针对贝氏体研究中的超级贝氏体组织，设计了试验用钢70MnSi2CrMo，经低温等温处理，获得贝氏体铁素体＋残余奥氏体的组织，利用X射线衍射XRD、扫描电子显微镜SEM、透射电子显微镜TEM等仪器对其进行相组成和形态的检测分析。结果表明：在马氏体转变开始温度Ms点稍上的中低温区等温处理，贝氏体铁素体沿γ相晶界转变，无碳化物析出；α相转变排碳导致成分起伏，α/γ交界处过冷奥氏体稳定性增加，难以转变成马氏体；贝氏体铁素体的转变特征、过饱和的碳浓度、高密度位错、以及纳米尺寸相界面和亚结构等，影响着超级贝氏体钢的力学性能。
The experimental steel 70MnSi2CrMo was designed for the purpose to obtain bainite ferrite and retained austenite microstructure by isothermal treatment at lower temperature. The microstructure and phase composition of the treated steel were investigated by XRD, SEM and TEM. The results showed that the phase transformation of the bainite ferrite generated along the grain boundary of the phase γ when the employed temperature was over the martensite start temperature( Ms) , with no carbide precipitation. Simultaneously, the inhomogeneous composition distribution in the α phase was obtained for the discharging of carbon atoms, therefore, the martensite was difficult to generate for the increasing stability of the undercooling austenite at the edge of α and γ phases. Generally, the transformation behavior of bainite ferrite, oversaturated carbon concentration, high dislocation density, and the nanoscale phase interface and substructure generated between bainite ferrite and retained austenite, are the factors affecting the mechanical properties of super bainitic steel.
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