退火温度对超细晶Q&P钢力学性能的影响

Effect of annealing temperature on mechanical properties of a ultra-fine-grained steel heat-treated by quenching and partitioning process

对传统淬火-配分钢(Q&P钢)添加合金元素Ni和Nb,并对实验钢采用两相区Q&P工艺处理,得到了一种超细晶Q&P钢,分析了实验钢的显微组织和力学性能。结果表明,该种成分钢得到了块状铁素体+块状马氏体+残留奥氏体的混合组织,且晶粒达到了亚微米级别。由于残留奥氏体的相变诱发塑性(TRIP)效应,使得实验钢获得了兼具强度和塑性的优异力学性能。在退火温度为690℃时,实验钢抗拉强度达到1195 MPa,断后伸长率为23.5%,强塑积达到28 GPa·%。

A low carbon alloy steel containing Ni and Nb was heat- treated by quenching and partitioning（ Q＆P） process at different intercritical temperatures,and the Q＆P treated steel with ultra- fine grains was obtained. Microstructure and mechanical properties of the steel were examined by optical microscope,SEM,XRD,EBSD technique and tensile tests. The results show that the microstructure of the steel consists of block ferrite and block martensite and retained austenite,and the grain size reaches submicron level. Due to the phase transformation induced plasticity（ TRIP） effect of retained austenite,excellent mechanical properties of strength and ductility are obtained. When annealed at 690 ℃,the tensile strength of the experimental steel reaches 1195 MPa and the elongation reaches 23. 5%with strength ductility product of 28 GPa·%.