Chapter 11: Applications and Processing of Metal Alloys
Chapter 11: Applications and
Processing of Metal Alloys
ISSUES TO ADDRESS...
• How are metal alloys classified and what are their
common applications?
• What are some of the common fabrication techniques
for metals?
• What heat treatment procedures are used to improve the
mechanical properties of both ferrous and nonferrous alloys?
Chapter 11 - 1
Classification of Metal Alloys
Metal Alloys
Ferrous
Steels
_____
Adapted from Fig.
11.1, Callister &
Rethwisch 10e.
Nonferrous
_________
<1.4wt%C
3-4.5 wt%C
__________
_________
microstructure: ferrite,
graphite/cementite
T(ºC)
1600
δ
L
1400
γ
austenite
1200
γ+L
4.30
1000
α+
727ºC
γ
α800
ferrite
Fig. 9.24, Callister & Rethwisch 10e.
Eutectoid:
600
0.76
400
0
(Fe)
1
2
Eutectic:
γ + Fe3C
Fe3C
cementite
α + Fe3C
3
[Adapted from Binary Alloy Phase Diagrams,
2nd edition, Vol. 1, T. B. Massalski (Editor-inChief), 1990. Reprinted by permission of ASM
International, Materials Park, OH.]
L+ Fe3C
1148ºC
4
5
6
6.7
Co , wt% C
Chapter 11 - 2
Steels
High Alloy
Low Alloy
low carbon Med carbon
<0.25 wt% C 0.25-0.6 wt% C
Name
plain
HSLA
plain
Cr,V
Additions none
none
Ni, Mo
Example 1010 4310
1040
Hardenability 0
+
+
TS
0
+
EL
+
+
0
Uses
auto
struc.
sheet
bridges
towers
press.
vessels
high carbon
0.6-1.4 wt% C
heat
plain
treatable
Cr, Ni
none
Mo
43 40 1095
++
++
++
+
-
crank
shafts
bolts
hammers
blades
pistons
gears
wear
applic.
wear
applic.
tool
Cr, V,
Mo, W
4190
+++
++
-drills
saws
dies
increasing strength, cost, decreasing ductility
Based on data provided in Tables 11.1(b), 11.3, and 11.4, Callister & Rethwisch 10e.
stainless
Cr, Ni, Mo
304, 409
varies
varies
++
high T
applic.
turbines
furnaces
Very corros.
resistant
Chapter 11 - 3
1
Chapter 11: Applications and Processing of Metal Alloys
Refinement of Steel from Ore
_____
Iron Ore
___________
BLAST FURNACE
heat generation
C + O2 →CO2
gas
refractory
vessel
reduction of iron ore to metal
CO2 + C → 2CO
_______________________
layers of _____
and _________
air
slag
Molten iron
purification
CaCO3 → CaO+CO2
CaO + SiO2 + Al2O3 → slag
Chapter 11 - 4
Ferrous Alloys
Iron-based alloys
• Steels
• Cast Irons
Nomenclature for steels (AISI/SAE)
10xx _____________________
11xx Plain Carbon Steels (resulfurized for machinability)
15xx Mn (1.00 - 1.65%)
40xx Mo (0.20 ~ 0.30%)
43xx Ni (1.65 - 2.00%), Cr (0.40 - 0.90%), Mo (0.20 - 0.30%)
44xx Mo (0.5%)
where xx is wt% C x 100
example: 1060 steel – plain carbon steel with 0.60 wt% C
_____________________ >11% Cr
Chapter 11 - 5
Cast Irons
• Ferrous alloys with > ____________more
commonly
__________________________Low melting
– relatively easy to cast
• Generally brittle
• Cementite decomposes to ______ + _______
Fe3C à 3 Fe (α) + C (___________)
– generally a slow process
Chapter 11 - 6
2
Chapter 11: Applications and Processing of Metal Alloys
Fe-C True Equilibrium Diagram
T(°C)
1600
Graphite formation
promoted by
L
1400
• ___________
1200
• ___________
γ
Austenite
Liquid +
Graphite
γ+L
1153°C
4.2 wt% C
1000
800
740°C
0.65
α+γ
γ + Graphite
600
α + Graphite
Fig. 11.2, Callister & Rethwisch 10e.
[Adapted from Binary Alloy Phase Diagrams,
T. B. Massalski (Editor-in-Chief), 1990.
Reprinted by permission of ASM International,
Materials Park, OH.]
400
(Fe)
0
1
2
3
4
90
C, wt% C
100
Chapter 11 - 7
Types of Cast Iron
Figs. 11.3(a) & (b),
Callister &
_______ iron
Rethwisch 10e.
• __________________
• weak & brittle in tension
• stronger in compression
• excellent _________ dampening
• wear resistant
[Courtesy of C. H.
Brady and L. C. Smith,
National Bureau of
Standards, Washington,
DC (now the National
Institute of Standards
and Technology,
Gaithersburg, MD]
_______ iron
• add Mg and/or Ce
• graphite as ________ not flakes
• matrix often pearlite – stronger
but less ductile
Chapter 11 - 8
Types of Cast Iron (cont.)
Figs. 11.3(c) & (d),
Callister &
Rethwisch 10e.
• < 1 wt% Si
• pearlite + _________
• very hard and ________
• heat treat white iron at 800-900°C
• graphite in ____________
• reasonably strong and ductile
Reprinted with permission of the
Iron Castings Society, Des Plaines, IL
__________ iron
Courtesy of Amcast Industrial Corporation
White iron
Chapter 11 - 9
3
Chapter 11: Applications and Processing of Metal Alloys
Types of Cast Iron (cont.)
Courtesy of Sinter-Cast, Ltd.
Compacted _________ iron
• relatively high _________________
• good resistance to thermal shock
• lower oxidation at elevated
temperatures
Fig. 11.3(e), Callister & Rethwisch 10e.
Chapter 11 - 10
Production of Cast Irons
Fig.11.5, Callister & Rethwisch 10e.
(Adapted from W. G. Moffatt, G. W. Pearsall,
and J. Wulff, The Structure and Properties of
Materials, Vol. I, Structure, p. 195. Copyright ©
1964 by John Wiley & Sons, New York.
Reprinted by permission of John Wiley & Sons,
Inc.)
Chapter 11 - 11
Limitations of Ferrous Alloys
1) Relatively high densities
2) Relatively low electrical conductivities
3) Generally poor corrosion resistance
Chapter 11 - 12
4
Chapter 11: Applications and Processing of Metal Alloys
Nonferrous Alloys
• Cu Alloys
• Al Alloys
-low ρ: 2.7 g/cm3
Brass: Zn is subst. impurity
(costume jewelry, coins,
-Cu, Mg, Si, Mn, Zn additions
corrosion resistant)
-solid sol. or precip.
Bronze : Sn, Al, Si, Ni are
strengthened (struct.
subst. impurities
aircraft parts
(bushings, landing
& packaging)
gear)
NonFerrous • Mg Alloys
Cu-Be :
-very low ρ: 1.7 g/cm3
Alloys
precip. hardened
-ignites easily
for strength
-aircraft, missiles
• Ti Alloys
• Refractory metals
-relatively low ρ: 4.5 g/cm3
-high melting T’s
vs 7.9 for steel
• Noble metals -Nb, Mo, W, Ta
-reactive at high T’s -Ag, Au, Pt
-oxid./corr. resistant
-space applic.
Based on discussion and data provided in Section 11.3, Callister & Rethwisch 10e.
Chapter 11 - 13
Metal Fabrication
• How do we fabricate metals?
– ___________ - hammer (forged)
– Cast molten metal into mold
• ____________________
– Rough stock formed to final shape
Hot working
vs.
Cold working
• Deformation ____________
high enough for
_______________
• Large _______________
• Deformation below
________________
temperature
• Strain hardening occurs
• Small ______________
Chapter 11 - 14
Metal Fabrication Methods (i)
FORMING
CASTING
MISCELLANEOUS
• Forging (__________________) • Rolling (_______________)
(wrenches, crankshafts)
force
(I-beams, rails, sheet & plate)
roll
die
A o blank
A d often at
elev. T
• Drawing
force
Ao
die
Ad
(rods, tubing)
Ao
tensile
force
die must be well lubricated & clean
Ad
roll
• ___________
(rods, wire, tubing)
die
Ao
force
container
ram
billet
Adapted from
Fig. 11.9,
Callister &
Rethwisch 10e.
die holder
extrusion
Ad
die
ductile metals, e.g. Cu, Al (hot)
container
Chapter 11 - 15
5
Chapter 11: Applications and Processing of Metal Alloys
Metal Fabrication Methods (ii)
FORMING
CASTING
MISCELLANEOUS
• _________ - mold is filled with molten metal
– _________________________, perhaps alloying
elements added, then _______ in a mold
– ____________________________
– gives good production of shapes
– weaker products, internal defects
– ____________________________
Chapter 11 - 16
Metal Fabrication Methods (iii)
FORMING
CASTING
MISCELLANEOUS
• ________ Casting
(large parts, e.g.,
auto engine blocks)
Sand
Sand
molten metal
• What material will withstand T >1600°C
and is ____________ and easy to mold?
• Answer: ______!!!
• To create mold, pack _____ around form
(pattern) of desired shape
Chapter 11 - 17
Metal Fabrication Methods (iv)
FORMING
CASTING
MISCELLANEOUS
• ______________________
(low volume, complex shapes
e.g., jewelry, turbine blades)
• Stage I — _____ formed by pouring
____________ around wax pattern.
Plaster allowed to harden.
• Stage II — Wax is melted and then
poured from mold—hollow mold
cavity remains.
• Stage III — ___________________
into mold and allowed to solidify.
wax
I
II
III
Chapter 11 - 18
6
Chapter 11: Applications and Processing of Metal Alloys
Metal Fabrication Methods (v)
FORMING
MISCELLANEOUS
CASTING
• Continuous Casting
• Die Casting
-- _________ shapes
(e.g., rectangular slabs,
cylinders)
-- high _________
-- for alloys having ____ melting
temperatures
molten
solidified
Chapter 11 - 19
Metal Fabrication Methods (vi)
FORMING
CASTING
• _________________
MISCELLANEOUS
• _________________
(metals w/low ductilities)
pressure
(when fabrication of one large
part is impractical)
filler metal (melted)
base metal (melted)
fused base metal
heat
area
contact
unaffected
piece 1
densify
heat-affected zone
unaffected
Fig. 11.10, Callister
piece 2
& Rethwisch 10e.
• Heat-affected ______:
point contact
at low T
densification
by diffusion at
higher T
(region in which the
microstructure has been
changed).
[From Iron Castings
Handbook, C.F. Walton
and T.J. Opar (Ed.),
Iron Castings Society,
Des Plaines, IL,1981.]
Chapter 11 - 20
Thermal Processing of Metals
Annealing: Heat to Tanneal, then cool slowly.
• Stress Relief: Reduce
• __________ (steels):
stresses resulting from:
- plastic deformation
- ___________ cooling
- phase transform.
Make very soft steels for
good machining. Heat just
below Teutectoid & hold for
15-25 h.
Types of
Annealing
• ______________:
Negate effects of
cold working by
(recovery/
recrystallization)
• Full Anneal (steels):
Make soft steels for
good forming. Heat
to get γ, then furnace-cool
to obtain coarse pearlite.
• _________(steels): Deform
steel with large grains. Then heat
treat to allow _______________
and formation of smaller grains.
Based on discussion in Section 11.8, Callister & Rethwisch 10e.
Chapter 11 - 21
7
Chapter 11: Applications and Processing of Metal Alloys
Heat Treatment Temperature-Time Paths
a) _____________
A
b) __________
c) ___
Tempering
P
(Tempered
Martensite)
B
A
10
0%
50
0%
%
Fig. 10.25, Callister & Rethwisch 10e.
[Adapted from H. Boyer (Editor), Atlas of
Isothermal Transformation and Cooling
Transformation Diagrams, 1977. Reproduced
by permission of ASM International, Materials
Park, OH.]
a)
b)
c)
Chapter 11 - 22
Hardenability -- Steels
• ___________ – measure of the ability to form martensite
• Jominy end quench test used to measure _____________.
flat ground
specimen
(heated to γ
phase field)
24°C water
Rockwell C
hardness tests
Fig. 11.15, Callister &
Rethwisch 10e.
(Adapted from A.G. Guy,
Essentials of Materials Science,
McGraw-Hill Book Company,
New York, 1978.)
Hardness, HRC
• Plot __________ versus distance from the quenched end.
Fig. 11.16, Callister &
Rethwisch 10e.
Distance from quenched end
Chapter 11 - 23
Reason Why Hardness Changes with
Distance
Hardness, HRC
• The cooling rate ________ with distance from quenched end.
60
40
20
0
1
2
3
distance from quenched end (in)
T(°C)
600
A
→
0%
100%
P
Fig. 11.17, Callister & Rethwisch 10e.
[Adapted from H. Boyer (Ed.), Atlas of
Isothermal Transformation and Cooling
Transformation Diagrams, 1977. Reproduced
by permission of ASM International, Materials
Park, OH.]
400
200
M(start)
A→M
0.1
1
10
te ar
rli Pe
lite ea +
ar P ite
Pe Fine ens
t
ar ite
M ens
t
ar
M
0 M(finish)
100
1000
lite
Time (s)
Chapter 11 - 24
8
Chapter 11: Applications and Processing of Metal Alloys
Hardenability vs Alloy Composition
100
Hardness, HRC
• _____________ curves for
60
five alloys each with,
C = _____________
10
3
100
4340
8640
40
20
• "Alloy Steels"
4140
10
(Adapted from figure furnished courtesy
Republic Steel Corporation.)
80 %M
50
40
Fig. 11.18, Callister & Rethwisch 10e.
2 Cooling rate (°C/s)
5140
0 10 20 30 40 50
Distance from quenched end (mm)
800
TE
T(°C)
(4140, 4340, 5140, 8640)
600
-- contain Ni, Cr, Mo
A
B
(0.2 to 2 wt%)
400
-- these ___________ shift
M(start)
the "nose" to longer times
200
M(90%)
(from A to B)
0
-- martensite is easier
-1
3
5
10 10 10 10 Time (s)
to form
Chapter 11 - 25
Influences of Quenching Medium &
Specimen Geometry
• Effect of quenching medium:
Medium
air
oil
water
Severity of Quench
__________
__________
__________
Hardness
__________
__________
__________
• Effect of specimen geometry:
When surface area-to-volume ratio increases:
-- cooling rate throughout interior increases
-- hardness throughout interior increases
Position
center
surface
Cooling rate
low
high
Hardness
low
high
Chapter 11 - 26
Precipitation Hardening
• Particles impede _________ motion.
700
• Ex: Al-Cu system
T(ºC)
• Procedure:
600
α+L
α
L
CuAl2
θ+L
-- Pt A: _______________
A
500
θ
(get α solid solution)
α
+
θ
-- Pt B: _______ to room temp.
400 C
(retain α solid solution)
-- Pt C: _______ to nucleate 300
small θ _________ within (Al) 0 B 10 20 30 40 50
wt% Cu
composition range
α phase.
• Other alloys that precipitation
harden: Temp.
• Cu-Be
• Cu-Sn
• Mg-Al
Adapted from Fig.
11.27, Callister &
Rethwisch 10e.
available for precipitation hardening
Pt A (sol’n heat treat)
Fig. 11.29, Callister & Rethwisch 10e.
(Adapted from J.L. Murray, International
Metals Review 30, p.5, 1985. Reprinted by
permission of ASM International.)
Pt C (precipitate θ)
Pt B
Time
Chapter 11 - 27
9
Chapter 11: Applications and Processing of Metal Alloys
Influence of Precipitation Heat
Treatment on TS, %EL
• 2014 Al Alloy:
400
300
200
100
204ºC
• _________ on %EL curves.
fe
p we
“o reci r lar
ve pit
rag ate ge
ed s
”
%EL (2 in sample)
n
ma
p re n y s
cip ma
ll
it
“a ates
ge
d”
no
so n-eq
lid
u
so il.
lut
io
tensile strength (MPa)
• _________ on TS curves.
• _________ T accelerates
process.
149ºC
1min
1h 1day 1mo 1yr
precipitation heat treat time
30
20
10
0
204ºC
149ºC
1min
1h 1day 1mo 1yr
precipitation heat treat time
Fig. 11.32, Callister & Rethwisch 10e. [Adapted from Metals Handbook: Properties and Selection: Nonferrous
Alloys and Pure Metals, Vol. 2, 9th ed., H. Baker (Managing Ed.), 1979. Reproduced by permission of ASM International,
Materials Park, OH.]
Chapter 11 - 28
Summary
• Ferrous alloys: steels and cast irons
• Non-ferrous alloys:
-- Cu, Al, Ti, and Mg alloys; refractory alloys; and noble metals.
• Metal fabrication techniques:
-- forming, casting, miscellaneous.
• Hardenability of metals
-- measure of ability of a steel to be heat treated.
-- increases with alloy content.
• Precipitation hardening
--hardening, strengthening due to formation of
precipitate particles.
--Al, Mg alloys precipitation hardenable.
Chapter 11 - 29
10