高强合金钢50SiMnVB动态再结晶模型研究

通过热模拟压缩试验研究了50SiMnVB合金钢在应变速率为0.01~10 s^-1、温度为800~1000℃条件下的高温热变形行为。利用金相显微镜观察了合金压缩变形后的显微组织,结果表明:50SiMnVB合金钢在高温热变形过程中发生了典型的动态回复和动态再结晶行为,其中,动态再结晶以连续再结晶的形式进行,且应变速率越小、温度越高,越容易发生动态再结晶。根据试验结果,基于应变硬化率θ与流动应力σ之间的关系,确定了50SiMnVB合金钢高温热变形动态再结晶的临界应变;采用线性回归拟合建立了包括临界应变方程、峰值应变方程以及体积分数方程的50SiMnVB合金钢的高温变形动态再结晶模型,经对比分析发现,该模型能较好地预测合金钢高温热变形动态再结晶的体积分数;建立了50SiMnVB合金钢高温热变形动态再结晶晶粒尺寸模型。

Study on dynamic recrystallization model for high-strength alloy steel 50SiMnVB

The high temperature thermal deformation behavior of 50 SiMnVB alloy steel under the strain rates of 0. 01-10 s^-1 and the temperatures of 800-1000 ℃ was studied by thermal simulation compression test,and the microstructure of alloy after compression deformation was observed by metallographic microscope. The results show that 50 SiMnVB alloy steel has typical dynamic recovery and dynamic recrystallization behaviors during the high temperature thermal deformation process,and the dynamic recrystallization takes place in the form of continuous recrystallization. The smaller the strain rate is and the higher the temperature is,the easier the dynamic recrystallization occurs. According to the test results,based on the relationship between strain hardening rate θ and flow stress σ,the critical strain for dynamic recrystallization of 50 SiMnVB alloy steel during the high temperature thermal deformation process was determined,and the dynamic recrystallization model of 50 SiMnVB alloy steel during the high temperature deformation including critical strain equation,peak strain equation and volume fraction equation was established by linear regression fitting. The comparative analysis shows that the model can better predict the volume fraction of dynamic recrystallization for alloy steel during the high temperature thermal deformation. And the grain size model of dynamic recrystallization for 50 SiMnVB alloy steel during high temperature thermal deformation was established.