Slide 1Phase diagram of steelMaterial properties of varying steelsPhase diagram of steelPhase transformation from austenitePhase structure changes by cooling ratesSlide 7Slide 8Quick quench transforms to martensiteSlow cooling produces pearliteRapid quench and temper make bainiteControlled cooling can make mixes of allSlide 13STEEL HEAT TREATMENTSMEEN 361 – LABFALL 2016Phase diagram of steel01/13/2019 2Image from: http://http://chemistry.about.com, accessed 2/20/12•Steels are Fe alloys containing less than 2%wt carbon•Most steels are less than 0.8%wt C•Phase diagram illustrates the phases present for a particular carbon content and temperature•Cast irons contain between 2-6%wt CMaterial properties of varying steels•Carbon works as an interstitial in BCC Fe•Increased carbon can help improve certain properties but hinder others•Selection of carbon content in steel depends on application01/13/2019 3Image from: Callister, 6th ed.Phase diagram of steel01/13/2019 4Image from: http://hemistry.about.com, accessed 2/20/15•Steels are Fe alloys containing less than 2%wt carbon•Most steels are less than 0.8%wt C•Phase diagram illustrates the phases at a particular condition•Cast irons contain between 2-6%wt CPhase transformation from austenite•As steel cools from austenite, it will transform to create ferrite and cementite•The proportion of each phase can be calculated by the lever rule.•Proportion of each is dependent on carbon content and temperature01/13/2019 5Image from: Askeland, 6th ed.Phase structure changes by cooling rates•An austenized steel will produce different microstructures depending on cooling rates•Each structure has different mechanical properties •Controlled cooling and tempering can produce steel with desired properties01/13/2019 601/13/2019 701/13/2019 8Quick quench transforms to martensite01/13/2019 9Slow cooling produces pearlite01/13/2019 10Rapid quench and temper make bainite01/13/2019 11Controlled cooling can make mixes of all01/13/2019 1201/13/2019
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