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Types of Material IE 351 Lecture 3. Why Materials ??? Ashby,: Material Selection in Mechanical Design.

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Presentation on theme: "Types of Material IE 351 Lecture 3. Why Materials ??? Ashby,: Material Selection in Mechanical Design."— Presentation transcript:

1 Types of Material IE 351 Lecture 3

2 Why Materials ??? Ashby,: Material Selection in Mechanical Design

3 Engineering Materials

4 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

5 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

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

7 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

8 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.

9 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.

10 Carbon and alloy steels Alloy 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.

11 Carbon and alloy steels High-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 steels 2.Micro alloyed steels 3.Nano-alloyed steels

12 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.

13 Stainless steels Five types of stainless steels: 1.Austenitic steels 2.Ferritic steels 3.Martensitic steels 4.Precipitation-hardening (PH) steels 5.Duplex-structure steels

14 Typical Selection of Carbon and Alloy Steels for Various Applications

15 Mechanical Properties of Selected Carbon and Alloy Steels in Various Conditions

16 AISI Designation for High-Strength Sheet Steel

17 Room-Temperature Mechanical Properties and Applications of Annealed Stainless Steels

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

19 Basic Types of Tool and Die Steels

20 Processing and Service Characteristics of Common Tool and Die Steels

21 Aluminium and aluminium alloys Factors for selecting are: 1.High strength to weight ratio 2.Resistance to corrosion 3.High thermal and electrical conductivity 4.Ease of machinability 5.Non-magnetic

22 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 aircraft and missile components. Also has good vibration-damping characteristics.

23 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.

24 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 for high temperature applications, such as jet-engine components and rockets.

25 Superalloys Superalloys are high-temperature alloys use in jet engines, gas turbines and reciprocating engines.

26 Titanium and titanium alloys Titanium (Ti) is expensive, has high strength- to-weight ratio and corrosion resistance. Used as components for aircrafts, jet-engines, racing-cars and marine crafts.

27 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.

28 Other nonferrous metals 1.Beryllium 2.Zirconium 3.Low-melting-point metals: - Lead - Zinc - Tin 4.Precious metals: - Gold - Silver - Platinum

29 Special metals and alloys 1.Shape-memory alloys (i.e. eyeglass frame, helical spring) 2.Amorphous alloys (Metallic Glass) 3.Nanomaterials 4.Metal foams

30 Heat Treatment of Metals Annealing –Full annealing –Normalising (faster rate of cooling) –Recovery annealing (longer holding time, slower rate of cooling,) –Stress relieving (lower temperature) Martensite formation in steel –Austenitizing (conversion to austenite) –Quenching (control cooling rate –Tempering (reduce brittleness)

31 Heat Treatment of Metals Precipitation hardening –Solution treatment ( -phase conversion) –quenching –precipitation treatment (aging) Surface hardening –Carburizing –Nitriding –Carbonitriding –Chromizing and Boronizing

32 Heat Treatment of Steel

33 Precipitation Hardening Solution treatment Quenching Precipitation treatment

34 Furnaces for Heat Treatment Fuel fire furnaces –gas –oil Electric furnaces –batch furnaces box furnaces - door car-bottom furnaces - track for moving large parts bell-type furnaces - cover/bell lifted by gantry crane –continuous furnaces

35 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.

36 Surface Hardening Methods Flame hardening Induction heating High-frequency resistance heating Electron beam heating Laser beam heating

37 Surface Hardening Methods Induction heating High frequency resistance heating

38 Classification of Ceramics Ceramics –Traditional ceramics –New ceramics –Glass

39 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.

40 Glass Glass products –window glass –containers –light bulb glass –laboratory glass –glass fibers –optical glass Glass ceramics - polycrystalline structure

41 Classification of Polymers –Thermoplastics –Thermosets –Elastomers

42 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 heating and cooling. Change to liquid phase when heated, then follow with an irreversible exothermic chemical reaction. Remain in solid phase subsequently. Elastomers - Rubbers

43 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 chloride (PVC)

44 Thermosets Amino resins Epoxies Phenolics Polyesters Polyurethanes Silicones

45 Elastomers Natural rubber Synthetic rubbers –butadiene rubber –butyl rubber –chloroprene rubber –ethylene-propylene rubber –isoprene rubber –nitrile rubber –polyurethanes –silicones –styrene-butadiene rubber –thermoplastic elastomers

46 Classification of Composite Materials –Metal Matrix Composites –Ceramic Matrix Composites –Polymer Matrix Composites

47 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.

48 Composite Materials 1D fibre Woven fabric Random fibre

49 Composite Materials

50 Taxonomy of Materials Selection Ashby,: Material Selection in Mechanical Design






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