “C (1380 “F), cool rapidly to 725 “C
(I 335 OF),then cool to 640 “C (118.5“F), at a rate not to exceed 6 “C (I 0
“F) per h; or heat to 750 “C (1380 “F), cool rapidly to 665 “C (1230 “F),
and hold for 8 h
Direct Hardening.
l
l
Tempering. After quenching, reheat immediately to the tempering temperaturethat will provide the desiredcombination of mechanicalproperties
Austenitize at 855 “C (1570 “F), and quench in oil
Nitriding. Respondswell to ammoniagas nitriding as well asto ni~ding
in any one of several proprietary mohen salt baths. The following is a
commonly used cycle for ammonia gas nitriding:
l
Seeprocessingdatafor 414OHfor other ni~ding cycles.Flamehardeningand
ion nitriding arealternativeprocesses
Parts are austenitized, quenched, and temperedat 540 “C (1000 “F) or
higher. (Temperingtemperaturemust always be higher than the nitriding
temperature)
Finish machine
Nitride in ammoniagas for 10 to 12 h with an ammoniagas dissociation
of 25 to 30%
Recommended
Processing
Sequence
Forge
* Normalize
l
Anneal
l
Rough and semifinish machine
l
Austenitize and quench
l
Temper
l
Finish machine (grind if reauired)
l
Nitride (optionaiy
1
l
8642, 8642H: Hardness vs Tempering Temperature.
sents an average based on a fully quenched structure
8642H: End-Quench
Distance from
quenched
surface
/16in.
mm
1
2
3
4
5
6
7
8
9
10
11
12
1.58
3.16
4.74
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardenability
Herdness.
ERC
max
min
62
62
62
61
61
60
59
58
57
55
54
52
55
54
53
52
50
48
45
42
39
37
34
33
Distance from
quenched
surface
l/16 in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.10
25.28
28.44
31.60
34.76
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
39
26
Repre-
Alloy Steel / 469
8642H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
Hardness
purposes
I distance,
nm
1.s
\
iardness
wrposes
; distance,
16 in.
845 “C (1555 “F)
limits for specification
Hardness,
Maximum
HRC
illioimum
62
67
62
61
60
59
58
56
52
47
+I
-II
-lo
39
39
limits for specification
Hardness,
Maximum
67
62
62
61
61
60
59
58
57
55
5-l
52
so
-19
-18
46
44
4’
-II
40
-IO
39
39
39
HRC
biinimum
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
470 / Heat Treaters
Guide
8645,8645H
Chemical Composition.
8655. AK1 and LNS: 0.43 to 0.48 C. 0.75
to I .OO Xln. 0.035 Pmax. O.O-lOS max. 0. I5 to0.30Si.0.40
too.70 Ni.0.40
to 0.60 Cr. 0. I5 IO 0.25 Ma IJNS H86450 and SAE/AISI 8645H: 0.Q to
0.49 C. 0.70 to 1.05 hln. 0.035 P max. 0.40 S mlt\. 0. IS to 0.30 Si. 0.35 to
0.75 Xi. 0.35 to 0.65 Cr. 0.15 10 0.25 Mo
Similar
Steels (U.S. and/or Foreign).
86-15.l-33 G86-ljO: hlIL
SPEC MLL-S- 16973; SAE J-W. J-l 12.5770.8645H.
A30-1: SAE Jl268
LX
H86450: AST\1
Hardening.
Characteristics.
A slightI> louer carbon version of 8650H. Asquenched hardness generally ranges from approximovly
5-l to 60 HRC.
depending on the precise carbon content N ithin the allowable range. Considered a relaii\ely
hiph-hardenahility
steel. Used extensiveI!
for a variety
of machinery parts where hiph strength is required for riporous senice.
including hiphly stressed shafts and springs. Can he forged. although just
as is nue for other hipher carbon. high-hardenabilitj
steels. forgings of
complex shape should he cooled slowI> from the forging temperature 10
minimize the possibility of cracking
Forging. Heat IO 1230 “C (2250 ‘F) maximum. Do not forge after
lemperature of forging stock drops helow approximateI!
925 “C (I695 “FL
Cool slo\r Iy from rhe forging temperature
Recommended
Heat Treating
Annealing.
For a predominantly
pearlitic structure. heat to 830 “C ( I525
“F). cool slowly IO 7 IO “C ( I3 IO -‘FL then cool IO 650 “C ( I200 “F), at a
rate not to exceed 8 “C (IS “F) per h: or heal to 830 “C (1525 “F), cool
rapidI> to 650 ‘C (I200 “FL and hold for 8 h. For a predominantly
spheroidized structure. heat to 750 “C (I380 “F). cool rapidly to 715 “C
(1320 ‘Fj. then cool to 650 “C ( I200 “Fj. a1 a rate not to exceed 6 “C (IO
‘F) per h: or heat to 750 “C ( I380 “F). cool rapidl) to 650 “C (I 200 “F),
and hold for IO h
Practice
hardening.
processes
After quenching. pans should be tempered immediately.
preferably when they are still warm to the touch. at 150 “C (300 “F) or
hipher. For mosl purposes. higher tempering temperatures are used. Selection of tempering temperature is hased on the desired combination
of
mechanical properties
Recommended
Processing
l
Forge
Normalize
l
Anneal
l
Rough and semifinish machine
Austenitize and quench
Temper
Finish machine
l
l
Heat to 870 ‘C ( 1600 ‘FL Cool in air
at 845 ‘C ( IS55 “F), and quench in oil. Flame
ion nitridinp.
and carbonitiding
are suitable
Tempering.
l
Normalizing.
Austenitize
gas nitridinp.
l
Sequence
8645, 8645H: Hardness vs Tempering Temperature. Represents an average
8645H: End-Quench Hardenability
Distance from
quenched
surface
‘/&in.
mm
1
2
3
4
5
6
7
8
9
10
11
12
1.58
3.16
4.14
6.32
7.90
9.48
11.06
12.64
14.22
15.80
17.38
18.96
Hardness,
EIRC
max
min
63
63
63
63
62
61
61
60
59
58
56
55
56
56
55
54
52
50
48
45
41
39
37
35
Distance from
quenched
surface
‘46 in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
41.40
50.56
Eardness.
ARC
41
27
based
on a fully quenched
structure
Alloy Steel / 471
8545: Microstructures.
(a) 2% nital. 825x. Hot rolled steel bar, 25 mm (1 in.) diam, austenitized at 815 “C (1500 “F) for 1 h and furnace
cooled, resulting in a fully annealed structure. Dark areas lamellar pearlite. white areas ferrite. (b) 2?L nital. 750x. Same steel and bar size
as (a). Austenitized at 815 “C (1500 “F) for 1 h, cooled to 675 “C (1245 “F), and held for 8 h (for spheroidizing).
Dark areas, partly
spheroidized pearlite, white areas ferrite. See (c). (c) 5% picric acid, 2 1Q ?& HNO,, in ethanol: 5000x. Same bar size as (a) and (b), same
heat treatment as (b). Replica electron micrograph shows a structure that consists of partly spheroidized pearlite. (d) 2% nital, 1000x. Same
bar size as (a), (b), and (c). Austenitized at 845 “C (1555 “F). water quenched, tempered at 260 “C (500 “F) for 1 h. Tempered martensite.
See (e). (e) 29/o nital. 1000x. Same bar size as (a), (b), (c) and (d). Heat treatment same as (d). except tempered at 370 “C (700 “F). Tempered martensite. See (f). (f) 59’0picric acid, 2 1,/2?0HNO,, in ethanol: 10 000x. Same bar size and heat treatment as (e). Electron micrograph
of platinum-carbon-shadowed
two-stage carbon replica, showing carbide particles that precipitated from the martensite matrix. (g) 2% nital,
1000x. Same bar size as (f), austenitized at 845 “C (1555 “F) for 1 h. water quenched, tempered at 480 “C (895 “F) for 1 h. Compare with
(d) and (e); increasing tempenng temperature has little effect on the appearance of the tempered martensite. (h) 5% picric acid, 2 1/2% HNO,,
in ethanol; 10 000x. Same bar size and heat treatment as (g). Electron micrograph. made using a platinum-carbon-shadowed
two-stage
carbon replica, shows particles of carbide that have precipitated from the matrix of tempered martensite
472 / Heat Treaters
Guide
8645H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
I distance,
mm
1.5
Hardness
purposes
I dislance.
%6 in.
IO
I1
12
13
14
15
16
18
!O
!2
!4
!6
!8
i0
!2
Curves. H at-treating
845 “C (1555 “F)
limits for specification
Hardness,
Maximum
HRC
Minimum
63
63
63
63
62
61
59
58
54
49
46
43
42
42
41
56
56
55
53
51
48
45
41
34
31
29
28
27
27
27
limits for specification
Hardness.
3latimum
63
63
63
63
62
61
61
60
59
58
56
55
54
52
51
49
47
45
43
42
42
41
41
41
HRC
\linimum
56
56
55
54
52
50
48
45
41
39
37
35
34
33
32
31
30
29
28
28
27
27
27
27
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
1
only): 870 “C
Alloy Steel / 473
86645,86645H
Chemical
Composition.
86845. AISI: 0.43 IO 0.48 C. 0.75 to I .Oo
~ln.O.O3SPmax.0.~0Smax.0.20to0.3SSi.0.~0to0.70Ni.0.~0to0.60
Cr. 0. IS to 0.75 MO. 0.0005 B min. Uh?k 0.13 to 0.48 C. 0.75 to 1.00 \ln.
0.035 Pmax. O.MO S max.0.1. too.30 Si. O.-IO too.70 Ni. 0.10 toO.hOCr.
O.lS to 0.25 MO. 0.0005 B min. LXS H&451 and SAE/AISI 86845H:
0.12 to 0.49 C. 0.70 to I.05 Sin. 0.15 to 0.35 Si. 0.35 to O.iS Si. 0.35 to
O.hS Cr. 0. IS to 0.X MO. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign).
ASTXl
ASl9: SAE J-IO-I. J-II?.
,430-t: SAE J I268
86BG.
5770. 86B45H.
LKS
LNS
H&IS
G86JSl.
I: ASTY
Characteristics.
LVith the exception of the boron addition. 86B-ISH is
identical in composition to 8tiSH. Commercial applications for these ttvo
steels are similar. 86BlSH is chosen \vhen more hardenabilitj
is needed
than can be provided b> 86-lSH. 86B-lSH is significantI>
higher in hardenahility. As-quenched surface hardness is the same for the t\io steels.
usually ranging from 51 to 60 HRC. Compares fa\orablj
uith 86-lSH in
forgeability
and response to heat treatment
Forging.
Heat to I??0 ‘?I (Z’S0 ‘F) masmium. Do not forge after
temperature of forging stock drops helow npprosmiatel>
9X “C ( I695 ‘FI
Recommended
Normalizing.
Hardening. .\ustenitize at X-IS ‘C t ISSS ‘F). and quench in oil. Flame
hardening. pas nitriding
eon nitridinp. carhonitridinp,
and fluidized bed
nitriding are suitable processes
Tempering.
.\fter quenching. parts should be tempered immediateI>.
Selection of tcmperinp temperature depends on the desired mechanical
properties
Recommended
l
l
l
l
Practice
l
Heat to 870 ‘C t I600 ‘FJ. Cool in air
l
86645: Isothermal
Heat Treating
Annealing.
For a predominantI> pearlitic structure. heat to 830°C (IXS
“F). cool rapidly to 73S ‘C t 1335 ‘FL then cool to 6-10 “C (I I85 “F). at a
rate not to exceed I I ‘C (20 “F) per h: or heat to 830 ‘C ( IS25 “F). cool
rapidly to 665 ‘C ( I230 “FL and hold for 7 h. For a predominantI>
spheroidized structure. heat to 7SO ‘C t 1380 “F). cool rapidly to 72.5 “C
( I.335 ‘F). then cool to 640 ‘C (I I85 ‘F). at a rate not to exceed 6 “C i IO
“F) per h: or heat to 750 ‘C i 1380 “FL cool rapidly to 665 “C (I230 “F).
and hold for IO h
Transformation
l
Diagram. Composition:
0.45 C. 0.89 Mn, 0.59 Ni. 0.66 Cr, 0.12 MO, 0.0015
at 845 “C (1555 “F). Grain size: 6 to 7
Processing
Sequence
Forge
Norninlize
Xnneai
Rough and semifinish machine
Austenitize and quench
Temper
Finish machine
86B45H: End-Quench Hardenability
B. Austenitized
Distance From
quenched
surface
1,SIbin.
mm
Hardness.
HRC
max
miu
Distance frum
quenched
surface
!I16 in.
mm
I.1
I-I
IS
I6
I8
20
22
2-t
26
28
30
32
20.51
‘2.12
Eardness.
ERC
max
min
59
19
23 70
59
58
48
46
3.X
x-u
3 I.60
58
58
5X
4s
12
39
31.76
37.9’
4 I .08
44.24
47 10
50.56
ST
s7
57
57
5b
56
37
35
3-l
32
32
31
474 / Heat Treaters
Guide
86845H: Hardenability
Curves. Heat-treating
“C (1600 “F). Austenitize: 845 “C (1555 “F)
Hardness
purposes
I distance,
nm
limits for specification
Eardoess,
Maximum
1.5
63
63
63
62
62
61
61
60
59
58
58
57
57
56
56
s
I1
13
I5
!O
!5
50
15
lo
I5
io
iardness
wrposes
I distance.
4,j in.
0
1
2
3
4
5
6
8
10
!2
!4
!6
!8
IO
I2
temperatures
limits fo
56
56
55
54
53
52
51
51
49
45
40
36
33
32
31
r specification
Hardness.
hlasimum
63
63
62
62
62
61
61
60
60
60
59
59
59
59
58
58
58
58
57
57
57
57
56
56
HRC
Minimum
ARC
Minimum
56
56
55
54
54
53
52
52
51
51
50
50
49
48
48
45
42
39
37
3.5
34
32
32
31
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870
Alloy
86B45: Hardness vs Diameter. Composition: 0.43 to 0.48 C,
0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20 to 0.35 Si, 0.40
to 0.70 Ni. 0.40 to 0.60 Cr, 0.15 to 0.25 MO, 0.0005 B min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F);
Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at
790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207
HB. normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to
1570 “F) in oil. Test specimens were normalized at 870 “C (1600
“F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil,
tempered at 540 “C (1000 “F), and tested in 12.8 mm (0.505 in.)
rounds. Tests from bars 38 mm (1.50 in.) and over are taken at half
radius position. Source: Republic Steel
Steel
/ 475
86845: Hardness vs Diameter. Composition: 0.43 to 0.48 C,
0.75 to 1 .OO Mn. 0.040 P max, 0.040 S max. 0.20 to 0.35 Si, 0.40
to 0.70 Ni, 0.40 to 0.60 Cr. 0.15 to 0.25 MO, 0.0005 6 min. Approximate critical points: AC,, 720 “C (1330 “F). AC,, 770 “C (1420 “F);
Ar,, 695 “C (1280 “F); Ar,, 650 “C (1200 “F). Recommended thermal treatment: forge at 1205 “C (2200 “F) maximum, anneal at
790 to 845 “C (1455 to 1555 “F) for a maximum hardness of 207
HB, normalize at 845 to 900 “C (1555 to 1650 “F) for an approximate hardness of 277 HB, quench from 830 to 855 “C (1525 to
1570 “F) in oil. Test specimens were normalized at 870 “C (1600
“F) in over-sized rounds, quenched from 845 “C (1555 “F) in oil,
tempered at 650 “C (1200
“F), and tested in 12.8 mm (0.505 in.)
rounds. Tests from specimens 38 mm (1 l/z in.) and over were
taken at half radius position. Source: Republic Steel
Alloy Steel / 475
8650,865OH
Chemical
Composition.
8650. AISI: 0.48 to 0.53 c, 1~75 to 1.00
Mn.0.~0Pn~lut.0.~0Sn~ax.0.30to0.35Si.0.~0to0.70Ni.0.10to0.60
Cr. 0.15 to 0.35 hlo. UNS: 0.48 to 0.53 C. 0.75 to 1.00 hln. 0.035 P max.
0.0-10 S max. 0.15 to 0.30 Si. O.-t0 to 0.70 Ni. 0.40 to 0.60 Cr. 0. IS to 0.X
Mo. UNS H86500 and SAE/AISI
86508: 0.47 to 0.5-I C. 0.70 to I .OS hln.
0.15 to 0.35 Si. 0.35 to 0.75 Ni, 0.35 to 0.65 Cr. 0. IS to 0.35 hlo
Similar
Steels (U.S. and/or Foreign). 8650.
UNS
G86500:
ASTM A322. A5 19: SAE J-KM. J-l I?. J770.86508.
UNS H86500: ASThl
A304: SAE J I368
spheroidired
structure. heat to 750 “C t 1380 “F), cool rapidly to 715 “C
I 1320 “F). then cool to 650 ‘C t IX) “F). at a rate not to exceed 6 “C t IO
“F) per h; or heat to 750 “C ( I380 “F). cool rapidly to 650 “C (I X0 “F).
and hold for IO h
Hardening. Austenitize at 845 “C I 1555 “F). and quench in oil. Flame
hardening. gas nitriding. ion nitriding. and carbonitriding are suitable processes
Tempering.
After quenching. parts should be tempered immediately
(preferahly
ashen they are still ~iarrn to the touch) at IS0 “C (300 “F) or
higher. For most purposes. higher tempering temperatures are used. Selection of temperins temperature is based on the desired combination
of
mechanical properties
Characteristics.
Borderline between I$ hat is usually considered a medium-carbon grade and a high-carbon grade alloy steel. When the carbon is
on the lower side of the allowable range. oil-quenched hardness of approxtmately 56 HRC can he expected. When the carbon content is near 0.5-L an
as-quenched hardness of approximately
61 HRC can be expected. Hardenability is relatively high. Used extenskely
for a variety of machiner)
parts where high strength is required for rigorous service. notahly for highly
stressed shafts and springs. Can be forged. although as is true for other higher
carbon. high-hatdenability
steels. forgings of complex shape should he cooled
slo~+ly from the forging temperature to minimize the possibilit) of cracking
l
Forging.
l
Recommended
l
l
l
l
l
Heat to 1130 “C (3%) “F) maximum. Do not forge after
temperature of forging stock drops below approximately
925 “C t I695 “F J
Cool slowly from the forging temperature
Recommended
Normalizing.
Annealing.
Heat Treating
Processing
Sequence
Forge
Nomralire
Anneal
Rough and semifinish machine
Austenitire
and quench
Temper
Finish machine
8850:
Approximate
Critical
Points
Practice
Heat to 870 “C (I 600 “FL Cool in air
For a predominantly
prarlitic structure. heat to 830 “C t IS25
OF), cool slowly to 7 IO “C ( I3 IO “F). then cool to 650 “C t I ZOO “F). at a
rate not to exceed 8 “C t IS “F) per h: or heat to 830 “C ( IS35 OF). cool
rapidly to 650 “C (IZOO “F), and hold for 8 h. For a predomjnantly
Temperature
Critical
As,
Acq
Ari
Ar.
point
T
OF
730
770
700
655
1350
I420
I295
1210
476 / Heat Treaters
Guide
8650: Continuous Cooling Transformation
Austenitized
Diagram. Composition:
0.48 C. 0.75 Mn, 0.020 P, 0.010 S. 0.34 Si. 0.60 Ni, 0.58 Cr, 0.20 MO.
at 850 “C (1560 “F)
8650: Hardness vs Tempering Temperature. Composition:
0.48 to 0.53
0.75 to 1.00
0.20 to 0.35
0.40 to 0.70
0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forged at 1175 “C (2150 “F)
maximum and annealed by furnace cooling from 815 to 925 “C
(1500 to 1695 “F). Maximum annealed hardness, 212 HB. Normalized at 870 “C (1600 “F) with a hardness of 355 HB for test
size. Quenched in oil at 845 “C (1555 “F) and tempered for 2 h.
Source: Republic Steel
Alloy
8650H: Hardenability
(1600 “F). Austenitize:
Hardness
purposes
I distance,
mm
I.:’
Hardness
purposes
I distance.
‘!,,6 in.
Curves. Heat-treating
845 “C (1555 “F)
limits for specification
Hardness,
Maximum
HRC
Minimum
59
SY
98
56
sj
53
50
16
38
3-f
32
31
30
29
29
6.5
65
65
65
64
63
62
61
59
57
51
52
19
-17
46
limits for specification
Hardness.
hlasimum
h5
cl.5
65
b-l
M
h3
63
h2
61
60
60
59
58
58
47
Sb
5s
53
52
SO
19
37
.lb
45
HRC
hlinimum
59
58
51
57
5h
51
53
SO
-1-l
4-l
-II
39
37
36
35
3-1
33
32
?I
31
30
30
2’)
29
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 477
only): 870 “C
478 / Heat Treaters
Guide
885OH: End-Quench Hardenability
Distance from
quenched
surface
!.‘16in.
mm
I
2
3
4
5
6
7
8
9
10
II
I..58
3 16
17-l
6.3’
7.90
9.48
II 06
1264
11.12
IS 80
17.38
Hardness,
HRC
max
min
65
65
6S
64
64
b3
63
62
61
60
60
99
58
57
57
56
S-l
53
so
47
4-I
II
8650: Microstructure.
Distance from
quenched
surface
!/IS in.
mm
13
I4
IS
lb
I8
20
‘2
7-l
‘6
28
20.5-l
x.1?.
23.70
25 28
‘8 4-l
31.60
34.76
37.92
-I I .oa
44.2-l
Hardness,
HRC
max
min
58
S8
57
56
5s
5.3
51
so
49
-17
37
36
3s
3-I
33
32
31
31
30
30
2% nital, 500x. Hot rolled steel bar, 7.936
mm (0.31 in.) hexagonal, austenitized at 750 “C (1380 “F) 3 h, furnace cooled to 665 “C (1230 “F) and held 6 h, air cooled, cold
drawn, reheated to 665 “C (1230 “F) for 10 h, furnace cooled.
Spheroidized cementite and lamellar peariite in ferrite
478 / Heat Treaters
Guide
8655,8655H
Chemical Composition.
8655. AISI and UN% 0.5 I to 0.59 C. 0.75
to I .OO hln.0.035 Pmax. 0.03OS max. 0.15 too.30 Si. 0.10 too.70 Ni.O.-lO
IO0.60Cr. 0.15to 0.35 hlo. UNSHS6550and SAE/AIS18655H:O.SOto
0.60C.0.70to
1.05 hln.0.15 to035 Si.O.35 too.75 Ni.O.lS 100.25 MO
Similar
Steels (U.S. and/or
ASTM A322
AW;SAEJI268
A33l:
Foreign).
SAE J-IO-L J-II’.
8655.
5770. %%H.
G86sso:
UNS
UNS H86Y5050:A!ST&l
Characteristics.
A high-carbon sted. A spnnp sled. although it is used
IO fabricate a variety of machinery parts not related to sprinps. .As-quenched
hardness after quenching tn oil usually ranges from 57 to 62 HRC. depending on exact carbon content. A high-hardenability
steel. although the hand
is generally wide. Is forgeable. but not recommended for iteldinp because
of its high carbon content rend high hardenability
Forging. Heat to 1200 “C (2190 “F) masimum. Do not forge after
temperature of forging stock drops below approximately
925 “C ( 1695 ‘F).
Forgings of this grade should he cooled slo\vly from the forging operntion.
especially if they have complex shapes. Bury them in an insulating compound or place them in a furnace
Recommended
Normalizing.
Heat Treating
Practice
Heat to 870 “C ( I600 “F). Cool in air
Annealing.
For a predominantly
spheroidized
structure. which is preferred for machining and heat treakng 86SSH. heat to 750 “C (I380 “F),
cool rnpidly to 700 “C ( I290 “F). then cool to 655 “C (I 2 IO “F). at a rate
not to exceed 6 “C t IO “F) per h: or heat IO 750 “C ( I380 “F), cool rapidly
to 650 “C ( I200 “FJ. and hold for IO h
Direct Hardening.
Flame hardening.
able processes
.Austenitizs ttt 830 “C ( lS2S “F), and quench in oil.
gas nitridinp. ion nitriding. and carbonitriding
are suit-
Tempering.
After quenching to nelu ambient temperature. temper immediately at I SO “C (300 “F) or higher. The selection of tempering temperature depends on the required hardness or mechanical properties. 86SSH is
sensitke to quench cracking. and 1001 steel practice should be obsemed in
tempering. Parts should not be allowed to become too cold after quenching
before they are placed in the tempering furnace. A uniform temperature of
approximately
38 to SO “C t 100 to I20 “F) is preferred
Austempering.
\\‘hen used for applications
such as heavy-duty
springs. 865SH is sustempered in a procedure such as the one that follows:
Alloy
Auslenitize at 830 “C (1525 “F)
Quench in an agitated molten salt hnth held at 315 “C (655 “F)
. Hold at 345 “C (655 “F) for I h
l
Air cool to room temperature
l
\Vash in hot natrr
Recommended
l
l
l
l
l
l
No tempering is required. Hardness for pxts should range from approximarsl)
47 10 57 HRC
l
l
l
8855, 8655H:
Distance from
quenched
surface
916 in.
mm
1
2
3
4
5
6
7
8
9
10
1.58
3.16
4.14
6.32
7.90
9.48
11.06
12.64
14.22
15.80
11
12
17.38
18.96
Hardenability
Hardness,
HRC
max
min
Distance from
quenched
surface
l/l6 in.
mm
Hardness,
HRC
min
max
65
60
59
59
58
57
56
55
54
52
49
13
14
15
16
18
20
22
24
26
28
20.54
22.12
23.70
25.28
28.44
31.60
34.76
37.92
41.08
44.24
64
63
63
62
61
60
59
58
57
56
41
40
39
38
31
35
34
34
33
33
65
64
46
43
30
32
47.40
50.56
55
53
32
32
I479
Sequence
Forge
Normalize
Anneal
Rough md semifinish machine
Austenitize and quench (or nuskmper)
Temper (or austrmper)
Finish machine CUSUAI~ grinding)
sents an average
8655H: End-Quench
Processing
Steel
Hardness
based
vs Tempering
Temperature.
on a fully quenched
structure
Repre-
480 / Heat Treaters
Guide
8655H: Hardenability
Curves. Heat-treating
845 “C (1555 “F)
(1600 “F). Austenitize:
Hardness
purposes
J distance.
mm
limits for specification
Hardness,
hladmum
HRC
Minimum
60
60
59
57
56
55
53
51
42
39
3h
34
34
33
32
65
h5
6-l
62
60
58
56
5-l
Hardness
purposes
J distance.
1/1b io-
0
1
2
3
4
5
6
8
:0
!2
!4
:6
:s
80
12
limits for specification
Hardness,
hlatimum
65
65
64
64
63
63
62
61
60
59
58
57
56
55
53
HRC
hfinimum
60
59
59
58
57
56
55
54
52
49
46
43
41
40
39
38
31
35
34
34
33
33
32
32
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
Alloy Steel / 481
8660,866OH
Chemical
Composition.
8660. AISI: 0.55 to 0.65 C. 0.75 to 1.00
hln.0.0-10Pmax,0.0~OSmax.O.2Oto0.3SSi.O.10to0.70Ni.0.-10to0.60
Cr. 0. IS to 0.X MO. UNS: 0.55 to 0.65 C. 0.75 to I.00 hln. 0.035 P max.
0 040 S max. 0.15 to 0.30 Si. O.JO to 0.70 Ni. O.-IO to 0.60 Cr. 0. IS to 0.25
hlo. UNS HS6600 and SAE/AISI 86608: 0.55 LO0.65 C. 0.70 to I .OS Mn.
0. IS to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr. 0. IS to 0.35 MO
Similar
Steels (U.S. and/or Foreign).
ASThl A27-L A33Z. A333. ASl9:
H86600: ASThl A3O-l: SAE J I?68
SAE J-W.
UNS
~86600;
8660.
J-ll2.1770.
86608. GINS
Characteristics.
A spring stssl used for a uide \ariety of machinsq
parts where high strength and high h,ardcnabilit) are important. Also used
for a variet) of metal working tools including cold \\orl; dies. When the
carbon is on the IOU side of the allo~~ablz range. the as-quenched hardness
for an oil-quenched
part ma) hz no higher than about 59 HRC. but when
the carbon approaches the upper limit. the as-quenched hardnesb can he as
high as 65 HRC. The hardenahilit)
hand is relativeI!
wide. hut the hardenahility can he \eq high. actually approaching that of an au-hardening
Steel
Forging. Heat to 1200 ‘C rZl9O “FI ma\irnum. Do not forge atier
temperature of forging stock drops belo\{ approsimatelj
925 YI ( 169.i “F).
Forgings of this grade should be cooled slou I! from the forging operation.
especially if they have complex ,hapcs. Buq them in an insulatmg compound or place them in a furnace
Tempering.
.After quenching to near ambient temperature, temper immediateI> al I SO “C 1300 “F) or higher. The selection oftempering
temperature depends on the required hardness or mechanical properties. 866OH is
sensiti\c to quench cracking. and tool steel practice should be observed in
tempertng. Parts should not be allowed to become too cold after quenching
before they are placed in the tempering furnace. A uniform temperature of
approximateI>
38 to SO ‘C t IO0 to I20 “F) is preferred
Austempering.
H’hen used for applications
such as heavy-duty
sprmgs. 86SSH is austempered in a procedure such as the one that follows:
l
l
l
l
l
No trmpenng
47 to 52 HRC
l
l
l
l
l
Normalizing.
Heat Treating
Practice
15
requued. Hardness for parts should range from approximately
Recommended
l
Recommended
Austenitize at 830 “C t IS25 “FI
Quench in an agitated molten salt bath held at 3-lS “C (655 “F)
Hold at 3-0 “C 1655 “F) for I h
Air cool lo room temperature
L\‘abh in hot \bater
l
Processing
Sequence
Forge
Normalize
.Anneal
Rough and semifinibh ~nnchins
jrulrtsnitize and quench (or austsmper)
Temper Ior austempcr)
Finish machine ~usuallg grinding)
Heat to 870 ‘C t I600 “F). Cool in air
Annealing.
For a przdormnantly
spheroidized structure. uhich is usually preferred for machining as well as heat treating. heat to 7S0 “C t 1380
“FJ. cool rapidI> to 700 “C ( I?90 ‘F). then cool to 6SS “C ( I2 IO “Ft. at a
rate not to esceed 6 “C ( IO “F) per h: or heat to 750 ‘C I I380 “F). cool
rapidly to 650 “C I I200 “F). and hold for IO h
8660:
Approximate
Critical
Points
Temperature
Critical point
Direct Hardening.
Flame hardening.
Austenitire at 830 “C I IS2 “FL and quench in oil.
gas nitriding. and ion nitridinp. are altematite procebses
8660: Isothermal
Transformation
C. 0.89 Mn, 0.53 Ni. 0.64
(1555 “F). Gram size: 8
Cr, 0.22
Diagram.
Composition:
0.59
MO. Austenitized
at 845 “C
482 / Heat Treaters
Guide
8660: Hardness vs Tempering Temperature. Composition:
0.55 to 0.65 C, 0.75 to 1.00 Mn, 0.20 to 0.35 Si, 0.40 to 0.70 Ni,
0.40 to 0.60 Cr, 0.15 to 0.25 MO. Forge at 1175 “C (2150 “F), anneal from 815 to 925 “C (1500 to 1695 “F) for a maximum hardness of 229 HB. Hardness after normalizing in test size, 321 HB.
Normalized at 870 “C (1600 “F), quenched in oil from 845 “C
(1555 “F), tempered 2 h. Source: Republic Steel
8660: End-Quench
Hardenability. Composition: 0.59 C, 0.89
Mn, 0.53 Ni, 0.64 Cr, 0.22 MO. Austenitized at 845 “C (1555 “F).
Grain size 8
8660H: End-Quench Hardenability
Distance from
quenched
surface
I.,16in.
mm
I
3
;
Hardness.
HRC
min
max
158
60
60
60
1.71
3.16
6 32
7.90
9.48
.::
.:’
II.06
12.6-l
11.22
IS.80
I7 38
I896
:”
.:
Distance from
quenched
surface
“16h.
I?
I-l
mm
Hardness,
HRC
max
min
X~..i-l
22.12
73 70
:
45
4-l
-I!
60
60
59
3.28
28.U
31.641
6i
6-l
6-I
42
40
39
58
57
34.76
37.92
63
62
38
37
5s
53
50
47
1 I .08
1-1.2-t
47.40
50.56
62
61
60
60
36
36
36
3s
Alloy Steel / 483
8860H: Hardenability Curves. Heat-treating
(1600 “F). Austenitize:
iardness
wrposes
distance,
om
845 “C (1555 “F)
limits for specification
Hardness, HRC
Maximum
hliuimum
.5
1
3
5
.O
:5
‘0
‘5
0
.5
10
iardness
wrposes
distance,
$6 in.
.
.
65
64
62
61
60
limits for specification
Hardness, HRC
Maximum
hlinimum
.
0
1
2
3
4
5
6
8
0
2
4
6
8
0
2
60
60
60
60
59
58
56
53
46
42
39
38
37
36
35
.
65
64
64
63
62
62
61
60
60
60
60
60
60
60
59
58
57
55
53
50
41
45
44
43
42
40
39
38
37
36
36
35
35
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
484 / Heat Treaters Guide
8720,8720H,
8720RH
Chemical Composition. 8720. AISI and UNS: 0.18 to 0.23 C, 0.70
to0.90Mn,0.035 Pmax,0.040Smax,0.15
to0.30Si,0.40to0.70Ni,0.40
to 0.60 Cr. 0.20 to 0.30 MO. UNS II87200 and SAE/AISI 8720H: 0.17 to
0.23 C, 0.60 to 0.95 Mn, 0.15 to 0.35 Si, 0.35 to 0.75 Ni, 0.35 to 0.65 Cr,
0.20to0.30Mo.8720RH:0.18to0.23C,0.70to0.90Mn,0.15to0.35Si,
0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.20 to 0.30 MO
Similar Steels (U.S. and/or Foreign). 8720.
UNS
G87200;
ASTM A322; SAE J404,5770; (Ger.) DIN 1.6543; (U.K.) B.S. 805 A 20.
8720I-I. UNS H87200; ASTM A304, A914; SAE J1268, J 1868; (Ger.) DIN
1.6543: (U.K.) B.S. 805 A 20
Characteristics.
With the exception of a minor increase in the molybdenum content (0.20 to 0.30% as opposed to 0.15 to 0.25%), the composition of 8720H is identical with that of 8620H, and the characteristics are
nearly identical. The only difference is that the hardenability of 87208 is
slightly higher. Used for carburizing and carbonitriding where just a bit
more hardenability is needed than can be provided by 82608. Has excellent
forgeability and is readily weldable, although alloy steel practice should be
used in welding to minimize susceptibility to weld cracking. Machinability
is fairly good
Forging. Heat to 1245 “C (2275 OF) maximum. Do not forge after
(1220 OF), and holding for 4 h; or heat to 790 “C (1450 “F), cool rapidly to
660 “C (1220 “F), and hold for 8 h
Tempering. Temper all carburized or carbonitrided parts at 150 “C (300
“F), and virtually no loss of case hardness results. If some decrease in
hardness can be tolerated, toughness can be increased by tempering at
somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening. See recommended carburizing and carbonitriding
procedures described for 86208. Ion nitriding and martempering are alternative processes. Quenchants include polymers
Recommended
l
l
l
l
l
l
l
Processing
Sequence
Forge
Normalize
Anneal (if required)
Rough machine
Semifinish machine allowing only grinding stock, no more than 10% of
the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step
Carburize or carbonitride and quench
Temper
temperature of forging stock drops below approximately 900 “C (1650 OF)
Recommended
Heat Treating Practice
Normalizing. Heat to 925 “C (1695 OF). Cool in air
Annealing. Structures having best machinability are developed by normalizing; or by heating to 885 “C (1625 “F), cooling rapidly to 660 “C
8720, 8720H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
8720H: End-Quench
Repre-
Hardenability
~
I
2
3
4
;
7
8
9
IO
II
12
I.58
3.16
4.7-l
6.32
7.90
9.1x
I I ah
12.6-I
14.22
IS.80
17.38
IX.96
-18
-17
4s
12
28
35
33
!I
30
29
2x
27
-II
38
3s
30
‘6
2-l
2’
21
20
13
II
I5
I6
18
20
22
21
26
2!3
30
32
10.5-l
22. I2
23.70
25.28
25-L-l
31.60
34.76
37.92
-I I .08
u.2-l
17.40
SO.56
26
26
3
‘5
2-l
21
73
23
23
23
1’
22
8720: Tempering Temperature
vs Case Hardness. Carburized
to a depth of 1.27 mm (0.050 in.). Rock bit journals 13 mm (0.50
in.) to 44.5 mm (1.75 in.) in cross section were carburized at 925
“C (1695 “F), air cooled from 845 “C (1555 “F), heated to 870 “C
(1600 “F), oil quenched, tempered at 650 “C (1200 “F), reheated
to 775 “C (1425 “F), oil quenched. and tempered at indicated temperatures
Alloy Steel / 485
8720H: Hardenability Curves. Heat-treating temperatures
(1700 “F). Austenitize:
925 “C (1700 “F)
Hardness limits for specification
purposes
J distance.
mm
Aardness.
Maximum
4x
-I7
45
II
37
33
31
29
‘7
25
2-l
23
23
23
22
HRC
hlinimum
-II
39
35
29
25
22
21
Hardness limits for specification
purposes
J distance,
1.‘16 in.
I
?
3
-I
s
6
7
8
9
IO
II
IZ
I3
IJ
IS
I6
18
‘0
‘2
21
26
28
3CJ
32
Hardness,
hlavimum
HRC
hlinimum
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
488 / Heat Treaters
Guide
8720RH: Hardenability
“C (1700 “F). Austenitize:
Hardness
purposes
J distance,
1,
4i”.
I
7
;
-I
5
6
7
8
9
I0
II
I:!
I3
I-l
IS
I6
IX
20
22
Hardness.
hlaximum
HRC
hlinimum
47
-2.5
13
.I0
36
33
-I2
39
37
32
28
26
2-l
23
72
31
29
28
27
26
2s
2s
2-l
2-l
23
23
22
22
2-l
21
20
J distance,
mm
925 “C (1700 “F)
limits for specification
26
2x
30
32
Hardness
purposes
Curves. Heat-treating
21
20
limits for specification
Hardness,
Maximum
HRC
Minimum
temperatures
recommended
by SAE. Normalize
(for forged or rolled specimens
only): 925
Alloy Steel / 487
8720: Microstructures.
Note: All microstructures for 8720 were hot rolled specimens treated uniformly before described heat treatments:
gas carburized for 9 h at 925 “C (1695 “F) at 1.35% carbon potential and diffused for 2 h at the same temperature at 0.90% carbon potential.
The center of the field in the micrographs ranges from 0.127 to 0.254 mm (0.005 to 0.010 in.) beneath the carburized surface. (a) 5% nital,
1000x. Slowly cooled in the furnace from the carburizing temperature. Light carbide network in a matrix of lamellar pearfite. (b) 5% nital,
1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered for 1 h at 190 “C (375 “F). Relatively lowcarbon tempered martensite. (c) 5% nital, 1000x. Same austenitizing and tempering treatments as (b). Globular carbide, retained austenite
in tempered martensite of highercarbon content than (b). (d)5?” nital. 1000x. Austenitized at 0.65% carbon potential for 1 h at 815 “C (1500
“F), oil quenched. tempered for 1 h at 190 “C (375 “F). Retained austenite (white constituent) in a matrix of tempered martensite. (e) 5% nital,
1000x. Austenitized at 1.35% carbon potential for 1 h at 815 “C (1500 “F), oil quenched, tempered 1 h at 190 “C (375 “F). Carbide (light
network, globular particles) in a matrix of tempered martensite. retained austenite not visible. (f) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), quenched in oil, tempered for 1 h at 260 “C (500 “F). Small amount of retained austenite (white
areas) visible in a matrix of over-tempered martensite. (g) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F),
quenched in oil, tempered for 1 hat 120 “C (250 “F). Tempered martensite. showing effects of undertempering. (h) 5% nital, 1000x. Austenitized at 0.90% carbon potential for 1 h at 815 “C (1500 “F), rapidly air cooled, tempered for 1 h at 190 “C (375 “F). Fine pearlite (dark constituent) in a matrix of bainite. (j) 5% nital, 1000x. Same as (h), except oil quenched. Surface was improperly ground, being heated above
the critical temperature and then rapidly cooled. Retained austenite (white) and untempered martensite result
L
(b)
Alloy Steel / 487
8740,874OH
Chemical
Composition.
to l.OOMn.0.035
Pmax.O.WOS
8740. AISI and UNS: 0.38 to 0.43 C. 0.7s
max.0.15 ~o0.30Si.0.40to0.70Ni.0.40
to0.60 Cr. 0.30to0.30 Mo. UNSH87JOO
and SAE/AISI874OH:0.3710
0.14 C. 0.70 to I.05 hln. 0.15 to 0.35 Si. 0.3.5 to 0.75 Ni. 0.35 to O.hS Cr.
0.30 10 0.30 MO
Similar Steels (U.S. and/or Foreign). 8740. UNS G87400; AhlS
6332. 6313. 633. 6327. 6358: ASThl A313. A331: ML SPEC MIL-S6019; SAE J-W. J-II?. 5770: tGsr., DIN 1.6546: (I~al.) UNI 10 NiCrhlo 2
KB;(U.K.b
B S.T!,pr7.874OH.
1lNS HX7100: ASTMA3M:SAEJl168:
(Grr.) DIN 1.6546: (Ital.1 LlNl 10 NiCrhlo 2 KB: (U.K.) B.S. Type 7
488 / Heat Treaters
Guide
NearI) identical in composition
to 8640H. The onl)
Characteristics.
difference is a sli_rhtl> higher molybdenum range. 0.20 to 0.303 for 8710H
as opposed to 0. IS IO 0.2‘-5
for 8640H. This minor difference does not
change the as-quenched hardness. but does offer a light increase In bardrnahilib.
If desired. can he nitrided to achis\r surfaces Ihal help 10 resist
abrasion and further Increase fatigue strenpth. An ns-quenched surface
hardness of approsimatel)
52 IO S7 HRC can he expected. depending on
the precise carbon content. Can he forged h! an> one of the wious forging
method\
Nitriding. Responds nell to ammoniagas nitridins as well as II) nitriding
in any one of several proprietary molten sah baths. The following is a cycle
used with ammonia &as mtriding:
l
l
l
Forging.
wmperature
Heat 10 1230 ‘C t22SO “F) maximum. Do not forge after
of iorging stock drops hslou appronnnatel~ 900 ‘xY ( l6SO “F)
Parts are austenitirsd.
quenched, and tempered al 540 “C (I000 “F) or
higher. (Tempering temperature must aLays he higher [ban the &riding
temperarure)
Finish machine (must he done hefore nitriding. because of resulting thin
case 1
Nilrids In ammonia gas for IO to I? h I\ ith an ammonia gas dissociation
of 2s to 305
See procrssmg data for 1 I-LOH for other nilriding
Recommended
Normalizing.
Heat Treating
Practice
Tempering.
.Aftcr quenching. reheat immediately to the tempering temperature that M ill provide the desired combination of mecharucal properties
Heal to 870 ‘C ( I600 “FJ. Cool in air.
In aerospace pracke.
parts are normalized
at 900 “C ( 1650 “F)
Annealing.
For a predominanU> penrlitic wuuc‘rure. heat to 830 ‘C ( IS3
“FL cool rapidly to 73 ‘C ( I335 “FL then cool to 640 ‘C ( I I85 “‘F), a~ a
ra[e not IO exceed I I “C (10 “F) per h: or heat to X30 “C ( IS3 ‘F). ~‘001
rapidly to 665 “C ( I230 “F). and hold for 6 h. For a pr?dominantl>
sphrroidized
wucture.
heat to 750 “C I 1380 “F). cool rapid11 to 73 “C
I I335 “FL then cool to 640 “C ( I I85 “FL at a rate nor to exceed 6 “C ( IO
“FB per h; or heat to 750 YI ( 13X0 ‘FJ. cool rapid11 to 665 “C ( 1230 “FJ.
and hold for 8 h
In aerospace practice. parts are annealed at 845 “C I ISSS “F). cooled
IO helo\\ S-IO “C ( 1000 “F) at a rate not IO exceed 95 “‘C 1200 “F) per h
Other Processes. Ion nitriding. austempering and martempering are
altemath e processes.
In aerospace practice. parts WC austenitized at 8-15 “C I IS55 “F). then
quenched in oil or polymers
Recommended
l
l
l
l
l
l
l
Hardening.
Direct
.Austenirizs
at XSS :‘C (’ IS70 “FL and quench in oil
l
Processing
Specimens
quenched
Hardness
in.
mm
Surface
on Hardness
Hardness,
HB
Size round
in oil
Size round
Sequence
Forge
Normalize
.Annsal
Rouph and semifinish machine
Austsnitize and quench
Temper
Finish machine (grind if required)
Nitride (optional)
8740: Effect of Heat Treating
8740: As-Quenched
cycles
Hardness, HRC
‘A_ radius
Condition
‘iin.
(13mm)
1 in.
(2.5 mm)
2ill.
(51 mm)
4in.
(102 mm)
201
169
352
302
285
261
331
‘71
25.5
755
277
X8
‘29
Center
r\nnrakdiar
Nomlalircd~ b)
011 qusnchrdli,
Oil quenchrdld,
311
011qucnshedlr)
3s
‘69
352
(al Haled m IWO “F 11115‘CL furnace cwlcd 20 ‘IF f I I “C) to I IO0 “F (595 “C).
cooled intir. lb) Healed to IhOO“Ft870 “CL cooled in air. (cl Fmm IS15 “F(830”C).
lemprrzd II 1001)“F (5-10 ‘Cl. Id) From I525 “F (8.10 “CJ. tempered at I IO0 “F (59.5
‘CL 151From IS3 “Ft830’C~. temperedat INJ”FI~SO”C).
Source: RepublicSteel
8740, 8740H:
sents an average
Hardness vs Tempering Temperature. Reprebased
on a fully quenched
structure
Alloy Steel / 489
3740H: Hardenability Curves. Heat-treating
:1600 “F). Austenitize:
lardness
lurposes
distance,
,m
.5
1
3
5
0
5
0
5
0
5
0
iardness
wrposes
distance,
‘16in.
845 “C (1555 “F)
limits for specification
Hardness, HRC
Minimum
Maximum
60
60
60
60
59
58
56
54
50
45
43
41
40
39
38
limits for specification
Hardness, HRC
Maximum
Minimum
60
60
60
0
1
2
3
4
5
6
8
0
2
4
6
8
0
2
53
52
51
49
46
43
39
36
31
29
28
27
27
26
26
60
59
58
57
56
55
53
52
50
49
48
46
45
43
42
41
40
39
39
38
38
53
53
52
51
49
46
43
40
31
35
34
32
31
31
30
29
28
28
21
21
27
27
26
26
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 870 “C
1
490 / Heat Treaters Guide
8740: Suggested Tempering Temperatures (Aerospace Practice)*
620460 MPa
(90-125 bi)
860-1035 hlPa
(125-150 ksi)
690 “C
I I275 “FJ
635 ‘T
11175°F)
Tensile Strength Range
1175-1210 MPa
1035-1175 hlPa
(170480 ksi)
(150-17Oksi)
1240-1380 hlPa
(180-200 ksi)
1380-1520 MPa
(200-220 ksi)
455 “C
(850°F)
385 “C
(735 “FJ
925 “C
(975 “F)
580 “C
(1075 “FJ
* Quench m oil or poljmrr. Source: AhlS 27S9/1
8740:
Suggested Tempering Temperatures Based on As-Quenched Hardness (Aerospace Practice)
Tensile strength range
RC 47-19
RC 50-52
RC 53-55
RC -56-58
620 - IO35 MPa
(90-1.50 ksi)
965-l 105 MPa
(140-160 ksl)
1035-l 175 MPa
(ISO-17Oksij
I I OS-I230 MPa
(160-180 ksl)
1175.1310MPa
(170-190 ksl)
1210-1380 MPa
(180-200 ksi)
1380-1515 MPa
(200-220 kji)
595 “C
(IIOO”FI
525 “C
197.5“FI
470 “C
187S’F)
620 ‘T
(1150°F)
550 “C
(IO2S “F,
510°C
(950 “F)
480 “C
(900 “F)
4lO”C
(775 ‘F)
385 “C
(725 OF)
(650 ‘T)
I 1200°F)
595 “C
(IIOO”FI
550 “C
(IO15 “R
52s “C
(975 “F)
470 “C
(R75 “F)
-130 @C
(825 OF)
110 T
(775 “F)
675 “C
( 1250 “F)
635 “C
(1175°F)
595 “C
(1100°F~
565 “C
(lOSO”F)
510°C
(950 “F)
500 “C
(925 “F)
470 “C
(875 OF)
Source: AhlS 2759/l
490 / Heat Treaters
8822,8822H,
Guide
8822RH
Chemical Composition.
8822. AISI and UNS: 0.20 to 0.25 C. 0.75
to I .OO Mn.0.035 Pmas. 0.040 S max. 0. IS toO.3OSi. 0.40 too.70 Ni.O.40
to 0.60 Cr. 0.30 to 0.10 hlo. LJNS 888220 and SAE/AISI
88228: 0. I9 to
0.15 C. 0.70 to 1.05 Mn. 0.1s to 0.35 Si. 0.35 to 0.75 Ni. 0.35 to 0.65 Cr.
0.30 to 0.40 MO. SAE 8822RH: 0.20 to 0.25 C. 0.75 to I.00 Mn. 0.15 to
0.35 Si. 0.40 to 0.70 Ni, 0.40 to 0.60 Cr. 0.30 to 0.40 hlo
Similar Steels (U.S. and/or Foreign). 8822. UNS G88220; SAE
J-W. J770: (Ger.) DlN I .6543: (U.K.) B.S. XOS A 20.8822H. IJNS H8822O:
ASThl A304 SAE 5407; t&r.) D[N 1.6543; iL1.K.) B.S. 805 A 20
Characteristics.
A modification
of 862OH. with a higher carbon range
(same as 8632H) and a substantialI> higher mol!hdenum
content to.30 to
O.-W? as opposed to 0. IS to O.YG for 8620 and 8622H). This increase in
molybdenum
content results in a significant
increase in hardenabilit).
As-quenched hardness usuallq ranges from approximateI>
-II to 47 HRC.
Can be processed by carbonitriding.
but usualI> is not used for producing
parts that will be carbonitrided
because most carbonitrided
pans are relatively, small, and the higher hardenabilitj
of 8822H is not required. Used
princtpall)
for producing parts L+ith heavy sections for which grades 8620H
and 8622H do not have sufficient hardenability.
such as heavy-duty gears
and pinions. Such parts are subjected to carburiring
treatments. Forges
easil). and forging is often used to produce gear blanks and similar parts.
Is readily heldable. although alloy steel practice should be used in welding
to minimize susceptibility
to weld cracking. Machinability
is considered
fairly good
Forging.
temperature
Heat to 1245 “C (2275 ‘F, maximum.
Do not forge after
of forging stock drops beIoN approximately
900 “C t IhSO “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 925 “C ( 16% “F). Cool in air
Annealing.
Structures ha\ ing best machinability
are developed by normalizing: or by heating to 885 “C (I625 “F). cooling rapidly to 665 “C
t I230 “F). and holding for -I h: or heat to 790 “C (l-i55 “F). cool rapidly to
665 “C t I230 “F). and hold for 8 h
Tempering.
Parts made from 50B14H should be tempered immediately
after the) ha\ e been uniformI) quenched to near ambient temperature. Best
practice is to place workpieces into the tempering furnace just before they
ha\ e reached room temperature. ideall) u hen they are in the range of 38 to
SO “C t 100 to 170 “F). Tempering temperature must be selected based upon
the tinal desired hardness.
After quenching to near ambient temperature. temper immediately at
I SO “C (300 “F) or higher. The selection of tempering temperature depends
on the required hardness or mechanical properties. 86SSH is sensitive to
quench cracking. and tool steel practice should be observed In tempering.
Parts should not be alloued to become too cold after quenching before they
are placed in the tempering furnace. A uniform temperature of approximately 38 to SO “C ( 100 to I20 “F) is preferred. Temper all carburized or
carbonitrided
parts at IS0 “C (300 “F). and virtually
no loss of case
hardness results. If some decrease in hardness can be tolerated, toughness
can be increased by tempering at somewhat higher temperatures; such as
up to 7-60 “C (SO0 “F)
Case Hardening.
scribed for 862OH
See carburizing
and carbonitriding
practices
de-
Alloy Steel / 491
Recommended
l
l
l
l
l
Processing
Sequence
l
Forge
Normalize
Anneal (if required)
Rough machine
Semifinish machine allowing only grinding stoch. no more than IO? of
the case depth per side for carburized parts. In most instances, carbonilrided parts are completely tinished in this skp
8822:
Approximate
Critical
point
OF
As,
XCJ
Ar,
Ar,
Sour~c: Republic
Carburize or carhonitride and quench
Temper
8822:
Approximate
Core Hardness
Normalized at 1700 “F (925 “C) in 1.25-in. (31.8-mm) rounds; machined to 1-in. (25mm) or 0.540-in. (13.7-mm) rounds; pseudocarburized at 1700 “F (925 “C) for 8 h; box cooled to room temperature,
reheated and oil quenched: tempered at 300 “F (150 “C); tested
0.505-in. (12.8-mm) rounds
Points
Temperature
Critical
l
1330
I510
IUS
II95
Steel
Reheat temperature
“F
T
1-m
1510
I590
17ool(1l
ca)Qurnched
775
820
865
9251a1
Hardness, HB
Heat treated in rounds
1 in.
0.540 in.
(25 mm)
(13.7 mm)
352
363
38X
388
from 17lXYF (925 ,;C, oficr psrudocmburiring
3s2
415
429
429
for8 h
8822, 8822H: Hardness vs Tempering
Temperature.
sents an average based on a fully quenched structure
8822: Cooling
Curve. Half cooling time. Source: Datasheet
l-60. Climax Molybdenum
Company
Repre-
492 / Heat Treaters
Guide
8822H: End-Quench Hardenability
Distance from
quenched
surface
‘.~bin.
mm
Hardness.
HRC
ma\
min
Distance from
quenched
surface
I ‘16in.
mm
Rardness.
HRC
may
min
I
1
I su
so
13
13
20.5-l
31
;
4.74
3 16
6 32
7.90
9.-M
49
-18
-lb
-13
40
37
42
39
IS
I-l
I6
18
70
‘2
3s
2-l
2-l
23.70
22
I?.
3.28
28.44
3 I 60
34.76
37.92
30
30
33
29
27
75
4
5
h
7
x
9
I I.06
I’.hl
19
3
28
‘7
27
l-l.12
3-l
7-l
3
11.08
l5YO
33
23
28
U.‘-l
27
II
17.38
32
23
I2
IS96
31
22
30
32
47.m
50.56
27
27
IO
27
8822: CCT Diagram. Composition for AISI, constructional
alloy steel: 0.24 C, 0.95 Mn, 0.28 Si, 0.019 P, 0.025 S. 0.44 Ni, 0.31 MO. Steel was
from commercial heat, and was austenitized at 850 “C (1560 “F) for 12 min. Determining heavy section hardenability was objective of study.
Source: Datasheet I-60. Climax Molydbenum Company
Alloy
8822H: Hardenability
Curves. Heat-treating
(1700 OF). Austenitize:
925 “C (1700 “F)
Hardness
wrposes
I distance,
nm
I.5
limits for specification
Eardness.
Maximum
ERC
hlinimum
SO
19
17
-IS
II
38
3s
33
31
29
29
28
‘7
17
27
Hardness limits for specification
wrposes
I distance,
k,6i”.
3
I0
II
IZ
I3
I-l
15
I6
I8
!O
12
t-1
!6
!8
NJ
Hardness,
hlauimum
50
49
-a
46
13
40
37
3s
31
33
31
31
31
30
30
29
29
23
27
27
17
27
27
27
HRC
hlinimum
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
Steel / 493
only): 925 “C
1
494 / Heat Treaters
Guide
8822RH: Hardenability
“C (1700 “F). Austenitize:
Hardness
purposes
J distance,
‘46io.
Curves. Heat-treating
925 “C (1700 “F)
limits for specification
Hardness.
Maximum
RRC
Minimum
I
-19
-I4
4
I3
13
-IO
37
35
33
32
31
30
30
'9
I-1
28
IS
16
IX
28
27
27
35
31
29
27
26
2.5
2s
2-l
‘3
23
'3
22
22
20
26
22
2-l
26
28
30
32
26
26
26
25
25
25
5
h
7
8
9
I0
II
I2
Hardness
purposes
J distunce.
mm
21
20
limits for specification
Hardness,
Maximum
HRC
Minimum
I .5
49
4-l
3
5
7
9
18
-16
12
38
II
3.5
I3
33
32
29
27
27
26
36
L-5
‘5
-I3
39
33
30
27
26
2s
23
22
IS
20
25
30
35
40
4s
so
71
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 495
9260,926OH
Chemical
Composition.
9260. MS1 and UNS: 0.56 to (X6-1C. 0.75
to I.00 Mn. 0.035 P max. 0.040 S max. I.80 to 2.30 Si. UNS H92600 and
SAE/AISI926OH:
03.5 to 0.65 C.O.65 to 1.10 hln. 1.70 to 2.20 Si
Similar
Steels (U.S. and/or Foreign). 9260. UNS
G9?600:
ASTM AZ9. AS9. AX?. A33 I ; SAE J-404, J4l2.5770:
(Ger.) DfN I .0909:
(Fr.) AFNOR 60 S 7,6l SC 7; (U.K.) B.S. 250 AS8.92608.
UNS H92600:
ASThl A304 SAE Jl268; (Ger.) DIN 1.0909; (Fr.) AFNOR 60s 7.61 SC
7: (U.K.) B.S. 30 A 58
Characteristics.
A special composition
the only steel in the present
AISI list where the silicon content il.7 to 2.2%) is high enough to he
considered an alloy. Principal use is for heavy-duty springs. notably coil
springs that are hot wound. Is nearly identtcal in composition
to S-t.
shock-resisting
tool steel. 9160H is used for tooling as ~rell as nontooling
applications.
such as coining dies. L\ here impact resistance is important.
As-quenched hardness can be expected to fall within the range of approximately 58 to 63 HRC. Hardenahility
is considered fairly high
Forging.
temperature
Annealing.
For a predominantly
spheroidized
structure (usually preferred). heat to 760 “C ( 1400 “F). then cool to 705 “C ( I300 “F). 31 a rate
not to exceed 6 ‘C (IO “F) per h; or heat to 760 “C ( 1100 “F). cool rapidly
to 665 “C ( I30 “F). and hold for IO h
Direct Hardening.
hlartemperinp
Tempering.
After parts have been unifomtiy quenched to near ambient
temperature. they should be placed in a tempering furnace immediately,
preferably when their temperature is within the range of 38 to 50 “C (100
to I70 “F). The tempertng tempernture must be at least IS0 “C (300 “F).
Higher tempering temperatures are usually used to develop maximum
toughness in this steel
Recommended
l
l
Heat to 1205 “C (X00 “F) maximum.
Do not forge after
of forging stock drops below approximately
93 ‘C (I695 “F)
Normalizing.
l
l
Practice
l
Heat to 900 “C ( 1650 “F). Cool in air
l
Recommended
Heat Treating
Austenitize at 870 “C ( 1600 “F). and quench in oil.
is an nltemati\e process. Quenchants Include polymers
l
Processing
Sequence
Forge. or hot wind if producing springs
Normalize
Anneal
Rough and semifinish machine (if applicable)
.Austenitire and quench
Temper
Finish machine
9260: Isothermal Transformation
Diagram. Composition:
C. 0.82 Mn, 2.01 Si. 0.07 Cr. Austenitized
Grain size: 6 to 7
at 870 “C (1600
0.62
“F).
496 / Heat Treaters
Guide
9260: Hardness vs Tempering Temperature. Composition:
0.55 to 0.65 C, 0.70 to 1 .OOMn. 1.80 to 2.20 Si. Forged at 1205 “C
(2200 “F) maximum, furnace cooled from 815 to 925 “C (1500 to
1695 “F). Maximum annealed hardness, 229 HB. Hardness when
normalized in test size, 302 HB. Normalized at 900 “C (1650 “F),
quenched in oil from 870 “C (1600 “F), tempered for 2 h. Source:
Republic Steel
9260H: End-Quench Hardenability
Dktance from
quenched
surface
‘&in.
mm
1
2
3
4
5
6
1.58
3.16
4.74
6.32
7.90
9.48
7
8
9
10
11
12
Hardness,
HRC
mas
min
Distance from
quenched
surface
&in.
mm
Hardness,
HRC
may
min
65
64
63
62
60
60
57
53
46
41
13
14
15
16
18
20
20.54
22.12
23.70
25.28
28.44
31.60
4.5
43
42
40
38
37
33
33
32
32
31
31
11.06
12.64
14.22
60
58
55
38
36
36
22
24
26
34.76
37.92
41.08
36
36
35
30
30
29
15.80
17.38
18.96
52
49
47
35
34
34
28
30
32
44.24
47.40
50.56
35
35
34
29
28
28
9260: End-Quench
Hardenability.
Mn, 2.01 Si. 0.07 Cr. Austenitized
6to7
Composition: 0.62 C, 0.82
at 870 “C (1600 “F). Grain size:
Alloy Steel / 497
9260H: Hardenability
Curves. Heat-treating
(1650 “F). Austenitize:
870 “C (1600 “F)
iardness
wrposes
I dbtancc.
nm
limits for specification
Hardness,
Maximum
HRC
Minimum
.:,
60
60
SY
SO
42
38
36
35
33
32
31
30
29
28
28
6.5
63
62
60
5x
54
47
40
38
37
36
3.i
35
iardness
wrposes
I distance.
46 in.
0
I
2
3
4
5
6
8
:o
12
!4
I6
8
IO
I2
limits for specification
Hardness,
Maximum
65
64
63
62
60
X3
5s
52
49
47
45
43
42
40
38
37
36
36
35
35
3s
34
HRC
lllinimum
60
60
57
53
46
41
38
36
36
35
31
3-1
33
33
32
32
31
31
30
30
29
29
28
2x
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900 “C
498 / Heat Treaters
9260: CCT Diagram.
method)
Guide
Composition:
0.57 C, 0.91 Mn, 1.95 Si. Grain size: 7. Austenitized
at 870 “C (1600 “F) (using interrupted
Jominy
498 / Heat Treaters Guide
931 OH, 931 ORH
Chemical
COf’IIpOSitiOn.
UNS H93100 and SAE/AISI 9310H: 0.07
to013 C. 0.40 to0.70 Mn.0.15 to030 Si. 2.95 to 3.55 Ni. 1.00 to I.-IS Cr.
0.08 to 0. IS hlo. SAE 9310RH: 0.08 to 0. I3 C. 0.45 to 0.65 hln. 0. IS to
0.35 Si. 3.00 to 3.50 Ni. I .OO to I .-IO Cr. 0.08 to 0.15 MO
Similar Steels (U.S. and/or Foreign).
UNS
G93 100:
ASTM
.A3(H: SAE Jl26X
Characteristics. A relati\elq high-allo!. high-qualit). and high-hardenability case hardening steel. Uwally
carburired.
Because of its relatimely low carbon content, as-quenched hardness is not usually higher than
approximately
32 to 38 HRC. depending on whether the carbon is near the
lo\\ side or the high side of the allowable range. Hardenabilit~.
ho\bever. is
high. Used for such applications as premium quality gears. such as aircraft
engines and pinions for which high hardenability
and an unusualI) high
degree of toughness are mandator). Relatively expensive and has a high
nickel content. b hich can be a scarce allo>. The use of 93 IOH has gradualI)
dsclined in favor of higher carbon. lower allo) grades of carburizing steels.
Can be case hardened by carbonitriding.
but economics usually exclude the
use of 93 IOH for parts that would require carbonitriding
Annealing.
Because of the sluggish transformation
characteristics
of
this steel. con\ entional annealing is not usually practical. A better means of
obtaining a spheroidized structure in 93 IOH is bj tempering for approximately I8 h at a subcritical temperature. usually 600 “C ( I I IO “F)
Tempering.
Temper all carburizrd parts at IS0 “C (300 “FL and virtualI> no loss of case hardness results. If some decrease in hardness can be
tolerated. toughness can be increased b) tempering at somewhat higher
temperatures. up to 260 ‘C (SO0 “F)
Case Hardening.
uum carburizing.
able processes
Recommended
l
l
l
Forging.
Heat to 1260 “C (2300 “F) maximum.
Do not forge after
temperature of forging stock drops below approximateI)
925 “C (16% ‘Fr
Recommended
Heat Treating Practice
Normalizing. Heat to 92s “C ( I695 “FL Cool in air
l
l
l
l
See carburizing practice described for 8620H. Vacion nitriding. austempenng. and martempering are suit-
Processing
Sequence
Forge
Normalize
Anneal (if required)
Rough machine
Semifinish machine. allowing only grinding
the case depth per side for carburizcd parts
Carburize and quench
Temper
stock. no more than 10% of
Alloy Steel I499
9310H: Hardness vs Tempering Temperature.
average based on a fully quenched structure
9310H: End-Quench
Distance frum
quenched
surface
1/l~in.
mm
1
2
3
4
5
6
Hardenability
Elardness,
ARC
max
min
1.58
3.16
4.74
6.32
1.90
9.48
I
11.06
8
9
12.64
14.22
10
11
15.80
17.38
12
18.96
43
43
43
42
42
42
42
41
40
40
39
38
Diagram.
36
35
35
34
32
31
30
29
28
27
21
26
Austenitized
Distance From
quenched
surface
916 in.
mm
13
14
15
16
18
20
22
24
26
28
30
32
20.54
22.12
23.10
25.28
28.44
31.60
34.16
37.92
41.08
44.24
47.40
50.56
Hardness,
HRC
mar
min
31
36
36
35
35
35
34
34
34
34
33
33
26
26
26
26
26
25
25
25
25
25
24
24
20 min at 829 “C (1525 “F). Source: Climax Molybdenum
Company
Represents
an
500 / Heat Treaters
Guide
9310: Microstructures.
Note: For (a to g), specimens were gas carburized at 925 to 940 “C (1695 to 1725 “F) for 4 h in a pit-type furnace,
furnace cooled, austenitized at 815 to 830 “C (1500 to 1525 “F), oil quenched, and tempered at 150 “C (300 “F) for4 h. Case carbon contents
vary because of variations in the carbon potential of the carburizing atmosphere. (a) 2% nital, 500x. Gas carburized to a maximum case
carbon content of 0.60% (lean). (b) 296 nital, 500x. Gas carburized to a maximum case carbon content of 0.85%. (c) 2% nital, 500x. Gas
carburized to a maximum case carbon content of 0.95?& (optimum). (d) 2% nital, 500x. Gas carburized to a maxrmum case carbon content
of 1.05%. (e) 2% nital, 500x. Gas carburized to a maximum case carbon content of 1.1046. (f) 2% nital, 500x. Gas carburized to a maximum
case carbon content of 1.20%. (g) Picral. 200x. Normalized by austenitizing 2 h at 885 “C (1625 “F) and cooling in still air. Scattered carbide
particles and unresolved pearlite in a matrix of ferrite (light constituent). (h) 396 nital, 500x. Annealed by austenitizing 2 h at 885 “C (1625 “F)
and cooling slowly in a furnace. Scattered carbide particles (dark constituent) in a matrix of ferrite (light constituent)
Alloy Steel / 501
9310H: Hardenability
Curves. Heat-treating
(1700 “F). Austenitize:
845 “C (1555 “F)
iardness
wrposes
distance.
qm
5
,l
13
15
!O
!5
30
15
to
$5
$0
iardness
wrposes
distance.
&ill.
0
1
2
3
14
15
16
18
!O
!2
!4
!6
18
$0
2
limits for specification
Hardness, HRC
hlavimum
Minimum
43
43
43
43
43
42
41
40
38
36
35
35
34
34
33
36
35
34
33
31
30
28
27
26
25
25
25
25
24
24
limits for specification
Hardness. HRC
Maximum
hlinimum
43
43
43
42
42
42
42
41
40
40
39
38
31
36
36
35
35
35
34
34
34
34
33
33
36
35
35
34
32
31
30
29
28
27
27
26
26
26
26
26
26
25
25
25
25
25
24
24
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925 “C
502 / Heat Treaters
Guide
9310RH: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitiie: 845 “C (1555 “F)
Hardness
purposes
limits
J distance.
I,16iIl.
for specification
Eardness,
Maximum
HRC
Minimum
-IT!
42
42
II
-II
40
4)
39
38
37
37
36
3s
34
31
33
33
3’
;:!
32
32
32
31
31
Hardness
purposes
J distance.
mm
I .s
1
limits
37
36
36
3s
34
33
32
31
30
29
29
18
28
2x
28
17
27
26
-76
26
26
26
2s
25
for specification
Hardness,
Maximum
-I?
-I?
42
-II
-IO
-IO
39
37
35
33
32
32
3’
;I
31
HRC
Minimum
37
36
36
3s
33
3’
3;
‘9
28
27
xl
76
26
25
3
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
1
Alloy Steel / 503
94Bl5,94Bl5H
Chemical
Composition.
9JB15. AM:
0.13
to
Recommended
0.18 C. 0.75 to I .OO
Heat Treating
Practice
hln. 0.035 P mas. O.O-tO S max. 0.30 to 0.60 Ni. 0.30 to 0.50 Cr. 0.08 to
0. IS MO. 0.0005 B min. UTVS: 0. I? to 0. I8 C. 0.75 to I.00 hln. 0.035 P
ma~.0.0-10Smax.0.15to0.30Si.0.30to0.60Ni.0.30to0.50Cr.0.08to
0. IS MO. 0.0005 B min. IJNS H94151 and SAE/AISI 9JBlSH: 0. I? to
0.18 C. 0.70 to I.05 Mn. 0.15 to 0.35 Si. 0.35 to 0.65 Ni. 0.25 to 0.55 Cr.
0.08 to 0. I5 MO. B (can be expected to he 0.0005 to 0.003 percent)
For a predominantly
pearlitic structure. heat to 900 “C ( 1650
“F). cool rapidly to 665 “C ( I230 “F) and hold for 5 h. For a predominantly
spheroidized structure. heat to 800 “C ( 1175 “F), cool rapidly to 665 “C
t 1330 “F). and hold for IO h
Similar
Tempering.
AMS
Steels (U.S. and/or
6375
ASTM
A;
ASTM
4519:
Foreign).
SAE
94B15. l!NS W-I IS I:
J-KJ-L 1770. 94B15H. 1rNS H9-tlSl:
A304: SAE J I268
Characteristics.
One of the tuo principal boron-containing
_erades
used for case hardening, either carburizing or carbonitriding.
Dependmg on
the precise carbon content within the allowable range. as-quenched hardness (without case) usually ranges from 35 to 40 HRC. However. because
of the boron addition. the hardenability
of this grade is higher than that 01
an X6OOH grade of similar carbon content. although the ranges of Ni. Cr.
and MO are lower for 94B I5H. Used for carburized parts ibhich have heavy
sections and need the higher hardenability.
Cost is generally less than that
of a higher alloy grade not containing boron Nhich would be required to
provide the same hardenahility
Forging.
temperature
Heat to 1245 “C (27-75 “F) maximum.
Do not forge after
of forging stock drops helo\{ approximately
900 “C t 1650 “F)
Normalizing.
Hsat
to 93.5 “C t 1695 “F). Cool
in air
Annealing.
Temper all carburized or carbonitrided
parts at I SO “C (300
“F), and virtually
no loss of case hardness results. If some decrease in
hardness can be tolerated. toughness can he increased by tempering at
somewhat higher temperatures. up to 260 ‘C (SO0 “F)
Case Hardening.
See carburizing
and carbonitriding
Processing
Sequence
Recommended
l
Distance &om
quenched
surface
1,‘,6 in.
mm
Hardenability
Bardness.
q RC
min
max
Distance From
quenched
surface
‘116 in.
mm
Bardness,
BRC
mltY
7
3
4
5
6
I
I.58
3.16
4.7-l
6.32
7.90
9.18
IS
1s
4-l
44
13
12
38
38
37
36
32
28
13
II
IS
I6
18
70
20 s-l
12.12
13.70
15.28
28 +I
31.60
30
29
28
27
‘6
7
8
9
I I.06
12.64
14.7-7
10
38
36
2s
13
II
2’
2-l
26
34 76
37.92
11.08
24
23
23
IO
IS.80
3-l
20
28
44.2-l
22
II
I?
17.38
I&%
33
31
30
3’
47.40
SO.56
27
22
I5
de-
l
l
l
l
l
l
Forge
Normalize
Anneal (if required)
Rough machine
Carburize or carhonitride and quench
Semifinish machine. allowing only grinding smck, no more than IO4 of
the case depth per side for carbuhzed parts. In most instances. carbonitrided parts~are’completely
finished in this step
Temper
94815,94615H:
HardnessvsTemparingTemperature.
sents an average based on a fully quenched structure
94B15H: End-Quench
processes
scribed for 8630H
Repre-
504 / Heat Treaters
Guide
94615H: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize:
925 “C (1700 “F)
Hardness
purposes
I distance,
nm
1.5
Hardness
wrposes
I distance.
j/16in.
1
limits for specification
Hardness. HRC
Maximum
Minimum
45
45
45
44
42
40
38
36
31
28
26
24
23
22
22
limits for specification
Hardness, HRC
hlinimum
hlasimum
45
45
44
44
43
42
40
IO
II
12
13
14
1s
16
18
20
22
24
26
28
30
32
38
38
37
34
30
26
22
20
38
36
34
33
31
30
29
28
27
26
25
24
23
23
22
22
22
38
38
37
36
32
28
25
23
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 505
94Bl7,94Bl7H
Chemical
Composition.
94B17. AISI: 0.1s 100.10 C. 0.75 to I .OO
hln.0.035 Pmax.0.010Smax.0.15
to0.30Si.0.30to0.60Ni.0.3Oto0.SC)
C-r, 0.08 to 0.15 MO, 0.0005 to 0.003 8. UNS: 0.15 to 0.20 C. 0.75 IO 1.00
hln,0.03SPmax.0.0~0Smax,O.lSto0.30Si,0.30to0.60Ni.0.30to0.S0
Cr. 0.08 to 0. IS MO. O.CHJOSB min. UNS A94171 and SAE/AISI 9JB17H:
0.1-l to 0.20 C, 0.70 to I.05 hln. 0.15 IO 0.35 Si. O.?S to 0.6s Ni. O.ZS to
0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 IO 0.003 percent)
Similar
Steels (U.S. and/or
AMS 6375: ASTM ASl9:
ASTM A30-l: SAE J I268
Foreign).
9JB17. LINS G9-l I7 I :
SAE J-IO-I. 5770. 94B17H.
UNS
H49-ll71:
Annealing.
For a predominantly
pearlitic structure, heat to 900 “C ( 1650
“F). cool rapidly to 665 “C ( I230 “F). and hold for -1 h. For a predominantly
sphsroidized structure, heat to 800 “C (l-l75 “F). cool rapidly to 665 “C
( I?30 “F). and hold for IO h
Tempering.
Temper all carburized or carbonitrided
parts at I50 “C (300
“F). and virtually
no loss of case hardness results. If some decrease in
hardness can be tolerated. toughness can be increased by tempering at
somewhat higher temperatures, up to 260 “C (500 “F)
Case Hardening.
Characteristics.
The compositions of 91B I7H and 9AB ISH are identical, escept for a slightly higher carbon range from 9dB l7H. The characteristics of these two pades are essentially the same. Because of the higher
carbon range, as-quenched hardness range without case is slightlq higher
for 9-lB l7H. approximate11 37 to -lZ HRC. The hardenabilit)
pattern for
9-1Bl7H is the same as for 91BlSH. except the entire band for 9-+Bl7H is
shifted upward because of the higher carbon content. Grade 91Bl7H
is
often used instead of 91B I SH I\ hen a higher core hardness is needed for
carburized parts
Recommended
l
l
l
l
l
Forging.
Heat to IX5 “C (‘775 ‘F) mzsimum. Do not forge atier
temperature of forging stock drops belo\\ approximately
900 “C I 1650 ‘F)
l
Recommended
Normalizing.
Heat Treating
Heat to 97-S “C (I695
Practice
See carburizing
and carbonitriding
processes
de-
scribed for 8610H
l
Processing
Sequence
Forge
Normalize
.Anncal (if required)
Rough machine
Semifinish machine. alloying only grinding stock. no more than IOQ of
the case depth per side for carburized parts. In most instances, carbonitrided parts are completely finished in this step
Carburize or carbonitride and quench
Temper
“F). Cool in air
94617: Isothermal
Transformation
Diagram. Composition:
O.l9C, 0.77 Mn, 0.42 Ni, 0.4OCr, 0.12 MO, 0.0018B.
at 925 “C (1695 “F). Grain stze: 7 to 8
Austenitized
94817,94617H:
Hardness vs Tempering Temperature. Repre-
sents an average
based
on a fully quenched
structure
506 / Heat Treaters
Guide
94B17H: Hardenability
Curves. Heat-treating
“C (1700 “F). Austenitize:
Hardness
surposes
I distance,
nm
I .5
1
925 “C (1700 “F)
limits for specification
Hardness, HRC
hlinimum
hlaximum
46
46
39
39
38
36
31
26
24
22
46
45
44
43
41
39
34
30
28
26
25
24
hardness
wrposes
I distance,
/I6 in.
.
limits for specification
Hardness,
hladmum
46
IO
II
12
13
14
I5
I6
I8
TO
12
!4
!6
!8
IO
)2
46
45
45
44
43
42
41
40
38
36
34
33
32
31
30
28
21
26
25
24
24
23
23
HRC
hlinimum
39
39
38
37
34
29
26
24
23
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 925
Alloy Steel / 507
94817H: End-Quench Hardenability
Distance from
quenched
surface
l/16 in.
mm
Hardness,
HRC
max
min
-l
5
6
7
I S8
3.16
4.7-l
6.33
7.90
9.18
Il.06
46
16
35
1s
J-4
43
-I?
39
39
38
37
3-l
29
26
8
9
I0
II
I2
I2.6-l
I-l.22
IS.80
17 38
I8.%
II
40
38
36
3-l
7-l
23
21
20
I
?
3
Distance from
quenched
surface
1,
mm
46 in.
I3
I-l
IS
I6
I8
20
Hardness,
HRC
max
22
10.51
2.12
23.70
2.5 33
28.4-l
31.60
31.76
3.1
32
31
30
28
27
26
21
26
7-8
30
32
37.92
41.08
-u.Ll
17.40
SO.56
2.5
L-l
2-i
23
23
94817: End-Quench Hardenability.
Composition: 0.19 C, 0.77
Mn, 0.42 Ni, 0.40 Cr, 0.12 MO, 0.0018 B. Austenitized at 925 “C
(1695 “F). Grain size: 7 to 8
Alloy Steel / 507
94B30,94B30H
Chemical
Composition.
93B30. AISI: 0.28
to
0.33 C. 0.75
to
I .OO
Mn.0.03SPn~ax,0.~0Sn~~~.0.lSto0.30Si.0.?0to0.60Ni.0.3OtoO.S0
Cr. 0.08 to 0. IS Mo. 0.0005 to 0.003 B. UNS: 0.28 to 0.33 C. 0.75 to 1.00
hln.0.03SPn~ax.0.~0Sn~~~.0.lSto0.3OSi.O.?Oto0.60Ni.0.30to0.S0
Cr. 0.08 to 0. IS MO. 0.0005 B min. UNS H9-1301 and SAE/AISI 91B30H:
0.27 to 0.33 C. 0.70 to I.05 Mn, 0.15 to 0.35 Si. 0.25 to 0.65 Ni. 0.25 to
0.55 Cr. 0.08 to 0. IS MO. B (can be expected to be 0.0005 to 0.003 percent)
Similar
Steels (U.S. and/or Foreign).
ASTM ASl9: SAE 1104, JJl2.
A304 SAE J I268
93B30. LlNS G9-1301;
1JNS H94301; ASTM
J770. 9JB30H.
Characteristics.
Clearly demonstrates the effects of boron upon hardenability. 91B30H is nearly identical with 86B?OH. although the alloy
ranges (Ni. Cr. Mo) are slightly lower for 91B30H. The hardenability
because of the boron addition is nearly as high for 86B?OH. As-quenched
hardness, which is controlled
mainly by carbon content. is the same for
94B30H as for 86B30H. approximately
46 to 52 HRC
Forging.
temperature
Heat to 1230 ‘C (2250 “F) maximum.
Do not forge after
of forging stock drops below approximately
925 “C (I695 “F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 900 “C t 1650 “F). Cool in ait
Annealing.
For a predominantly
pearlitic structure. heat to 845 “C ( IS55
“F). cool slowly to 730 “C t I ?SOW~F). then cool to 640 “C (I I85 “F). at a
rate not to esceed I I “C (20 “F) per h: or heat to 845 “C ( IS55 “F), cool
rapidly. to 665 “C (I230 “FL and hold for 7 h. For a predominantly
spherotdired
structure. heat to 760 “C (1300 “F), cool rapidly to 730 “C
t I350 “FL then cool to 650 “C t I200 “F), at a rate not to exceed 6 “C ( IO
“F) per h: or heat to 760 “C ( 1100 “F). cool rapidly to 665 “C ( I230 “F).
and hold for IO h
Hardening.
Austsnitire
Tempering.
Parts should be tempered immediately
after quenching
\c hich will pro\ ide the required hardness
the temperature
at 870 “C ( 1600 “FL and quench in oil
at
508 / Heat Treaters
Guide
Processing
Recommended
Sequence
l
l
l
l
l
Forge
Normalize
r\nneal
l
l
Rough and semifinish machine
Austenitize and wench
Temper
Finish machine
94830: Hardness vs Tempering
Temperature.
Composition:
0.28 to 0.33 C. 0.75 to 1 .OO Mn, 0.040 P max, 0.040 S max, 0.20
to0.35Si,0.30to0.60Ni,0.30to0.50Cr,0.08to0.15Mo,0.0005
B min. Approximate critical points: AC,, 720 “C (1330 “F); AC,, 805
“C (1480”F);Ar,, 750°C (1380”F);Ar,, 655°C (1210°F). Recommended themal treatment: forge at 1230 “C (2250 “F), anneal at
815 to 870 “C (1500 to 1600 “F) for a maximum hardness of 174
HB, normalize at 870 to 925 “C (1600 to 1695 “F) for an approximate hardness of 217 HB. quench from 855 to 885 “C (1570 to
1625 “F) in oil. Test specimens were normalized at 900 “C (1650
“F), quenched from 870 “C (1600 “F) in oil, tempered at 56 “C (100
“F) intervals
in 13.7 mm (0.540 in.) rounds. Tested in 12.8 mm
(0.505 in.) rounds. Source: Republic Steel
94B30H: End-Quench
Distance from
quenched
W-fNe
‘[bin.
mm
Hardenability
Hardness,
HRC
min
ma\:
Distance from
quenched
surface
’ 16 in.
mm
Hardness.
HRC
min
may
I
2
I SY
3 16
Sh
56
19
1Y
I!
I-I
20.54
22.12
SO
19
30
2Y
3
4
s
6
7
1.7-t
6 32
7.90
9.33
I I.06
12.64
I-I.22
ss
ss
51
51
5.;
53
s?.
48
48
-I7
46
u
42
39
IS
I6
I8
20
22
2-l
26
‘3.70
15.28
‘8.44
31 60
31.76
37.92
-II 0s
4x
46
4.4
12
40
38
37
28
‘7
2s
24
23
23
22
I0
IS.XrJ
52
II
I2
I7 38
I X.96
51
Sl
37
31
32
28
30
32
44.21
47.10
so 56
3s
3-1
3-t
21
21
20
x
9
Alloy Steel / 509
94B30H: Hardenability
“C (1650 “F). Austenitize:
Hardness
wrposes
I distance.
nm
..5
3
11
13
15
!O
!5
SO
$5
lo
15
50
I distance,
!& in.
2
3
Q
5
6
7
8
9
10
11
12
13
14
15
16
18
20
22
24
26
28
30
32
Curves. Heat-treating
870 “C (1600 “F)
limits for specification
Hardness,
hlaximum
HRC
Minimum
56
49
56
56
55
55
54
53
53
51
47
43
40
31
36
34
49
48
47
46
44
41
38
31
26
24
23
22
21
20
Hardness,
hlaximum
56
56
55
55
54
54
53
53
52
52
51
51
50
49
48
46
44
42
40
38
37
35
34
34
HRC
hlinimum
49
49
48
48
47
46
44
42
39
37
34
32
30
29
28
21
25
24
23
23
22
21
21
20
temperatures
recommended
by SAE. Normalize (for forged or rolled specimens
only): 900
510 / Heat Treaters
Guide
No. 5317
0.50 C. 0.50 Mn. 0.25 Si. I.75 Ni. I .OO Cr
Hardening.
A cold melt. grain controlled. electric furnace steel
heat treatable to combination of hardness and toughness for machine parts
in t\\o classes:
Tempering.
Chemical
Composition.
Characteristics.
Hard tempering group. for gears and other hard parts. hardened and
tempered between 105 to 345 “C WJO to 655 “F)
2. Tough tempering group for parts such as shafts. hardened and tempered
between 370 to 595 “C (700 to I IO5 “F)
Heat to 790 to 8 IS “C f I.455 to 1500 “F). and quench in oil
Temperature used depends on service conditions.
Lower
temperatures (see table beloa ) are used when greater surface hardness and
strength are required. Higher temperatures are used for greater toughness
I
Steel has no special tendencies to decarburize. Machinabilit)
is 65 to 75 percent
of I percent carbon. Mater hardening tool steel. or about SO percent that of
BIII’
Forging.
Heat to I I SO “C i2 100 “F) maximum. Air cool in dQ place. Do
not forge after temperature of forging stock drops belo\i approximate11 8 I5
“Ctl5OO”F)
Recommended
Normalizing.
Heat Treating
Practice
Heat to 815 to 900 “C ( 1555 to 1650 “FJ. Cool in air
Annealing.
Pack steel in container. usmg neutral packing compound. or
treat in controlled atmosphere furnace. Heat parts to 760 “C ( 1400 “F). cool
slowly in furnace at a rate not to exceed I I “C (20 “F) per h until furnace is
black. and may then be turned off and allowed to cool naturally. Parts have
maximum hardness of 201 HB
No. 5-317:
Effect of Tempering
Tempering temperature
OF
T
As quenched
300
350
-u?o
150
500
540
600
700
800
900
loo0
1100
3 mm ( I in. I. seaion.
As quenched
149
177
20-i
232
260
288
316
371
4’7
J82
538
593
oil quenched From 790 “C I 1450 “Fb
Ruckwell ‘C”
56
56
55
54
53
53
52
SO
46
-l-t
40
35
31
510 / Heat Treaters
Guide
CRB-7
MO. I .OOV. 0.25 Cb
soak forging at this temperature until temperature of forging is uniform.
then shut off heat. let forging cool in furnace. Annealing follows
Characteristics.
Recommended
Chemical
Composition.
I.10 C. 0.10 hln. 0.30 Si. I-I.00 Cr. 2.00
A corrosion resistant. \rear resistant. and secondq
hardening. high temperature bearing steel. which has high heat treated
hardness that is maintained at elevated temperatures
Forging.
Preheat slou ly to 815 to 870 “C ( IS00 to 1600 “Ft. then
increase furnace temperature to full heat of I095 to I I?0 YI (2005 to 2050
“F). Do not forge after temperature of forging stock drops below approsimatell 980 “C ( I795 “F). Can be reheated as often as necessary. Slow cool
forgings IO room temperature m dq ash. vemticulite.
or in a furnace \\ hen
forging cooling. First set furnace at about 760 to 790 “C t l-t00 to 1455 “Ft.
CRB-7:
Effect of Tempering
Rnckwell
T
r\s quenched + reirigrratrd
300
l-l9
100
mo
hfxl
700
800
900
loofl
I lcil
Annealing.
Practice
Not recommended
Tno methods are available:
I Pack parts in container. using clean. cast iron borings
1. hned
in a controlled atmosphere furnace with a dew point of I .S to 8
“C (35 to IS “FJ. Heat unifomtl~ to 870 to 900 ‘C (I600 to 1650 “F),
cool slowly in furnace to about 595 “C t I IO5 “F) at a rate not to exceed
6 “C (20 “F) per h. air cool to room temperature.
Temperatures
Tempering temperature
OF
Normalizing.
Heat Treating
‘0-l
160
316
371
427
3x2
S38
SY3
CRB-7:
C
Elevated
Hardness
63.5
61.0
59.5
58.0
5X.0
58.0
605
62 0
53 s
Rockwell
Eardnes
260
316
371
127
482
538
62.5
59.0
58.5
58.0
57.0
56.0
51.0
Room temperature
500
600
700
800
900
1000
“FL and
Hardness
DC
Test temperature
OF
64.0
Parts were oil quenched from I I SO “C (2 IO0 ‘FL refrigwatrd
BI -7S ‘C f-105
tempered I h a~ temperature. Source. Carpenter Technolog? Corporation
Temperature
C
Hardnesses uere measured on specimrw
heat treated as follows: salt quenched from
I ISOYZ t Z IO0 “F) to Ml ‘C t 1000°F~ equaltzcd, then aircooled toroom temperature,
streisrelievedat
ISO”C(3Ot”Fb
I h,refrigcratedat-7S”C(-105”F).douhletempered
2 + 2 hat 525 “C (975 “F). Source: CarpznterTechnolo~
Corporation
Alloy Steel / 511
Average hardness of parts will be 2-I I HB
Hardening. Parts are treated in neutral salt baths or in controlled atmosphere furnaces. For the latter, a dew point of - I7 “C (+ IO “F) is suggested.
For the furnace procedure. oarts are preheated to 800 to 830 “C t 1375 to
IS3 “F). then transferred to a superheating furnace maintained at I I-IO to
I IS5 “C (2085 to 21 IO “F). Small parts may be oil quenched to room
temperature. Preferred practice is to harden by quenching in molten salt at
a temperature of S-IO to 595 “C ( 1000 to I 100 “F). followed by air cooling
to room temperature. Parts are then stress relief tempered at -ISO “C (3%
“F) for I h. For higher hardness and dimensional stability, parts are allowed
to return to room temperature before tempering
Tempering.
Double tempering is recommended for maximum hardness
and dimensional stability. Parts are allowed to return to room temperature
before tempering
Tool Steels
Introduction
Tool steels represent a small, but mlportant segment of the total
production of steel. These steels are made and processed IO meet extremeI>
high standards of qualiy control and are used principally
for tools, dies. and
components of mechamcal de\ ices that demand steels with special properties. Well over IO0 different kinds of tool steels are produced at the present
time. and if all the trade names Mere added together. the total \\ould far
exceed 100.
Tool steels vary in composition
from plain carbon steels containing
carbon with no significant
amounts of alloying
iron and up to 1.X
elements. to veq highly alloyed grades. in which the total allo) content
approaches 50% Many tool steels are identical in composition
to carbon
and alloy steels that are produced in large tonnages. The ditierences lie in
the small amount produced and the high level ofqualitj
control in\ol\ed.
Classification
of Tool Steels. Tool steels do not lend themselves to the type of classification
used by the Societ) of Automotive
Engineers (SAE) and the American Iron and Steel Institute (AISI) for
low-alloy
steels. because in these systems an entire series of steels is
defined numerically, based upon a variation of carbon content alone. \\Iile
some carbon tool steels and low-alloy tool steels are made in a u ide range
of carbon contents. most of the higher alloyed tool steels have a compamlively narrow carbon range makmg such a classiticatlon
meaningless.
Instead a mixed classification
system is used uith tool steels. in M hich some
steels are grouped hy use. others by composition or bq certain mechanical
properties. and still others by the method of heat treatment (precIseI) hy the
quenching technique). High-speed steels are grouped together because the)
have certain common properties, the water-hardening
steels because the)
are hardened in a common manner. the hot \\ork steels because they have
certain common properties, and the high-carbon.
high-chromium
steels
because they have similar compositions
and similar applications.
The American Iron and Steel Institute System. The table
at the end of this introduction
includes compositions
for most of the
proprietary tool steels-Unified
Numbering System (UNS) specifications
are also given. Elements are listed in nominal amounts which ma) vary
someis hat for different tool steel producers. U’hen heat treating shops
receive tools for heat treatment that are identified only by proprictq
name.
the AISI identiticatton
should heobtained before attempting to perform an!
heat treating operation. A number of grades ha\e heen deleted from the
AISI list because thsj were no longer manufactured in signiticant quantities. and the steels listed in the table cover every conceivable
tooling
requirement. Statistics show that over S(Y? of the total tonnage of tool steels
produced is confined to no more than about I? or I5 of the compositions
included in the Table.
The grouping of tool steels published bq AISI has proved MoorlaMe.
and the nine main groups and their corresponding
sjmhols are giLen as
follows~
Identifying
symbol
Name
IVater-hardening
1001 SltXlj
M
Shock-resisting tool steels
Oil-hardrmngsold work tool ~IZZIZ
Air-hardening. medium-alloy cold \rorh tool SIeelb
High-carbon, high-chromium cold \rorli 1o4 steels
S
0
.A
D
hlold steels
P
H
Hot #ark tool steels. chromium, tungsvn. and mol)bdcnum
Tungsten high-speed rool su&
T
hlol) bdenum high-speed tool seeIs
hl
Water-Hardening
Tool Steels. The grades listed in the Table
under the symbol IV are essentially c,arbon steels and are among the least
expensive of tool steels. They must he water quenched to attain the necessary hardness, and except in veq small sizes, will harden with a hard case
and a soft core. These steels ma) be used for a wide variety of tools. but
the) do have limitations.
H’ steels are available in a range of carbon
contents. and the selcctlon of carbon content is based upon whether maximum toughness or mrt\imum wear resistance is the more important. A
lower carbon content pro\ ides maximum toughness. Although all W steels
have rslntivel~
low hardenabilitl.
these grades are usually available as
shallow. medium. or deep hardening. and this property is controlled by the
manufacturer. Of the three compositions
listed. WI is the most extensively
used.
Shock-Resisting
Tool Steels. Steels are listed under the symhol S. As ma) be noted in the Table. the alloy content in these steels varies
uidelj,
resulting in a \yidc variation in hardenability
among the grades.
However. all S steels are intended for applications
that require extreme
chisels.
toughness including
punches, shear knives. and air-operated
Grades Sl (tungsten bearing), and SS (high silicon) are most widely used.
Oil-Hardening,
Cold Work Tool Steels. These grades are
listed in the table under the symbol 0. As agroup, the hardenability ofthese
steels is much higher than that of the W grades: therefore, they can be
hardened hq quenching in oil. Grade 01 is by far the most popular of this
group. A portion of the carbon in 06 is in the form ofgraphite.
which allows
helter machinability,
a factor HI making intricate dies. In addition. the
graphite particles in its microstructure
provide a built-in lubricant, giving
these steels a better die life for deep dra\b ing operations. 07 is sometimes
used for certain dies where it is essential to retain keen cutting edges
hecause these steels have a higher carbon and the tungsten addition.
Air-Hardening,
Medium-Alloy
Cold Work Tool Steels.
The cold work tool steels listed under the symbol A cover a wide range of
carbon and alloy contents, but all habe high hardenability andexhibit a high
degree of dimensional stahilit) in heat treatment. The low-carbon types, A8
and A9. offer greater shock resistance than the other steels in this group, but
are lo\rer in their wear resistance. Type .A7, which has high carbon and
vanadium contents. exhibits maximum abrasion resistance, but should be
restricted to applications where toughness is not a prime consideration.
As
ma) be noted in the Table, A IO is also a graphitic steel, and it has properties
similar IO 06 except that A IO is higher in hardenability. Of the grades listed
in this group. A). is the most wideI> used.
High-Carbon,
High-Chromium
Cold Work Tool Steels.
The cold work steels listed under the symbol D are all characterized by a
high carbon content t I .S to 2% ) and a nominal 12.08 chromium content.
T> pes containing mol> bdenum can he air hardened. All grades of this group
have extremely high resistance to abrasive wear, which increases as the
carbon and vanadium increase. Grade D7 is one of the most abrasion-resistrng steels knon n. and it is often used for such rigorous applications as
brick molds. Ho\\e\er.
the characteristics
uhich provide its abrasion resistance make it \ery difficult to machine or grind. Grade D5, because of its
cobalt addition. can he used for hot fomting or shearing operations at
tempemtures up to 480 “C (895 “F). Of the five grades listed in this group,
D2 is the most \I idsI> used.
Low-Alloy,
Special-Purpose
Tool Steels. The tool steels
listed under the symbol L cover a wide range of alloy content and mechanical properties. They are wideI> used for die components and machinery
parts. Both L6 and the lo\rcr carbon versions of L? are often used for
514 / Heat Treaters
Guide
Classification
and approximate
AISI
UNS
No.
Water-hardening
WI
W2
W5
C
Oil-hardening,
Air-hardening,
A2
A3
Al
A6
A7
A8
A9
AlO
High-carbon,
D?
D3
M
DS
D7
Identifying elements, 70
v
If
hlo
co
Ni
025
2 so
1.50
0.80
I.10
I In
2.00
2.25
0 w,
0.40
0.40
I.40
I.50
3.25
cold work tool steels
0.90
0.90
I .-IS
I.20
medium-alloy
I .tMl
1.60
0.80
0.50
0.90
0.75
1.75
I.00
0 25
cold Hark tool steels
I .OO
I.25
1.00
0.70
2.25
0.55
0.50
1.35
T-30102
T30103
T3Olo-1
T30106
T30 IO7
T30108
no109
T30110
bighchromium
5.00
5.00
I.00
lo0
_ _
3 .2 >
5.00
S.00
2 00
2.00
1.80
I SKI
-1:;5
I OO(Cl
I .29
I Ml
I.25
I On
I .OO
I.00
I.25
I .OO
I.25
I .-lu
I .SO
I50
1.80
cold work steels
11.00
l-7.00
1200
I2.00
I’.00
1.50
2.3
2.3
I so
2.35
special-purpose
L6
Cr
o.;o
0.50
0.50
0.55
0.45
0.50
T30402
l-30403
T3o-Io-1
T3040.5
T30407
Low-alloy,
I2
types of tool steels
tool steels
T3lSOl
T3 1502
T31506
l-3 I so7
01
02
06(b)
07
Si
0.60-I .-m(S)
0.60-1.10(a)
I.10
T-II901
T-l I902
T4 I905
T-II906
T4 I907
SI
S2
S5
S6
Sl
hln
of principal
tool steels
T72301
l-7230’
l-72305
Shock-resisting
compositions
I00
I Ml
-1.00
1.00
I SKI
I.00
3.00
tool steels
T6 I202
T61206
O.SO-l.IO(ar
0.70
I 00
0 75
TS I602
T5 1603
TSl6O-l
T5 160s
TSl606
TSl620
TSl621
0.07
0.10
0.07
0.10
0.10
0.35
0.30
2 00
060
5 00
‘5
-’ -_
I SO
I .70
0.20
O.GiCl
I .so
0.20
0.50
1.2.5
Mold steels
P2
P3
P-l
PS
P6
P20
El
Chromium
0.75
3.50
O.-l0
itlo
I.lO~Al)
hot work tool steels
T?0810
T208ll
I’20812
l-20813
l-208 I J
T20819
HI0
HII
HI2
HI3
HI1
HI9
0.40
0.3S
0.35
0.35
0.40
0.40
3.15
S.00
s.00
S.00
5 00
l.2.s
0.35
0.35
0.30
0.45
0.25
0.50
0.60
0.40
040
O-IO
1.00
I .so
2.00
;:im
4.25
3.50
2.00
12.00
3.00
4.00
4.00
I:&
9.00
II.00
I2.00
I S.00
IS.00
18.00
1.00
200
6.00
2 50
I .SO
I so
I so
1.25
Tungsten hot work tool steels
T-2081 I
I20822
l-20823
TzO82-l
l-20825
r-0826
HZI
H22
H23
HZ-l
H?S
H26
hlolybdenum
H-U
lbgsten
TI
IT!
(81 A\ailsble
hot work tool steel
T208-l’
high-speed tool steels
TllOOl
Tl2002
with different
-1.00
1.00
Ironllnu~dI
0.751a1
0.80
carbon conlen&.
I b, Contains graphw.
(L‘J Opional
I .Ou
2.00
18.00
18.00
5.00
Tool Steels / 515
Classification
and approximate
AISI
UNS
No.
Tl2OOS
Tl2006
TX
TIS
TlNQ8
T170lS
hfolybdeoum
hll
hl2
h13. class I
M3. class 2
hll
h16
h17
hfl0
hl30
hl33
h13-I
h135
M36
Ultrahard
h1-l I
M1?
hl-13
MU
hi&speed
of principal
types of tool steels
Identifying
C
Rmgsleo high-speed tool steels
Tl2004
l-4
TS
T6
compositions
hln
Si
Cr
elements, %
v
w
-1.00
-I.00
-I.50
-I.00
1.00
1.00
2.00
1.50
2.00
5.00
4.00
4.00
1.00
-I.00
4.00
-I.00
4.00
1.00
-l.oCJ
-loo
4.00
3.75-1.50
4.oCJ
1.00
2.00
2.10
3.00
4.00
200
2.00
2.00
I.25
I.15
2.00
1.75-1.20
2.00
4.3
3.75
3.75
1.25
1.00
3.75
3.50.4.00
3 75-1 so
3 504.30
3 50-400
2.00
I.15
I.60
2.00
3.20
I.25
2.75-3.x
0.80-I .3
I .65-2.2.5
I .80-2.00
0.75
0.80
0.80
0.75
I.50
(continued)
hlo
18.00
co
Ni
5.00
8.00
18.00
‘0.00
14.00
I ?.(JO
12.00
5.ocl
5.00
.
tool steels
Tll301
Tll30’
Tll313
TI 1323
Tll301
Tll306
TI 1307
Tll3lO
Tll3.30
Tll333
0.8Ois)
0.85-1.00(a)
I.05
1.20
1.30
0.80
I .OO
0.85-l w(a)
0.80
0.90
TI 13.33
TI I.335
TI 1336
high-speed bol steels
Tll311
Tll3-U
TI 1313
hl-16
M47
hl-48
hlS0
Tll3-U
Tll34.6
Tll347
TI 13-18
TI I350
hlS2
h162
TI 1352
TI 1362
0.90
0.X2-0.88
0 80
0. I s:o.10
0.20-0.4s
I.10
I.10
1.20
I.15
I J.5
I IO
I .-l1- I .52
0.15-0.40
0 78-0.8X
0.85-0.95
1.25-1.3s
0 IS-O.45
0. IS-O.-IS
0.15-0.40
0.15-010
0.20-0.60
0.20-0.60
0. I s-o.40
I.50
6.00
6.00
6.00
5.50
-1.00
I .75
1.00
I so
2.00
9.50-6.75
6.00
6.75
I .so
2.75
5.25
2.00
I.50
9 50. IO.50
0.75-I so
5.75-6.50
8.00
5.00
5.00
s.ocl
-1.50
5.00
8.75
x.00
8.00
9.50
8.w
5.00
3.75
9.50
8.00
6.25
8.25
9.50
0 IS -0.40
3.90-4.7s
4.00-4.90
lO.W- I I .oo
12.00
5.00
8.00
8.00
1.50-5.50
8.00
0.30 max
5.00
8.ocl
8.25
12.00
8.2s
5.00
8.00-10.00
0.30“’ rllax
0.30 max
0.30 max
0.30 max
~a) Available with different cabon sontents. (b) Contains graphite. tc) Optional
applications
tools.
requiring
extreme
toughness
including
punches and heading
Mold %%!I% Tool steels listed under the symbol P are generalI>
intended for mold applications. Types P2 and P6 are low in carbon content
and are usually supplied at low hardness to facilitate cold hubbing of the
impressions. They are then carburized to develop the required surface
properties for injection and compression molds for plastics.
Types P20 and P2l are usually supplied in the pre-hardened condition.
to allow the cavity to be machined and the mold to be placed directly in
service. These grades may be used for plastic molds. zinc die casting dies.
and holder blocks.
Hot Work Steels.
Hot work steels are divided into three groups:
chromium. tungsten, and molybdenum.
Of the grades of chromium hot work steels listed in the Table. grades
HI I and H I3 are the most widelq used. Both of them are also used for
nontooling applications,
notably in the aerospace industry. Principal tooling applications include forging dies and die inserts. blades for hot shearing, and dies for die casting of aluminum alloys. Grades HI1 and HI9 are
sometimes used for applications where greater heat resistance IS required.
Including dies for die casting brass.
The tungsten types are intended for hot work applications
bhcre
resistance to the softening effect of elevated temperature is of greatest
importance. and a lesser degree of toughness can be tolerated. Of the grades
listed in the Table, H2 I and H26 are most often used. Die casting dies for
the copper-base alloys and hot extrusion tools are typical examples of their
applications.
The molybdenum types are low-carbon modifications
of molybdenum
high-speed steels. They offer excellent resistance to the softening effect of
elevated temperature. but similar to the tungsten types. should be restricted
to those applications where less ductility is acceptable. These steels are not
readily available except on a mill delivery basis.
High-Speed Steels. The high-speed steels are divided into three
groups: (a) those bearing the symbol T where tungsten is the major alloying
element; (b) those bearing the symbol M indicating that molybdenum is the
principal alloying element: (c) a group of more highly alloyed steels that
are capable of attaining unusually high hardness values.
TI was one of the original high-speed steels. although all tungsten
grades are used to a limited extent because of the cost and questionable
availability
of tungsten. Of the T steels, general purpose TI and high-vanadium-cobalt Tl5 are most commonly used. Tl5 is used forcutting tools that
are exposed to extremely rigorous heat or abrasion in service.
The hl tool steels generally are considered to have molybdenum as the
principal alloying element. although several contain an equal or a slightly
greater amount of such elements as tungsten or cobalt. Types with higher
carbon and vanadium contents offer improved abrasion resistance. but
machinability
and grindability
may be adversely affected. The series beginning with M-l I is characterized by the capabilib of attaining exceptionally
high hardness in heat treatment. reaching hardnesses as high as Rockwell
C. In addition to being used for cutting tools. some of the M high-speed
steels are successfull>. used for such cold work applications as cold header
die inserts. thread rollmg dies, and blanking dies. For such applications, the
high-speed steels are hardened from a lower temperature than that used for
cutting tools to increase toughness.
Water-Hardening
Tool Steels
(W Series)
Introduction
The v,ater-hardening
tool steels considered here (W I. H’2. and WS) are
essentially carbon steels and are among the least expensive tool steels As
a class, these steels are relatively
low in hardenabilitj.
although they arc
arbitrarily classified and available as shallo\\-hardening.
medium-hardening. and deep-hardening
types. Except in very small sizes. LV steels u’ill
harden with a hard case and a soft core. Their IOU hardenabilitl
is frequently an advantage. because it allows tough core properties in combination with high surface hardness. They are available in a range of carbon
content. allowing for maximum tou@u~ess with loser carbon content or
maximum wear resistance with higher carbon content, depending on
planned use.
Water-hardening
tool steels are most commonly hardened by qusnching in water or brine. However. thin sections may be hardened suitably bj
oil quenching with less distortion
and danger of cracking than if the
sections were quenched in water or brine. In general, these steels are not
normalized except after forging or before reheating treatment. for refining
the grain and producing a more uniform structure. Parts should be protected
against decarbunzation
during au cooling.
These steels are received from the supplier in the annealed condition.
and further annealing is generally not required. Stress relieving prior to
Water-Hardening
mum Hardness.
Tool Steels:
Oil quenched
Section
to 60 HRC
Thickness
vs Mini-
hardening is sometimes emplqcd to minimize distortion and cracking,
particularly
when tools are cornpIe\ or have been severely cold marked
Similarly, prrheatinp prior to austenitizinp
is unusual except for very large
tools or those with intricate crosb sections.
To produce maximum depth of hardness in Nater-hardening
tool steels.
it is essential that the) be quenched as rapidly as possible. In most instances. iiater or a brins solution consisting of IO wt C NaCl in water is
used. For an Eden fa>ter quench. an Iced brine solution may be used. These
steels should be tempered immediately
atier hardening, preferably before
the? feach room temperature. Salt bnthh. oil baths, and air furnaces are all
satlstactoc; for tempenng. However. working temperatures for both oil and
salt are lirmted: the minimum for salt is approximately
I65 “C (330 “F), and
the maximum for oil is approximately
205 “C (100 “F). Tools should be
placed in a \\arm furnace of Y-l to I20 “C (200 to 250 “F) and then brought
to the tempering temperature I$ ith the furnace. The resistance to fracture by
impact initially increases u ith tempering temperature to approximately
I80
‘C i35S “F) but falls off rapidly to a minimum at approximately
260 “C
(500 “F). Double tempering may be requued to temper any martensite that
may have formed from retained nustenite dunng cooling in the first tempering c~cls.
Nater-Hardening
sracking
Tool Steels:
Fracture
Grain Size vs Quench
Tool Steels / 517
Water-Hardening
Tool Steels: Hardness vs Tempering
Temperature.
Specimens held for 1 h at the tempering
temperature in a recirculating-air furnace. Cooled in air to
room temperature. Data represent twenty 25 mm (1 in.) diam
specimens for each steel. Each quenched from temperatures indicated. (a) Shallow hardening: 0.90 to 1 .OOC, 0.18
to 0.22 Mn, 0.20 to 0.22 Si, 0.18 to 0.22 V. (b) Medium hardening: 0.90 to 1 .OO C, 0.25 Mn, 0.25 Si. no alloying elements. (c) Deep hardening; 0.90 to 1 .OOC, 0.30 to 0.35 Mn,
0.20 to 0.25 Si. 0.23 to 0.27 Cr
Water-Hardening
Tool Steels: Hardness vs Tempering Temperature. 1% C. Size: 25 mm (1 in.) round by 51 mm (2 in.) long.
Valid fortempering times from l/2 to 2 h. Quench temperature: 790
“C (1455 “F) in water. First stage: The decomposition of martensite into low-carbon martensite (about 0.25 C) and epsilon carbide
(Fe,&). Epsilon carbide precipitates in the form of film at subgrains, 4 to 8 l.rin. in diam in the martensite. In steels containing
more than 0.8 C, the early part o