EA4T钢热变形行为及组织演变规律研究

Investigation on hot deformation behavior and microstructure evolution of EA4T steel

通过Gleeble-3200热模拟机对EA4T钢进行热压缩实验,研究了应变速率为0.01~10 s^（-1）,变形温度为950~1150℃条件下,EA4T钢的热变形行为和组织演变。分析其流变曲线发现,EA4T钢的峰值应力随着温度增大而减小,随着应变速率增大而增大,得到该材料在高的温度和低的应变速率条件下容易发生动态再结晶。基于Arrhenius双曲正弦方程建立了EA4T钢的热变形本构方程;运用数值计算方法,确定了EA4T钢的峰值激活能和稳态激活能分别为385.4和395.4 kJ·mol^（-1）;观察温度以及应变速率对试验钢组织演变的影响发现,动态再结晶晶粒尺寸随着变形温度的增加而增大,随着应变速率的增加而减小;通过测量晶粒度,获得动态再结晶晶粒尺寸和Z参数的关系式。

The hot compression tests of EA4 T steel were carried out by Gleeble-3200 thermal simulator,the hot deformation behavior and the microstructure evolution were investigated at the strain rate of 0. 01-10 s^（-1） and the deformation temperature of 950-1150 ℃.Through analyzing the rheological curves,it is found that the peak stress of EA4 T steel decreases with the increase of temperature,and increases with the increase of strain rate,it can be concluded that the dynamic recrystallization is easy to happen at high temperature and low strain rate. The constitutive equations of EA4 T steel during hot deformation were established based on hyperbolic sine equations of Arrhenius type. The peak and steady activation energy of the test steel are 385. 4 and 395. 4 kJ·mol^（-1） respectively by using the method of numerical calculation. By observing the influence of temperature and strain rate on the microstructure evolution of test steel,it is obtained that the recrystallization grain size increases with the increase of temperature and decreases with the increase of strain rate,and the relationship between the dynamic recrystallization grain size and Z parameters is fitted by measuring the grain size.