超细晶铁素体基体Q&P钢恒应力下的变形行为

采用预淬火热处理工艺得到了超细晶Q&P钢，通过力保载程序控制试验研究了试验钢在某一恒定应力作用下的组织演变和变形行为。结果表明，随着保载应力不断增大，应变量逐渐增加，应变随保载时间的延长略微增加；当加载应力低于屈服强度时，随保载时间延长，应变无变化；加载应力高于屈服强度时，变形量剧烈增加，在变形过程中应变诱导的残留奥氏体向马氏体转变；同时随着应变量不断增加，残留奥氏体的稳定性呈先降低再升高趋势。

Deformation behavior of Q&P steel with ultrafine-grained ferrite matrix under constant stress

Pre-quenching heat treatment process was adopted to obtain Q&P steel with ultrafine-grained ferrite. The microstructure evolution and deformation behavior of the tested steel under a constant stress were studied through a load-holding control experiment. The results show that the mount of strain increases gradually with the increasing of holding stress, and the strain increases slightly with the prolonging of the holding time. When loading stress is lower than the yield stress, the strain does not change with the prolonging of the load-holding time. When loading stress is higher than the yield stress, the amount of strain increases significantly and the strain-induced transformation from retained austenite to martensite occurs during the deformation process. In addition, the stability of retained austenite first decreases and then increases with the increase of strain.