Plastic Deformation & Alloys Keyword: Malleable, Elastic Deformation, Plasticity, Ductile

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Transcript of Plastic Deformation & Alloys Keyword: Malleable, Elastic Deformation, Plasticity, Ductile

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Plastic Deformation & Alloys Keyword: Malleable, Elastic Deformation, Plasticity, Ductile Slide 2 Malleable A temporary shape change that is self- reversing after the force is removed, so that the object returns to its original shape, is called elastic deformation. In other words, elastic deformation is a change in shape of a material at low stress that is recoverable after the stress is removed. This type of deformation involves stretching of the bonds, but the atoms do not slip past each other. Slide 3 Plastic Deformation Beyond the elastic limit the material undergoes plastic deformation. Unlike elastic deformation, plastic deformation is not recoverable, i.e. the change is permanent. Ductile materials undergo large plastic deformations and waisting before fracturing; brittle materials undergo very little plastic deformation. Also known as placticity Slide 4 Plastic Deformation Failure by plastic deformation Use the info link to see examples of designs and materials testing, using rapid prototyping Slide 5 Plastic Deformation Slide 6 Alloys A mixture containing two or more metallic elements or metallic and non-metallic elements usually fused together or dissolving into each other when molten; "brass is an alloy of zinc and copper Ferrous and nonferrous alloys Slide 7 Alloys Change the melting point Increase strength, hardness & ductility Change colour Give rise to better casting Change electrical and thermal properties Slide 8 Iron & Carbon Stainless Steel is an alloy of Carbon and Iron Stainless steel is one of the fastest growing metals. Today, it is difficult to imagine life without this most durable and versatile material. And, it is 100% recyclable. Slide 9 Steel Stainless steel (steel and 18% chromium, 8% nickel, 8% magnesium) High-speed steel (steel and tungsten) Mild steel (iron and 0.15-0.35% carbon) Medium carbon steel (0.4-0.7% carbon) High-carbon steel (0.8-1.5% carbon) High tensile steel (low carbon steel & nickel) Manganese steel (1.5% manganese) Slide 10 Task 1 Explain the term alloy and give examples of two ferrous and two non- ferrous alloys. Give one example of how the following metals might be used and state which of the materials characteristics makes it particularly appropriate for the application that you have given. Cast ironCopper AluminiumBrass Slide 11 In search of superalloys Slide 12 Slide 13 Superalloys A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Superalloys typically have an austenitic face-centred cubic crystal structure. Slide 14 Superalloys A superalloy's base alloying element is usually nickel, cobalt, or nickel-iron. Superalloy development has relied heavily on both chemical and process innovations and has been driven primarily by the aerospace and power industries. Slide 15 Superalloys Typical applications are in the aerospace industry, eg. for turbine blades for jet engines Slide 16 Task 2 Define the following words and add a suitable images to illustrate your answer Plastic deformation Elastic deformation Superalloys Creep Oxidisation Malleable Ductile Slide 17 Links and Revision http://www.ndt- eformation.htmhttp://www.ndt- eformation.htm