A100超高强度钢的动态再结晶行为及组织演变研究

Research on dynamic recrystallization behavior and microstructure evolution of A100 ultra-high strength steel

借助Gleeble-3500热模拟试验机研究了A100超高强度钢在变形温度为850-1200℃、应变速率为0.001-10 s^（-1）和变形程度为60%条件下的热变形行为。基于实验数据计算了动态再结晶激活能,通过引入无量纲Z参数表征了动态再结晶的临界应变/应力、峰值应变/应力和稳态应变/应力模型,并绘制了动态再结晶状态图,同时对该钢的组织演变进行了分析。结果表明：该钢的动态再结晶激活能为380.177 k J·mol^（-1）;随着变形温度的升高或应变速率的下降,Z参数逐渐减小,更容易发生动态再结晶行为,但其晶粒尺寸随之增大,其中在950-1050℃、0.01-0.1 s^（-1）和1050-1150℃、1-10 s^（-1）范围内进行热加工可获得细小、均匀的晶粒组织。根据实验结果建立了动态再结晶晶粒尺寸预测模型,其预测值与实验值具有较高的吻合度。

Hot deformation behavior of A100 ultra-high strength steel was studied at temperature range of 850^（-1）200 ℃,strain rate range of 0. 001^（-1）0 s^（-1） and deformation degree of 60% by employing Gleeble-3500 thermal simulator. Dynamic recrystallization activation energy was calculated based on the experimental data. Models of dynamic recrystallization such as model of critical strain/stress,model of peak strain/stress and model of steady strain/stress were characterized by considering the dimensionless Z parameter,the dynamic recrystallization state graph was drawn,and the microstructure evolution of the steel was analyzed. The results show that the dynamic recrystallization activation energy of the steel is 380. 177 k J·mol^（-1）. With the increase of deformation temperature or the decrease of strain rate,the Z parameter decreases gradually,and the dynamic recrystallization behavior is more likely to occur,but its grain size increases. The refined and uniform grain organization is obtained in the range of 950^（-1）050 ℃,0. 01-0. 1 s^（-1） and 1050^（-1）150 ℃,1^（-1）0 s^（-1）. According to the experimental results,dynamic recrystallization grain size prediction model was established. And its predicted value is in good agreement with the experimental data.