基于DMNR模型建立EB炉熔炼TC4钛合金的双重多元非线性回归本构方程

Dual Multivariate Nonlinear Regression Constitutive Equation of EB Furnace Smelting TC4 Titanium Alloy Based on DMNR Model

通过热模拟压缩实验研究EB炉熔炼TC4钛合金在应变速率为0.01~10 s^(-1),变形温度为800~1100℃条件下的热变形行为,计算合金在不同变形条件下的应变速率敏感性指数m,并基于DMNR模型建立EB炉熔炼TC4钛合金的双重多元非线性回归本构方程。结果表明:在变形开始阶段,加工硬化占主导作用,流动应力随着应变的增加而增加,当达到峰值应力后,软化作用占主导,位错开始发生滑移和攀移,流动应力随着应变的增加而降低。在低温小应变速率下m值较大,在高温大应变速率下m值较小。m值越大,对应的显微组织越均匀。采用所建立的非线性回归本构方程能够较好地预测EB炉熔炼TC4钛合金的流动应力,预测值与实测值之间的平均绝对相对误差为5.83%,相关系数为0.98。

The thermal simulation compression experiment was used to study the thermal deformation behavior of EB furnace smelting TC4 titanium alloy at a strain rate of 0.01~10 s^(-1) and a deformation temperature of 800~1100℃,the strain rate sensitivity index m of the alloy under different deformation conditions was calculated,and a dual multivariate nonlinear regression constitutive equation for EB furnace smelting TC4 titanium alloy was established based on the DMNR model.The results show that at the beginning of deformation,work hardening is dominant,and the flow stress increases with the increase of strain.After reaching the peak stress,the softening effect is dominant,the dislocations begin to slip and climb,and the flow stress decreases with the increases of strain.The value of m is larger at low temperature and small strain rate,and smaller at high temperature and large strain rate.The larger the value of m,the more uniform the corresponding microstructure.The established nonlinear regression constitutive equation can better predict the flow stress of TC4 titanium alloy smelted by EB furnace.The average absolute relative error between the predicted value and the measured value is 5.83%,and the correlation coefficient is 0.98.