高铝TRIP钢的微观组织与残余奥氏体稳定性研究

Microstructure and Stability of Retained Austenite in a High Al-Containing TRIP Steel

主要研究了高Al TRIP钢的显微组织与残余奥氏体的稳定性。通过光学显微镜、SEM、TEM观察了其微观组织。通过TEM观察了钢中马氏体与贝氏体的形貌。通过电子衍射斑分析,得出了残余奥氏体与马氏体的位向关系为K-S位向关系,奥氏体母相与贝氏体的位向关系为N-W位向关系。为研究残余奥氏体机械稳定性,对试验用钢进行了不同应变量的单向拉伸,用X射线测量了残余奥氏体体积分数。结果表明,真应变小于0.11时残余奥氏体体积分数随应变量增加而减少。真应变量大于0.11后,残余奥氏体体积分数随应变量增加变化不大。为了研究残余奥氏体热稳定性,将试验用钢冷却至不同的温度。发现高Al TRIP钢残余奥氏体热稳定性很高,深冷至-196℃条件下不发生马氏体转变。

The morphology and stability of retained austenite in a high Al-containing TRIP steel were studied by means of optical microscope,SEM,TEM and X-ray diffraction.The results show that the orientation relationship between martensite and retained austenite is K-S relationship,and the orientation relationship between bainite and retained austenite is N-W relationship.It is found that the volume fraction of retained austenite decreases with strain increasing when the true strain is smaller than 0.11.However,when the true strain is larger than 0.11, the volume fraction of retained austenite hardly changes with the strain. It is shown that the retain austenite has very high thermal stability and can not transform to martensite even at -196℃.