35CrMo模具钢的相变规律及硬度研究

Research on the Phase Transformation Law and Hardness of 35CrMo Mould Steel

利用MMS—200热模拟试验机研究了35CrMo模具钢的相变规律,采用热膨胀法及金相法建立了CCT曲线,分析了工艺参数对组织的影响。结果表明,冷却速度<0.2℃/s时,钢的组织为铁素体+珠光体;冷速0.2~0.5℃/s时,为贝氏体及少量铁素体+珠光体;冷速0.5~2℃/s时,为贝氏体;冷速2~7℃/s时,为贝氏体、马氏体混合组织;冷速7~15℃/s时,组织中主要是马氏体及少量的残余奥氏体,随冷速增大,贝氏体减少,马氏体增加,试样的硬度也随之增加。

The transformation law of 35CrMo mould steel is studied by means of MMS--200 thermal simulator. The CCT curve is set up and the influencing law of technological parameters on microstructure is analyzed by using thermal expansion method and metallographic method. The test results show that the cooling rate is less than 0.2 ℃/s, the microstructure of the steel is ferrite and pesxlite. The cooling rate is 0.2 to 0.5 ℃/s, the micrestructure is bainite and a small amount of ferrite with pearlite. The cooling rate of 0.5 to 2 ℃/s, the microstructure is bainite. When the cooling rate is 2-7 ℃/s, the microstructure is bainite and martensite. The cooling rate is 7 to 15 ℃/s, the microstructure is mainly martensite and a small amount of residual austenlte. The bainite decreases, martensite increases, the hardness of samples increases with the increasing of cooling rate.