高温回火对20Cr2Ni4A钢渗碳层中残留奥氏体的影响

Influence of high temperature tempering on retained austenite in carburized 20Cr2Ni4A steel

减少20Cr2Ni4A钢渗碳后残留奥氏体的途径主要有高温回火和深冷处理。研究不同高温回火工艺对20Cr2Ni4A渗碳层中残留奥氏体转变的影响,尤其是高温回火时间的影响。结果表明:采取第一次回火温度高和第二次回火时间长的工艺后进行淬火,表面硬度超过62 HRC,渗层组织为细密的隐针马氏体+均匀的碳化物+较少的残留奥氏体,保证产品渗碳淬火后表面硬度满足了生产需要。

The main ways for reducing retained austenite of carburized 20Cr2Ni4A steel are high temperature tempering and cryogenic treatment.The influence of different high temperature tempering on retained austenite in carburized 20Cr2Ni4A steel was researched,especially the tempering time.The results show that after tempering with high tempering temperature at first and then prolonged temper holding time,the hardness of hardened case heat treatment can be over 62 HRC and the microstructure in the case is cryptocrystalline martensite ＋ uniform carbides ＋ small amount of austenite,therefore the surface hardness of parts after carburizing and quenching as well as tempering can meet the requirements.