基于应变补偿TC4-DT钛合金高温变形本构模型

通过TC4-DT钛合金在1181~1341 K,0.01~10 s~(-1)条件下热模拟压缩试验,得到其在不同条件下高温变形真应力-真应变曲线。采用回归分析和多项式拟合建立了应变补偿高温变形本构方程。结果表明:各变形条件下的流变应力曲线均呈现应变硬化和流动软化,低温高应变速率特征更明显。当应变速率低于1 s~(-1)时,预测值与实验值吻合程度较高,相关系数和平均相对误差绝对值分别为0.9952和5.78%,此修正模型可作为TC4-DT钛合金高温变形本构方程。

Constitutive Model of TC4-DT Titanium Alloy at Elevated Temperature Considering Compensation of Strain

Elevated-temperature flow behavior of TC4-DT titanium alloy was investigated by conducting isothermal hot compression tests at strain rate from 0.01 to 10 s-1 and in the temperature range of 1181~1341 K on Gleeble-3500 simulator. The Arrhenius constitutive equation considering the strain was established based on the experiment data with the material constants expressed by a polynomial fitting of strain. The results show that all the true stress-strain curves exhibit the characteristics of strain hardening followed by flow softening and it is particularly significant at higher strain rates and lower temperatures. The flow stress values predicted by the developed constitutive model demonstrate a well agreement with the experimental results at the strain rates under 1 s-1. The correlation coefficient (R) and average absolute relative error (AARE) are 0.9952 and 5.78%, respectively, which con?rm that the modi?ed constitutive equation could give an accurate and precise estimate of the ?ow stress of TC4-DT titanium alloy.