1. Metal – Designation & Properties
R. Lindeke
Engr. 2110
Introduction to Materials for Engineers

6. Taxonomy of Metals Steels Cast Irons <1.4 wt% C 3-4.5 wt% C
Alloys
Steels
Ferrous
Nonferrous
Cast Irons Cu Al Mg Ti
<1.4wt%C
3-4.5
wt%C
Adapted from Fig. 11.1, Callister 7e.
Steels
<1.4 wt% C
Cast Irons
3-4.5 wt% C
microstructure:
ferrite, graphite
cementite Fe 3 C
cementite
1600
1400
1200
1000
800
600
400 1 2 4 5 6
6.7 L g
austenite +L
+Fe3C a
ferrite +
L+Fe3C d
(Fe)
Co , wt% C
Eutectic:
Eutectoid:
0.76
4.30
727°C
1148°C
T(°C)
Adapted from Fig. 9.24,Callister 7e. (Fig adapted from Binary Alloy Phase Diagrams, 2nd ed.,
Vol. 1, T.B. Massalski (Ed.-in-Chief), ASM International, Materials Park, OH, 1990.)

7. Alloy Taxonomy – (FerrousFocus!)

8. Steels Low Alloy High Alloy low carbon <0.25 wt% C Med carbon
high carbon
wt% C
plain
HSLA
heat
treatable
tool
austenitic
stainless
Name
Additions
none
Cr,V
Ni, Mo
Cr, Ni Mo
Cr, V,
Mo, W
Cr, Ni, Mo
Example
1010
4310
1040 43 40
1095
4190
304
Hardenability + ++
+++ TS - + ++ EL + + - - -- ++
Uses
auto
bridges
crank
pistons
wear
drills
high T
struc.
towers
shafts
gears
applic.
saws
applic.
sheet
press.
bolts
wear
dies
turbines
vessels
hammers
applic.
furnaces
increasing strength, cost, decreasing ductility
blades
V. corros.
resistant
Based on data provided in Tables 11.1(b), 11.2(b), 11.3, and 11.4, Callister 7e.

9. LOW-CARBON STEEL ~<0.25%C High Strength Low Alloy Steel
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

10. 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

11. 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

13. 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), Non-magnetic & most corrosion resistant

14. 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

16. Types of Cast Iron Gray iron Ductile iron graphite flakes
weak & brittle under tension
stronger under compression
excellent vibrational dampening
wear resistant
Ductile iron
add Mg or Ce
graphite in nodules not flakes
matrix often pearlite - better ductility
Adapted from Fig. 11.3(a) & (b), Callister 7e.

17. Types of Cast Iron White iron <1wt% Si so harder but brittle
more cementite
Malleable iron
heat treat at ºC
graphite in rosettes
more ductile
Adapted from Fig. 11.3(c) & (d), Callister 7e.

18. Production of Cast Iron
Adapted from Fig.11.5, Callister 7e.

19. Nonferrous Alloys NonFerrous Alloys • Cu Alloys • Al Alloys
Brass: Zn is subst. impurity
(costume jewelry, coins,
corrosion resistant)
Bronze
: Sn, Al, Si, Ni are
subst. impurity
(bushings, landing
gear)
Cu-Be :
precip. hardened
for strength
• Al Alloys
-lower r
: 2.7g/cm3
-Cu, Mg, Si, Mn, Zn additions
-solid sol. or precip.
strengthened (struct.
aircraft parts
& packaging)
NonFerrous
Alloys
• Mg Alloys
-very low r
: 1.7g/cm3
-ignites easily -
aircraft, missiles
• Ti Alloys
-lower r
: 4.5g/cm3
vs 7.9 for steel
-reactive at high T -
space applic.
• Refractory metals
-high melting T
-Nb, Mo, W, Ta
• Noble metals
-Ag, Au, Pt -
oxid./corr. resistant
Based on discussion and data provided in Section 11.3, Callister 7e.

20. Copper Alloys

21. Aluminum Alloys

22. 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.

23. Magnesium Alloys

24. Titanium Alloys

25. Metal Fabrication How do we fabricate metals? Forming Operations
Blacksmith - hammer (forged)
Molding - cast
Forming Operations
Rough stock formed to final shape
Hot working vs Cold working
• T high enough for • well below Tm recrystallization • work hardening
• Larger deformations • smaller deformations

26. Metal Fabrication Methods - I
FORMING
CASTING
JOINING A o d
force
die
blank
• Forging (Hammering; Stamping)
(wrenches, crankshafts)
often at
elev. T
Adapted from Fig. 11.8, Callister 7e.
roll A o d
• Rolling (Hot or Cold Rolling)
(I-beams, rails, sheet & plate)
tensile
force A o d
die
• Drawing
(rods, wire, tubing)
die must be well lubricated & clean
ram
billet
container
force
die holder
die A o d
extrusion
• Extrusion
(rods, tubing)
ductile metals, e.g. Cu, Al (hot)

27. 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

28. Metal Fabrication Methods - II
FORMING
CASTING
JOINING
• Sand Casting
(large parts, e.g.,
auto engine blocks)
• Die Casting
(high volume, low T alloys)
Sand
molten metal
• Continuous Casting
(simple slab shapes)
molten
solidified
• Investment Casting
(low volume, complex shapes
e.g., jewelry, turbine blades)
plaster
die formed
around wax
prototype
wax

29. Metal Fabrication Methods - III
FORMING
CASTING
JOINING
• Powder Metallurgy
(materials w/low ductility)
• Welding
(when one large part is
impractical)
• Heat affected zone:
(region in which the
microstructure has been
changed).
Adapted from Fig. 11.9, Callister 7e.
(Fig from Iron Castings Handbook, C.F. Walton and T.J. Opar (Ed.), 1981.)
piece 1
piece 2
fused base metal
filler metal (melted)
base
metal (melted)
unaffected
heat affected zone
pressure
heat
point contact
at low T
densification
by diffusion at
higher T
area
contact
densify

30. Thermal Processing of Metals
Annealing: Heat to Tanneal, then cool slowly.
Types of
Annealing •
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. •
Full Anneal
(steels):
Make soft steels for
good forming by heating
to get g
, then cool in
furnace to get coarse P. •
Process Anneal:
Negate effect of
cold working by
(recovery/
recrystallization) •
Normalize
(steels):
Deform steel with large
grains, then normalize
to make grains small.
Based on discussion in Section 11.7, Callister 7e.

31. Heat Treatments Annealing Quenching Tempered Martensite a) b) c) TE
800
Austenite (stable) a) b) TE
T(°C) A
Annealing P
600
Quenching
Tempered Martensite B
400 A
100%
Adapted from Fig , Callister 7e.
50% 0% c) 0%
200
M + A
50%
M + A
90% -1 3 5 10 10 10 10
time (s)

32. Hardenability--Steels
• Ability to form martensite
• Jominy end quench test to measure hardenability.
24°C water
specimen
(heated to g
phase field)
flat ground
Rockwell C hardness tests
Adapted from Fig , Callister 7e. (Fig adapted from A.G. Guy, Essentials of Materials Science, McGraw-Hill Book Company, New York, 1978.)
• Hardness versus distance from the quenched end.
Hardness, HRC
Distance from quenched end
Adapted from Fig , Callister 7e.

33. Why Hardness Changes W/Position
• The cooling rate varies with position. 60
Martensite
Martensite + Pearlite
Fine Pearlite
Pearlite
Hardness, HRC 40 20
distance from quenched end (in) 1 2 3
600
400
200 A M P
0.1 1 10
100
1000
T(°C)
M(start)
Time (s) 0%
100%
M(finish)
Adapted from Fig , Callister 7e.
(Fig adapted from H. Boyer (Ed.) Atlas of Isothermal Transformation and Cooling Transformation Diagrams, American Society for Metals, 1977, p. 376.)

34. Hardenability vs Alloy Composition
Cooling rate (°C/s)
Hardness, HRC 20 40 60 10 30 50
Distance from quenched end (mm) 2
100 3
4140
8640
5140
1040 80 %M
4340
• Jominy end quench
results, C = 0.4 wt% C
Adapted from Fig , Callister 7e.
(Fig 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.
T(°C) 10 -1 3 5
200
400
600
800
Time (s)
M(start)
M(90%)
shift from
A to B due
to alloying B A TE

35. 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

36. Precipitation Hardening
• Particles impede dislocations.
• Ex: Al-Cu system
• Procedure: 10 20 30 40 50
wt% Cu L
+L a
a+q q
+L
300
400
500
600
700
(Al)
T(°C)
composition range
needed for precipitation hardening
CuAl2 A
--Pt A: solution heat treat (get a solid solution) B
Pt B
--Pt B: quench to room temp. C
--Pt C: reheat to nucleate small q crystals within a crystals.
Other precipitation systems: • Cu-Be • Cu-Sn • Mg-Al
Adapted from Fig , Callister 7e. (Fig adapted from J.L. Murray, International Metals Review 30, p.5, 1985.)
Temp.
Time
Pt A (sol’n heat treat)
Consider: 17-4 PH St. Steel and Ni-Superalloys too!
Pt C (precipitate )
Adapted from Fig , Callister 7e.

37. Effect of time at Temperature during Precipitation Hardening