HEAT AND CORROSION RESISTANT CASTINGS:
THEIR ENGINEERING PROPERTIES
AND APPLICATIONS
Publication No 266
NiDl
Distributed by the
Nickel Development Institute,
courtesy of Inco Limited
Contents
Pages
Part I. Heat-Resistant Alloy Castings ........................................................... 4-26
Introduction ....................................................................................................... 4
Typical Casting Compositions of Heat-Resistant Alloy Castings, Table I ...... 4
Effect of Constituents ........................................................................................ 5
Groups of Heat-Resistant Alloy Castings ...................................................... 6-8
Chromium-Iron Alloys (HA, HC, HD)
Chromium-Nickel-Iron Alloys (HE, HF, HH, HI, HK, IN-519, HL)
Nickel-Chromium-Iron Alloys (HN, HP, HT, HU, HW, HX)
Chromium-Nickel Alloys (50Cr-50Ni, IN-657)
Selecting the Proper Alloy ................................................................................. 8
Heat-Resistant Alloy Casting Design ................................................................ 9
High-Temperature Mechanical Properties ................................................... 9-15
High-Temperature Corrosion Resistance .................................................. 14,16
Room Temperature Properties ....................................................................... 16
Industrial Applications of Heat-Resistant Alloy Castings
Aeronautical ................................................................................................. 17
Cement ........................................................................................................ 17
Glass & Enameling ................................................................................. 17-18
Heat Treating .......................................................................................... 18-21
Petroleum, Petrochemical Refining &Chemical ...................................... 22-24
Power Plants ............................................................................................... 25
Steel Mill Equipment .................................................................................... 26
Smelting & Refining Equipment ................................................................... 26
2
Part II. Corrosion-Resistant Alloy Castings .......................................................... 27-47
Introduction ............................................................................................................... 27
Typical Casting Compositions of Corrosion-Resistant Alloy Castings, Table V .... 27
Room Temperature Properties ................................................................................. 28
Effect of Constituents ........................................................................................... 29-30
Corrosive Attack ................................................................................................... 30-31
Groups of Corrosion-Resistant Alloy Castings ..................................................... 31-33
Martensitic Alloys (CA-15, CA-40, CA-6NM, CA-6N)
Ferritic and Duplex Alloys (CB-30, CC-50, CD-4MCu)
Austenitic Alloys (CE-30, CF types, CG-8M, CH-20, CK-20, CN-7M, CN-7MS,
IN-862)
Precipitation Hardenable Alloys (CB-7Cu-1, CB-7Cu-2)
Nickel-Base Alloys (CZ-100, M-35, CY-40, Alloy 625, CW-12M, N-12M, Ni-Si)
Corrosion Data ..................................................................................................... 34-37
Industrial Applications of Corrosion-Resistant Alloy Castings .............................. 38-48
Aeronautical .......................................................................................................... 38
Architectural .......................................................................................................... 38
Chemical & Petroleum ....................................................................................... 39-40
Process Industries Equipment ........................................................................... 41-44
Hydraulics .............................................................................................................. 45
Marine ................................................................................................................... 44
Power–Nuclear & Conventional ........................................................................ 45-48
Part Ill. Fabrication Data for Heat & Corrosion-Resistant Alloy Castings .... 49-52
Machining ............................................................................................................. 49-51
Welding ................................................................................................................. 51-52
3
Part I
Heat-Resistant Alloy Castings
The heat-resistant casting alloys are those compositions that contain at least 12% chromium which are
capable of performing satisfactorily when used at temperatures above 1200 ºF. As a group, heat-resistant
compositions are higher in alloy content than the
corrosion-resistant types. The heat-resistant alloys are
composed principally of nickel, chromium and iron together with small percentages of other elements. Nickel
and chromium contribute to the superior heat resistance
of these materials. Castings made of these alloys must
meet two basic requirements:
1. Good surface film stability (oxidation and corrosion resistance) in various atmospheres and at the
temperature to which they are subjected.
2.Sufficient mechanical strength and ductility to meet
high temperature service conditions.
The heat-resistant alloys are listed in Table I along with
their chemical compositions and designations.
Commercial cast heat-resistant alloys can be identified
by designations of the Alloy Casting Institute, now a
division of the Steel Founders' Society of America, and
the American Society for Testing and Materials.* Some
of these materials are also listed in the Aerospace Mate*See ASTM Specification A 297
rial Specifications (AMS) of the Society of Automotive
Engineers, United States Government Military Specifications (MIL), the Society of Automotive Engineers
Specifications and the Unified Numbering System
(UNS) developed by the Society of Automotive Engineers and the American Society for Testing and Materials. Standard ACI designations are listed in Table I.
The Alloy Casting Institute designations use "H" to
indicate alloys generally used in applications where the
metal temperature exceeds 1200 ºF. The second letter
indicates the nominal nickel content, increasing from A
to X.
The chemical compositions of the heat-resistant casting alloys are not the same as those of the wrought
alloys. Therefore, Table I lists only the nearest wrought
alloy AISI type number. Alloy Casting Institute designations or their equivalents should always be used when
identifying castings.
The SAE specification designations use the nearest
wrought composition (AISI type number) and prefix it
with the number 70 ºFor heat-resistant castings: for example, 70310 is equivalent to HK. In the Unified Numbering System, the Jxxxx number series is assigned to
cast steels.
TABLE I
Compositions of Heat-Resistant Alloy Castings
Alloy
Casting
Institute
Designation
HA
HC
HD
HE
HF
HH
HI
HK
1
IN-519
HL
HN
HP
HP-50WZ
HT
HU
HW
HX
Chromium
Nickel
IN-6571
1
Alloy
Type
ASTM
Specification
8-10Cr
28Cr
28Cr-6Ni
28Cr-9Ni
19Cr-9Ni
25Cr-12Ni
28Cr-15Ni
25Cr-20Ni
24Cr-24Ni
30Cr-20Ni
25Ni-20Cr
35Ni-26Cr
35Ni-26Cr
35Ni-17Cr
39Ni-18Cr
60Ni-12Cr
66Ni-17Cr
A217
A297
A297
A297
A297
A297, A447
A297
A297, A351
A567
–
A297
A297
A297
–
A297, A351
A297
A297
A297
50Cr-5ONi
50Cr-48Ni
A560
–
INCO Designation
4
CHEMICAL COMPOSITION, %
Nearest
AISI
Type
UNS
No.
–
446
327
312
302B
309
–
310
–
J92605
J93005
J93403
J92603
J93503
J94003
J94224
–
–
–
–
–
330
–
–
–
–
–
Ni
Cr
C
–
4 max
4-7
8-11
9-12
11-14
14-18
18-22
8-10
26-30
26-30
26-30
19-23
24-28
26-30
24-28
–
J94604
J94213
J95705
–
J94605
J95405
–
–
23-25
18-22
23-27
33-37
33-37
33-37
37-41
58-62
64-68
–
–
bal
bal
Other
0.20 max
0.50 max
0.50 max
0.20-0.50
0.20-0.40
0.20-0.50
0.20-0.50
0.20-0.60
Mn
max
0.35-0.65
1.00
1.50
2.00
2.00
2.00
2.00
2.00
Si
max
1.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
Mo
max
0.90-1.20
0.5
0.5
0.5
0.5
0.5
0.5
0.5
23-25
28-32
19-23
24-28
24-28
15-19
17-21
10-14
15-19
0.25-0.35
0.20-0.60
0.20-0.50
0.35-0.75
0.45-0.55
0.35-0.75
0.35-0.75
0.35-0.75
0.35-0.75
1.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
1.00
2.00
2.00
2.00
2.50
2.50
2.50
2.50
2.50
–
0.5
0.5
0.5
–
0.5
0.5
0.5
0.5
Cb 1.4-1.8; Fe bal
Fe bal
Fe bal
Fe bal
W 4-6; Zr 0.1-1.0; Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
48-52
48-52
0.10 max
0.10 max
0.30
0.30
1.00
0.50
–
–
Fe 1.0 max
Cb 1.4-1.7; N 0.16 max;
Fe 1.0 max
Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
EFFECT OF CONSTITUENTS
Nickel
Nickel is present in cast heat-resistant alloys in
amounts up to 70%. Its principal function is to strengthen
and toughen the matrix. Microstructurally, nickel
promotes the formation of austenite which is stronger
and more stable at elevated temperatures than ferrite.
Nickel contributes to resistance to oxidation, carburization, nitriding and thermal fatigue.
others in the United States, Japan and Britain. Alteration
of the carbide morphology from lamellar to discrete
particles seems to be the important factor; HP-50WZ
(Table I) and IN-657 (Tables I through IV) are examples
of commercial alloys with improved property levels.
Chromium
The iron-chromium-nickel heat-resistant alloys designed for service up to 1200 ºF often have mixed
ferriteaustenite matrices. However, alloys intended for
service above 1200 ºF are austenitic. The compositions
of these alloys are generally adjusted to prevent the formation of ferrite which has a detrimental effect on hightemperature creep-rupture strength. Long-time exposure at high temperatures, e.g., 1500 ºF, can result in
transformation of ferrite to the sigma phase with significant loss of toughness at room temperature. Thus, in
these alloys, the high-temperature strength is based
primarily on the solid solution strengthening of the austenite by the addition of nickel, chromium and certain
minor elements.
The chromium content in heat-resistant alloys varies
from approximately 10 to 30%. Chromium imparts resistance to oxidation (scaling) at elevated temperatures,
and to sulfur-containing atmospheres. Also, chromium
carbides precipitate in the matrix and contribute to hightemperature creep and rupture strength. In some alloys,
chromium increases resistance to carburization. It also
improves the resistance of the alloys to the action of
many other corrosive agents at normal and elevated
temperatures. It promotes the formation of ferrite in the
microstructure.
Other Elements
INFLUENCE OF MICROSTRUCTURE
Carbides also contribute to strengthening these alNickel and chromium have the greatest effect on the
loys. As noted previously, these alloys have carbon
properties of heat-resistant castings but the minor alloycontents ranging from 0.20 to 0.75%. In the as-cast
ing elements also influence the properties.
condition, the microstructures consist of carbides disCarbon content ranges from 0.20 to 0.75%. It pro- persed in an austenite matrix which also contains dismotes dispersion-strengthening through the formation of solved carbon. By interfering with dislocation movecarbide in the structure. Increasing the carbon content ment, these precipitated carbides assist in strengthenimproves the high-temperature strength and creep ing the alloy. During long service at elevated temperaresistance of the heat-resistant alloys at the expense of tures in the range 1000 to 1800 ºF, additional chromium
lower ductility.
carbides precipitate in finely divided form and also asSilicon has a beneficial effect on the high- sist in strengthening the alloys. At temperatures sometemperature corrosion resistance and on resistance to what above 1800 ºF, the primary carbides have a tencarburization. In amounts greater than 2%, it lowers the dency to coalesce and the secondary carbides to redishigh-temperature creep and rupture properties and, in solve in the matrix. Nickel and chromium retard this
general, the silicon content is limited to 1.5% in castings tendency.
intended for service above 1500 ºF. Silicon promotes the
formation of ferrite.
GROUPS OF HEAT-RESISTANT
Manganese, although important in melting operations, has little or no effect on the mechanical properties ALLOY CASTINGS
or corrosion resistance when present in moderate
The heat-resistant alloys can be classified according
amounts.
to composition and metallurgical structure into three
Molybdenum improves the high-temperature creep broad groups:
and rupture strength by promoting stabilization of car1. Chromium-iron alloys: HA, HC, HD.
bides. In some instances, it also increases high2. Chromium-nickel-iron alloys: HE, HF, HH, HI, HK,
temperature corrosion resistance. It slightly increases
IN-519, HL.
resistance to carburization.
3. Nickel-chromium-iron alloys: HN, HP, HT, HU, HW,
Work to improve the creep and stress rupture properHX.
ties of the heat resisting chromium-nickel-iron alloys
In addition, chromium-nickel heat-resistant alloys inthrough the addition of small amounts of tungsten, zirco- clude 50Cr-50Ni and IN-657.
nium, titanium, columbium, nitrogen, or combinations of
A general discussion of each group is followed by a
them, has been pursued for several years under Steel
discussion
of each alloy.
Founders' Society of America sponsorship and by
5
CHROMIUM-IRON ALLOYS
This group consists of alloys in which chromium predominates with up to 30% chromium and up to 7% nickel.
These alloys are ferritic and have relatively low hot
strength. They are seldom used in critical loadbearing
parts at temperatures above 1400 ºF, but have found use
in applications involving uniform heating and certain
atmospheric conditions, such as high-sulfur atmospheres.
The alloys in this group include the HA, HC and HD types.
resistance and is frequently recommended for service in
sigh-sulfur atmospheres where alloys containing higher
nickel cannot be used. Because of its high alloy content,
it is suitable for use up to 2000 ºF. The alloy has moderately high hot strength and excellent ductility. It is widely
used for parts such as conveyors in furnaces, recuperators, coke oven exhaust castings, roasting furnace center shafts and tube support castings. Prolonged exposure at temperatures around 1500 ºF may promote formation of the sigma phase with consequent low ductility
at room temperature.
HA (9Cr)
Type HA is a chromium-molybdenum-iron alloy that is
resistant to oxidation up to about 1200 ºF. The molybdenum content contributes desirable strength properties
to the alloy at these moderate temperatures. Typical
uses are furnace rollers, Lehr rolls, refiner fittings and
trunnions.
HC (28Cr-4Ni max)
The HC type is limited to applications where strength
is not a consideration or for moderate load-bearing
service around 1200 ºF. It provides excellent resistance
to oxidation and flue gases containing sulfur at temperatures as high as 2000 ºF. It is also used where high nickel
content tends to crack hydrocarbons through catalytic
action. Due to the low nickel content, the ductility and
impact toughness are very low at room temperatures
and the creep strength is very low at elevated temperatures. Typical uses are boiler baffles, furnace grate
bars, kiln parts, recuperators, salt pots and tuyeres.
HD (28Cr-6Ni)
HF (19Cr-9Ni)
This type is comparable to the popular wrought
corrosion-resisting 18-8 compositions and is suitable for
use up to around 1600 ºF. It approaches the HH grade
in many properties and combines moderately high hot
strength and ductility. Its microstructure is essentially
austenitic. Typical uses include burnishing and coating
rolls, furnace dampers, annealing furnace parts, etc.
HH (25Cr-12Ni)
This type is one of the most popular of the heatresistant alloys and accounts for about one-fifth of all
heat-resistant casting production. This alloy contains
the minimum quantities of chromium and nickel to supply a useful combination of strength and corrosion resistance for elevated temperature service above 1600 ºF.
The chromium range is high enough to assure good
scaling resistance up to 2000 ºF in air or normal
products of combustion. Sufficient nickel is present,
aided by carbon, nitrogen and manganese, to maintain
austenite as the major phase; however, the
microstructure is sensitive to composition balance. For
high ductility at 1800 ºF, a two-phase structure of
austenite and ferrite is appropriate but such a structure
has lower creep strength If high creep strength is
needed and lower ductility can be tolerated, a
composition balanced to be completely austenitic is
desirable.
The HD type has the best hot strength, weldability
and high-temperature corrosion resistance of the
chromium-iron group. HD can be used for load-bearing
applications up to 1200 ºF, and where only light loads
are involved up to 1900 ºF. It is suitable for use in highsulfur atmospheres. Long exposures to temperatures in
the range 1300 to 1500 ºF may in some cases result in
Alloy HH is covered by ASTM specification A 447
considerable hardening, accompanied by a severe loss
which
recognizes two types. Type I is partially ferritic
of room temperature ductility through the formation of
and
Type
II predominately austenitic. Type I has a maxthe sigma phase. Typical applications are roaster furimum
magnetic
permeability of 1.70 and Type II of 1.05.
nace rabble arms and blades, salt pots and cement kiln
ends.
Because of its high creep strength and relatively low
ductility, Type II is useful in parts subject to high constant
load conditions in the range from 1200 to
CHROMIUM-NICKEL-IRON ALLOYS
1800 ºF Some typical uses are for furnace shafts, beams,
These alloys are characterized by good high- rails and rollers, tube supports and cement and lime kiln
temperature strength, hot and cold ductility, and resis- ends. Type I alloy is used where hot ductility is more
tance to oxidizing and reducing conditions. They are important than hot strength, and is preferred for welding.
useful for atmospheres high in sulfur, particularly under
Both types of HH alloy have good resistance to surreducing conditions. These alloys contain 8 to 22%
nickel and 18 to 32% chromium, and may have either a face corrosion under the various conditions encounpartial or a completely austenitic microstructure. They tered in industry, but are seldom used for carburizing
applications because of embrittlement caused by abinclude types HE to HL.
sorption of carbon. Experience has indicated that HH
alloys can withstand repeated temperature changes or
HE (28Cr-9Ni)
differentials reasonably well; however, they are not genThis type has excellent high-temperature corrosion erally recommended for severe cyclic service such a
6
HI (28Cr-15Ni)
HN (25Cr-20Ni)
This alloy is resistant to oxidation up to 2150 ºF. Its
composition is such that it is more likely to be completely
austenitic than the lower alloys of this group, hence it
has more uniform high-temperature properties. This
type is used for billet skids, conveyor rollers, furnace
rails, lead pots, retorts for magnesium production,
hearth plates and tube spacers.
This alloy has properties somewhat similar to the
more widely used HT alloy but has better ductility. It is
used for highly stressed components in the
1800-2000 ºF range. It has also given satisfactory service in several specialized applications, notably brazing
fixtures at temperatures up to 2100 ºF. Among its applications are chain, furnace beams and parts, pier caps,
brazing fixtures, radiant tubes, tube supports and torch
nozzles.
HK (25Cr-20Ni)
The HK alloy provides one of the most economical
combinations of strength and surface stability at tem- HP (35Ni-26Cr)
peratures up to and above 1900 ºF and accounts for
This alloy is related to the HN and HT types but
almost half of the heat-resistant alloy tonnage.
contains more nickel than the HN alloy and more chroIt can be used in structural applications up to 2100 ºF mium than the HT alloy. This composition makes the HP
but is not recommended where severe thermal shock is a alloy resistant to both oxidizing and carburizing atmofactor. It is used for parts where high creep and rupture spheres at high temperatures and provides high stressstrengths are needed such as steam methane reformer rupture properties in the range 1800-2000 ºF. It is used
tubing, ethylene pyrolysis tubing, gas turbines, furnace for ethlene pyrolysis tubing, steam methane reformer
door arches and chain, brazing fixtures, cement kiln tubing, heat treating fixtures and radiant tubes. Several
nose segments, rabble arms and blades, radiant tubes, proprietary modifications containing columbium and/or
tungsten are also being used.
retorts and stack dampers.
IN-519 (24Cr-24Ni-1.5Cb)
HT (35Ni-17Cr)
About one-seventh of the total production of heatresistant castings is HT alloy because of its value in
resisting thermal shock, its resistance to oxidation and
carburization at high temperatures, and its good
strength at heat treating furnace temperatures. Except
in high-sulfur gases, it performs satisfactorily up to
2100 ºF in oxidizing atmospheres and up to 2000 ºF in
reducing atmospheres. It is used for load-bearing members in many furnace applications, retorts, radiant tubes,
HL (30Cr-20Ni)
cyanide and salt pots, hearth plates and trays quenched
This alloy has excellent resistance to oxidation at with the work.
temperatures over 2000 ºF, and is resistant to corrosion
in flue gases containing a moderate amount of sulfur up HU (39Ni-18Cr)
to 1800 ºF. It is used where higher strength is required
This type has an exceptionally high combination of
than obtainable with lower nickel content alloys. Leading creep strength and ductility up to 2000 ºF and is used
applications are for radiant tubes, furnace skids and where high hot strength is required. It is suited for severe
stack dampers where excessive scaling must be service conditions involving high stress and rapid thermal
avoided, such as in enameling furnace carriers and cycling. HU alloy has good resistance to corrosion by
fixtures.
either oxidizing or reducing hot gases containing
This alloy is a modification of HK alloy in which the
25-20 base has been altered, the carbon content has
been reduced and columbium (niobium) has been
added. As a result, the high-temperature stress-rupture
strength has been improved. It is used for centrifugally-cast catalyst tubes in steam-hydrocarbon reformer furnaces.
moderate amounts of sulfur. Typical uses are heat treating salt pots, quenching trays, fixtures and gas dissociaThe nickel-chromium-iron alloys are fully austenitic
tion equipment.
and contain 25 to 70% nickel and 10 to 26% chromium.
They can be used satisfactorily up to 2100 ºF because
no brittle phase forms in these alloys. They have good HW (60Ni-12Cr)
weldability and are readily machinable if proper tools
The HW alloy performs satisfactorily up to 2050 ºF in
and coolants are used. The specific types of alloys in strongly oxidizing atmospheres and up to 1900 ºF in
this group are HN, HP, HT, HU, HW and HX.
oxidizing or reducing products of combustion, provided
NICKEL-CHROMlUM-IRON ALLOYS
These austenitic heat-resistant alloys have good hot
strength and good resistance to carburization and thermal
fatigue. They are used widely for load-bearing applications and for castings subject to cyclic heating and
large temperature differentials. They will withstand reducing and oxidizing atmospheres satisfactorily but highsulfur atmospheres should be avoided.
that sulfur is low or not present in the gas. The adherent
nature of its oxide scale makes HW alloy suitable for
enameling furnace service where even small flecks of
dislodged scale could ruin the work in process. Hightemperature strength, resistance to thermal fatigue and
resistance to carburization, are obtainable with this alloy
and its high electrical resistivity suits it for electrical
7
heating elements. Other applications are cyanide pots, CHROMIUM NICKEL ALLOYS
gas retorts, hardening fixtures (quenched with the work), Chromium-Nickel Alloy (50Cr-50-Ni)
hearth plates, lead pots, muffles and other parts in
This alloy was developed to improve the resistance of
cyaniding and carburizing operations.
heat-resistant alloys to fuel oil ash. It is widely used
worldwide (and in fact is specified almost exclusively in
HX (66Ni-17Cr)
Europe) for resistance to oil ash corrosion in power
The high-alloy content of this grade confers high re- plants, petroleum refinery heaters and marine boilers at
sistance to hot gas corrosion even in the presence of temperatures up to about 1650 ºF. Its applications insome sulfur and permits it to be used for severe service clude such parts as sidewall and roof hanger supports inapplications where corrosion must be minimized at tem- furnace radiant sections, tube sheets, re-radiation cone
peratures up to 2100 ºF. It is used to great advantage tips in vertical furnaces and for burner parts.
where maximum and widely fluctuating temperatures are
encountered because of its ability to withstand cycling IN-657 (50Cr-48Ni-1.5Cb)
without cracking or severe warping. Thus, a leading
This more recent development is a columbium
application is for quenching fixtures. It is also useful in
(niobium) modification of the 50Cr-50Ni alloy also with
carburizing and cyaniding equipment. Typical applicahigh resistance to fuel oil ash corrosion but with creep
tions in which it gives excellent service include nitriding,
and stress-rupture properties superior to those of the
carburizing and hardening fixtures (quenched with the
50Cr-50Ni alloy. IN-657 is used in petroleum refinery
work), heat-treating boxes, retorts and burner parts.
heaters, marine and land-based boilers in such applications as convection section tube sheets; it is produced
by several U.S. and European foundries under license
from Inco.*
SELECTING THE PROPER ALLOY
The selection of the proper cast alloy for a given
high-temperature application requires knowledge of
various factors and the related mechanical and physical
properties that must be matched with them. Some of
these properties are listed below and are discussed
later under "Alloy Casting Design."
Operating Conditions
Related Property
1. Anticipated service and maximum
temperature of operation
Short-time tensile properties
Creep strength
Stress-rupture properties
Hot ductility
2. Type and size of maximum load
Short-time tensile properties
Creep strength
Stress-rupture properties
Hot ductility
3. Temperature cycling
Thermal fatigue properties
a. Range of temperature cycling
b. Frequency of temperature cycling
c. Rate of temperature change
4. Type of atmosphere or other corrosive Oxidation resistance
conditions
Carburization resistance
Sulfidation resistance
Surface stability
5. Size and shape of part
Temperature gradients
6. Further processing, such as welding
and machining
7. Abrasive or wear conditions
Fabrication data
8. Cost
9. Ease of replacement
The governing economic consideration in the selection of heat-resistant alloy castings is the cost per hour
at operating temperatures. Equipment downtime can
result in a loss of production that is far more expensive
than the cost of the alloy involved. Ease of replacement
–
–
–
must also be considered in the selection of the alloy.
With rare exceptions, the use of heat-resistant alloys is
justified at all temperatures above 1200 ºF.
In selecting heat-resistant alloys for castings, the significant properties that must be considered are shown in
Tables II, III and IV.
*Trademark of the Inco family of companies.
8
HEAT-RESISTANT ALLOY CASTING DESIGN
The properties listed in Table II and Figures 1 through
4, inclusive, are the basis for the design of heat-resistant
alloy castings. This selection is concerned with the ap-
plication of these properties in casting design together
with other design considerations that are not amenable
to tabulation.
TABLE II
Room Temperature Mechanical Properties of Heat-Resistant Alloy Castings
PROPERTY
Tensile Strength, ksi
As-Cast
Aged
HA
HF
Type I Type II
HH
HH
HC
HD
HE
95
2
107
1
70
115
85
–
95
90
92
100
85
86
80
92
HK
IN519
HL
HN
80
90
75
85
75
–
82
–
68
–
71
–
70
75
52
–
38
–
40
–
19
–
13
–
11.5
–
HI
Yield Strength
(0.2% offset), ksi
As-Cast
Aged
65
2
81
1
65
80
48
–
45
55
45
50
50
55
40
45
45
65
50
50
35
–
Elongation in 2 in., %
As-Cast
Aged
23
2
21
1
2
18
16
–
20
10
38
25
25
11
15
8
12
6
17
10
25
–
Brinell Hardness
As-Cast
Aged
180 1
220 2
190
190
–
200
270
165
190
185
200
180
200
180
200
170
190
–
–
24 hours
at
1400 ºF
Furnace
Cooled
27
24 hours
at
1400 ºF
Furnace
Cooled
27
–
Aging Treatment
Modulus of Elasticity
in Tension, ksi x 103
-
- 24 hours – 24 hours 24 hours 24 hours 24 hours
at
at
at
at
at
1400 ºF
1400 ºF 1400 ºF 1400 ºF 1400 ºF
Furnace
Furnace Furnace Furnace Furnace
Cooled
Cooled Cooled Cooled Cooled
29
29
27
25
28
27
27
23
3
192 160
–
–
–
–
27
27
HP
HT
–
27
50Cr- IN
50Ni 657
HW
HX
70
73
68
84
65
73
80
–
4
87
–
40
45
40
43
36
52
36
44
50
–
4
54
–
10
5
9
5
4
4
9
9
15
–
28
–
180
200
170
190
185
205
176
185
–
–
–
–
24 hours 48 hours 48 hours 48 hours –
at
at
at
at
1400 ºF 1800 ºF 1800 ºF 1800 ºF
Air
Air
Furnace
Air
Cooled Cooled Cooled Cooled
27
27
25
25
–
–
–
–
HU
1
Annealed
Normalized at 1825 ºF and tempered at 1250 ºF.
0.2% Proof Stress
4
Minimum
2
3
HIGH-TEMPERATURE MECHANICAL
PROPERTIES
In common with all metals, the load-carrying ability of
heat-resistant casting alloys decreases as the temperature increases. However, the fall-off in strength is less
pronounced than it is with less highly alloyed materials.
At elevated temperatures, metals under stress are
subject to slow plastic deformation as well as to elastic
deformation. Therefore, time becomes a critical factor
and conventional tensile tests do not furnish values that
are useful in design. The data required are those indicating the load which will produce no more than an allowable percentage of elongation at a specified temperature in a given period of time. Thus, the factors of time
and deformation as well as stress and temperature are
involved in high-temperature strength properties.
Creep Strength
The slow plastic deformation that occurs under load
at elevated temperatures is known as creep. In the
design of furnace parts, experience indicates that a
creep rate of 0.0001% per hr is satisfactory for compari-
son of alloys, and Table III shows the data on this basis.
This is sometimes expressed as 1 % creep in 10,000 hr.
It should be kept in mind that when creep is expressed
in the latter terms it does not mean that this rate of creep
can be expected to continue in every instance for 10,000
hours without failure.
Figure 1 and Table III compare the creep strengths
of representative heat-resistant alloy castings.
Creep values that are obtained under constant load
and constant temperature conditions are applicable to
design, however, safety factors should always be incorporated. The safety factor will depend on the degree to
which the application is critical.
Stress-Rupture Properties
Stress-rupture properties determined under constant
load at constant temperature are useful in approximating
the life of the alloy (time to fracture) under the specific
conditions and also for comparing alloys which are
subject to loading that might produce failure in a
relatively short time.
9
30
3
TABLE III
Elevated Temperature Properties of Heat-Resistant Alloy Castings
PROPERTY
Short-Time
Tensile
Strength, ksi, at
1000 ºF
1200 ºF
1400 ºF
1600 ºF
1800 ºF
2000 ºF
HA
HC
HD
HE
HF
Type l Type II
HH
HH
HI
HK
IN-519
HL
HN
HP
HT
HU
HW
–
–
50
30.4
18.7
–
–
–
–
20.2
11.9
6.2
–
–
43
26
14.5
7.5
–
42.4
35
18.8
11
6
–
–
40
19.6
10
–
45
–
20.5
10.7
–
–
–
32
19
10
–
866
4
79
681
2
36
–
–
–
–
–
–
23
15
8
–
–
20
–
17.5
6.9
–
–
–
–
–
–
–
36
4
46
1
29
2
15
–
–
–
–
–
20
28
–
–
–
–
–
40
–
–
8
–
48
40
–
126
44
31
52
–
–
166
154
151
192
–
–
8
4.5
2
0.5
0.15
–
–
8.5
5.0
2.2
0.6
–
–
–
6
3
1.4
–
–
–
–
6.4
3.2
1.6
0.6
–
–
–
–
–
–
–
–
–
184
6.51
2.52
0.53
–
–
–
–
16
8.9
4.4
2.1
–
–
15
8
4.5
–
–
–
10
6
3.6
–
–
–
13
6.7
3.5
1.7
–
–
–
–
–
–
–
304
14.51
7.22
3.83
1.65
–
–
–
–
–
–
–
–
36
23
15
–
–
–
–
–
–
–
–
60
38
21
–
–
–
–
33
18.5
9
–
–
60.5
37.4
21.5
10.9
5.5
–
–
38
26
–
–
–
–
37.5
23.3
12.4
5.6
–
–
391
2
23
3
15
Short-Time Yield
Strength (0.2%
Offset), ksi, at
1000 ºF
1200 ºF
1400 ºF
1600 ºF
1800 ºF
2000 ºF
42
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
31.5
25
15.5
–
–
–
–
17
13.5
6.3
–
–
32.2
19.8
16
7.3
–
–
–
–
–
–
–
–
–
24.4
14.7
8.7
5.0
–
–
1
20
2
13
3
9
–
–
–
–
–
–
–
–
–
–
14.5
9.6
4.9
–
–
29
17.5
11.0
6.2
–
28
26
15
8
–
–
–
–
–
6.2
–
Elongation in
2 in., %, at
1000 ºF
1200 ºF
1400 ºF
1600 ºF
1800 ºF
2000 ºF
–
–
–
–
–
–
–
–
–
–
–
–
–
–
14
18
40
–
–
–
–
–
–
–
–
10
16
16
–
–
–
–
18
30
45
–
–
14
16
18
31
–
–
–
6
12
–
–
–
–
12
16
42
55
–
–
321
432
373
–
–
–
–
–
–
–
–
–
–
37
51
55
–
–
15
27
46
69
–
5
10
26
28
–
Creep Stress
0.0001%/hr, ksi, at
1000 ºF
1200 ºF
1400 ºF
1600 ºF
1800 ºF
2000 ºF
2150 ºF
16
3.1
–
–
–
–
–
–
–
1.3
0.75
0.36
–
–
–
–
3.5
1.9
0.9
0.2
–
–
–
4
2.4
1.4
0.4
–
–
18
6.8
3.9
–
–
–
–
–
3
1.7
1.1
0.3
–
–
18
6.3
3.9
2.1
0.8
–
–
–
6.6
3.6
1.9
0.8
0.15
–
–
10.2
6.0
2.5
0.65
–
–
–
8.61
4.52
1.83
–
–
–
–
7.0
4.3
2.2
–
–
–
–
–
6.3
2.4
1.0
–
–
–
–
5.8
2.8
1.0
–
–
–
Stress to Rupture
in 100 hr, ksi, at
1000 ºF
1200 ºF
1400 ºF
1600 ºF
1800 ºF
2000 ºF
37
–
–
–
–
–
–
–
3.3
1.7
0.85
–
–
–
10
5
2.5
–
–
–
11
5.3
2.5
–
–
33
13.5
7.2
–
–
–
–
–
35
14
6.8
3.2
1.4
–
–
15.5
9.2
4.7
2.2
–
–
141
92
53
–
–
–
15.0
9.2
5.2
–
–
–
–
11
5.6
2.9
–
–
–
10
5.9
2.8
1
4
2
5
1470 ºF
1650 ºF
3
1830 ºF
14
6.4
3.1
1.5
6
1290 ºF
2010 ºF
6
1110 ºF
Stress-rupture properties are a valuable adjunct to
creep-strength values in the selection of heat-resistant
casting alloys and in the establishment of allowable
design stresses. Figures 2, 3, and 4 compare the stressrupture properties of representative casting alloys for
various time periods. Frequently, designers of furnaces
and furnace tubing use the 100,000-hour stress-rupture
properties with some factor of safety. A comparison of
Figures 1 and 2 shows that, in general, stress-rupture
tests rank the alloys in much the same order as the
creep tests.
10
50Cr-50Ni IN-657
446
4
40
361
2
18
–
67
–
–
–
–
–
–
–
13
7.5
4.1
1.9
HX
Ductility
An accurate comparison of hot ductility of heatresistant casting alloys is difficult since there is no generally accepted reference test. Total elongation values
on both creep and stress-rupture tests are often used
as criteria. Also, the elongation in short-time hightemperature tensile tests is commonly used in specifications as an indication of high-temperature ductility. In
many applications where castings are handled at normal
temperatures, room temperature ductility is a consideration. Heat treating to remove sigma phase by
heating castings to 1800 ºF and cooling to below 1200 ºF
improves ductility.
Figure 1– Creep Strength of Heat-Resistant Alloy Castings (HT curve is included in both
graphs for ease of comparison).
11
Figure 2 –1,000-Hour Stress-Rupture Properties of Heat-Resistant Alloy Castings (HT curve is
included in both graphs for ease of comparison).
12
Figure 4–100,000-Hour Stress-Rupture Properties of Several Heat-Resistant Alloy Castings.
13
Short-Time Tensile Properties
Short-time hot-tensile tests in which the test specimen is held at the test temperature for one hour and
then pulled at temperature, cannot be relied upon to
indicate how heat-resistant alloys will behave in service.
The values obtained are as much as five or six times
the limiting creep stress values, and, therefore, greatly
over-evaluate load-carrying ability over long periods of
time. Nevertheless, short-time tensile tests can be helpful in evaluating resistance to momentary overloads and
are included in some specifications. The short-time
mechanical properties for the standard heat-resistant
alloys are given in Table Ill.
Thermal Fatigue
In many high-temperature applications, intermittent
or widely fluctuating temperatures (cyclic heating) are
encountered, and therefore the ability of the various
heat-resistant casting alloys to withstand such thermal
fatigue service must be considered.
Thermal fatigue failure involves cracking caused by
heating and cooling cycles. Crazing and checking of
heat-treating fixtures are typical examples. Such failures are the result of many reversals of thermal stresses
in the part as contrasted to common mechanical fatigue
failures, which are caused by externally applied loads.
Very little experimental thermal fatigue information is
available on which comparison of the various alloys can
be based, and no standard test as yet has been
adopted. Field experience indicates that, usually, resistance to thermal fatigue is improved with increasing
nickel content. Columbium-modified ACI alloys have
been employed successfully where a high degree of
thermal fatigue resistance is desired such as in reformer
outlet headers.
Temperature Gradients
Non-uniform heating or cooling causes temperature
gradients and the attendant unequal dimensional
changes result in stresses within the casting, These
stresses may be accompanied, particularly at high temperatures, by some degree of plastic deformation. The
magnitude of the stress and/or the amount of the plastic
deformation will depend on the temperature differential
within the casting.
mining the life of castings in service. For this reason, the
heat-resistant casting user should consult with the producers in the early stages of design in order to obtain the
benefit of their experience with similar applications.
DESIGN DATA
The curves shown in Figure 5 are constructed to
indicate the values of allowable stress that result from
applications of code criteria to the short-time tensile,
creep, and stress-rupture properties of the heatresistant alloys, HF, HH-II, HK and HN. The ASME
Boiler Code allowable stresses for wrought compositions are included in two of the graphs to offer a comparison.
HIGH-TEMPERATURE CORROSION
RESISTANCE
High-temperature equipment is exposed to many different atmospheres and corrosive conditions and an
important requirement of heat-resistant alloys is surface
film stability. No single alloy will show satisfactory resistance to all of the high-temperature environments.
High-temperature corrosive conditions may involve
simple oxidizing or reducing atmospheres or they may be
complicated by sulfur compounds in the products of
combustion. Oxidizing flue gases are slightly more corrosive than air if the sulfur concentration is low. Corrosive attack by reducing flue gases is similar to that of an
oxidizing gas if the sulfur content is not greater than 100
ppm. At higher sulfur concentrations, attack by reducing
gas is much more severe. The high nickel alloys, types
HN to HW, give good service under oxidizing and reducing conditions if the sulfur content of the gas is low.
Types HH and HL, for example, should be considered
for service in sulfur-bearing atmospheres.
Cyclic heating under reducing conditions increases
metal loss in alloys containing from 10 to 50% nickel.
Under oxidizing conditions, cyclic heating has little effect in alloys containing more than 20% nickel.
Different corrosive conditions are encountered with
equipment in contact with fused salts or molten metals.
Types HT to HX should be considered for service under
these conditions. Still other conditions are met in the
Heat-resistant alloys inherently have high coefficients chemical, petroleum, and petrochemical industries
of thermal expansion and low heat conductivity, both where new processes with new corrosive conditions are
properties tending to produce temperature and stress constantly under development.
In the heat-treating industry, only the high nickeldifferences between various regions of a casting. The
unequal stresses set up within the casting tend to distort chromium alloys give satisfactory service under nitriding
or fracture it; thus, maximum articulation should be de- conditions. Another important process in the heatsigned into elevated temperature parts by making them treating industry is carburization, which is considered in
of a number of small components that are free to expand some detail below.
and contract. All sharp corners and abrupt changes in
Carburization Resistance
section are to be avoided.
When heat-resistant castings are used as muffles,
Proper design, taking all thermal conditions into consideration, is as important as alloy composition in deter- holding fixtures or baskets for work being carburized,
14
Figure 5–Design Data for Four Heat-Resistant Steels.
15
con content should be kept on the high side. Carburization resistance of types HH and HK is improved with
silicon content above 1.6%.
the castings also pick up carbon. The same effect occurs in any high-temperature carbon-bearing atmosphere under reducing conditions. Some alloys absorb
from 0.30 to 2% carbon within a period of several
months when used in a carburizing application. A large
increase in carbon pickup leads to volume changes
which can cause warpage and distortion. The additional
carbon also leads to difficulties if repair welding of the
casting is necessary. Increasing the nickel content reduces the effect of increased carbon content on the
mechanical properties of heat-resistant alloys. Hence,
the nickel-chromium-iron grades HP to HX are preferred
because they withstand thermal fatigue and shock loading at higher carbon levels than alloys with less nickel.
ROOM TEMPERATURE PROPERTIES
The room temperature properties of the various
alloys shown in Table II have little relationship to hightemperature behavior. These properties are useful only
for acceptance purposes and for instances where the
nature of the service requires good strength at room
temperature.
Acceptance tests of a particular composition at room
temperature are used only with the supposition that the
alloy will behave at elevated temperatures in the same
way that the same composition has behaved previously
in the same application.
Resistance to carbon penetration increases as the
nickel content increases and to some extent as the
chromium content increases. Therefore the high nickel
types HP to HX are all good in this respect with the HW
and HX types, being highest in nickel content, rating as
excellent.
The room temperature properties after aging are
given as an indication of the structural stability of the
alloy after high-temperature exposure.
The high chromium types are generally not suitable
for service under carburizing conditions unless other
requirements dictate their selection. In such cases, sili-
The physical properties of the heat-resistant alloys
are given in Table IV.
TABLE IV
Physical Properties of Heat-Resistant Alloy Castings
Property
HA
Density, lb/cu in.
0.279
Mean Coefficient of
Linear Thermal Expansion,
-6
in./in./° F x 10
70 - 212 ºF
6.1
70 - 1000 ºF
7.1
70- 1200 ºF
7.5
70 - 1400 ºF
70 - 1600 ºF
70 - 1800 ºF
70 - 2000 ºF
1200 - 1600 ºF
1200 - 1800 ºF
Specific Heat,
Btu/Ib/° F at 70 ºF
0.11
Specific Electrical
Resistance,
microhm-cm at 70 ºF
70
Thermal Conductivity,
Btu/hr/sq ft/ft/°F
At 212 ºF
15.0
At 1000 ºF
15.7
At 1400 ºF
At 1500 ºF
At 2000 ºF
Melting Point (approx), ºF 2750
Magnetic Permeability Ferro-
HC
0.272
6.3
6.4
6.6
7.0
7.4
7.7
8.7
9.3
0.12
HD
0.274
7.7
8.0
8.3
8.6
8.9
9.2
10.3
10.6
6
2
7
68- 212 ºF
68- 930 ºF
3
68-1470 ºF
4
68-1650 ºF
5
68-1830 ºF
16
1110 ºF
1470 ºF
75 ºF
aCalculated
8
9.6
9.9
10.2
10.5
10.8
11.1
12.2
12.5
9.9
10.1
10.3
10.5
10.6
10.7
11.5
-
0.12
0.14
0.12
77
81
85
80
12.6
17.9
20.3
24.2
2725
12.6
17.9
20.3
24.2
2700
8.5
12.4
14.6
18.2
2650
Ferro- 1.3-2.5
FerroMagnetic Magnetic Magnetic
1
Type
II
Type l
HE
HF
HH
HH
HI
0.277 0.280 0.279 0.279 0.279
9.5
9.7
9.9
10.2
10.5
10.7
11.4
11.7
0.12
9.5
9.7
9.9
10.2
10.5
10.7
11.4
11.7
0.12
9.9
10.0
10.1
10.3
10.5
10.8
11.0
12.0
9.4
9.6
9.8
10.0
10.2
10.4
11.4
9.2
9.4
9.6
9.7
9.9
10.1
10.5
10.7
9.3
9.5
9.7
9.9
10.1
10.2
11.0
HT
HU
0.286 0.290
50Cr- IN
HW HX 50Ni 657
0.294 0.294 0.291a 0.288
9.2
9.5
9.8
10.0
10.3
10.6
11.4
11.9
7.9
8.8
9.1
9.3
9.6
9.8
10.0
10.8
11.0
7.0
7.9
8.2
8.5
8.7
9.0
9.3
10.0
10.3
8.8
9.0
9.2
9.4
9.6
9.7
10.5
10.6
7.8
8.1
8.5
8.8
9.2
9.5
10.7
11.3
-
5.91
7.42
8.33
8.34
8.25
-
0.11
0.11
0.11
0.11
0.11 0.11
-
0.11
978
99.1
102
100
105
112
116
-
988
8.3
8.2
8.2
8.2
7.9 8.2
8.2 7.5
7.5
7.0
7.0
6
12.3 12.0 12.0
12.0
11.8 12.9 12.2 11.0
11.0
10.8
10.8
14.6 14.1 14.1
14.1
14.2
14.7 13.2
13.2
12.9
12.9
7
14.8
17.5 17.5 17.5
18.6
19.3 17.0
17.0
16.3
16.3
2550 2500 2500 2550 2550 2490 2600 2500
2450
2450
2450
1.00 1.0-1.9 1.0-1.05 1.0-1.7 1.02
1.01 1.10 1.02-1.25 1.10-2.00 1.102.00
7.2
11.1
13.3
17.0
2350
16.0
7.2
11.1
13.3
17.0
2350
2.0
-
8.2
6
13.4
7
15.5
2400
-
85
0.13
7.21
9.12
9.33
9.44
9.55
-
HP
0.284
0.11 0.12
75-85 75-85
0.12
INHK
519 HL
HN
0.280 0.286 0.279 0.283
90
94
-
Industrial Applications
of Heat-Resistant Alloy Castings
Typical Applications
AERONAUTICAL
The high temperatures encountered in aircraft power plants
and afterburners have been controlled by the use of heatresistant alloy castings.
Jet engine rotors
Jet engine rings
Afterburner parts
Gun blast tubes
CEMENT
In kiln processes, heat, corrosion and abrasion are constantly attacking operating equipment. High-alloy castings
resist high temperatures, corrosive gases and abrasives and
reduce breakage, shut-down time and rapid wear.
Burner nozzles
Conveyors
Cooler lifters
Dampers
Kiln chains
Typical Applications
Kiln end rings
Kiln feed chutes
Kiln shell segments
Slurry feed pipes
CONTINUOUS CAST CHAIN
Alloy: HH (25Cr-12Ni)
Weight: 50 Ib
Use: Cement Kiln
GLASS AND ENAMELING
In the glass, pottery and enameling industries, handling
equipment must have sufficient strength at elevated temperatures to resist bending and warpage. The alloys used must
resist scaling or flaking to prevent contamination of the product. Some heat-resistant cast alloys have both these characteristics and they are used extensively.
LEHR ROLLS
Alloy: HF (19Cr-9Ni)
Weight: 1040 Ib
Size: 8 in. O.D., 6 in. I.D., 168 in. long
Use: Supports glass without bending at operating temperature of
1500 ºF.
Typical Applications
Trays
Molds
Fixtures
Hangers
Burning tools
Brick supports
Suspension bars
Hearth plates
Kilns and furnaces
Lehr rolls
17
Glass and Enameling (Cont'd.)
MUFFLER ASSEMBLIES
Alloy: HT (35Ni-15Cr)
Size: Each casting 24 in. long, wall thickness ¼ in.
Use: Handle hot gases (1750-1800 ºF) of glassmaking furnace.
ENAMELING FURNACE FLOOR IRONS
Alloy: HT (35Ni-15Cr)
Weight: 575 Ib (large casting)
Use: Operates at 1800 ºF
HEAT TREATING
The advantages of high-alloy castings have been frequently
demonstrated in heat-treating equipment. High temperatures,
heavy loads, thermal shock and the continuous operation of
heat-treating furnaces require the use of heat-resistant alloy
Typical Applications
Trays
Boxes and baskets
Retorts
Fixtures
Conveyor belts and chains
Furnace hearths
Furnace hearth supports
Roller rails
Grates
Roller conveyors
Screw conveyors
Skid rails
Hot fans
Molten metal pots
Furnace muffles
Radiant tubes
Dampers
Heat exchangers
SHAFT FIXTURE ON TRAY
Alloy: HU (39Ni-15Cr)
Weight: 87 Ib
Use: Carburizing furnace
18
castings for long uninterrupted service and low maintenance
and operating costs. The uses of high-alloy castings in heattreating operations are extensive.
Heat Treating (Cont'd.)
GEAR FIXTURE ON TRAY
Alloy: HU (39Ni-18Cr)
Weight: 75 Ib
Use: Carburizing furnace
TRAY WITH CRISS-CROSS FIXTURE
Alloy: HU (39Ni-18Cr)
Weight: 56 Ib
Use: Carburizing furnace
RIVETLESS CHAIN
Alloy: HW (60Ni-12Cr)
Weight: 5 lb each
Size: 5 in. x 6 in. x 1¾in.
Use: Convey parts through hardening
furnace operating at 1650 ºF.
TRAY
Alloy: HU (39Ni-18Cr)
Weight: 40 lb
Use: Roller rail furnace
ARTICULATED TRAY WITH TUBULAR FIXTURE
Alloy: HX (66Ni-17Cr)
Weight: 178 lb
Use: Solution treat aircraft parts (water quenched).
19
GRID WITH LIFTING LOOPS
Alloy: HU (39Ni-18Cr)
Weight: 265 lb
Use: Pit furnace top support
TUBULAR GRID ROLLER TRAY
Alloy: HT (35Ni-17Cr)
Weight: 164 lb
Use: Malleablizing furnace
TUBULAR BASE WITH GRIDS
Alloy: HT (35Ni-17Cr)
Weight: 1170 lb
Use: Pit furnace base support
SIDE HEARTH LINK BELT
Alloy: HH (25Cr-12Ni)
Weight: According to size
Size: 3 in., 4 in., or 6 in. pitch
Use: Convey parts through continuous furnaces
operating at 1600 to 1800 ºF
20
PIT FIXTURE WITH SPACER GRIDS
Alloy: HT (35Ni-17Cr)
Weight: 1173 Ib
Use: Carburizing furnace
PIT FIXTURE CAGE
Alloy: HX (66Ni-17Cr)
Weight: 930 Ib
Use: Solution treat space parts.
PIT FURNACE RING
Alloy: HX (66Ni-17Cr)
Weight: 849 Ib
Use: Solution treat space parts (water quenched).
TRAY WITH TWO CRISS-CROSS FIXTURES
Alloy: HU (39Ni-18Cr)
Weight: 115 Ib
Use: Carburizing furnace
21
PETROLEUM, PETROCHEMICAL REFINING AND CHEMICAL
The heat-resistant grades of high-alloy castings are used
extensively in the petroleum refining industry. High-pressure
and high-temperature refining units depend on high-alloy supports, tubes, headers and other castings which can withstand
excessive heat and corrosion. Metal parts used in refineries
and rectifying plants are subject to extreme temperatures,
heavy loadings, and corrosive liquids and gases. Among heatresistant alloy casting grades are those that assure protection
from deterioration caused by heating and cooling cycling and
resist corrosive media at temperatures up to 2000 ºF. HK-40
and IN-519 are used extensively for catalyst tubes in steamhydrocarbon reforming furnaces. The chromium-nickel alloys,
50Cr-50Ni and IN-657, show excellent resistance to fuel oil
ash attack and are used extensively in Europe to resist this
material.
High-alloy castings serve many applications in the chemical
equipment field where heat-resistant castings are permitting
CAST WELDING WYE
Alloy: HP (35Ni-26Cr)
Weight: 74 lb
Size: 14 in. long, 10 in. center to center
Use: Pyrolysis furnace
22
high output operation under severe corrosive and temperature
conditions.
Typical Applications
Beams and channels
Tube sheets
Pumps
Tubes
Valves
Tube supports and wall ties
Pistons
Heater tubes
Retorts
Fittings
Roof tube hangers
Burners and nozzles
Dampers
U-BEND RETURN
Alloy: HK-40 (25Cr-20Ni)
Weight: 45 Ib
Size: 4 in. O.D. x 10 in. center to center
Use: Ethylene converter furnace
FLANGES AND REDUCERS
Alloy: HF with 5-15% ferrite (19Cr-9Ni)
Weight: 1500 lb (flanges)
Use: High temperature piping in
petrochemical plant.
FURNACE TUBE ASSEMBLIES
Alloy: HP (35Ni-26Cr)
Weight: 500 lb per assembly
Size: 3.75 in. O.D. x 3.12 in. I.D. x 20 ºFt
long Use: Coil, radiant section, pyrolysis
furnace
WELD ELBOW
WITH TRUNNION PAD
Alloy: HK-40 modified with Cb (25Cr-20Ni-Cb)
Weight: 23 Ib
Size: 4 in. O.D. x 3 in. ID
Use: Ethylene converter furnace
VERTICAL TUBULAR BEAM
WITH LOOSE ACCESSORIES
Alloy: HK (25Cr-20Ni)
Weight: 153 Ib
Use: Petrochemical tube support
TUBE SUPPORT
Alloy: HH (25Cr-12Ni)
Weight: 15 Ib
Use: Petrochemical industry
23
TUBE SUPPORTS
Alloy: HH (25Cr-12Ni)
Weight: 6 Ib
Use: Petrochemical industry
SIDE SUPPORTS AND TUBE SHEETS
Alloy: HK (25Cr-20Ni)
Weight: Sheets, 170 lb; supports, 407 lb
HORIZONTAL TUBULAR BEAM WITH ACCESSORIES
Alloy: HK (25Cr-20Ni)
Weight: 253 Ib
Use: Petrochemical tube support
24
HORIZONTAL TUBULAR BEAM WITH ACCESSORIES
Alloy: HK (25Cr-20Ni)
Weight: 299 Ib
Use: Petrochemical tube support
REDUCING ELBOW
Alloy: HK-40 (25Cr-20Ni)
Weight: 10 Ib
Size: I.D. reduction 4½ in. to 1½ in.
Use: Reformer tube assemblies
BURNER DIFFUSER
Alloy: HX (66Ni-17Cr)
Weight: 27 Ib
Use: Petrochemical industry
CENTRIFUGALLY-CAST
FURNACE TUBE
Alloy: HK-40 (25Cr-20Ni)
Weight: 245 Ib
Size: 4 in. O.D. x 3 in. I.D. x 156 in. long
Use: Furnace tube section
POWER PLANTS
Because of the higher operating temperatures being used
in superheater and boiler units, extensive use is being
made of heat-resistant cast alloys. The proper use of
high-alloy castings avoids costly shutdowns and reduces
maintenance requirements
BURNER NOZZLES
Alloy: HE (29Cr-9Ni)
Weight: 10 to 15 lb each
Use: Burners operating at temperatures up to 1800 ºF
Typical Applications
Tube supports
Hanger bolts
Brick and tile supports
Dampers
Nozzles
Beams
Burner diffusers
Valve bodies
25
STEEL MILL EQUIPMENT
The advantages of heat-resistant alloy castings have been
demonstrated by the steel industry in many high-temperature
applications. These alloys are capable of operation at high
speeds, temperatures and loads and provide reliable operation for long periods, thus reducing equipment upkeep and
operating costs.
Typical Applications
Baffles
Furnace beams and rails
Conveyor parts
Furnace doors and frames
Dampers
Retorts
Radiant tubes
Recuperators
Skid rails
Muffles
FURNACE DRUM
Alloy: HK-40 (25Cr-20Ni)
Weight: 10,000 Ib
Size: 60 in. major O.D.
Use: Turn-down roll in steel mill furnace for normalizing sheet.
GUIDES
Alloy: HH (25Cr-20Ni)
Weight: 2 and 14 Ib
Use: Steel rod mill guides
REFRACTORY-LINED BLOWPIPES
Alloy: HP (35Ni-26Cr)
Weight: 600 Ib (pipe)
Size: 10 in. O.D. barrel with 14 in. O.D. bell ends
Use: Steel mill blast furnace
SMELTING AND REFINING EQUIPMENT
Many years ago, this industry recognized the savings that
were possible if high-alloy castings were properly utilized. In
the sintering and smelting of ores, high temperatures, acid
gases and abrasion contribute to the destruction of furnace,
hearth, kiln and sintering machine parts. Heat-resistant alloy
castings reduce operating and maintenance costs by providing durability and heat resistance.
COOLER GRATES
Alloy: HH (25Cr-12Ni)
Weight: 20 to 40 Ib
Use: Iron ore pelletizing and cement kiln
26
Typical Applications
Rabble arms
Feed spouts
Plows
Rabbles
Air arms
Chains
Hearth plates
Lute rings
Grate
Seal plates
Dampers
Furnace tubes
GRATE BARS
Alloy: HH (25Cr-12Ni)
Weight: 12 Ib
Use: Iron ore sintering and pelletizing furnace
Part ll
Corrosion-Resistant Alloy Castings
The corrosion-resistant casting alloys are those compositions capable of performing satisfactorily in a large
variety of corrosive environments. They are composed
principally of nickel, chromium and iron; sometimes also
containing other elements. Castings made of these alloys offer two basic advantages:
1.
2.
VI, the physical properties in Table VII and the heat
treating temperatures in Table VIII.
Commercial cast corrosion-resistant alloy can be
identified by the designations of the Alloy Casting Institute, now a division of the Steel Founders' Society of
America, and the American Society for Testing and
Materials.* Some of these materials are also listed in the
Aerospace Material Specifications (AMS) of the Society
of Automotive Engineers, the United States Government Specifications (MIL and QQ), the Society of Automotive Engineers Specifications and the Unified Numbering System (UNS) developed by the Society of Automotive Engineers and the American Society for Testing
and Materials.
Facility of the production of complex shapes at
low cost.
Ease of securing rigidity and high strength-toweight ratios.
Some typical alloy compositions are given in Table V,
the room temperature mechanical properties in Table
TABLE V
Compositions of Corrosion-Resistant Alloy Castings
CHEMICAL COMPOSITION, %
Alloy
Type
ASTM
(or other)
Specification
AISI
(or other)
Wrought
Comparative
UNS
No.
Ni
Cr
Mo
Cu
C
Max
Mn
Max
Si
Max
Other
CA-15
CA-40
CA-6NM
CA-6N1
CB-30
CB-7Cu-1
12Cr
12Cr
12Cr-4Ni
12Cr-7Ni
20Cr
17Cr-4Ni
A296, A487
A296
A296,A487
A296
A296
A747
410
420
–
–
442
17-4PH2
J91150
J91153
J91540
–
J91803
–
1.0
1.0
3.5-4.5
6.0-8.0
2.0
3.6-4.6
11.5-14.0
11.5-14.0
11.5-14.0
10.5-12.5
18-22
15.5-17.7
0.5
0.5
0.40-1.0
–
–
–
–
–
–
–
–
2.5-3.2
0.15
0.20-0.40
0.06
0.06
0.30
0.07
1.00
1.00
1.00
0.50
1.00
0.70
1.50
1.50
1.00
1.00
1.50
1.00
CB-7Cu-2
15Cr-5Ni
A747
15-5PH2
–
4.5-5.5
14.0-15.5
–
2.5-3.2
0.07
0.70
1.00
CC-50
CD-4MCu
CE-30
CF-3
CF-8
28Cr
26Cr-5Ni
29Cr-9Ni
19Cr-10Ni
19Cr-9Ni
446
–
312
304L
J92615
–
J93423
J92500
4.0
4.75-6.0
8-11
8-12
26-30
25-26.5
26-30
17-21
–
1.75-2.25
–
–
–
2.75-3.25
–
–
0.50
0.04
0.30
0.03
1.00
1.00
1.50
1.50
1.50
1.00
2.00
2.00
CF-20
CF-3M
CF-8M
CF-8C
19Cr-9Ni
19Cr-10Ni
19Cr-10Ni
19Cr-10Ni
A296
A296
A296
A296, A351
A296, A351
MIL-S-867
A296
A296, A351
A296, A351
A296, A351
Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
Cb 0.20-0.35; N 0.05
max; Fe bal
Cb 0.20-0.35: N 0.05
max; Fe bal
Fe bal
Fe bal
Fe bal
Fe bal
304
302
316L
316
347
J92600
J92602
J92800
J92900
J92710
8-11
8-11
9-13
9-12
9-12
18-21
18-21
17-21
18-21
18-21
–
–
2.0-3.0
2.0-3.0
–
–
–
–
–
–
0.08
0.20
0.03
0.08
0.08
1.50
1.50
1.50
1.50
1.50
2.00
2.00
1.50
1.50
2.00
CF-16F
CG-8M
19Cr-10Ni
19Cr-10Ni
303
J92701
9-12
18-21
1.50
–
0.16
1.50
2.00
CH-20
CK-20
25Cr-12Ni
25Cr-20Ni
317
309
J93000
J93402
9-13
12-15
18-21
22-26
3.0-4.0
–
–
–
0.08
0.20
1.50
1.50
1.50
2.00
Fe bal
Fe bal
CN-7M
IN-8623
CW-12M1
20Cr-29Ni
–
–
A296
A296
MIL-S-867
A296, A351
A296, A351
AMS 5365
A296, A351
–
A296, A494
Fe bal
Fe bal
Fe bal
Fe bal
Cb 8XC min, 1.0 max
or Cb-Ta 9XC min,
1.1 max; Fe bal
Se 0.20-0.35; Fe bal
310
–
–
–
J94202
J95150
–
–
19-22
27.5-30.5
23-25
bal
23-27
19-22
20-22
15.5-20.0
–
2.0-3.0
4.5-5.5
16.0-20.0
–
3.0-4.0
–
–
0.20
0.07
0.07
1.50
1.50
1.50
2.00
1.50
1.00
0.12
1.00
1.50
Fe bal
Fe bal
Fe bal
W 5.25 max; V 0.40
max; Fe 7.50 max
CY-401
Ni-Cr-Fe
A296, A494
INCONEL4
alloy 600
–
–
–
bal
bal
14.0-17.0
20-23
–
8.0-10.0
–
–
0.40
0.06
1.50
1.00
3.00
0.75
–
bal
–
–
1.25
1.0
1.50
2.00
–
–
–
bal
bal
bal
–
1.00
1.00
–
26.0-33.0
–
26.0-33.0
–
2.4
Alloy Casting
Institute
Designation
Alloy 6253
1
–
CZ-100
M-351
Ni
Ni-Cu
1
Ni-Mo
Ni-Si
N-12M
–
–
A296, A494
A296, A494
QQ-N-288
A296, A494
–
Nickel 200
MONEL4
alloy 400
–
–
1
3
2
4
ASTM designation
Trademark of Armco Steel Corporation
0.35
0.12
–
1.50
1.00
0.50-1.25
Fe 11.0 max
Cb 3.15-4.50;
Fe 5.0 max
Fe 3.0 max
2.00
Fe 3.50 max
1.00
V 0.60 max; Fe 6.0 max
8.5-10.0 W 1 max
INCO designation
Trademark of the INCO family of companies
Note: ASTM A.296 will be replaced by two new standards, A 743 and A 744 in the 1978 Annual Book of ASTM Standards. A 743 will cover the martensitic and ferritic types and A 744 the
austenitic types. A 296 will appear in the 1978 Book of Standards but will be dropped in the 1979 Book.
*See ASTM Specification A 296
27
TABLE VI
Room Temperature Mechanical Properties of Corrosion-Resistant Alloy Castings
CA- CA
CBCBCDPROPERTY CA-15 CA-40 6NM -6N CB-30 7Cu-1 7Cu-2 CC-50 4MCu CE-30 CF-3 CF-8 CF-20 CF-3M
Tensile
Strength,
ksi
1
200
1352
1153
1004
1
5
6
220 120 140 95
1502
1403
1104
7
Yield
1501 1651 1005 1356 607
Strength
1152 1252
(0.2% offset) 1003 1133
ksi
754 674
Elongation
in 2 in., %
71
172
223
304
11
102
143
184
245 156 157
Brinell
3901 4701 2695
Hardness
2602 3102
2253 2673
1854 2124
Modulus of
Elasticity,
ksi x 103
29
29
–
12a
12a
170
15012b
14512c
13512d
12512e
14512a
14012b
11512c
11012d
9712e
170
15012b
14512c
13512d
12512e
14512a
14012b
11512C
11012d
9712e
512a
912b
912c
912d
1012e
512a
912b
912c
912d
1012e
8a
70
108
95 8b
9
10
95
9711
77
11
77
11
77
11
80
11
CFIN- CWF-8C 16F CG-8M CH-20 CK-20 CN-7M 862 12M
77
11
77
11
82
11
88
11
76
11
69
11
60
72
Alloy
CY-40 625
6
65-90
10
70
6
CZ100
50-65
M-35
10
65-85
N-12M
10
726
65 8a
60 8b
829
4510
6311
3611 3711
3611
3811
4211
3811
4011
4411
5011
3811
3211
25
466
32-5010,13 406 15-3010,13 30-4010,13
466
2 8a
15 8b
259
1510
1811
6011 5511
5011
5511
5011
3911
5211
4511
3811
3711
4811
40
46
20-1010
50-2510
66
15011 156–17011 14911 15011 17611 19011 14411 13011 130
–
150–20010
–
90–
10
130
125–17010
–
–
23
–
21.5
23
–
1957 37512a 37512a 212 8a 2539 19010 14011 14011 16311
31112b
27712c
26912d
26912e
29 29.5 29
28.5
80
11
CF-8M
31112b 193 8b
27712c
26912d
26912e
–
29
206 30-1510
19011
29
25
28
28
28
28
28
28
28
28
28
29
24
–
9
Solution annealed at 2050 ºF. Water quenched from 1900 ºF.
As cast
Water quenched from 2000-2050 ºF.
12
a PH heat treatment H900, minimum values.
b PH heat treatment H1025, minimum values.
c PH heat treatment H1075, minimum values.
d PH heat treatment H1100, minimum values.
e PH heat treatment H1150, minimum values.
13
0.5% extension
1
Air cooled from 1800 ºF. Tempered at 600 ºF.
Air cooled from 1800 ºF. Tempered at 1100 ºF.
3
Air cooled from 1800 ºF. Tempered at 1200 ºF.
4
Air cooled from 1800 ºF. Tempered at 1400 ºF.
5
Air cooled from above 1750 ºF. Tempered at 1100-1150 ºF.
6
Minimum
7
Annealed at 1450 ºF. F.C. to 1000 ºF, then air cooled.
8a
Under 1% Ni
10
2
11
b Over 2% Ni with 0.15 Nitrogen, minimum
TABLE VII
Physical Properties of Corrosion-Resistant Alloy Castings
CACBCBCDPROPERTY CA-15 CA-40 6NM CA-6N CB-30 7Cu-1 7Cu-2 CC-50 4MCu CE-30
Density, Ib/cu in. 0.275 0.275 0.278 0.280 0.272 0.280 0.269a 0.272 0.280 0.277
Specific Heat,
Btu db/°F at 70
0.11
0.11
0.11
0.11
0.11
0.12
0.11
0.14
ºF
Mean Coefficient
of Linear Thermal
Expansion,
in./in./°F x 106
70 - 212 ºF
5.5
5.5
6.0
5.7
6.0
5.9
6.3
70 - 1000 ºF
6.4
6.4
7.0
6.21
6.5
6.4
6.9
9.6
70 - 1200 ºF
7.0
9.9
70 - 1300 ºF
6.7
6.7
6.7
70 - 1400 ºF
10.2
70 - 1600 ºF
10.5
Specific
Electrical
Resistance
microhm
cm at 70 ºF
78
76
78
76
77
77
75
85
Thermal
Conductivity,
Btu/hr/sq
ft/ft/°F
at 212 ºF
14.5
14.5
14.5
12.8
9.9
12.6
8.8
8.5
at 1000 ºF
16.7
16.7
16.7
14.5
17.9
13.4
12.4
Melting Point
_
(approx), ºF
2750
2725
2750
2725
2750
2725 2700 2650
Ferro FerroMagnetic
Ferro- Ferro- FerroFerro- Ferro- over
–
Magnetic Magnetic
Permeability
Magnetic Magnetic Magnetic
Magnetic Magnetic 1.5
1
70-600 ºF
Data from wrought equivalent
aCalculated
2
28
CWAlloy- CZN12M CY-40 625 100 M-35 12M
0.280 0.280 0.280 0.280 0.280 0.280 0.280 0.280 0.279 0.280 0.289 0.292a 0.336 a 0.300 0.305 0.301 0.312 0.334a
CF-3 CF-8
CF20
CF3M
CF- CF- CF- CG- CH- CK- CN8M 8C 16F 8M 20
20 7M
IN862
0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.11
-
-
0.11
0.10 0.13 0.13
-
9.0 9.0 9.6
10.0 10.0 10.4
10.2 -
8.9
9.7
-
8.9
9.7
-
-
-
8.9
-
7.1
7.8
8.2
8.5
8.8
8.9
-
-
-
76.2 76.2 77.9
82
82
9.2
12.1
_
2650
1.203.00
9.3 9.0
10.3 9.9
-
8.9
9.7
-
8.6
9.5
-
8.3
9.4
-
8.6
9.7
-
82
84
90
89.6
-
-
116
129
21
53
-
9.2 9.2 9.4 9.4 9.3 9.4 9.4 8.2 7.9 12.1
12.1 12.1 12.3 12.3 12.8 12.3 12.3 12.0 11.8 -
-
-
8.7
6.3
10.0
34
15.5
-
2600 2575 2600 2550 2600 2550 2550 2600 2600 2650
1.001.50- 1.50- 1.20- 1.00- 1.501.011.30 1.01 3.00 250 1.80 2.00 3.00 1.71 1.02 1.10
-
-
2600 2460 2600 2400
-
71
72
-
1.00
The Alloy Casting Institute and ASTM designations
use "C" to indicate alloys used primarily for their
corrosion-resistant properties. The second letter indicates the nominal nickel content, increasing from A to Z.
The S.A.E. specifications use the nearest wrought
composition (AISI type number) and prefix it with the
number 60 ºFor corrosion-resistant castings; for example, 60304 is equivalent to CF-8. In the Unified Num-
bering System, Jxxxx number series has been assigned
to cast steels.
The chemical compositions of the corrosion-resistant
casting alloys are not the same as those of the wrought
alloys. Therefore, Table V lists only the nearest AISI or
other wrought comparative. Alloy Casting Institute designations or their equivalent should always be used to
identify castings.
TABLE VIII
Heat Treatment of Corrosion-Resistant Alloy Castings
Alloy Casting
Institute Designation
CA-15
CA-40
CA-6NM
CA-6N
CB-30
CB-7Cu-1
CB-7Cu-2
CC-50
CD-4MCu
CE-30
CF-3
CF-8
CF-20
CF-3M
CF-8M
CF-8C
CF-16F
CG-8M
CH-20
CK-20
CN-7M
IN-862
CW-12M
CY-40
Alloy 625
Cz-100
M-35
N-12M
Anneal at
Harden at
1450-1650 ºF
1450-1650 ºF
1450-1500 ºF
1
1900 ºF
1450 ºF, min
1925 ºF
1925 ºF
1450 ºF, min
2050 ºF, min4
2000-2050 ºF
1900-2050 ºF
1900-2050 ºF
2000-2100 ºF
1900-2050 ºF
1950-2100 ºF
1950-2050 ºF
1950-2050 ºF
1900-2050 ºF
2000-2100 ºF
2000-2150 ºF
2050 ºF, min
2150 ºF
2200-2250 ºF
2150 ºF
2100-2150 ºF
1800-1850 ºF
1800-1850 ºF
1900-1950 ºF
-
Temper at
600
600
600
800
ºF, max or 1100-1500 ºF
ºF, max or 1100-1500 ºF
ºF, max or 1100-1500 ºF
2
ºF
900-1150 ºF3
3
900-1150 ºF
-
Quench
air cool
air cool
air cool
air cool
air or furnace cool
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water, oil or air
water
water
water
water
1
Reheat to 1500 ºF, air cool
Aging Temperature
Precipitation hardened
Temperature
Condition
900 ºF
H 900
925 ºF
H 925
1025 ºF
H1025
1075 ºF
H1075
1100 ºF
H1100
1150 ºF
H1150
*Held 3 hours, slowly cooled to 1400-1750 ºF, cooled in water, oil or air.
2
3
EFFECT OF CONSTITUENTS
Chromium
A chromium content of at least 11.5% is required to
provide surface passivity under oxidizing conditions and
to form an inert adherent surface film rich in chromium
oxide which is highly resistant to attack. A higher chromium content broadens the range of oxidizing conditions under which passivity is maintained. The chromium content of corrosion-resistant castings ranges
from 12 to 28% in the ACI alloys.
Nickel
The addition of nickel supplements the passivating
effect of chromium under oxidizing conditions and also
increases the resistance of the alloys to attack under
reducing conditions. Nickel in sufficient concentration
results in a desirable austenitic structure and preserves
this structure through the many heat treatments to
which castings may be subjected during production and
subsequent fabrication. In the higher nickel alloys,
nickel provides increased resistance to most reducing
29
environments. It also provides improved resistance to
those chemical compounds to which nickel is particularly resistant. These are typified by strong alkalies and
halogen compounds. In corrosion-resistant castings,
the nickel content ranges from 1 to 96%.
Molybdenum
Molybdenum has specific beneficial effects in improving resistance to sulfuric, phosphoric and hydrochloric
acids. It also reduces the tendencies toward pitting in
sea water and other chloride solutions. In the ACI alloys,
the molybdenum content ranges from none to 30%.
Other Elements
Although chromium, nickel and molybdenum have
the greatest influence on the properties of corrosionresistant castings, other alloying elements also have
their effects.
Carbon can have a detrimental effect on corrosion
resistance by combining with chromium to form a carbide. This undesirable effect can be eliminated by:
(a) Holding the carbon content below 0.03%.
(b) Introducing columbium or titanium to form carbides of these elements instead of the harmful
chromium carbide.
(c) Heating the alloy to a temperature sufficiently
high to dissolve the carbon and cooling rapidly
enough to hold the carbon in solution.
Columbium is added as a stabilizer to prevent precipitation of chromium carbides.
Copper acts in the same manner as molybdenum to
improve resistance to sulfuric and phosphoric acids.
Selenium in small quantities improves machinability
but it reduces corrosion resistance somewhat.
Silicon also contributes to resistance to reducing
acids such as sulfuric, but impairs resistance to nitric
acid. The silicon content of cast corrosion-resistant alloys
is higher than that of the wrought alloys because this
element contributes the fluidity required to obtain
satisfactory casting characteristics. However, silicon is a
promoter of ferrite formation and, as a consequence,
tends to cause the formation of small amounts of ferrite in
the austenitic matrix. As one result, silicon increases the
resistance of cast corrosion-resistant alloys to chloride
ion stress-corrosion cracking.
CORROSIVE ATTACK
Corrosion is a complex phenomenon in which numerous variables influence not only the severity but also the
type of attack. Therefore, it is not possible to make
specific recommendations for alloy selection in a general publication. Certain limitations on the use of
corrosion-resistant alloy castings and suggestions for
counteracting them are discussed below. Table IX is
included to serve as a guide in selecting candidate
alloys for an environment. Where corrosion data on cast
30
alloys were sparse, data on the wrought counterpart
were included on the assumption that corrosion rates for
both cast and wrought alloys would be similar.
Pitting Corrosion
Stainless steels are subject to localized loss of passivity and subsequent pitting by the action of chloride
ions which penetrate the passive surface films. The
incidence of such pitting is determined by the competition between the chloride ions which destroy passivity
and dissolved oxygen or other oxidizing substances
which passivate the surface. It is affected also by the
composition of the alloy and the exposure conditions.
Favorable factors are the presence of molybdenum and
a high nickel content represented, for example, by the
51% Ni-17% Mo-16.5% Cr compositions which is usually resistant to pitting by chloride solutions even under
adverse conditions. Favorable environmental factors are
a plentiful supply of oxygen or other oxidizing agent or,
conversely, no oxygen at all, a high alkalinity and low
temperature, a medium to high flow rate and freedom
from deposits. The most unfavorable condition is represented by exposure beneath deposits to a stagnant
solution containing some dissolved oxygen. Turbulence
associated with high velocity flow is generally beneficial.
Sensitization
When an austenitic stainless steel containing more
than 0.03% carbon, which is not stabilized by the presence of columbium or titanium, is heated in the 9001400 ºF range, chromium carbide will precipitate at the
grain boundaries. The localized depletion of chromium
may make the alloy susceptible to intergranular attack in
environments in which it ordinarily shows good
resistance. Sensitization can usually be avoided by
keeping the carbon content at 0.03% or less, by adding
small quantities of columbium or titanium, or by heating
to 2000 ºF for one hour per inch of thickness followed by
quenching in water.
Magnetic Properties
The Alloy Casting Institute grades containing up to
4% nickel are all magnetic, as is the CE-30 grade. AIl
other grades fall within the austenitic alloy class, because of their compositions, and are substantially nonmagnetic. A small amount of magnetic ferrite is desirable to facilitate weld repair although this ferrite may not
be detected by a magnet. Occasionally, when the chromium is on the high side of the specification and the
nickel is on the low side, an unbalanced condition will
develop in austenitic alloys that results in the formation
of a two-phase alloy composed of austenite and ferrite
The presence of ferrite in the structure will cause the
alloy to be slightly magnetic. This two-phase structure
will have corrosion resistance in practically all environments equivalent to that of the single-phase austenitic
structure. An exception is in ammonium carbamate solutions such as are encountered in urea production.
Stress-Corrosion Cracking
Under the combined effects of tensile stress and corrosion by specific environments (most commonly concentrated chlorides), certain stainless steel compositions are subject to stress-corrosion cracking. Nickel
has the greatest effect on resistance to this form of
attack. Resistance to such cracking is improved by increasing the nickel content above the 8% level of the
common CF-8 grade.
Although cast austenitic stainless steels are often
considered to be similar to their wrought counterparts,
there is a difference. There is usually a small amount of
ferrite present in austenitic stainless steel castings, in
contrast with the single-phase austenitic structure of the
wrought alloys. The presence of ferrite in the castings is
desirable to facilitate weld repair but also increases
resistance to stress-corrosion cracking. There have
been only a few stress-corrosion cracking failures with
cast stainless steels in comparison with the approximately equivalent wrought compositions. The principal
reasons for this resistance are apparently (a) lower
stresses, (b) silicon added for fluidity is also beneficial
from the standpoint of stress-corrosion cracking and (c)
sand castings are usually tumbled or sandblasted to
remove molding sand and scale which probably tends to
put the surface in compression.
GROUPS OF CORROSION-RESISTANT ALLOY CASTINGS
The iron-base corrosion resistant alloys can be classifed according to composition and metallurgical structure into four broad groups:
1. Martensitic Alloys: CA-15, CA-40, CA-6NM,
CA-6N
2. Ferritic and Duplex Alloys: CB-30, CC-50,
CD-4MCu
3. Austenitic Alloys: CE-30, CF types, CG-8M,
CH-20, CK-20, CN-7M, CN-7MS, IN-862
4. Precipitation Hardenable
Alloys: CB-7Cu-1,
Cb-7Cu-2
In addition, nickel-base corrosion-resistant alloys include nickel, high nickel-copper alloys, high nickelchromium alloys and other proprietary alloys.
MARTENSITIC ALLOYS
CA-15 (12Cr-1Ni)
This alloy contains the minimum content required to
attain surface passivity under oxidizing conditions. It
has good resistance to many mildly corrosive environments that are oxidizing in character. It also has good
resistance to velocity effects in solutions for which it is
suitable. The alloy is used widely for seats and discs in
valves in steam service and for parts of turbines exposed to high velocity steam
CA-40 (12Cr-1Ni)
This is the cutlery type of stainless steel which, by
virtue of its higher carbon content, can be hardened to a
greater depth than type CA-15. It has good corrosion
resistance to many environments, is tough and has
good resistance to abrasion. It is used for chipper
blades, cutter blades, cylinder liners, grinding plugs,
shredder sleeves and steam turbine parts.
CA-6NM (12Cr-4Ni)
This is an iron-chromium-nickel-molybdenum alloy
that is hardenable by heat treatment. In general corrosion resistance, it is similar to CA-15 and has been
widely substituted for CA-15 because of easier processing through the foundry cleaning room. Among uses are
compressor wheels, diaphragms, hydraulic turbine
parts, impulse wheels and pumps and valves for boiler
feedwater service.
CA-6N (12Cr-7Ni)
This is a higher nickel content modification of CA-15
which has an excellent combination of strength, toughness and weldability. It has moderately good corrosion
resistance.
FERRITIC AND DUPLEX ALLOYS
CB-30 (20Cr-2Ni)
Because of its higher chromium content, this alloy has
better resistance to corrosion in many oxidizing environments than the CA alloys. The addition of 2% nickel
enhances corrosion resistance and increases toughness. It also has good abrasion resistance. Uses include pump parts, turbine parts and valve trim.
CC-50 (28Cr-4Ni)
Alloys containing about 28% chromium and up to 4%
nickel are resistant to a number of highly oxidizing media such as hot nitric acid. They are also used in handling corrosives such as acid mine waters which are
oxidizing and may be mildly abrasive. Among applications are cylinder liners, digester parts, pump casings
and impellers.
CD-4MCu (26Cr-5Ni-3Cu-2Mo)
As cast, this alloy has a duplex ferrite and austenite
structure. Because of its low carbon content, there are
only small amounts of chromium carbides distributed
throughout the matrix, but for maximum corrosion resistance, these carbides must be dissolved by suitable heat
treatment. Although the alloy can be precipitation
hardened, the ACI recommends that this alloy be used
only in the solution annealed condition. It is highly resistant to attack by some concentrations of sulfuric and
hydrochloric acids and is exceptionally resistant to
stress-corrosion cracking in chloride-containing solutions or vapors. It has also shown outstanding resistance to such mixtures as nitric-adipic acid slurries and
wet process phosphoric acid slurries. Uses include
compressor cylinders, pump impellers, digester valves
and feed screws.
31
AUSTENITIC ALLOYS
CE-30 (29Cr-9Ni)
This alloy also is resistant to a number of highly
oxidizing corrosives and is particularly used for pumps,
valves and fittings handling sulfite liquors in the paper
industry and some acid slurries in the metallurgical industries. Because of its high chromium content, the
alloy can be made with a higher carbon content than the
CF type alloy without suffering the injurious effects of
carbide precipitation. For the same reason, it may be
used in place of the CF alloys where they must be
welded without subsequent heat treatment. While often
used in the as-cast condition, ductility and corrosion
resistance of the CE alloy may be improved somewhat
by quenching from about 2000 ºF. Uses include digester
necks and fittings, circulating systems, fractionating
towers, pump bodies and casings.
CF Alloys (19Cr-9Ni)
The austenitic alloys containing about 19% chromium, 9% nickel and less than 0.20% carbon constitute
by far the most widely used group of corrosion-resistant
stainless alloys. These alloys are used for handling a
wide variety of corrosive solutions in the chemical, textile, petroleum, pharmaceutical, food and numerous
other process industries. In the chemical industry, they
are particularly useful in handling oxidizing solutions
such as nitric acid and peroxides and mixtures of acids
such as sulfuric and phosphoric with oxidizing salts
such as ferric, cupric, mercuric and chromic salts.
These stainless alloys are resistant to most organic
acids and compounds as encountered in the food, dairy
and pharmaceutical industries. They also are resistant
to most waters including mine, river, boiler and tap
waters. They are resistant to sea water under the high
velocity conditions associated with pumping but are
subject to severe pitting attack in stagnant or slow moving sea water.
The limitation of the CF alloys is that most halogen
acids and halogen acid salts tend to destroy their surface passivity. Thus, they are subject to considerable
attack in such media as hydrochloric acid, acid chloride
salts, wet chlorinated hydrocarbons, wet chlorine and
strong hypochlorites.
For best resistance to corrosion, this alloy is produced
in the low carbon CF-3 and CF-8 grades and should be
solution annealed to prevent intergranular attack in
severely corrosive media. Heat treated CF-3 castings can
be field welded or hot formed without subsequent resolution annealing, a major advantage in many applications.
Columbium (niobium) or columbium plus tantalum
are sometimes added to produce carbide-stabilized CF8C alloy which, after heat treating, can be field welded or
used at elevated temperatures without the precipitation of
chromium carbides and resultant susceptibility to
intergranular attack of chromium depleted regions.
The addition of molybdenum as in grades CF-3M and
CF-8M considerably increases the resistance of the
CF-alloys to such corrosive media as sulfuric, sulfurous
32
and phosphoric acids and to certain hot organic acids
such as formic, acetic and lactic acids. Molybdenum
also improves resistance to pitting in chloride salt solutions and sea water.
Grade CF-16F is similar to grades CF-8 and CF-20
to which small amounts of selenium have been added to
improve the machinability. The corrosion resistance of
this alloy is somewhat inferior to that of the CF-20 alloy
but is adequate for many purposes.
Controlled Ferrite Types
The strength of the CF alloys cannot be improved by
heat treatment but these alloys can be strengthened by
increasing the ferrite phase at the expense of the austenite phase in these duplex microstructures. This fact
has led to the introduction of controlled ferrite types,
designated with an "A" suffix in some CF alloys, i.e.,
CF-3A and CF-8A, for applications where higher
strength is desired than is obtainable in the CF-3 and
CF-8 types. Minimum tensile strengths for these controlled ferrite types are 7 to 10 ksi higher than for the
regular types. The increased ferrite content generally
improves the resistance of the alloy to stress-corrosion
cracking in addition to increasing the strength. Because
of the thermal instability of the higher ferrite microstructure, however, the controlled ferrite types are not considered suitable for service at temperatures above
650 ºF (CF-3A) or 800 ºF (CF-8A).
CG-8M (19Cr-8Ni)
The high molybdenum content of this alloy (3-4%)
gives it improved resistance to hot sulfurous and organic acids and to dilute sulfuric acid. It also has great
resistance to pitting. Uses include dyeing equipment,
flow meter components, pump parts and propellers.
CH-20 (25Cr-12Ni)
With a carbon content of less than 0.20%, this alloy is
similar in corrosion resistance to the CE-30 composition. It is used for specialized applications in the chemical and paper industries. Uses include digester fittings,
roasting equipment, valves and pump parts.
CK-20 (25Cr-20Ni)
This alloy is somewhat similar to the CE and CH types
but has higher nickel content. It is sometimes made with a
columbium, or columbium plus tantalum addition, to
minimize the effect of carbide precipitation. It is used in
the pulp and paper industry to handle sulfite solutions.
Uses include digesters, filter press plates and frames,
mixing kettles and return bends.
CN-7M (29Ni-20Cr)
This designation covers a group of complex nickel
chromium-copper-molybdenum alloys containing more
nickel than chromium. The increased nickel content
together with the addition of copper and molybdenum
give the alloy especially good resistance to sulfuric acid
and to many reducing chemicals. It has good resistance
to dilute hydrochloric acid and to hot chloride salt solutions. The alloy also has excellent resistance to nitric
and phosphoric acids. Uses include filter parts, heat
exchanger parts, mixer components, pickling hooks and
racks, steam jets and ventilating fans; pumps and valves
represent a major part of CN-7M applications.
CN-7MS (24Ni-19Cr-3Mo-2Cu)
The CN-7MS modification of CN-7M was developed
for improved castability and weldability. Its corrosion
resistance is substantially equivalent to the CN-7M
alloy.
IN-862 (24Ni-21Cr-5Mo)
This alloy was developed as an alternative to CN-7M
for service in sea water. With its increased molybdenum
content, it has better resistance to pitting and crevice
corrosion than CN-7M but its corrosion resistance in
sulfuric acid environments is lower. It has excellent
casting and welding properties, thus giving it advantages in production and repair compared with CN-7M.
PRECIPITATION HARDENABLE ALLOYS
CB-7Cu-1 (16Cr-4Ni-3Cu)
This complex chromium-nickel-copper alloy can be
hardened by a precipitation heat treatment after solution
annealing. It is not intended for use in the solution
annealed condition. The alloy can be used in service
requiring corrosion resistance and high strength at temperatures up to 600 ºF. In the precipitation hardened
condition, its corrosion resistance approaches that of the
CF-8 alloy under certain conditions.
CB-7Cu-2 (15Cr-5Ni-3Cu)
This complex chromium-nickel-copper alloy can be
hardened by a precipitation hardening heat treatment
after solution annealing. It is not intended for use in the
solution annealed condition. It has a superior combination of strength, toughness and weldability with moderately good corrosion resistance.
NICKEL-BASE ALLOYS
CZ-100 (95Ni min)
Cast nickel is outstanding for maintaining the purity of
a wide range of drugs, foods and chemicals. It is widely
used for the manufacture of caustics and for handling
caustics in processes where low iron and copper content
in the equipment is important.
M-35 (63Ni-30Cu)
This alloy shows good resistance to attack in reducing
environments. It is widely used in handling sulfuric,
hydrochloric and organic acids in the marine, petroleum, chemical, power, sanitation, plastics, steel and
food processing industries.
CY-40 (74Ni-15Cr)
This nickel-base alloy has a superior combination of
corrosion resistance under a wide variety of conditions
plus high levels of strength, ductility and weldability. It
protects product purity much as nickel does, but is more
*Trademark of the INCO family of companies
resistant to oxidizing conditions. It is stronger and harder than nickel, and as tough. Industries in which it is
used are: dairy, chemical, pharmaceutical, nuclear, petroleum and food processing. Its corrosion resistance to
nitric acid, fatty acids, ammonium hydroxide solutions
and oxidizing conditions in general is superior to nickel.
This alloy is particularly useful in handling corrosive
vapors above 1470 ºF.
Alloy 625 (60Ni-21Cr-9Mo)
This high nickel-chromium-molybdenum alloy, like its
wrought counterpart INCONEL* alloy 625, has excellent
corrosion resistance, especially in sea water, and is
highly resistant to chloride stress-corrosion cracking. It
has superior corrosion resistance in oxidizing atmospheres and to sulfur, and organic and inorganic compounds over a wide temperature range. Cast Alloy 625
has high levels of fatigue and creep strength, above
those of CY-40. Sand-cast Alloy 625 can be air melted
and poured, processed through the cleaning room in the
as-cast condition, and can be welded using SMA
(coated electrode) or GMA (gas metal arc) processes
without preheat or postweld heat treatments.
CW-12M (55Ni-18Cr-18Mo)
This complex nickel-chromium-molybdenum alloy
sometimes contains 5% tungsten and minor amounts of
other elements. It has outstanding resistance to such
highly corrosive media as wet chlorine, strong hypochlorite solutions, ferric chloride and cupric chloride and
is often applied in the handling of such chemicals. It
also has good resistance to boiling concentrated organic acids such as acetic, formic, lactic and fatty
acids. Maximum corrosion resistance is obtained by quenching the cast alloy from an annealing temperature of
2200-2250 ºF.
N-12M (63Ni-30Mo)
This alloy was developed particularly for resistance
to corrosion by hot concentrated hydrochloric acid solutions and wet hydrogen chloride. It is also resistant to
hot concentrated solutions of pure phosphoric acid and
to hot dilute sulfuric acid. The alloy is most resistant
under reducing conditions and is not considered suitable
for handling oxidizing acids or solutions containing
oxidizing salts. Maximum corrosion resistance is obtained by quenching the cast alloy from an annealing
temperature of 2100-2150 ºF.
Nickel-Silicon Alloy (82Ni-10Si)
This nickel-silicon alloy which sometimes also contains 3% copper has exceptional resistance to all concentrations of sulfuric acid up to the boiling point; consequently it is used in the concentration of sulfuric acid. It
is also resistant to many other chemicals including phosphoric, formic and acetic acids under reducing conditions but is not resistant to strong oxidizing acids. Because of its high hardness, this alloy is used extensively
to resist wear, abrasion and galling where corrosion may
33
TABLE IX
Corrosion Data
Corrosive Medium
CA-15
Acetic Acid
5%
10%
15%
20%
30%
40%
50%
60%
80%
99.9%
Acetic Anhydride
90%
Acetic Acid Vapors
30%
100%
Aluminum Acetate
Aluminum Chloride
Aluminum Hydroxide
Aluminum Sulfate
5%
10%
Saturated
Alum (Aluminum Potassium Sulfate)
10%
Saturated
Ammonium Bicarbonate
Ammonium Carbonate
Ammonium Chloride
1%
10%
20%
50%
Ammonium Nitrate
Ammonium Sulfate
1%
5%
10%
Saturated
Bromine Liquid (Dry)
Bromine Liquid (H2O Saturated)
Bromine Water (Dilute)
Calcium Chloride
Calcium Hypochlorite
Chlorine Gas (Moist)
Copper Sulfate
Ethylene Glycol
Fatty Acids
Ferric Chloride
Ferric Sulfate
Ferrous Sulfate
CA-40 CB-30 CC-50
CD4MCu
CF-3 CF-3M
CE-30 CF-8 CF-8M CF-8C CF-16F
CF-20
4
4
4
5
5
5
5
5
5
5
4
4
4
5
5
5
5
5
5
5
3
4
4
4
5
5
5
5
5
5
3
4
4
4
5
5
5
5
5
5
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
3
3
3
3
2
2
2
2
2
2
3
3
3
3
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
3
3
3
3
2
2
2
3
3
3
3
3
3
3
5
5
5
5
2
3
3
2
3
3
5
5
4
5
4*
5
5
4
5
4*
5
5
4
5
4*
5
5
4
5
4*
2
3
1
4
3
3
4
2
5
4*
3
4
2
5
4*
2
3
1
5
3
3
4
2
5
4*
3
4
2
5
4*
4
5
5
4
5
5
4
5
5
4
5
5
1
1
1
2
3
5
2
3
5
1
1
1
2
3
5
2
3
5
5
5
3
3
5
5
3
3
5
5
2
2
5
5
2
2
1
2
1
1
3
4
1
1
3
4
1
1
1
2
1
1
3
4
1
1
3
4
2
2
2*
3*
5
5
2
2*
3*
5
5
2
2*
3*
5
5
2
2*
3*
5
5
2
1*
2*
2*
3*
1
1*
2*
4*
4*
1
1*
2*
4*
4*
1
1
2*
3*
3*
1
1*
2*
4*
4*
1
1*
2*
4*
4*
1
3
3
4
5
5
5
3
3
4
5
5
5
3
3
4
5
5
5
3
3
4
5
5
5
1
1
1
2
4
5
1
2
2
3
5
5
1
2
2
3
5
5
1
1
1
2
4
5
1
2
2
3
5
5
1
2
2
3
5
5
5
5
5
5
4
5
5
4
5
5
5
5
5
5
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
4
4
3
3
1
2
2
1
2
2
3
3
3
3
1
2
2
1
2
2
300 ºF 300 ºF 300 ºF 300 ºF 600 ºF 400 ºF 400 ºF 600 ºF 400 ºF 400 ºF
5
5
5
5
5
5
5
5
5
5
4
4
4
4
2
3
3
2
3
3
4
4
4
4
1
2
2
1
2
2
LEGEND
1. Good resistance to boiling.
2. Good resistance to 160 ºF.
3. Good resistance to 120 ºF.
34
4. Good resistance to 70 ºF.
5. Not recommended.
*Subject to pitting.
**Dilute concentrations.
TABLE IX
Corrosion Data
Corrosive Medium
Fluosilicic Acid
Formic Acid
5%
10%
50%
100%
Hydrochloric Acid
Hydrobromic Acid
Hydrofluoric Acid
Hydrogen Peroxide
Lactic Acid
5%
10%
100%
Magnesium Chloride
Magnesium Sulfate
Nickel Chloride
Nickel Nitrate
Nickel Sulfate
Nitric Acid
5%
20%
40%
50%
65%
100%
Oxalic Acid
5%
10%
25%
50%
Phosphoric Acid (Pure)
5%
10%
25%
50%
85%
Potassium Sulfate
Sodium Carbonate
Sodium Chloride
Sodium Hydroxide
< 20%
20-30%
30-50%
50-70%
70-80%
Sulfuric Acid
5-10%
10-20%
20-40%
40-60%
60-75%
75-85%
85-90%
90-100%
Zinc Chloride
Zinc Sulfate
CA-15 CA-40 CB-30 CC-50 CD-4MCu CE-30
CF-3 CF-3M
CF-8 CF-8M CF-8C CF-16F
CF-20
5
4
5
5
5
5
5
5
4
5
4
4
4
5
5
5
5
3
4
4
4
5
5
5
5
3
4
4
4
5
5
5
5
3
4
4
4
5
5
5
5
3
2
2
3
3
5
5
5
2
2
2
3
3
5
5
5
2
2
2
3
3
5
5
5
2
1
1
1
2
5
5
5
2
2
2
3
3
5
5
5
2
2
2
3
3
5
5
5
2
3
5
5
5
5
5
3
5
3
5
5
5
5
5
3
5
3
5
5
5
3
5
2
5
3
5
5
5
3
5
2
5
1
2
2
4*
2
4*
2
1
2
3
3
5
2
4*
2
3
2
3
3
5
2
4*
2
3
1
2
2
5
1
4*
2
2
2
3
3
5
2
4*
2
3
2
3
3
5
2
4*
2
3
3
3
4
4
4
5
3
3
4
4
4
5
2
2
3
3
3
4
2
2
3
3
3
4
1
1
1
1
1
4
1
1
1
1
2
4
1
1
1
1
2
4
1
1
1
1
3
4
1
1
1
1
2
4
1
1
1
1
2
4
4
5
5
5
4
5
5
5
3
4
4
5
3
4
4
5
1
2
2
2
2
3
3
4
2
3
3
4
1
2
2
3
2
3
3
4
3
3
4
5
3
3
5
5
5
4
4
5
3
3
5
5
5
4
4
5
3
3
4
4
4
3
3
4*
3
3
4
4
4
3
3
4*
1
1
1
1
2
1
1
2*
1
1
2
2
3
3
2
3*
1
1
2
2
3
3
2
3*
1
1
1
1
2
2
1
2*
1
1
2
2
3
3
2
3*
1
1
2
2
3
3
2
3*
4
4
5
5
5
4
4
5
5
5
4
4
5
5
5
4
4
5
5
5
1
2
2
5
5
1
2
2
5
5
1
2
2
5
5
1
2
2
5
5
1
2
2
5
5
1
2
2
5
5
5
5
5
5
5
5
5
4
5
5
5
5
5
5
5
5
5
4
5
5
5
5
5
5
5
5
5
4
5
5
5
5
5
5
5
5
5
4
5
5
2
2
3
4
4
3
2
2
3*
1
4
5
5
5
5
5
4
3
5
4
4
5
5
5
5
5
4
3
5
4
3
3
5
5
5
5
3
2
3*
2
4
5
5
5
5
5
4
3
5
4
4
5
5
5
5
5
4
3
5
4
(Continued on pages 36 and 37)
NOTE:
It is not the purpose of this table to make specific recommendations. It should be used simply as a guide to indicate the most suitable candidate
alloys. The effects of contamination, velocity, aeration, etc., will all tend to alter the rating of an alloy exposed to a corrosive environment.
35
TABLE IX
Corrosion Data
Corrosive Medium
Acetic Acid
5%
10%
15%
20%
30%
40%
50%
60%
80%
99.9%
Acetic Anhydride
90%
Acetic Acid Vapors
30%
100%
Aluminum Acetate
Aluminum Chloride
Aluminum Hydroxide
Aluminum Sulfate
59%
10%
Saturated
Alum (Aluminum Potassium Sulfate)
10%
Saturated
Ammonium Bicarbonate
Ammonium Carbonate
Ammonium Chloride
1%
10%
20%
50%
Ammonium Nitrate
Ammonium Sulfate
1%
5%
10%
Saturated
Bromine Liquid (Dry)
Bromine Liquid (H2O Saturated)
Bromine Water (Dilute)
Calcium Chloride
Calcium Hypochlorite
Chlorine Gas (Moist)
Copper Sulfate
Ethylene Glycol
Fatty Acids
Ferric Chloride
Ferric Sulfate
Ferrous Sulfate
CH-20 CK-20
CN-7M N-12M CW-12M
Alloy
625
Ni-Si
Alloy
CZ-100
M-35
CY-40
2
2
2
2
2
2
2
3
3
3
2
2
2
2
2
2
2
3
3
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1
1
2
2
2
2
2
2
2
2
3
3
1
1
1
1
1
3
3
2
3
4
2
5
4*
3
4
2
5
4*
1
1
1
4
2
1
1
1
1
1
1
1
1
3
1
1
1
1
4
2
1
1
1
2
1
3
3
3
2
2
3
3
3
2
2
2
2
2
2
2
2
3
4
2
2
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
5
3
3
5
3
3
3
3
3
1
1
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
3
5
2
2
3
5
2
2
3
4
2
2
1*
2*
4*
4*
1
1*
2*
4*
4*
1
1*
2*
2*
2*
1
1
1
2
2
2
1
1
1
1
1
1*
1*
1*
2*
1
1
1
2
2
2
1
1
1
1
5
1
1
1
1
5
1
2*
2
2*
1
1
2
2
3
5
1
2
2
3
5
1
1
1
1
3
1
1
1
1
3
1
1
1
1
2
1
1
1
1
3
1
1
1
1
3
3
3
3
3
1
3
3
3
3
1
3
3
3
3
1
5
5
4
3
2
3
3
3
3
3
5
2
5
5
4
2
400 ºF
5
5
3
5
2
5
5
4
2
400 ºF
5
5
3
5
2
5
5
2
1
600 ºF
5
3
3
5
5
3
2
2
3
2
5
5
4
3
1
3
3
5
5
5
5
3
4
5
5
5
4
3
1
4
3
1
1
1
4
1
1
4
2
2
1
1
1
1
1
400 ºF 400 ºF 600 ºF+ 600 ºF+ 600 ºF+ 600 ºF 400 ºF
5
5
5
5
2
4
5
3
3
2
5
2
2
5
2
2
1
2
1
1
2
LEGEND
1. Good resistance to boiling.
2. Good resistance to 160 ºF.
3. Good resistance to 120 ºF.
36
4. Good resistance to 70 ºF.
5. Not recommended.
*Subject to pitting.
**Dilute concentrations.
TABLE IX
Corrosion Data
Corrosive Medium
Fluosilicic Acid
Formic Acid
5%
10%
50%
100%
Hydrochloric Acid
Hydrobromic Acid
Hydrofluoric Acid
Hydrogen Peroxide
Lactic Acid
5%
10%
100%
Magnesium Chloride
Magnesium Sulfate
Nickel Chloride
Nickel Nitrate
Nickel Sulfate
Nitric Acid
5%
20%
40%
50%
65%
100%
Oxalic Acid
5%
10%
25%
50%
Phosphoric Acid (Pure)
5%
10%
25°%
50%
85%
Potassium Sulfate
Sodium Carbonate
Sodium Chloride
Sodium Hydroxide
<20%
20-30%
30-50°%
50-70%
70-80%
Sulfuric Acid
5-10%
10-20%
20-40%
40-60%
60-75%
75-85%
85-90%
90-100%
Zinc Chloride
Zinc Sulfate
Alloy
CH-20 CK-20 CN-7M N-12M CW-12M 625
Ni-Si
Alloy
CZ-100 M-35 CY-40
5
5
3
3
2
2
3
4
1
4
2
2
3
3
5
5
5
2
2
2
3
3
5
5
5
2
1
1
1
1
5
5
4
2
2
2
3
3
2
2
4
5
1
1
1
1
3
3
3
3
1
1
1
1
4
3
4
3
2
2
3
3
5
5
4
5
2
2
2
2
3**
5**
4
3
1
1
1
1
3**
5
1
4
2
2
2
2
4**
5
4
2
2
3
3
5
2
4*
2
3
2
3
3
5
2
4*
2
3
1
1
1
4*
1
3*
2
1
3
4
4
1
1
1
4
2
1
1
2
1
1
2
2
1
1
1
2
1*
1
3*
2
2
3
4
4
1
1
3
5
2
3
3
3
1
2
2
5
2*
2
2
2
1
2
2
5
2*
2
2
2
2*
2
3*
3
2
1
1
1
1
2
4
1
1
1
1
2
4
1
1
1
1
2
3
5
5
5
5
5
5
1
2
3
3
4
5
2
3
3
3
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
3
3
3
3
3
3
2
3
3
4
2
3
3
4
1
1
1
1
1
1
2
3
1
1
1
1
1
1
1
1
1
3
3
4
3
3
3
3
2
2
2
2
3
3
3
3
1
1
1
2
3
3
2
3*
1
1
1
2
3
3
2
3*
1
1
1
1
2
1
1
1*
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
2
1
1
1
4
4
4
4
4
3
1
2
1
1
2
2
3
1
1
1
3
3
3
3
3
2
1
2*
1
2
2
5
5
1
2
2
5
5
1
1
1
270 ºF
270 ºF
1
1
1
4
4
1
1
1
4
4
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
5
5
5
5
5
4
3
5
4
4
5
5
5
5
5
4
3
5
4
2
1
2
1
2
1
3
1
3
2
3
2
2
2
225 ºF 250 ºF
2*
1
1
1
1
1
2
2
2
2
2
2
2*
1
1
2
3
4
4
4
3
2
2*
1
1
1
1
1
2
2
2
2
1
1
4
4
4
5
5
5
5
4
2
2
2
2
4
4
5
5
5
4
1
1
3
3
3
4
5
5
3
3
2*
3
NOTE:
It s not the purpose of this table to make specific recommendations. It should be used simply as a guide to indicate the most suitable candidate
alloys The effects of contamination, velocity, aeration, etc., will all tend to alter the rating of an alloy exposed to a corrosive environment.
37
Industrial Applications
of Corrosion-Resistant Alloy Castings
AERONAUTICAL
Although the greatest use for high alloys in this industry
is for engine parts required to withstand high temperatures,
there are applications for the corrosion-resistant grades in
components that must resist both corrosive and erosive
effects to insure dependable operation.
BALL VALVE
Alloy: CF-8 (19Cr-9Ni)
Use: Cryogenic ball valve for service on advanced rocket engine.
Typical Applications
Fuel jets
Fuel valves
Engine supports
CONTROL VALVE
Alloy: CB-30 modified
Use: Aircraft fuel control valve subject to high rate fuel impingement on 2000
mph aircraft.
ARCHITECTURAL
The cast chromium-nickel alloys are used as ornaments
and other components in the architectural treatment of
buildings, bridges, etc. Where these will be exposed to a
marine environment, the molybdenum-containing austenitic
grades have the most satisfactory resistance to corrosion.
38
Typical Applications
Ornaments
Hand rail fittings
Fire wall fittings
Grilles
CHEMICAL AND PETROLEUM
Chemical
The corrosion-resistant alloys have their widest application
in the chemical industry. Their function is two-fold: they provide good equipment life and prevent product contamination.
Many chemical operations would not be economically feasible
if it were not for the corrosion and abrasion-resistant properties
of these alloys.
Typical Applications
Grinders
Mixers
Pumps
Valves
Nozzles
Vessels
Piping and fittings
Conveyors
Petroleum
Cast corrosion-resistant alloys of all types are used extensively in the petroleum industry to withstand the corrosive
effects of moist sulfur and carbon dioxide-bearing gases, sour
crudes, sulfuric acid and caustic treating equipment, phosphoric acid, salt water and the many forms of organic acids
produced as by-products during the refining operations.
Typical Applications
Valves
Pumps
Heater tubes
Pipe fittings
Nozzles
CENTRIFUGAL PUMP CASING AND COVER
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 4000 Ib each pump
Use: Pump to circulate 5500 gpm of highly corrosive chemicals with low
specific gravity.
CENTRIFUGALLY-CAST FLANGE
Alloy: CH-20 modified with free ferrite controlled at 5-15% (25Cr-12Ni)
Weight: 150 Ib
Size: 4 in. 2500 Ib welding neck flange @ 14 in. flange O.D. x 3 in. thick x 4½
in. neck O.D. x 7¾ in. O.A.L.
Use: Hydrocracker refinery unit
PRESSURE VESSEL
Alloy: CK-20 (25Cr-20Ni)
Weight: 8,900 Ib
Use: Dissolver vessel in chemical processing plant.
PROCESS PIPING
Alloy: CF-3M (19Cr-10Ni-2Mo)
Weight: 1400 Ib
Size: 16 in. O.D. x ¾ in. wall; flange 26 in. O.D.
Use: Acetic acid processing
39
BUTTERFLY VALVE-AUTOMATIC, ON-OFF
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: Body and disc 300 Ib
Size: 12 in.
Use: Chemical service
BUTTERFLY VALVE–AUTOMATIC CONTROL
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 600 Ib
Size: 24 in.
Use: Chemical service
PUMP COMPONENTS
Alloy: CF-8 (19Cr-9Ni) and CF-8M (19Cr-9Ni-2Mo)
Parts: Housings, gears, impellers
Use: Pumps in a variety of applications primarily in
the Chemical Processing Industry.
All parts are investment castings
PUMP
Alloy: CG-8M (Modified)–wetted parts
Size: 16 in.
Use: Flash cooler service in
phosphoric acid plant.
GATE VALVE
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: Body casting, 1603 lb;
bonnet casting, 414 Ib
Use: Wedge gate valve for chemical
plant service.
40
PROCESS INDUSTRIES EQUIPMENT
Food Processing
The corrosion-resistant stainless steels are widely used in
all types of food handling equipment. Their good resistance to
both corrosion and abrasion avoids the hazard of contamination with metal compounds that might be toxic or might lead to
food spoilage.
Typical Applications
Mixers
Grinders
Valves
Pumps
Agitators
Nozzles
Disintegrators
Screw spindles
Screens
Metal Mining and Refining
The austenitic stainless steels have good resistance
to all mine waters which contain sulfur compounds. The
CF-8M alloy is usually reliable for most of these
conditions.
In the sulfuric acid leaching of copper ores, the CN-7M alloy
is used in pumps and valves required to handle the 66° Bé
sulfuric acid solution. The copper-containing solution accumulated after leaching is resisted satisfactorily by the CF-8M
alloy.
The CN-7M alloy is also widely used in the sulfuric acid
treatment of phosphate ore for the production of phosphoric
acid.
Typical Applications
Valves
Pumps
Pipe fittings
Filters
Pharmaceutical
The CF alloys (19Cr-9Ni) are widely used in the pharmaceutical industry and in the fine chemical industry in corrosive
as well as in relatively non-corrosive environments for maintaining purity and color of the products. Stainless steels are
used in processing Vitamin C, acid solutions containing chloroform, ammonium sulfate, sodium sulfite and to resist organic
acids from protein extraction and biological mediums.
Plating
The austenitic stainless steels are used in the electroplating
industry for equipment to handle alkaline cyanide copper plating
baths, sulfuric acid copper plating baths and some chromic acid
plating baths. They are employed in pumps and valves in
equipment used for the storage and handling of 66° Bé sulfuric
acid. The stainless steels are not suitable for handling nickel
chloride and other type plating baths. Tests should be conducted in solutions of this type to determine the suitability of
alloys such as N-12M and CW-12M.
The austenitic stainless steels are used in equipment for
handling the nitric-phosphoric bright-dip solution for aluminum.
Typical Applications
Valves
Pumps
Filters
Fittings
Typical Applications
Pumps
Valves
Agitators
Nozzles
Pulp and Paper
The severely corrosive conditions developed in both
the sulfite and the sulfate treating of wood require use of
corrosion-resistant alloys for good service life and to
avoid contamination by corrosion products. In the sulfite
process, alloys having good resistance to acid
environments are required while in the sulfate process
alloys are required that have good resistance to caustic
environments. Frequently, an alloy will be found that has
satisfactory resistance to conditions encountered in both
operations.
Many of the corrosion-resistant alloys have excellent
resistance to erosive effects. This property is exploited
in early grinding steps as well as in subsequent steps
employed in processing the wood pulp.
Typical Applications
Grinders
Digester blow valves
Stock line valves
Stock lines and fittings
White liquor equipment
Green liquor equipment
Black liquor equipment
Causticizing equipment
Bleaching equipment
Sulfuric and sulfurous acid
equipment
Chlorine dioxide
Sulfur dioxide
41
CENTRIFUGAL PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: Upper half 1175 lb; lower half 3000 lb
Size: 57½ in high x 645/8 in. wide x 58½ in. deep
Use: Pump for handling 14,800 gpm of caustic, corrosive paper stock ("white water").
CENTRIFUGE BOWL
Alloy: CG-8M (19Cr-10Ni-3Mo)
Weight: 1679 Ib
Size: 28 in. O.D., 78 in. long
Use: Centrifuges in municipal
sewage treatment plant.
VERTICAL PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)–wetted parts
Size: 24 in.
Use: Liquid end of pump handling 20,000 gpm acid contaminated water.
42
TURBINE PUMP
Alloy: CF-8M (19Cr-9Ni 2Mo)
–wetted parts
Use: Dewatering service in gold
mine.
DIGESTER SCREENS–PIPE FITTINGS
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: various–screen segments 100 Ib each
Size: 6 in. pipe size at digester fitting
Use: Screens separate pulp from liquor inside digester. Complex fittings
used at bottom of digester between it and blow pit. Liquor is
ammonium sulfite (acid base).
PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 450 Ib
Size: 6 in. x 8 in.–1800 rpm
Use: Sulfuric acid leaching of copper silicate ores at ambient
temperature. Sulfuric acid strength 1-2%.
SUCTION ROLL SHELLS
(Suspended Castings)
(Casting being bored)
Alloy: CA-15 (12Cr)
Alloy: CF-8M (19Cr-10Ni-2Mo)
Weight: 97,200 lb
Weight: 64,600 lb
Use: Both used in wet end of paper machine to resist corrosion by white water while
aiding in drying paper.
SINGLE-STAGE CENTRIFUGAL PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 450 Ib
Size: 8 in. x 10 in.–1800 rpm
Use: Pumping silicate-sulfuric acid liquor in copper leaching
operation.
43
CENTRIFUGAL PUMP
Alloy: CF-8M (Modified)
Weight: Top casing, 1600 lb; lowercasing, 2380 lb
Use: Handling acidic river water in steel plant–after 22 years, pump
showed no sign of corrosion.
SINGLE STAGE CENTRIFUGAL PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 600 lb
Size: 6 in. x 8 in–1800 rpm
Use: Stock pump in pulp mill based on ammonium sulfite process–
acid-base sulfite liquor is present.
MARINE
Although CF-type alloy castings have to be used selectively
in the marine field because of their susceptibility to pitting
corrosion, they have applications where, because of velocity
conditions, this form of deterioration cannot develop. The
chromium-nickel type (CF-8) steels have been used successfully
for propellers on tugs and other types of work-boats that are in
relatively constant service.
The CF-3M, CF-8M and CN-7M alloys are frequently used
for components in salt water pumps and valves. These alloys
have also been used successfully in equipment which is
exposed to a marine atmosphere.
Typical Applications
Ship propellers
Salt water pumps
Salt water valves
Some marine hardware
PROPELLER
Alloy: CF-3 (19Cr-9Ni)
Weight: 22,660 Ib
Size: 15 ft O.D.
Use: Workboat
44
POWER–NUCLEAR AND CONVENTIONAL
Nuclear Energy
In this field, heat and corrosion-resistant alloys are used
in both statically and centrifugally cast forms.
Rigid specifications may require tensile property tests,
hydrostatic tests, radiographic and dye penetrant examinations, depending upon the particular application.
Typical Applications
Valves
Pump impellers
Pump casings
Control mechanisms
Reactor components
Power Plants
The use of chromium-nickel stainless steels for components in power plant equipment has increased the ability of
this industry to meet the ever increasing demand for more
industrial power. These alloys have made it possible for
power plant engineers to design equipment for operation at
increased pressures and temperatures.
In nuclear power plants, the chromium-nickel stainless
steels are used to avoid contamination of the coolants by
metallic corrosion products that would become radioactive.
CENTRIFUGALLY-CAST PIPE
Alloy: CF-8A (19Cr-9Ni)
Weight: 11,500 Ib (front piece)
Size: 32 in. O.D., 184 in. long (front piece)
Use: Nuclear reactor coolant loop pipe for pressurized water
reactor. Meets requirements of ASME Sec. III.
Typical Applications
Feed water heating equipment
Boiler water deaerator heaters
Valve components (feed water, steam, condensate, fuel oil)
Pump components (feed water, condensate, fuel oil)
Hydraulics
In the hydraulics field, the good resistance to
abrasion and cavitation of the chromium-nickel alloys is
of more significance than their corrosion resistance.
This property makes it possible to design smaller
diameter equipment that will convey large volumes at
higher velocity than it would be possible with other
alloys that do not have this inherent characteristic.
Typical Applications
Pumps
Valves
Torque tubes
CENTRIFUGALLY-CAST TUBE
Alloy: CF-8 (19Cr-9Ni)
Weight: 410 Ib
Size: 8.2 in. O.D. x 5 in. I.D. x 56 in. long
Use: Nuclear control rod drive latch housing.
CENTRIFUGALLY-CAST FLANGES
Alloy: CF-8M with controlled ferrite (19Cr-10Ni-2Mo)
Weight: 1500 Ib
Size: up to 24 in. pipe size
Use: Nuclear piping flowmeter flanges
Nozzles
Piping and fittings
45
VALVE BODY AND BONNET CASTINGS
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: Body casting, 1565 lb; bonnet casting, 740 Ib
Use: Castings meet Nuclear Class II, used in valves for nuclear power
plant.
BUTTERFLY VALVE BODIES
Alloy: CF-8M (19Cr-10Ni-2Mo)
Weight: 300 Ib
Size: 16 in.
Use: Nuclear service–must meet ASME Class II requirements.
FRANCIS TYPE RUNNER
Alloy: CF-20 (19Cr-9Ni)
Weight: Range from 460 to 3030 Ib
Size: 325/8 in. dia
Use: For hydraulic turbine installations
in the power industry.
CENTRIFUGALLY-CAST BEARINGS
Alloy: CF-3A (19Cr-9Ni)
Weight: 800-900 Ib
Size: 331/2 in. flange O.D. x 28 in. barrel
O.D. x 25 5 / 8 in. I.D. x 17 in. long
Use: Hydrostatic bearings for nuclear
recirculating pumps.
46
FLOWMETER NOZZLES
Alloy: CF-8M with controlled ferrite (19Cr-10Ni-2Mo)
Weight: 975 Ib
Size: 243/8 in. flange x 16 in. barrel O.D. x 1¼ in. wall
x 341/8 in. long
Use: Venturi-style flowmeter bodies for use inside main water
recirculating in nuclear power plants.
CHECK VALVE
Alloy: CF-8 (19Cr-9Ni)
Weight: 450 Ib
Size: 6 in. pipe size
Use: Nuclear water service handling
demineralized water in the
primary loop of a pressurized
light water reactor.
CONTROL VALVE, AUTOMATIC CONTROL
Alloy: CF-8 (19Cr-9Ni)
Weight: 250 Ib
Size: 6 in. pipe size
Use: Nuclear service, light water reactor,
PWR primary loop, by-pass.
STEAM TURBINE CASING
Alloy: CK-20 (25Cr-20Ni)
Weight: 9000 Ib
Use: High temperature, high pressure steam
service.
47
BUTTERFLY VALVE DISC
Alloy: CF-3M (19Cr-9Ni-2Mo)
Weight 160 lb
Size: 20 in. dia
Use: Control valve handling raw fresh water from California project to filtering
plant.
BAILEY CONTROL VALVE
Alloy: CF-3M (19Cr-9Ni-2Mo)
Weight: 5200lb
Size: 32 in. dia (port size)
Use: Potable water service, Metropolitan Water District of Southern
California.
MULTISTAGE WATERFLOOD PUMP CASING
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 4200 lb
Size: 4 in. x 6 in -3600 rpm
Use: Waterflood Huntington Beach, California. Aminol-treated sea water,
de-aerated, inhibited, biocides added.
CENTRIFUGAL PUMP IMPELLER
Alloy: CF-8M (19Cr-9Ni-2Mo)
Height: 36,000 lb
Size: 144 in. dia
Use: Handling freshwater containing silt, on Central Valley California
water project. Replaced bronze which suffered cavitation and
erosion corrosion.
HORIZONTALLY SPLIT, 5 STAGE, HIGH PRESSURE PUMP
Alloy: CF-8M (19Cr-9Ni-2Mo)
Weight: 1050 Ib (part shown)
Size: 4 in. x 6 in. -3600, rpm
Use: Treated sea water–oil field water flood service.
48
Part III
Fabrication Data
For Heat and Corrosion-Resistant Alloys
Casting is a fabricating step and by its nature is the
quickest method of converting an alloy into a nearly
finished product. The elimination of intermediate steps
between the molten metal stage and the shaped part
provides important economic advantages to the casting
process.
High speed steel and cemented carbide tools are
used for machining the high alloy castings. Cutting
speeds and feeds for high speed steel tools are shown
in Table X for heat-resistant alloys and in Table XI for
corrosion-resistant alloys. With carbide tools, about two
to three times these speeds should be used. The tool
should not be permitted to dwell in the cut as work
hardening of the material will result. Machines should be
powerful and rigid and tool mountings stiff.
Many castings can be used directly after cleaning and
cutting off the gates and risers but some require machining to finished dimensions or welding into assemblies.
This section presents information on the machining and
welding practices used on heat and corrosion-resistant
castings.
Cutting lubricants are essential for all machining operations on these castings. For best results, a continuous and abundant supply of cutting fluid should be fed to
the tool and thereby act also as a coolant. All lubricants
should be removed completely from the machined parts
that are to be subjected to high temperatures, either
during subsequent fabrication or in service. For high
speed steel tools, sulfurized cutting oils are the preferred cutting lubricants. A lubricant of soluble oil and
water is used with cemented carbide tools.
MACHINING
High-alloy castings are more difficult to machine than
carbon steel because of the characteristics built into
them for heat and corrosion-resistant service. With
proper tools and coolants, however, all necessary machining can be performed under conditions of comparatively slow speeds and moderate feeds.
Single point tool grind angles for high speed steel are
shown in Figure 6.
TABLE X
Machining and Welding of Heat-Resistant Alloy Castings
HA
MACHINING
Rough Turn
Speed, sfm
Feed, ipr
Finish Turning
Speed, sfm
Feed, ipr
Drilling
Speed, sfm
Feed, ipr
Tapping
Speed, sfm
Remarks
WELDING
Electrode Type
HC
HD
HE
HF
HH
HI
HK
HL
HN
HP
HT
HU
HW
HX
40-50
40-50
40-50
30-40
25-35
25-35
25-35
25-35
30-40
35-45
35-45
40-45
40-45
40-45
40-45
.010-.030 .025-.035 .025-.035 .020-.025 .015-.020 .015-.020 .015-.020 .020-.025 .020-.025 .020-.025 .020-.025 .025-.035 .025-.035 .025-.035 .025-.035
80-100 80-100
80-100
60-80
50-70
50-70
50-70
50-70
60-80
70-90
70-90
80-90
80-90
80-90
80-90
.005-.010 .010-.015 .010-.015 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .010-.015 .010-.015 .010-.015
35-70
40-60
40-60
30-60
20-40
20-40
20-40
20-40
30-60
40-60
40-60
40-60
40-60
40-60
40-60
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
10-25
10-25
10-25
10-25
10-20
10-20
10-20
10-20
10-25
5-15
5-15
5-15
5-15
5-15
5-15
15 17
15 17
15 17
17
16 17
16 17
16 17
16 17
17
16 17
–
16 17
16 17
16 17
16 17
E505-18 E446-15 E446-15 E312-15 E308-15 E309-15 E310-15HC E310-15 E310-15HC E330-15 E310-15 E330-15
Oxy-acetylene Rod Type 410 Bare
Oxy-acetylene Flux
None
–
Oxy-acetylene Flame
1
Character
Preheat and Interpass
450-550
Temperature, F
Post Heat Treatment, F
2
5
Annealing Treatment, F 1625
446 Bare 327 Bare 312 Bare 308 Bare 309 Bare 309 Bare 310 Bare 310 Bare 330 Bare
None
None
None
None
None
None
None
None
None
–
–
–
–
S
S
M
M
60-100
–
–
–
E330-15 ENiCr-1 or ENiCrFe-1
(also 18Cr- ENiCrFe38Ni Bare)
1
330 Bare 330 Bare Inconel Inconel
None
None Stainless Stainless
V
V
–
–
Not. Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req.
1550 A. C. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req.
3
4
4
4
As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast As-Cast
Notes for Table X with Table XI on page 50.
49
TABLE XI
Machining and Welding of Corrosion-Resistant Alloy Castings
CA-15
MACHINING
Rough Turn
Speed, sfm
Feed, ipr
Finish Turning
Speed, sfm
Feed, ipr
Drilling
Speed, sfm
Feed, ipr
Tapping
Speed, sfm
Remarks
CA-40
CA6NM
CB-30
CC-50
CD4MCu
CE-30
CF-20 CF-3M CF-8M CF-8C CF-16F CG-8M CH-20
CK-20 CN-7M
80-100
50-70
80-100 80-100 80-100 80-100
60-80
50-70
50-70
50-70
50-70
50-70
60-80
90-110
50-70
50-70
50-70
90-110
.003-.010 .015-.020 .005-.010 .010-.015 .010-.015 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010 .005-.010
Heat Treatment for
Increasing Strength
Hardening Temp., ºF
Quenching Medium
Tempering Temp., ºF
35-70
30-60
20-50
30-60
40-60
20-40
30-60
20-40
20-40
20-40
20-50
20-50
30-60
30-80
20-50
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
10-25
10-20
10-20
10-25
10-25
10-20
10-25
10-20
10-20
10-20
10-20
10-20
10-25
15-30
12
13
–
14
14
–
15
15
15
15
15
15
15
–
E410-15
E410-15
–
410 Bare 420 Bare
–
E442-15 E446-15
–
–
–
–
20-50
20-40
30-60
10-20
10-20
10-20
10-25
15
15
15
–
E312-15 E308L-15 E308-15 E308-15 E316L-15 E316-15 E347-15 E308-15 E317-15 E309-15 E310-5
–
–
–
–
–
–
–
–
–
–
–
E320-15
–
400-600 400-600 500-600 600-800 350-400 Not. Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. Not Req. 400-500
1125112511001450- 1650 A. C. 2050
1950- Not Req. 19502000- Not Req. 195019502000195020002WQ1950
1400 A.C. 1400 A.C. 1150 A.C. 1500 A.C.
20507
20507
21007
21007
20507
21007
2050
21007
21507
20507
2050 F.C.
14501450155015501450to 17501500 F.C.
1500
F.C.
1650 F.C. 1650 F.C. 1500 F.C.
1900
8
or A.C.
A.C.
–
18001850
oil
or air
600 max
–
–
10
9
–
9
9
9
11
11
11
11
11
11
11
11
11
11
11
11
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
10
S – slightly rich in acetylene; excess acetylene feather should project ¼" beyond tip of
inner core.
Heat to original draw temperature, hold sufficiently long to insure uniform heating
throughout section, then air cool.
3
When castings are repeatedly heated and cooled in service, properties may be
improved by heating at 1900 ºF for six hours, then furnace cooling.
4
When castings are repeatedly heated and cooled in service, properties may be
improved by heating at 1900 ºF for twelve hours, then furnace cooling.
5
For improved strength, castings are normalized by heating to 1825 ºF, air cooling to
below 1300 ºF, followed by tempering at 1250 ºF.
6
Drilling feeds:
Drill Diameter
Feed, ipr
001-.002
Under 1/ 8 “
1/ 8 - ¼
002-.004
.004-.007
.007-.015
015-.025
This post-weld heat treatment is to restore maximum corrosion resistance.
Quench should be in water, oil or air according to section size, geometry and
cooling rate that will hold as great a portion of the carbides in solution as
possible.
8
Furnace cool to 1000 ºF, then air cool.
9
Same as post-heat treatment.
10
Avoid tempering around 900 ºF. Lower strengths than obtained with 600 ºF
max temper may be achieved by tempering in 1100-1500 ºF range.
11
This alloy normally supplied in the annealed condition.
12
Cuts best when hardened to 225 Brinell.
13
Chips are stringy.
14
Chips are short and brittle.
15
Use chip curler.
16
Use chip curler and breakers.
17
Chips are tough and stringy.
–usually not required.
–air cool
–furnace cool
9
–
–
2
Over 1
9
–
V – very rich in acetylene; excess acetylene feather should project 1" beyond tip of inner
core.
M – medium rich in acetylene; excess acetylene feather should project ½" beyond tip of
inner core.
7
9
19502150
11
1
½-1
9
–
Notes for Tables X and XI
¼-½
9
19502050
11
180019001850
1950
oil
oil
or air
or air
600 max 600 max
10
50
CF-8
40-50
25-35
40-50
40-50
40-50
40-50
30-40
25-35
25-35
25-35
25-35
25-35
30-40
45-55
25-35
25-35
25-35
45-55
010-.030 .030-.040 .010-.030 .020-.030 .025-.035 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025 .020-.025
WELDING
Electrode Type
Oxy-acetylene
Rod Type
Preheat and
Interpass
Temperature, ºF
Post Heat
Treatment, ºF
Annealing
Treatment, ºF
Not Req.
A.C.
F.C.
CF-3
Figure 6–Tool Bit Angles for High Speed Steel Tools for Machining
Stainless Steel Castings.
WELDING
All of the common welding methods can be used on
high-alloy castings. Information on pre-heat and postheat treatments are given for the heat-resistant alloys in
Table X and for corrosion-resistant alloys in Table XI.
The metal-arc process is used in most cases, especially
for the corrosion-resistant alloys, while oxy-acetylene
welding is usually limited to the heat-resistant types.
Oxy-acetylene welding is not normally used for
corrosion-resistant castings because carbon pick-up is
possible if the flame is not correctly adjusted. Carbon
pick-up would decrease the corrosion-resistance of the
chromium-nickel alloys. In the relatively tougher heatresistant alloys, this limitation does not exist and oxyacetylene welding can be employed. Inert-gas welding
with tungsten or consumable electrodes is common in
the repair welding of investment castings. Submerged
arc welding is confined mainly to fabrication of
corrosion-resistant alloys. Flash welding is utilized in
special applications, such as the joining of tubular
sections.
1.
Welding Nickel-Chromium and Chromium-Nickel
Groups of Both Heat and Corrosion-Resistant
Grades.
Alloy castings of the nickel-chromium-iron and
chromium-nickel-iron groups can be welded satisfactorily and the resultant joints will have the same mechanical and physical properties as the base metal. These
alloys have better weldability than the straight chromium alloys. Preheating is seldom required, but postweld heat treatments are employed with the corrosionresistant types to restore uniform corrosion resistance.
The thermal conductivity of these alloys is about onethird that of carbon steel and the thermal expansion
coefficient is about 50% greater. This low conductivity
results in the retention of local heat for longer times and
the high coefficient of expansion means that higher
residual stresses and more distortion can be anticipated.
A. Arc Welding – The electrical resistance of nickelchromium and chromium-nickel castings is about six
times that of carbon steel, and the melting point of the
alloys is approximately 100 ºF lower. This combination
of greater resistance and lower melting point permits
these alloys to be arc welded using lower currents than
those required for welding carbon steels. Particular care
must be exercised with the corrosion-resistant types to
have the welding groove well cleaned and free of grease
or dirt, for any contamination of the weld might result in
carbon pick-up. When welding heat-resistant alloys of
the nickel-chromium group, the work must be kept clean
of lubricants and marking crayons that contain sulfur or
lead; otherwise cracking may result. Weaving of the
bead should be avoided because a large puddle promotes weld cracking unless bead width is limited to 3
times the electrode diameter.
Welding Current – Reverse polarity D.C. is most
commonly used for welding the nickel-chromium and
chromium-nickel alloys. Table XII lists suggested electrical settings and electrode sizes for these alloys of
different thicknesses. (In general, these alloys require
about 10% less current than the carbon steels.)
Electrode Selection – The electrode selected to weld a
corrosion-resistant cast alloy should deposit the same
alloy content as the casting. To accomplish this, the
electrode core and coating are adjusted to compensate
for melting losses that occur during welding. Particular
care should be exercised with the corrosion-resistant
cast alloys of low carbon content to assure that the
electrode does not add more carbon.
For the heat-resistant alloys, welding electrodes capable of depositing high carbon weld metal help prevent
cracking. The varying levels of silicon present in the
several heat-resisting alloy compositions, sometimes
require an adjustment of the carbon introduced into the
weld deposit by the electrode. This is done by the electrode manufacturer to maintain the proper carbonsilicon ratio in the weld deposit and thus eliminate cracking.
Lime coated electrodes are usually preferred for
welding high-alloy castings. All welding slag must be
removed after welding, for when service temperatures
approach the melting point of the slag, severe metal
attack can occur.
B. Oxy-Acetylene Welding–Oxy-acetylene welding
may be used on the heat-resistant types but this type of
welding should not be used on chromium-nickel castings intended for corrosion-resistant service. For the
heat-resistant grades, a carburizing flame rich in acetylene is suggested, especially if service conditions
include a carburizing atmosphere.
2. Welding the Straight Chromium Alloys
The straight chromium alloys are divided into hardenable and non-hardenable groups.
51
The virtue of the hardenable alloys is that their use
permits refinement of the grain size, and also the developent of a variety of mechanical properties by suitable
heat treating procedures. This hardenability, however,
necessitates extra care when welding, for it can result in
brittle structures in the weld deposits and heat-affected
zone if the weld casting is allowed to cool down to room
temperature in air. Heat treatment is necessary to restore ductility and must be done immediately following
welding, and care must be taken that the castings receive no rough handling between welding and heat
treating. Cracking and distortion can be minimized by
welding the castings only after annealing and not in the
as-cast condition.
The non-hardenable straight chromium alloys contain
18 to 30% Cr, and, although they do not harden when
cooled rapidly, grain growth and brittleness result. Generally speaking, these grades have limited weldability
and call for extreme care in welding and in composition
control (i.e., nickel content should be kept near the
maximum allowable in the specification).
A. Arc Welding – In arc welding straight chromium
heat and corrosion-resistant castings, the welding currents used are qenerally lower than those employed for
Welding Current – Reverse polarity direct current is
most commonly used in welding straight chromium
alloys; however, AC can be employed. The type of
welding current used, whether direct or alternating, is a
function of the flux casting present on the electrode.
Table XIII shows suggested electrical settings and electrode sizes for the various section thicknesses.
Electrode Selection – In selecting the proper electrode, it is important that the weld metal have the same
corrosion and heat-resistant properties as the parent
metal. The composition of the casting and commercial
electrodes are not exactly the same, for the electrode is
generally made to an AWS specification as listed it
Tables X and XI.
Lime coated electrodes are generally used for welding the straight chromium alloys, for they are considered
to give cleaner weld metal and allow for better bead
build-up than the titania or titania lime-coated rod.
B. Oxy-Acetylene Welding – Gas welding does not
find wide application for the straight chromium alloys
and is limited to those with less than 14% chromium.
TABLE XII
TABLE XIII
Electrical Settings and Electrode Size for Welding
Chromium-Nickel Alloy Castings
Electrical Settings and Electrode Size for Welding
Straight Chromium Alloy Castings
Casting
Thickness
at Weld,
in.
Under 1/16
1/16-7/64
7/64-3/16
3/16-1/2
1/2 and above
52
carbon steel because of their greater electrical resistance and lower melting points.
Electrode
Diameter,
In.
1/16
5/64
3/32
1/8
5/32
3/16
Amperes
25-40
35-55
45-70
70-105
100-140
130-180
Arc Volts,
max
22
23
24
25
25
26
Casting
Thickness
at Weld.
in
Under 1/16
1/16-9/64
9/64-3/16
3/16- 1/2
1/2 and above
Electrode
Diameter,
in
Amperes
Volts
5/64
3/32 or 1/8
1/8 or 5/32
5/64 or 3/16
3/16
25-40
50-90
90-125
100-150
125-175
20-22
22-24
22-24
23-27
26-29