Engineering Materials. Materials. Metals. Material Properties. Solidification of Molten Metal. Grain Structure. Page 1

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1 Materials Engineering Materials R. Jerz 1 1/21/2006 R. Jerz 2 1/21/2006 Material Properties Metals R. Jerz 3 1/21/2006 R. Jerz 4 1/21/2006 Solidification of Molten Metal Grain Structure Figure 1.11 Schematic illustration of the stages during solidification of molten metal; each small square represents a unit cell. (a) Nucleation of crystals at random sites in the molten metal; note that the crystallographic orientation of each site is different. (b) and (c) Growth of crystals as solidification continues. (d) Solidified metal, showing individual grains and grain boundaries; note the different angles at which neighboring grains meet each other. R. Jerz 5 1/21/2006 Figure 4.3 (a) Schematic illustration of grains, grain boundaries, and particles dispersed throughout the structure of a two-phase system, such as a lead-copper alloy. The grains represent lead in solid solution in copper, and the particles are lead as a second phase. (b) Schematic illustration of a two-phase system consisting of two sets of grains: dark and light. The dark and the light grains have separate compositions and properties. R. Jerz 6 1/21/2006 Page 1 1

2 Microstructure for Cast Irons Cold, Warm and Hot Working Figure 4.13 Microstructure for cast irons. Magnification: 100x. (a) Ferritic gray iron with graphite flakes. (b) Ferritic ductile iron (nodular iron) with graphite in nodular form. (c) Ferritic malleable iron. This cast iron solidified as white cast iron with the carbon present as cementite and was heat treated to graphitize the carbon. R. Jerz 7 1/21/2006 R. Jerz 8 1/21/2006 Mechanical Properties Stress-strain Curve R. Jerz 9 1/21/2006 Figure 2.2 A typical stress-strain curve obtained from a tension test, showing various features R. Jerz 10 1/21/2006 Other Mechanical Properties Hardness-testing Methods R. Jerz 11 1/21/2006 R. Jerz 12 1/21/2006 Page 2 2

3 Brinnel Testing Indentation Strength versus Temperature R. Jerz 13 1/21/2006 R. Jerz 14 1/21/2006 Heat Treating (Ch.4) Hardness and Time R. Jerz 15 1/21/2006 Figure 4.16 Hardness of tempered martensite as a function of tempering time for the 1080 steel quenched to 65 HRC. Hardness decreases because the carbide particles coalesce and grow in size, thereby increasing the interparticle distance of the softer ferrite. R. Jerz 16 1/21/2006 Gear Teeth Cross-section Heat Treatment Processes Figure 4.1 Cross-section of gear teeth showing induction-hardened surfaces. Source: Courtesy of TOCCO Div., Park-Ohio Industries, Inc. R. Jerz 17 1/21/2006 R. Jerz 18 1/21/2006 Page 3 3

4 Heat Treatment Processes (cont.) Metals Irons Cast irons Steels Stainless steel Tool steels Non-irons Aluminum Copper Magnesium Nickel Titanium R. Jerz 19 1/21/2006 R. Jerz 20 1/21/2006 Nonferrous Metals and Alloys Polymers Thermoplastics Thermosets Elastomers R. Jerz 21 1/21/2006 R. Jerz 22 1/21/2006 Properties of Plastics Ceramics and Graphite Glass Mineral Brick Mineral Diamond R. Jerz 23 1/21/2006 R. Jerz 24 1/21/2006 Page 4 4

5 Ceramics in Products Ceramic Components Figure 8.1 A variety of ceramic components. (a) High-strength alumina for hightemperature applications. (b) Gas-turbine rotors made of silicon nitride. Source: Courtesy of Wesgo Div., GTE. R. Jerz 25 1/21/2006 R. Jerz 26 1/21/2006 Composites Composites Reinforced plastics Ceramic-based Plywood and particleboard R. Jerz 27 1/21/2006 Figure 9.2 Schematic illustration of methods of reinforcing plastics (matrix) with (a) particles, (b) short or long fibers or flakes, and (c) continuous fibers. The laminate structures shown in (d) can be produced from layers of continuous fibers or sandwich structures using a foam or honeycomb core (see also Fig ). R. Jerz 28 1/21/2006 Boeing Changing the Nature of Materials Mix/blend/grow Process Work» Hot» Warm» Cold Heat treatment, anneal, hardening, quench Layer Figure 9.1 Application of advanced composite materials in Boeing commercial aircraft. Source: Courtesy of Boeing Commercial Airplane Company. R. Jerz 29 1/21/2006 R. Jerz 30 1/21/2006 Page 5 5

6 Selection American Society of Materials How do we select materials? Resources and Standards Reference books Internet» Software (Cambridge Engineering Selector) R. Jerz 31 1/21/2006 R. Jerz 32 1/21/2006 Page 6 6