中锰QP钢残余奥氏体的稳定性及其TRIP效应

摘要

The influence of the macro stress state on retained austenite stability of a quenched and partitioned (Q&P) steel with Mn content of 7 ％ was investigated by uniaxial tension and plane strain experiments.To evaluate the volume fraction of retained austenite under variable plastic strain,X-ray diffraction method was adopted.The deformation mechanism of the medium manganese Q&P steel was studied by observing the tensile curve,analyzing the change in microstructure of Q&P steel in deformation process by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results showed that the stress state had a great effect on the stability of retained austenite,and the plane strain was more conducive to the performance of the transformation induced plasticity (TRIP) effect.The tensile deformation characteristics of the 7Mn Q&P steel can be attributed to the interaction of ultrafine grain hardening mechanism and TRIP effect.The plastic deformation mechanism of the medium Q&P steel was mainly TRIP effect,the thin film and fine globular particles were more stable.%通过单向拉伸及平面应变实验研究了Mn含量为7％的中锰淬火-配分(Q&P)钢残余奥氏体的机械稳定性,利用X射线衍射仪(XRD)测定试验钢残余奥氏体的含量,通过观察试验钢的拉伸曲线及扫描电镜(SEM)、透射电镜(TEM)照片,分析变形前后的微现组织,研究中锰Q&P钢的变形机制.结果表明:应力状态对残余奥氏体稳定性有较大的影响,平面应变更有利于相变诱导塑性(TRIP)效应的发挥;中锰Q&P钢的拉伸变形特征是由超细晶硬化机制和TRIP效应相互作用产生的,通过微观组织观察发现中锰Q&p钢的塑性变形主要是残余奥氏体的TRIP效应,其中薄膜状的残余奥氏体的稳定性最高.