低碳Q690qENH高强桥梁钢的动态再结晶行为

Dynamic Recrystallization Behaviors of Low Carbon Q690qENH High-strength Bridge Steels

对低碳Q690qENH高强桥梁钢进行压缩实验,研究了动态再结晶行为。结果表明,在低碳Q690qENH高强桥梁钢的轧制热变形过程中,其软化以动态回复为主,只在0.1 s^(-1)和0.2 s^(-1)低应变速率下才发生明显的动态再结晶.通过计算将应力因子α修正为0.0099 MPa^(-1),得到了实验钢的动态再结晶激活能,建立了动态再结晶动力学模型。采用P-M-K法确定了εc/εp约为0.72,且峰值应变与Z/A满足幂函数关系,建立了动态再结晶临界应变模型,其计算值与热变形中的显微组织演变规律一致。研究了温度对动态再结晶过程中界面迁移速率的影响规律。

The dynamic recrystallization behaviors of low carbon Q690qENH high-strength bridge steel were investigated by hot compression deformation using MMS-300 thermo-simulation machine. The results show the softening of low carbon Q690qENH high-strength bridge steel is mainly controlled by dynamic recovery during hot rolling deformation and the dynamic recrystallization occurs obviously at low strain rates of 0.1 s^-1 and 0.2 s^-1. The stress factor was modified as 0.0099 MPa-1, the dynamic recrystal- lization activation energies were gained, and the dynamic recrystallization kinetics model was established. The expression of εc=0.72εp was determined using P-M-K method. Correlations between peak strain and Z/A are power function, and dynamic recrystallization critical strain model was established calculation values of which are good agreement with evolution of microstructure during hot deformation. EfFects of temperature on migration-rate of interface were also investigated during dynamic recrystallization.