ch11 - metals

17
PART T W O CHAPTER 11 Metals These automotive steering and suspension com- ponents are made of wrought aluminum to pro- vide reduced weight and improved fuel econ- omy. (Courtesy of TRW.)

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Page 1: Ch11 - Metals

P A R TT W O

CHAPTER 11Metals

These automotive steering and suspension com-ponents are made of wrought aluminum to pro-vide reduced weight and improved fuel econ-omy. (Courtesy of TRW.)

Page 2: Ch11 - Metals

(a)

(b)

Figure 11-1 Typical microstructures of (a)white iron (400×), eutectic carbide (lightconstituent) plus pearlite (dark constituent).(b) gray iron (100×), graphite flakes ina matrix of 20% free ferrite (light con-stituent) and 80% pearlite (dark con-stituent).

Page 3: Ch11 - Metals

(d)

(c)

Figure 11-1 (c) ductile iron (100×), graphite nodules (spherulites)encased in envelopes of free ferrite, all in a matrix of pearlite.(d) malleable iron (100×), graphite nodules in a matrixof ferrite. (From Metals Handbook, 9th Ed., Vol. 1, Amer-ican Society for Metals, Metals Park, Ohio, 1978.)

Page 4: Ch11 - Metals

Coalmines

Coal

Cokeovens

Limestonequarries

Rawlimestone

Preparedlimestone

High-gradeIron-bearing

materials

As-minedore

Moltensteel

Moltensteel

Moltenpig iron

(hot metal)

Crushing,screening,

etc.

Blastfurnace

Steelmakingfurnaces

(open-hearthbasic oxygen

andelectric-arc)

Ladle

Iron-orebeneficiating

plants

Continuouscasting

machine

Ingotmolds

Solid steel

Solid steel

Ingots

Blooms

Billets

Slabs

Primaryrolling mills

(blooming mills,slabbing mills,

billet mills)

Soakingpits

Alloyingelements

andadditionagents

Iron-oremines

Scrap

Coke

STEELMAKINGFrom raw materials to finished mill products

(excluding coated products)

Figure 11-2 Schematic summary of the wrought process for producing various steel prod-uct shapes. (From W. T. Lankford et al., Eds., The Making, Shaping, and Treating ofSteel, 10th Ed., United States Steel, Pittsburgh, Pa., 1985. Copyright 1985 by UnitedStates Steel Corporation.)

Page 5: Ch11 - Metals

Beams Angles Tees

Standard rails Crane rails

Round

Sheets Coils

Hexagonal Flat Half roundSquare Octagonal Triangular

Wire Wire rope Nails Wire fabric

Note: Some tubular products includeelectric-welded large-diameterpipe made from plates, andelectric-resistance-welded (ERW)pipe made from hot-rolled andcold-rolled strip.

Joint bars

Zees Channels PilingHeatingfurnaces

Railmills

Structuralmills

Structural shapesSome product forms (not to scale)

Rails and joint bars

Heatingfurnaces

Rodmills

Seamlesspipe andtube mills

Barmills

Heatingfurnaces

Platemills

Hot-stripmills

Skelpmills

Continuousbutt-weldpipe mill

Coldreduction

mills

Hot-rolledbreakdownsin coil forms

Bars

Rods

Skelp

Plates

Hot-rolled sheets and strips

Cold-rolled sheetsand strip

(inc. black plate)

Wiremills

Wireand wireproducts

Pipeand tubes

Figure 11-2 (Continued)

Page 6: Ch11 - Metals

Handle

Patternassembly

Pouring basin

Lug

Sprue

(a) Wax sprue pattern (b) Pattern assembly(wax patterns attachedto wax sprue)

(e) Solidified casting aftermold has been broken away

(f) One of four castings afterremoval from sprue

(d) Mold after pouring

(c) Pattern assembly in flask after mold slurry has been poured (Precoating of pattern assembly with slurry is required for metals with pouring temperatures above 2000 F.)

Wax sprue

Flask

Mold slurry

Wax attaching moldto base plate

Wax pattern(1 of 4)

Workpiece(1 of 4) Gate stub

(to be removed)

Figure 11-3 Schematic illustration of the casting of a metal alloy form by the “in-vestment molding” process. (From Metals Handbook, 8th ed., Vol. 5: Forgingand Casting, American Society for Metals, Metals Park, Ohio, 1970.)

Page 7: Ch11 - Metals

Figure 11-4 Microstructure of a cast alloy (354-T4 aluminum),50×. The black spots are voids, and gray particles are a silicon-rich phase. (From Metals Handbook, 9th ed., Vol. 9: Met-allography and Microstructures, American Society for Met-als, Metals Park, Ohio, 1985.)

Page 8: Ch11 - Metals

A B0 10050

Composition (wt % B)

Temperature

Figure 11-5 Schematic illustration of the development of a cored structurein the nonequilibrium solidification of a 50:50 alloy in a system exhibit-ing complete solid solution. (This case can be contrasted with the equi-librium solidification shown in Figure 9–33.) During the rapid coolingassociated with casting, the liquidus curve is unaffected given the rapiddiffusion in the liquid state, but solid state diffusion may be too slowto maintain uniform grain compositions upon cooling. As a result, thesolidus curve is shifted downward as indicated by the dashed line.

Page 9: Ch11 - Metals

Figure 11-6 Example of a tree-like dendritic structurein a 20 Pb–80 Sn alloy. A eutectic microstructureis seen at the base of the dendrites. (From MetalsHandbook, 9th ed., Vol. 9: Casting, ASM Interna-tional, Materials Park, Ohio, 1988.)

Page 10: Ch11 - Metals

Bore section for contact

Flux-covered portion

Weld metal

Ground clamp

Electrode

Electrode holder

To power supply

To power supply Workpiece

Core wire

Slag blanket

Depth of fusion Heat-affected zone

Section A-A

Arcstream

Weldcrater

Gaseous shield

Weld puddle

Electrode covering(flux)Cup formed on

electrode tip

Insulated handle

A

A

60 to 80

Figure 11-7 Schematic illustration of the welding process. Specifi-cally, “shielded metal-arc” welding is shown. (From Metals Hand-book, 8th ed., Vol. 6: Welding and Brazing, American Society forMetals, Metals Park, Ohio, 1971.)

Page 11: Ch11 - Metals

1.000

0.300

1.440 diameter

Die cell

0.960

(a) Green compact

Green compact

(b) Die cavity filled with powder

Loose powder

Inner upperpunch

Outer upperpunch

Intermediatelower punch

Outer lowerpunch Stationary

lower punch

(d) Powder forced intoupper punch cavity

(e) Compact pressed

(e) Compact ejected

Fill shoe

(c) Powder leveled in cavity

0.190

Core rod

Core rod

4.240

Figure 11-8 Schematic illustration of powder metallurgy. The green, or unfired, com-pact is subsequently heated to a sufficiently high temperature to produce a strongpiece by solid-state diffusion between the adjacent powder particles. (From MetalsHandbook, 8th Ed., Vol. 4: Forming, American Society for Metals, Metals Park,Ohio, 1969.)

Page 12: Ch11 - Metals

Overbore for cladding Place cans and weld

Hot outgas Hot isostatically pressto compact (using inert gas)

2

Load powder

3

Remove can

64 5

1

Figure 11-9 Hot isostatic prossing (HIP) of a cladding for a complex-shaped part. (After AdvancedMaterials and Processes, January 1987.)

Page 13: Ch11 - Metals

Bubbleplate

Toolplate

Figure 11-10 Superplastic forming allows deep parts to be formed with a rela-tively uniform wall thickness. Modest air pressure (up to 10 atmospheres)stretches a heated “bubble” of metal sheet, which then collapses over a metalformer pushed up through the plane of the original sheet. (After Super-form USA, Inc.)

Page 14: Ch11 - Metals

Conductive heat removal: splatcooling, planar flow casting, double roller quenching, injectinchilling, plasma spray deposition.

Heat transfer coefficient, h, =0.1–100 kW/m2K

Convective heat removal: variousforms of gas and water atomizers, unidirectional and centrifugalatomizers, rotating cup process, plasma spray deposition.

h = 0.1– 100 kW/m2K

Radiative heat romoval: electro-hydrodynamic process, vacuumplasma process.

h = 10 W/m2K

Directed and concentrated energytechniques: conductive heatremoval lasers (pulsed andcontinuous), electron beam.

h → ∞

Metal liquiddroplets

Emulsion

Droplet emulsion

Liquid

Solid

Eqilibrium mushy zone

Levitatedliquid

Heating andlevitation coils

Levitation (gas jet or induction current)

Liquid

Glass

Nucleant fluxing

Liquid

P

P

PP

P

P

P

P

Rapid pressure application

Chilling Techniques

Undercooling Techniques

Figure 11-11 Schematic summary of severaltechniques for the rapid solidification ofmetal alloys. (From Metal Progress, May1986.

Page 15: Ch11 - Metals

120

100

80

60

400 50

Nickel, %(c)

Har

dnes

s, R

f

100

50

30

40

20

10

00 50

Nickel, %(d)

Elo

ngat

ion,

% in

50

mm

(2

in.)

100

500

400

300

2000 50

Nickel, %(a)

Tens

ile s

tren

gth,

MP

a

Tens

ile s

tren

gth,

100

0 ps

i

100

70

60

50

40

30

300

200

100

00 50

Nickel, %(b)

Yie

ld s

tren

gth,

MP

a

Yie

ld s

tren

gth,

100

0 ps

i

100

40

30

20

10

0

Figure 11-12 Variation of mechanical properties of copper–nickel alloys withcomposition. Recall that copper and nickel form a complete solid-solutionphase diagram (Figure 9–9). (From L. H. Van Vlack, Elements of Mate-rials Science and Engineering, 4th Ed., Addison-Wesley Publishing Co.,Inc., Reading, Mass., 1980.)

Page 16: Ch11 - Metals

90

70

80

60

500 3010 20 40 50

Cold work, %(a)

Har

dnes

s, R

B

60

85 Cu–15 Zn

70 Cu–30 Zn80

40

60

20

00 3010 20 40 50

Cold work, %(c)

Elo

ngat

ion,

% in

50

mm

(2

in.)

60

85 Cu–15 Zn

70 Cu–30 Zn

600

500

400

3000 3010 20 40 50

Cold work, %(b)

Tens

ile s

tren

gth,

MP

a

60

85 Cu–15 Zn

70 Cu–30 Zn

Tens

ile s

tren

gth,

100

0 ps

i

80

70

60

50

Figure 11-13 Variation of mechanical properties of two brass alloys with degree of cold work. (From L. H. VanVlack, Elements of Materials Science and Engineering, 4th Ed., Addison-Wesley Publishing Co., Inc., Read-ing, Mass., 1980.)

Page 17: Ch11 - Metals

(Courtesy of the Casting Emissions Reduction Program [CERP].)