TWIP钢在不同温度变形的加工硬化行为

通过温控拉伸试验、光学显微镜、X射线衍射技术和透射电镜分析了在298、373、473、573 K温度下变形时,20Mn24Cr5Al2Ni2TWIP钢的力学性能和显微组织变化规律。结果表明,TWIP钢的强度随变形温度的升高而降低,伸长率在373 K变形时比298 K变形显著下降;在373～573 K变形时伸长率有上升趋势;温度升高,组织中形变孪晶的数量减少,孪晶交叉现象减弱。研究TWIP钢的加工硬化行为表明,TWIP钢在拉伸过程中的加工硬化指数n值随真应变的增加而增加,在低应变区温度升高n值增加。在298～373 K变形时,形变孪晶占主导作用,在473～573 K变形时,形变孪晶和动态应变时效共同作用。

Temperature dependence of strain hardening behavior of TWIP steel

The mechanical properties of 20Mn24Cr5Al2Ni2 TWIP steel and the microstructure evolution with the temperature were investigated through tensile test,OM,XRD and TEM at 298,373,473 and 573 K.The results show that the strength decreases with deformation temperature increasing,elongation at 373 K obviously decreases in comparison with that at 298 K,but elongation between 373 K and 573 K is on the rise.With the deformation temperature increasing,the number of deformation twin and cross-twin reduce.The work hardening behavior of TWIP steel shows that work hardening index n increases with the true strain increasing.In low stain,the index n increases with the temperature increasing.Deformation twinning is the main mechanism at 298-373 K.During the deforming at 473-573 K,the main mechanism is interaction between deformation twinning and dynamic strain aging.