Ti40合金的高温本构模型研究

Study on High Temperature Constitutive Model of Ti40 Alloy

采用电子万能试验机对Ti40合金进行应变率为10（-2）、10（-3）、10（-4 ）s（-1）,温度为25、300、600、800℃的等温热压缩实验,得到该合金的真应力-真应变曲线。以Arrhenius模型为基础,结合合金的真应力-真应变曲线,提出了新的本构模型来表征Ti40合金在较大温度范围的力学性能。并采用指数函数拟合模型中的参数,通过分解-综合的方法,求解出本构模型中的各项参数,确立了Ti40合金的高温本构模型,并对所建立的模型进行定性的误差分析和定量的精度检验。结果表明：随着应变量的增加,应力计算值与实验曲线发展趋势吻合良好,且计算值与实验值的相对误差平均绝对值为AARE=3.8592%,证明本文提出的本构模型具有良好的精度,从而为Ti40合金的热加工模拟奠定了基础。

The true stress-true strain curves of Ti40 alloy were obtained by isothermal compression under temperatures of25℃,300℃,600℃,800℃and strain rate of 10^（-2）s^（-1）,10^（-3）s^（-1）and 10^（-4）s^（-1）using electronic universal testing machine.Based on Arrhenius model and combining true stress-true strain curves of Ti40 alloy,a new constitutive model was proposed to characterize the mechanical properties of Ti40 alloy in the wider range of temperature.The parameters of the constitutive model were solved to establish high temperature constitutive model of Ti40 alloy by adopting exponential function to fit the parameters of the model and using approach of decomposition-synthesis.The established model was validated with qualitative error analysis and quantitative precision test.The results show that the calculated values of stress is in good agreement with experimental curves with strain increasing,and the average absolute value of relative error between the calculated values and the experimental curves is 3.8592%,and all of these prove that the proposed constitutive model has a good accuracy so as to lay a foundation for hot working simulation of Ti40 alloy.