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ME 111L unit 3 ppt conclusion

ME 111L unit 3 ppt conclusion - hardness of the...

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(Each 2 lined space between the bullets indicates a new slide) Different microstructures formed At higher isothermal transformation temperatures, pearlite forms. Coarse pearlite – thicker lamellar structure Medium pearlite – thick lamellar structure Fine pearlite – thinner lamellar structure Different microstructures formed At temperatures below pearlite formation region, bainite forms. Bainite consists of elongated particles of Fe 3 C embedded in α–ferrite matrix. Upper bainite – smaller, finer particles than pearlite Lower bainite – smaller, finer particles than upper bainite At temperatures below bainite formation region, martensite forms. How microstructural changes affect mechanical properties Pearlite and bainite form finer grains due to less carbon diffusion when the heat treatment temperature decreases. Finer microstructures have more grain boundaries. This increases the strength and
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Unformatted text preview: hardness of the microstructures while decreasing ductility. • Martensite has carbon interstitials in the crystal structure and is the strongest, hardest, and most brittle. Observed trends in mechanical properties data • The strength of the specimens (both tensile and yield strength) increases as the isothermal transformation temperature decreases. • Hardness increases as the heat treatment temperature decreases. • The young’s modulus should be constant because it is an intrinsic property of the metal and not dependent on the heat treatment. Observed trends in mechanical properties data • Ductility increases as the treatment temperature increases. This was seen by looking at the percent reduction in area and percent elongation. • Impact energy increases as the ductility increases. • All our results followed the expected trends....
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