材料期刊网

采用Gleeble-1500热模拟试验机对一种中碳钒微合金钢在变形温度900～1100℃、应变速率0．01～10 s-1条件下的热变形行为进行研究．分别建立了实验钢的幂律、指数和双曲正弦本构方程，观察了实验钢在不同变形条件下的显微组织，得出了实验钢的动态再结晶稳态晶粒尺寸和峰值应变与Zener-Hollomon参数的关系．结果表明：双曲正弦本构方程具有最高的拟合精度；实验钢热变形激活能Q为273．225 kJ/mol，与奥氏体的自扩散激活能（270 kJ/mol）十分接近，说明实验钢在此变形条件下的速率控制机制是扩散控制的位错攀移；显微组织观察表明，实验钢的动态再结晶行为受变形温度和应变速率的影响；拟合得出实验钢的动态再结晶稳态晶粒尺寸（ Ds）和峰值应变与Z参数的关系为ln Ds＝-0．20031ln Z＋7．94165和ln εp＝0．18456ln Z-5．37383．

The compressive deformation behaviors of a medium carbon vanadium microalloyed steel were investigated at the temperatures from 900 ℃ to 1 100 ℃ and strain rates from 0. 01 s-1 to 10 s-1 on a Gleeble-1500 thermo-simulation machine, and the power law, exponential and hyperbolic sine types of Zener-Hollomon equations were established for this steel. The hot deformation microstructure was observed, and the dependence of steady-state grain size and the peak strain on Zener-Hollomon parameter of this steel was plotted. Results showed that the highest correlation coefficient was achieved for the hyperbolic sine law for this steel. The activation energy Q for this steel was determined as 273.225 kJ/mol, very close to the austenite lattice self-diffusion activation energy ( 270 kJ/mol ) , indicating that the rate-controlling mechanism is dislocation climb controlled by diffusion. Microstructure observation showed that the dynamic recrystallization behavior of this steel was affected by both deformation temperature and strain rate. The dependence of steady-state grain size and the peak strain on Zener-Hollomon parameter was obtained as ln Ds=-0. 200 31ln Z+7.941 65 and ln εp=0.184 56ln Z-5.373 83.