淬火合金钢中的奥氏体稳定化

研究了马氏体(M)和贝氏体(B)两相温度区等温淬火组织中的奥氏体稳定化．在一定等温时间内，奥氏体稳定化程度，即残余奥氏体量与等温温度间的关系呈马鞍型曲线．在实验钢中，其谷底值低于用同冷却介质淬火组织中的AR，表明在一定条件下等温停留并不引起残余奥氏体量增多．可利用马鞍型曲线调整AR与M及B的含量配比，获得无变形或强韧性配合最佳的准贝氏体等温淬火工艺．奥氏体稳定化为热稳定化、化学稳定化、相致稳定化和宏观热应力稳定化诸机制的综合作用．马氏体临界点Mc点无特殊物理意义。

Stabilization of Austenite in Quenched Alloy Steels

Retained austenite exists in alloy steels both continuously quenched and isothermally quenched, so its content relates to the austenitic stabilization. The article focuses on the investigation for the austenitic stabilization in isothermally quenched microstructures from duplex phase (martensite-M, bainite-B) temperature region. Within a certain isothermal time, the relationship of the amount of retained austenite (AR.) vs isothermal temperature is a saddle-like curve, and the valley value for testing steel is less than that of continuous quenching with a same cooling medium, which proves that isothermal soak does not increase retained austenitic quantity on certain condition. By adjusting the content ratios of AR/M and AR/B on the saddle-like curve, an isothermal quenching of the less deformation or a meta-bainitic isothermal quenching with strength-toughness optimized combination can be achieved. Austenitic stabilization is the synthetic effect of thermal, chemical, phase induced and macro-thermal stress stabilized mechanisms. The martensite critical point Mc has not the special physical meaning.