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利用热力模拟实验技术、OM及TEM等,研究了一种低碳含V微合金钢在温度为900—1150℃及应变速率为0.01—10s~(-1)条件下奥氏体动态再结晶和析出行为.采用回归法确定了该微合金钢的热变形激活能和表观应力指数,建立了该钒微合金钢的热加工方程;根据应变硬化率与应力的P-J方法,结合高阶多项式拟合,精确确定了动态再结晶临界应变值,获得了临界应变、峰值应变与Z参数之间的关系;最后,研究了低应变速率变形时该钢中V(C,N)粒子的动态析出行为.结果表明,在某一变形温度和应变速率下,随着应变的进行,V(C,N)粒子的平均尺寸增加,且尺寸分布范围变宽;再结晶驱动力和钉扎力的计算结果表明,一旦动态再结晶开始发生,动态析出就不能阻止动态再结晶过程的进行.
The effects of austenite dynamic recrystallization and microstructure of low carbon microalloyed V-alloy at 900-1150 ℃ and strain rate of 0.01-10s ~ (-1) were investigated by means of thermodynamic simulation, OM and TEM. The thermal deformation activation energy and apparent stress index of the microalloyed steel were determined by regression method and the thermal processing equation of the microalloyed steel was established. According to the PJ method of strain hardening rate and stress, combined with the high-order polynomial simulation Finally, the dynamic behavior of V (C, N) particles in the steel at low strain rate deformation was studied. The critical strain, dynamic strain rate and critical strain were obtained. The results show that the average size of V (C, N) particles increases and the size distribution broadens with the strain at a certain deformation temperature and strain rate. The calculation results of the recrystallization driving force and pinning force Show that, once dynamic recrystallization begins to occur, dynamic precipitation can not stop the dynamic recrystallization process.