Ti-6Al-4V热变形行为及利用多项耦合进行本构关系修正

采用热模拟试验机对钛合金Ti-6Al-4V进行高温压缩试验，研究其在850~1100 ℃温度下，0.001~0.1 s?1应变速率的流动应力行为。结果表明:钛合金Ti-6Al-4V具有应变速率、温度敏感性；随着温度的升高和应变速率的减小，流动应力逐渐降低，加工硬化速率与动态软化速率达到动态平衡。通过分析工艺参数对材料参数的影响，发现合金的材料参数(N、A、Q)随变形条件的变化而变化。在传统双曲正弦函数型Arrhenius方程的基础上提出一种考虑应变速率、温度和应变耦合修正的双曲正弦本构方程，并用相关系数R和平均相对误差(AARE)来评价所建立的本构模型的准确性，定量分析结果表明，修正的本构方程能够较准确地预测钛合金Ti-6Al-4V的流动应力。

Hot Deformation Behavior and Constitutive Relations of Titanium Alloy Ti-6Al-4V and Modified by Multinomial Coupling

The flow stress behavior of Ti-6Al-4V in the temperture range of 850~1100 ℃ and the strain rate range of 0.001~0.1 s?1 was investigated through the high temperature compression test using a thermal simulation tester.The results show that the titanium alloy Ti-6Al-4V has strain rate and temperature sensitivity. As the temperature increases and the strain rate decreases, the flow stress gradually decreases, and the work hardening rate and the dynamic softening rate reach a dynamic balance. By analyzing the influence of process parameters on material parameters, it is found that the material parameters (N, A, Q) of the alloy are not constants, but change with the change of deformation conditions. Based on the traditional hyperbolic sine function Arrhenius equation, a hyperbolic sine constitutive equation considering the coupling correction of strain rate, temperature and strain is proposed. The accuracy of the established constitutive model is evaluated by the correlation coefficient R and the average relative error (AARE). The quantitative results show that the modified constitutive equation can predict the flow stress of titanium alloy Ti-6Al-4V more accurately.