4- Lec 3_1 Material First

8/7/2019 4- Lec 3_1 Material First

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Types of Material


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Why Materials ???

Ashby,: Material Selection

in Mechanical Design


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Engineering Materials


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Materials

Nanomaterials, shape-memory alloys, superconductors,

Ferrous metals: carbon-, alloy-, stainless-, tool-and-die steels

Non-ferrous metals: aluminum, magnesium, copper, nickel,

titanium, superalloys, refractory metals,

beryllium, zirconium, low-melting alloys,

gold, silver, platinum,

Plastics: thermoplastics (acrylic, nylon, polyethylene, ABS,)

thermosets (epoxies, Polymides, Phenolics, )

elastomers (rubbers, silicones, polyurethanes, )

Ceramics, Glasses, Graphite, Diamond, Cubic Boron Nitride

Composites: reinforced plastics, metal-, ceramic matrix composites


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Properties of materials

Mechanical properties of materials

Strength, Toughness, Hardness, Ductility,

Elasticity, Fatigue and Creep

Chemical properties

Oxidation, Corrosion, Flammability, Toxicity,

Physical properties

Density, Specific heat, Melting and boiling point,

Thermal expansion and conductivity,

Electrical and magnetic properties


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Material Specification

Chemical composition

Mechanical properties Strength, hardness

(under various conditions: temperature,

humidity, pressure)

Physical properties density, optical,

electrical, magnetic

Environmental green, recycling


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Metals

Ferrous Metals

Cast irons

Steels

Super alloys Iron-based

Nickel-based

Cobalt-based

Non-ferrous metals

Aluminum and its alloys

Copper and its alloys

Magnesium and its alloys Nickel and its alloys

Titanium and its alloys

Zinc and its alloys Lead & Tin

Refractory metals

Precious metals


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General Properties and Applications of

Ferrous Alloys

Ferrous alloys are useful metals in terms of

mechanical, physical and chemical properties.

Alloys contain iron as theirbase metal. Car bon steels are least expensive of all metals

while stainless steels is costly.


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Carbon and alloy steels

Carbon steels

Classified as low, medium and high:

1. Low-carbon steel or mild steel, < 0.3%C,

bolts, nuts and sheet plates.

2. Medium-carbon steel, 0.3% ~ 0.6%C,

machinery, automotive and agricultural

equipment.

3. High-carbon steel, > 0.60% C, springs,

cutlery, cable.


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Alloy steels

Steels containing significant amounts of

alloying elements.

Structural-grade alloy steels used forconstruction industries due to high strength.

Other alloy steels are used for its strength,

hardness, resistance to creep and fatigue, andtoughness.

It may heat treated to obtain the desired

properties.


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High-strength low-alloy steels

Improved strength-to-weight ratio.

Used in automobile

bodies to reduce weig

htand in agricultural equipment.

Some examples are:

1. Dual-phase steels2. Micro alloyed steels

3. Nano-alloyed steels


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Stainless steels

Characterized by their corrosion resistance,high strength and ductility, and high

chromium content.

Stainless as a film ofchromium oxide protects

the metal from corrosion.


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Stainless steels

Five types of stainless steels:

1. Austenitic steels

2. Ferritic steels3. Martensitic steels

4. Precipitation-hardening (PH) steels

5. Duplex-structure steels


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Typical Selection of Carbon and Alloy Steels

for Various Applications

TAB L E 5 . 1

P ro d u ct S tee l P ro d u ct S tee l

Aircraft forgings,

tu b ing, f it t ings

A u tomo b i le b odies

Axles

Bal l b ear ings and races

Bolts

C a m sh aftsC h ains ( transmission)

Coil spr ings

Connect ing rods

Cranksh afts (forged )

4140 , 8740

1010

1040 , 4140

52100

1035, 4042, 4815

1020 , 10403135 , 3140

4063

1040, 3141, 4340

1045, 1145, 3135, 3140

Differential gears

G ears (car and truck)

Landing gear

Lock w ash ers

N u ts

Rai l road ra i ls and w h eels

Spr ings (coi l )Springs ( leaf)

T u b in g

W ire

W i re (mus ic)

4023

4027 , 4032

4140 , 4340 , 8740

1060

3130

1080

1095 , 4063 , 61501085 , 4063 , 9260 , 6150

1040

1045 , 1055

1085


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Mechanical Properties of Selected Carbon and

Alloy Steels in Various Conditions

TABLE 5.2 Typical Mechanical Properties of Selected Carbon and Alloy Steels in the Hot-Rolled,

Normalized, and Annealed Condition

AISI Condition Ultimate

tensile

strength

(MPa)

Yield

Strength

(MPa)

Elongation in

50 mm (%)

Reduction of

area (%)

Hardness

(HB)

1020

1080

3140

4340

8620

As-rolled

NormalizedAnnealed

As-rolled

Normalized

Annealed

Normalized

Annealed

Normalized

AnnealedNormalized

Annealed

448

441393

1010

965

615

891

689

1279

744632

536

346

330294

586

524

375

599

422

861

472385

357

36

3536

12

11

24

19

24

12

2226

31

59

6766

17

20

45

57

50

36

4959

62

143

131111

293

293

174

262

197

363

217183

149


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AISI Designation for High-Strength Sheet

Steel

TABLE 5.3

Yield Strength Chemical

Composition

Deoxidation

Practice

psi x 103

MPa

35

40

4550

60

7080

100120

140

240

275

310350

415

485550

690830

970

S = structural alloy

X = low alloy

W = weathering

D = dual phase

F = killed plus sulfide inclusion control

K = killed

O = nonkilled


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Room-Temperature Mechanical Properties and

Applications of Annealed Stainless SteelsTABLE 5.4 Room-Temperature Mechanical Properties and Typical App lications of S elected Annealed

Stainless Steels

AISI

( S)

ltimate

te sile

stre gt

( a)

iel

stre gt

( a)

Elo gatio

i 50 mm

( ) aracteristics a ty ical a licatio s

30 3

(S30300)

550620 240260 5350 Scre machine products, shafts, valves, bolts,

bushings, and nuts; aircraft fittings; bolts; nuts;

rivets; scre s; studs.30 4

(S30400)

565620 240290 6055 hemical and food pro cessing equipment,

bre ing equipment, cryogenic vessels, gutters,

do nspouts, and flashings.

31 6

(S31600)

550590 210290 6055 igh corrosion resistance and hig h creep strength.

hemical and pulp handling equipment,

photographic equipment, brandy vats, fertilizer

parts, ketchup cooking kettles, and yeast tubs.

41 0(S41000)

480520 240310 3525 Machine parts, pump shafts, bolts, bushings, coalchutes, cutlery, tackle, hard are, jet engine parts,

mining machinery, rifle barrels, scre s, and

valves.

41 6

(S41600)

480520 275 3020 Aircraft fittings, bolts, nuts, fire extinguisher

inserts, rivets, and scre s.


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Tool and die steels

Designed forhigh strength, impact toughness,and wear resistance at a range of

temperatures.


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Basic Types of Tool and Die Steels

TABLE 5.5

Type AISI

High speed

Hot work

Cold work

Shock resisting

Mold steels

Special purpose

Waterhardening

M (molybdenum base)

T (tungsten base)

H1 to H19 (chromium base)

H20 to H39 (tungsten base)

H40 to H59 (molybdenum base)D (high carbon, high chromium)

A (medium alloy, airhardening)

O (oil hardening)

S

P1 to P19 (low carbon)

P20 to P39 (others)

L (low alloy)F (carbon-tungsten)

W


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Processing and Service Characteristics of

Common Tool and Die Steels

TABLE 5.6 Processing and Service Characteristics of Common Tool and Die Steels

AISI

desig

atio

esista

ce to

decar

rizatio

esista

ce to

cracki

g

Appro imate

ardness

(

) ac ina ility To g ness

esistance to

softening

esistance to

ear

2 edium edium 6065 edium o

ery high Very high

T1 igh High 6065 edium o Very high Very high

T5 o

edium 6065 edium o Highest Very high

H11, 12, 13 edium Highest 3855 edium to high Very high High Medium

2 Medium Highest 5762 Medium Medium High High

A9 Medium Highest 3556 Medium High High Medium to

high

D2 Medium Highest 5461

o

o

High High to very

high

D3 Medium High 5461 o

o High Very high

H21 Medium High 3654 Medium High High Medium to

high

H26 Medium High 4358 Medium Medium Very high High

P20 High High 2837 Medium to high High Lo Lo to

medium

P21 High Highest 3040 Medium Medium Medium Medium

W1, W2 Highest Medium 5064 Highest High Lo Lo tomedium

Source: Adapted rom Tool teels, American Iron and teel Institute, 1978.


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Aluminium and aluminium alloys

Factors for selecting are:1. High strength to weight ratio

2. Resistance to corrosion

3. High thermal and electrical conductivity4. Ease of machinability

5. Non-magnetic


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Magnesium and magnesium alloys

Magnesium (Mg) is the lightest metal. Alloys are used in structural and non-

structural applications.

Typical uses of magnesium alloys are aircraftand missile components.

Also has good vibration-damping

characteristics.


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Copper and copper alloys

Copper alloys have electrical and mechanical

properties, corrosion resistance, thermal

conductivity and wear resistance.

Applications are electronic components,

springs and heat exchangers.

Brass is an alloy of copper and zinc.

Bronze is an alloy of copper and tin.


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Nickel and nickel alloys

Nickel(Ni) has strength, toughness, and

corrosion resistance to metals.

Used in stainless steels and nickel-base

alloys.

Alloys are used forhigh temperatureapplications, such as et-engine components

and rockets.


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Superalloys

Superalloys are high-temperature alloys use

in et engines, gas turbines and reciprocatingengines.


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Titanium and titanium alloys

Titanium (Ti) is expensive, has high strength-

to-weight ratio and corrosion resistance.

Used as components for aircrafts, et-engines,

racing-cars and marine crafts.


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Refractory metals

Refractory metals have a high melting point

and retain their strength at elevated

temperatures.

Applications are electronics, nuclear power

and chemical industries.

Molybdenum, columbium, tungsten, and

tantalum are referred to as refractory metal.


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Other nonferrous metals

1. Beryllium

2. Zirconium

3. Low-melting-point metals:- Lead

- Zinc

- Tin

4. Precious metals:

- Gold

- Silver

- Platinum


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Special metals and alloys

1. Shape-memory alloys (i.e. eyeglass frame, helical

spring)

2. Amorphous alloys (Metallic

Glass)

3. Nanomaterials

4. Metal foams


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Heat Treatment of Metals

Annealing Full annealing

Normalising (faster rate of cooling)

Recovery annealing (longerh

olding time,slower rate of cooling,)

Stress relieving (lower temperature)

Martensite formation in steel

Austenitizing (conversion to austenite)

Quenching (control cooling rate

Tempering (reduce brittleness)


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Heat Treatment of Metals

Precipitation hardening

Solution treatment (E-phase conversion)

quenching

precipitation treatment (aging)

Surface hardening

Carburizing

Nitriding Carbonitriding

Chromizing and Boronizing


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Heat Treatment of Steel


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Precipitation Hardening

Solution treatment

Quenching

Precipitation treatment


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Furnaces for Heat Treatment

Fuel fire furnaces gas

oil

Electric furnacesbatch furnaces

box furnaces - door

car-bottom furnaces - track for moving large parts

bell-type furnaces - cover/bell lifted by gantry crane

continuous furnaces


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Furnaces for Heat Treatment

Vacuum furnaces

Salt-bath furnaces

Fluidized-bed furnaces

Some of the furnaces have special atmosphere

requirements, such as carbon- and

nitrogen- rich atmosphere.


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Surface Hardening Methods

Flame hardening

Induction heating

High-frequency resistance heating

Electron beam heating

Laserbeam heating


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Surface Hardening Methods

Induction

heating

High frequency

resistance

heating


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Classification of Ceramics

Ceramics

Traditional ceramics

New ceramics

Glass


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Ceramics

Traditional ceramics

clays: kaolinite

silica: quartz, sandstone

alumina

silicon carbide

New ceramics

oxide ceramics : alumina carbides : silicon carbide, titanium carbide, etc.

nitrides : silicon nitride, boron nitiride, etc.


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Glass

Glass products

window glass

containers

light bulb glass

laboratory glass

glass fibers

optical glass Glass ceramics - polycrystalline structure


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Classification of Polymers

Thermoplastics

Thermosets

Elastomers


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Polymers

Thermoplastics - reversible in phase by heating

and cooling. Solid phase at room temperature

and liquid phase at elevated temperature.

Thermosets - irreversible in phase by heatingand cooling. Change to liquid phase when

heated, then follow with an irreversible

exothermic c

hemical reaction. Remain in solidphase subsequently.

Elastomers - Rubbers


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Thermoplastics

Acetals

Acrylics - PMMA

Acrylonitrile-Butadiene-Styrene - ABS

Cellulosics

Fluoropolymers - PTFE , Teflon

Polyamides (PA) - Nylons, Kevlar

Polysters - PET

Polyethylene (PE) - HDPE, LDPE Polypropylene (PP)

Polystyrene (PS)

Polyvinyl ch

loride (PVC)


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Thermosets

Amino resins

Epoxies

Phenolics

Polyesters

Polyurethanes

Silicones


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Elastomers

Natural rubber

Synthetic rubbersbutadiene rubber

butyl rubber

chloroprene rubber

ethylene-propylene rubber

isoprene rubber

nitrile rubber

polyurethanes

silicones

styrene-butadiene rubber

thermoplastic elastomers


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Classification of Composite Materials

Metal Matrix Composites

Ceramic Matrix Composites

Polymer Matrix Composites


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Composite Materials

Metal Matrix Composites (MMC)Mixture of ceramics and metals reinforced by strong,

high-stiffness fibers

Ceramic Matrix Composites (CMC)

Ceramics such as aluminum oxide and silicon carbide

embedded with fibers for improved properties,

especially high temperature applications.

Polymer Matrix Composites (PMC)Thermosets or thermoplastics mixed with fiber

reinforcement or powder.


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Composite Materials

1D fibre

Woven fabric

Random fibre


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Composite Materials


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Taxonomy of Materials Selection

Ashby,: Material Selection

in Mechanical Design


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4- Lec 3_1 Material First