Quenching
quenching heats up the steel to critical temperature Ac3 (hypo-eutectoid steel) or Ac1 (hyper-eutectoid steel) above some temperature, keeps warm for some period of time. causes it completely or the partial austenite 1,than cool the steel quickly at the speed which is faster than the speed of critical cooling.
Quenching is widely used in modern machine-buildbing industry. Important parts in the machinery ,especialy for the application of steels in cars,planes and rocks are almost dealing with quenching treatment. In order to meet different technical requirements of all kinds of mechanical parts,a variety of quenching process were developed. there are "local quenching","surface quenching","completely quenching","incomplete quenching","step quenching","isothermal quenching" and slack quenching. The processes of quenching include:"heating","heat preservation" and "cooling".
The purpose of quenching is to transform the underheating austenite to martensite or bainite, obtains their organization, then coordinate with the different temperature's tempering,to largely enhances the steel’s intensity, hardness, the wear resistance, fatigue as well as tough strength and so on.
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