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采用Gleeble-3500热模拟实验机对低合金钢Q345B进行热压缩实验,研究其在变形温度为900～1100℃和应变速率为0.01～10s-1条件下的动态再结晶行为。结果表明:低合金钢Q345B在变形过程中存在动态再结晶现象,且随着温度的升高和应变速率的降低,临界应变越小,动态再结晶越易发生。根据流变应力、应变速率和变形温度的相关性,得到了动态再结晶激活能。通过对热模拟实验数据的分析计算,建立了峰值应变模型,动态再结晶临界应变模型和动态再结晶动力学模型。并对动态再结晶动力学模型进行了误差分析,证明了模型具有较高的精确性。最后,通过所建立的模型分析了变形条件对动态再结晶的影响,验证了实验所得出的在高温、低应变速率下更有利于动态再结晶发生的规律。
The hot compression experiment of low alloyed steel Q345B was carried out by Gleeble-3500 thermal simulation machine. The dynamic recrystallization behavior of Q345B was studied under the condition of deformation temperature of 900-1100 ℃ and strain rate of 0.01-10 s-1. The results show that there is dynamic recrystallization during the deformation of low alloy steel Q345B. With the increase of temperature and strain rate, the critical strain becomes smaller and the dynamic recrystallization occurs more easily. According to the correlation between flow stress, strain rate and deformation temperature, dynamic recrystallization activation energy is obtained. Through the analysis and calculation of thermal simulation data, the peak strain model, the dynamic recrystallization critical strain model and the dynamic recrystallization kinetics model were established. The error analysis of dynamic recrystallization kinetics model is also carried out, which proves that the model has high accuracy. Finally, the influence of deformation conditions on dynamic recrystallization was analyzed by the established model, which verified the rule that dynamic recrystallization was more favorable under high temperature and low strain rate.