Study_Guide_Exam_3 - Met 121 Study Guide Exam #3 1. Be able...

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Met 121 Study Guide Exam #3 1. Ferrite ( α ) - BBC form of iron / max solubility = 0.0218%C / relatively soft and ductile / usually the intended matrix/is present in pearlite, spheroidite, bainite and tempered martensite Cementite (Fe 3 C) – contains 6.67%C / is very hard and brittle / usually the intended precipitate that provides strength to ferrite / is present in pearlite, spheroidite, bainite, and tempered martensite Austenite ( γ ) – FCC form of iron / max solubility =2.11%C / soft and ductile / “in the beginning there was austenite” – the starting point for most heat treatments Martensite (M) – very strong, hard, and brittle / a “metastable” phase that does not appear on the FE-C phase diagram / amount & carbon content = amount & carbon content of austenite / forms by athermal, diffusionless reaction / reaction accompanied by expansion (leading to quench cracks) / hardness depends only on carbon content /is Pearlite (P) – the lamellar mixture of plates of ferrite and cementite / contains 0.77%C / relatively low strength microconstituent / produced by annealing, normalizing, isothermal annealing Bainite (B) – mixture of ferrite and “elongated or oval” cementite / higher strength than pearlite / produced by austempering between nose and M s in TTT diagram Spheroidite – mixture of ferrite and very large spherical cementite / an intermediate microconstituent produced to provide good machinability – it is later replaced by tempered martensite / not strong Tempered Martensite – a mixture of ferrite and tiny spherical cementite / produced by heating martensite below the A 1 / capable of high strength with still usable ductility/ optimum dispersion strengthening
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This note was uploaded on 05/20/2008 for the course MET 121 taught by Professor Kohser during the Spring '07 term at Missouri S&T.

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Study_Guide_Exam_3 - Met 121 Study Guide Exam #3 1. Be able...

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