By K.G.S.Prasad RaoConsultant Metallurgist

16/03/2016

Basis for usage of Material

Engineering Materials

Representative strengths of various categories of materials© 2003 Brooks/Cole Publishing / Thomson Learning™

Functional Classification of MaterialsAerospace

Biomedical Electronic Materials Energy Technology and Environmental TechnologyMagnetic Materials Photonic or Optical Materials Smart Materials Structural Materials

Classification of Materials-Based on Structure

Crystalline material is a material comprised of one or many crystals. In each crystal, atoms or ions show a long-range periodic arrangement. Single crystal is a crystalline material that is made of only one crystal (there are no grain boundaries). Grains are the crystals in a polycrystalline material. Polycrystalline material is a material comprised of many crystals (as opposed to a single-crystal material that has only one crystal). Grain boundaries are regions between grains of a polycrystalline material.

Classification of following factors to make it suitable to the appropriate functioning or end use of the component Temperature Corrosion Fatigue Strain Rate

Environmental and Other Effects

Effect of temperature on different type of material

Understanding the density and strength of weight ratio

Properties of materials

Mechanical properties of materialsStrength, Toughness, Hardness, Ductility,Elasticity, Fatigue and Creep

Chemical propertiesOxidation, Corrosion, Flammability, Toxicity, …

Physical propertiesDensity, Specific heat, Melting and boiling point,Thermal expansion and conductivity,Electrical and magnetic properties

Material Specification Chemical composition Mechanical properties – Strength, hardness (under various conditions: temperature, humidity, pressure) Physical properties – density, optical, electrical, magnetic Environmental – green, recycling

MetalsFerrous 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

General Properties and Applications of Ferrous Alloys• Ferrous alloys are useful metals in terms of mechanical, physical and chemical properties.• Alloys contain iron as their base metal.• Carbon steels are least expensive of all metals while stainless steels is costly.

Carbon and alloy steelsCarbon 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.

Carbon and alloy steelsAlloy steels• Steels containing significant amounts of alloying elements.• Structural-grade alloy steels used for construction industries due to high strength.• Other alloy steels are used for its strength, hardness, resistance to creep and fatigue, and toughness.• It may heat treated to obtain the desired properties.

Carbon and alloy steelsHigh-strength low-alloy steels• Improved strength-to-weight ratio.• Used in automobile bodies to reduce weight and in agricultural equipment.• Some examples are:1. Dual-phase steels2. Micro alloyed steels3. Nano-alloyed steels

Stainless steels• Characterized by their corrosion resistance, high strength and ductility, and high chromium content.• Stainless as a film of chromium oxide protects the metal from corrosion.

Stainless steels• Five types of stainless steels:1. Austenitic steels2. Ferritic steels3. Martensitic steels4. Precipitation-hardening (PH) steels5. Duplex-structure steels

Typical Selection of Carbon and Alloy Steels for Various ApplicationsTABLE 5.1Product Steel Product SteelAircraft forgings,

tubing, fittingsAutomobile bodiesAxlesBall bearings and racesBoltsCamshaftsChains (transmission)Coil springsConnecting rodsCrankshafts (forged)

4140, 874010101040, 4140521001035, 4042, 48151020, 10403135, 314040631040, 3141, 43401045, 1145, 3135, 3140

Differential gearsGears (car and truck)Landing gearLock washersNutsRailroad rails and wheelsSprings (coil)Springs (leaf)TubingWireWire (music)

40234027, 40324140, 4340, 87401060313010801095, 4063, 61501085, 4063, 9260, 615010401045, 10551085

Mechanical Properties of Selected Carbon and Alloy Steels in Various ConditionsTABLE 5.2 Typical Mechanical Properties of Selected Carbon and Alloy Steels in the Hot-Rolled,Normalized, and Annealed ConditionAISI Condition Ultimate

tensilestrength(MPa)

YieldStrength(MPa)

Elongation in50 mm (%)

Reduction ofarea (%)

Hardness(HB)

1020

1080

314043408620

As-rolledNormalizedAnnealedAs-rolled

NormalizedAnnealed

NormalizedAnnealed

NormalizedAnnealed

NormalizedAnnealed

44844139310109656158916891279744632536

346330294586524375599422861472385357

363536121124192412222631

596766172045575036495962

143131111293293174262197363217183149

AISI Designation for High-Strength Sheet SteelTABLE 5.3

Yield Strength ChemicalComposition

DeoxidationPractice

psi x 103 MPa35404550607080100120140

240275310350415485550690830970

S = structural alloy

X = low alloyW = weatheringD = dual phase

F = killed plus sulfide inclusion control

K = killedO = nonkilled

Room-Temperature Mechanical Properties and Applications of Annealed Stainless SteelsTABLE 5.4 Room-Temperature Mechanical Properties and Typical Applications of Selected AnnealedStainless Steels

AISI(UNS)

Ultimatetensile

strength(MPa)

Yieldstrength(MPa)

Elongationin 50 mm

(%) Characteristics and typical applications303(S30300)

550–620 240–260 53–50 Screw machine products, shafts, valves, bolts,bushings, and nuts; aircraft fittings; bolts; nuts;rivets; screws; studs.

304(S30400)

565–620 240–290 60–55 Chemical and food processing equipment,brewing equipment, cryogenic vessels, gutters,downspouts, and flashings.

316(S31600)

550–590 210–290 60–55 High corrosion resistance and high creep strength.Chemical and pulp handling equipment,photographic equipment, brandy vats, fertilizerparts, ketchup cooking kettles, and yeast tubs.

410(S41000)

480–520 240–310 35–25 Machine parts, pump shafts, bolts, bushings, coalchutes, cutlery, tackle, hardware, jet engine parts,mining machinery, rifle barrels, screws, andvalves.

416(S41600)

480–520 275 30–20 Aircraft fittings, bolts, nuts, fire extinguisherinserts, rivets, and screws.

Tool and die steels• Designed for high strength, impact toughness, and wear resistance at a range of temperatures.

Basic Types of Tool and Die SteelsTABLE 5.5Type AISIHigh speedHot work

Cold workShock resistingMold steelsSpecial purposeWater hardening

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, air hardening)O (oil hardening)SP1 to P19 (low carbon)P20 to P39 (others)L (low alloy)F (carbon-tungsten)W

Processing and Service Characteristics of Common Tool and Die SteelsTABLE 5.6 Processing and Service Characteristics of Common Tool and Die SteelsAISIdesignation

Resistance todecarburization

Resistance tocracking

Approximatehardness(HRC) Machinability Toughness

Resistance tosoftening

Resistance towear

M2 Medium Medium 60–65 Medium Low Very high Very highT1 High High 60–65 Medium Low Very high Very highT5 Low Medium 60–65 Medium Low Highest Very highH11, 12, 13 Medium Highest 38–55 Medium to high Very high High MediumA2 Medium Highest 57–62 Medium Medium High HighA9 Medium Highest 35–56 Medium High High Medium to

highD2 Medium Highest 54–61 Low Low High High to very

highD3 Medium High 54–61 Low Low High Very highH21 Medium High 36–54 Medium High High Medium to

highH26 Medium High 43–58 Medium Medium Very high HighP20 High High 28–37 Medium to high High Low Low to

mediumP21 High Highest 30–40 Medium Medium Medium MediumW1, W2 Highest Medium 50–64 Highest High Low Low to

mediumSource: Adapted from Tool Steels, American Iron and Steel Institute, 1978.