Metal – Designation &
Properties
R. Lindeke
Engr. 2110
Introduction to Materials for Engineers
Taxonomy of Metals
Metal Alloys
Ferrous
Steels
Steels
<1.4wt%C
<1.4
wt% C
Cast Irons
Cast
Irons
3-4.5
wt%C
3-4.5 wt% C
Cu
Al
1600
d
L
1400
g
austenite
g+L
a800
ferrite
600
400
0
(Fe)
L+Fe3C
1148°C
4.30
1000
727°C
Eutectoid:
0.76
1
2
Eutectic:
g+Fe3C
4
Ti
Adapted from Fig. 9.24,Callister 7e.
(Fig. 9.24 adapted from Binary Alloy
Phase Diagrams, 2nd ed.,
Vol. 1, T.B. Massalski (Ed.-in-Chief),
ASM International, Materials Park, OH,
1990.)
Fe3C
cementite
a+Fe3C
3
Mg
microstructure:
ferrite, graphite
cementite
T(°C)
1200
Adapted from
Fig. 11.1,
Callister 7e.
Nonferrous
5
6
Co , wt% C
6.7
Alloy Taxonomy – (FerrousFocus!)
Steels
High Alloy
Low Alloy
low carbon Med carbon
<0.25 wt% C 0.25-0.6wt% C
high carbon
0.6-1.4wt% C
heat
plain
treatable
Cr,V
Cr, Ni
Additions none
none
none
Ni, Mo
Mo
Example 1010 4310
1040
4340 1095
Hardenability 0
+
+
++
++
TS
0
+
++
+
EL
+
+
0
Name
plain
Uses
auto
struc.
sheet
HSLA
bridges
towers
press.
vessels
plain
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), 11.2(b), 11.3, and 11.4, Callister 7e.
austenitic
stainless
Cr, Ni, Mo
304
0
0
++
high T
applic.
turbines
furnaces
V. corros.
resistant
-LOW-CARBON STEEL
~<0.25%C
•Unresponsive to heat treatment
•Consist of ferrites and pearlite
•Relatively soft and weak
•Relatively ductile and tough
•Weldable and machinable
•Economical amongst all steel
-High Strength Low Alloy Steel
-Alloying up to 10%
-Increase corrosion properties
-Higher strength
SAE – Society of Automotive engineers
AISI- American Iron and Steel Institute
ASTM- American Society for Testing
and Materials
UNS- Unified Numbering System
MEDIUM CARBON STEELS – 0.25-0.6 wt%C
•Heat treated by austenizing, quenching, and then tempering to improve their mechanical
properties. Most often utilized in tempered condition with tempered martensite microsture.
•Low hardenability  can be heat treated only in very thin sections and with rapid quenching
High Carbon steels: 0.60-1.4 wt%C – hardest, strongest, least ductile
Always used in hardened/tempered condition – wear and indentation resistant
Tool/die steels contain high Carbon and Chromium, Vanadium, tungsten and molybdenum
 Carbides
Stainless Steel
Corrosion resistant
 Cr of at least 11
wt%
Three classes
-Martensitic – heat
treated (Q&T), Magnetic
-Ferritic – not heat
treated, Magnetic
-Austenitic – heat
treatable (PH), Nonmagnetic & most
corrosion resistant
CAST IRONS – Carbon > 2.14 wt. %C , usually 3-4.5wt%C
Complete Melting 1150 oC-1300 oC
Silicon > 1%, slower cooling rates during solidification
Gray, White, Nodular, malleable
Types of Cast Iron
Gray iron
•
•
•
•
•
graphite flakes
weak & brittle under tension
stronger under compression
excellent vibrational dampening
wear resistant
Adapted from Fig. 11.3(a) & (b), Callister 7e.
Ductile iron
•
•
•
add Mg or Ce
graphite in nodules not flakes
matrix often pearlite - better ductility
Types of Cast Iron
White iron
• <1wt% Si so harder but
brittle
• more cementite
Malleable iron
• heat treat at 800-900ºC
• graphite in rosettes
• more ductile
Adapted from Fig. 11.3(c) & (d), Callister 7e.
Production of Cast Iron
Adapted from Fig.11.5,
Callister 7e.
Nonferrous Alloys
• Cu Alloys
• Al Alloys
-lower r: 2.7g/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. impurity
aircraft parts
(bushings, landing
& packaging)
gear)
• Mg Alloys
NonFerrous
Cu-Be:
-very low r: 1.7g/cm3
Alloys
precip. hardened
-ignites easily
for strength
-aircraft, missiles
• Ti Alloys
• Refractory metals
-lower r: 4.5g/cm3
vs 7.9 for steel
-reactive at high T
-space applic.
• Noble metals
-Ag, Au, Pt
-oxid./corr. resistant
Based on discussion and data provided in Section 11.3, Callister 7e.
-high melting T
-Nb, Mo, W, Ta
Copper Alloys
Aluminum Alloys
Additions to Cu and Al alloy
Designations
Temper designation scheme for alloys: a letter and possibly a
one- to three-digit number:
F, H, and O represent, respectively, the as-fabricated, strain
hardened, and annealed states.
T3 means that the alloy was solution heat treated, cold
worked, and then naturally aged (age hardened).
T6 means that the alloy was solution heat treated followed by
artificial aging.
Magnesium Alloys
Titanium Alloys
Metal Fabrication
• How do we fabricate metals?
– Blacksmith - hammer (forged)
– Molding - cast
• Forming Operations
– Rough stock formed to final shape
Hot working
• T high enough for
recrystallization
• Larger deformations
vs.
Cold working
• well below Tm
• work hardening
• smaller deformations
Metal Fabrication Methods - I
FORMING
CASTING
JOINING
• Forging (Hammering; Stamping) • Rolling (Hot or Cold Rolling)
(wrenches, crankshafts)
(I-beams, rails, sheet & plate)
force
die
A o blank
often at
Ad
elev. T
roll
Ao
roll
• Drawing
• Extrusion
force
(rods, wire, tubing)
die
Ao
Ad
Ad
Adapted from
Fig. 11.8,
Callister 7e.
(rods, tubing)
Ao
tensile
force
die
die must be well lubricated & clean
force
container
ram
billet
container
die holder
extrusion
die
ductile metals, e.g. Cu, Al (hot)
Ad
Metal Fabrication Methods - II
FORMING
CASTING
JOINING
• Casting- mold is filled with liquid metal
– metal melted in furnace, perhaps alloying
elements added. Then cast in a mold
– most common, cheapest method
– gives good reproduction of shapes
– weaker products, internal defects
– good option for brittle materials or microstructures
that are cooling rate sensitive
Metal Fabrication Methods - II
FORMING
CASTING
• Sand Casting
(large parts, e.g.,
auto engine blocks)
Sand
• Die Casting
(high volume, low T alloys)
Sand
molten metal
• Investment Casting
(low volume, complex shapes
e.g., jewelry, turbine blades)
plaster
die formed
around wax
prototype
JOINING
• Continuous Casting
(simple slab shapes)
molten
solidified
wax
Metal Fabrication Methods - III
FORMING
CASTING
• Powder Metallurgy
(materials w/low ductility)
JOINING
• Welding
(when one large part is
impractical)
pressure
filler metal (melted)
base metal (melted)
fused base metal
heat
area
contact
densify
unaffected
piece 1
heat affected zone
unaffected Adapted from Fig.
piece 2
11.9, Callister 7e.
• Heat affected zone:
point contact
at low T
densification
by diffusion at
higher T
(region in which the
microstructure has been
changed).
(Fig. 11.9 from Iron
Castings
Handbook, C.F.
Walton and T.J.
Opar (Ed.), 1981.)
Thermal Processing of Metals
Annealing: Heat to Tanneal, then cool slowly.
• Stress Relief: Reduce
stress caused by:
-plastic deformation
-nonuniform cooling
-phase transform.
• Spheroidize (steels):
Make very soft steels for
good machining. Heat just
below TE & hold for
15-25 h.
Types of
Annealing
• Process Anneal:
Negate effect of
cold working by
(recovery/
recrystallization)
Based on discussion in Section 11.7, Callister 7e.
• Full Anneal (steels):
Make soft steels for
good forming by heating
to get g, then cool in
furnace to get coarse P.
• Normalize (steels):
Deform steel with large
grains, then normalize
to make grains small.
Heat Treatments
800
Austenite (stable)
TE
T(°C)
A
a) Annealing
P
600
b) Quenching
c) Tempered
Martensite
400
B
A
Adapted from Fig. 10.22, Callister 7e.
0%
M+A
200
50%
M+A
90%
a)
b)
10
-1
10
10
time (s)
3
10
5
c)
Hardenability--Steels
• Ability to form martensite
• Jominy end quench test to measure hardenability.
flat ground
specimen
(heated to g
phase field)
24°C water
Rockwell C
hardness tests
Adapted from Fig. 11.11,
Callister 7e. (Fig. 11.11
adapted from A.G. Guy,
Essentials of Materials
Science, McGraw-Hill Book
Company, New York,
1978.)
Hardness, HRC
• Hardness versus distance from the quenched end.
Adapted from Fig. 11.12,
Callister 7e.
Distance from quenched end
Why Hardness Changes W/Position
Hardness, HRC
• The cooling rate varies with position.
60
40
20
0
1
2
3
distance from quenched end (in)
T(°C)
0%
100%
600
Adapted from Fig. 11.13, Callister 7e.
(Fig. 11.13 adapted from H. Boyer (Ed.)
Atlas of Isothermal Transformation and
Cooling Transformation Diagrams,
American Society for Metals, 1977, p.
376.)
400
200
M(start)
A  M
0 M(finish)
0.1
1
10
100
1000
Time (s)
Hardenability vs Alloy Composition
Adapted from Fig. 11.14, Callister 7e.
(Fig. 11.14 adapted from figure furnished
courtesy Republic Steel Corporation.)
• "Alloy Steels"
(4140, 4340, 5140, 8640)
--contain Ni, Cr, Mo
(0.2 to 2wt%)
--these elements shift
the "nose".
--martensite is easier
to form.
100
Hardness, HRC
• Jominy end quench
results, C = 0.4 wt% C
10
3
2 Cooling rate (°C/s)
60
100
80 %M
4340
50
40
4140
8640
20
5140
0 10 20 30 40 50
Distance from quenched end (mm)
800
T(°C)
600
A
TE
shift from
A to B due
to alloying
B
400
M(start)
M(90%)
200
0 -1
10
10
10
3
5
10 Time (s)
Quenching Medium & Geometry
• Effect of quenching medium:
Medium
air
oil
water
Severity of Quench
low
moderate
high
Hardness
low
moderate
high
• Effect of geometry:
When surface-to-volume ratio increases:
--cooling rate increases
--hardness increases
Position
center
surface
Cooling rate
low
high
Hardness
low
high
Precipitation
Hardening
• Particles impede dislocations.
• Ex: Al-Cu system
• Procedure:
700
T(°C)
--Pt A: solution heat treat
(get a solid solution)
--Pt B: quench to room temp.
--Pt C: reheat to nucleate
small q crystals within
a crystals.
500
400
a+L
q+L
A
a+q
C
300
(Al) 0 B 10
20
30
40
q
50
wt% Cu
composition range
needed for precipitation hardening
• Other precipitation
systems:
• Cu-Be
• Cu-Sn
• Mg-Al
600 a
CuAl2
L
Adapted from Fig. 11.24, Callister 7e. (Fig. 11.24 adapted from J.L.
Murray, International Metals Review 30, p.5, 1985.)
Temp.
Pt A (sol’n heat treat)
Pt C (precipitate q)
Adapted from Fig.
11.22, Callister 7e.
Pt B
Time
Consider: 17-4
PH St. Steel and
Ni-Superalloys
too!
Effect of time
at
Temperature
during
Precipitation
Hardening