42CrMoA钢热变形过程动态再结晶行为

Dynamic Recrystallization Behavior of 42CrMoA Steel during Thermal Deformation

目的通过Deform-3D软件模拟42CrMoA钢的热压缩过程,研究在压缩量为60%、变形温度为950~1100℃和应变速率为0.01~10s^(-1)条件下42CrMoA钢再结晶模型的可靠性。方法将热压缩试样沿轴线对半分开,以试样中心和边部位置作为金相观察区,分析42CrMoA钢的热变形行为,将计算得到的动态再结晶临界模型输入Deform-3D软件的前处理模块中,模拟过程的变形参数与实验过程的相同,通过在模拟试样的心部和边部位置进行点追踪,实现模拟结果和实验结果中组织的对比分析。结果在压缩过程中42CrMoA钢真应力的变化受加工硬化和动态软化协同作用影响。随着温度的升高,试样心部和边部的再结晶体积分数均有所上升,且试样心部动态再结晶体积分数大于边部的。模拟结果显示,当温度由1000℃升高至1100℃时,试样心部动态再结晶体积分数由75.6%升高至89.5%,在相同条件下,通过金相观察到试样心部的动态再结晶体积分数由73.2%升高至85.3%。结论基于Johnson-Mehl-Avrami模型改进的Yada再结晶模型可以较好地描述42CrMoA钢的动态再结晶过程,实验结果与模拟结果间的相对误差小于8.35%,验证了动态再结晶模型的准确性。

The work aims to study the reliability of the 42CrMoA steel recrystallization model under the total compression strain of 60%,deformation temperature of 950-1100℃and strain rate of 0.01-10 s^(−1) by Deform-3D software.The compressed sample was cut along the axis,and the center and edge position of the sample were used as the metallographic observation area.The thermal deformation behavior of 42CrMoA steel was analyzed.The calculated dynamic recrystallization model was input to the pre-processing module of Deform-3D software,and the deformation parameters of the simulation process were the same as those of the experimental process.The point tracking of the simulation results was carried out at the same position as the metal-lographic observation area.The results of simulation and experiment were compared and analyzed.It was found that the change of flow stress of 42CrMoA steel was affected by processing hardening and dynamic softening.The recrystallization volume fraction of the center and edge of the sample increased with the increase of temperature.The recrystallization grain volume frac-tion in the sample center was greater than that at the edge.The simulation results showed that when the temperature increased from 1000℃to 1100℃,the dynamic recrystallization grain volume fraction of the sample center increased from 75.6%to 89.5%,and the dynamic recrystallization volume fraction of the sample center of the sample increased from 73.2%to 85.3%under the same conditions.The improved Yada recrystallization model based on the Johnson-Mehl-Avrami model can better de-scribe the dynamic recrystallization process of 42CrMoA steel,and the relative error between simulation and test results is smaller than 8.35%,which verifies the accuracy of dynamic reconstruction models.