TA32新型钛合金高温流变行为及本构模型研究

Research on Flow Behavior of TA32 Titanium Alloy at High Temperature and Constitutive Model

摘要:

为了研究TA32钛合金的高温流变行为,建立该材料本构模型,本文对TA32钛合金进行了温度范围为650℃~850℃,应变速率为10_-1~10_-4 s_-1条件下的高温拉伸试验。从实验结果可得,TA32型钛合金较高的温度(650℃)依然能保持较好的综合性能,在650℃~750℃区间内应变速率为10_-1~10_-3s_-1条件下,变形呈现出明显的加工硬化和再结晶现象,当温度升至800℃及以上时其塑性延伸率显著提高而强度发生下降,同时出现了稳态流动应力。随后,本文基于统计学和正则化原理,提出一种修正本构模型参数的方法,并建立了T32新型钛合金的Arrhenius-type型应力流变本构模型。对比实验结果可知,相对于传统的最小二乘法得到的模型,该修正方法得到的模型能有效地提高模型的精度。

Abstract:

In order to study the flow behavior of TA32 titanium alloy and set up the constitutive model at high temperature, this paper carries out a tensile experiment at temperatures in the range of 650℃-850℃ and at strain rates of 0.1-0.0001s_-1. The result indicated that the TA32 titanium alloy maintains a comprehensive performance at high temperature (about 650℃) . the behavior of tensile process at high temperature arises work hardening and dynamic recovery obviously at the range from 650℃ to 750℃ and low strain rate of 10_-1-10_-3s_-1 while the elongation of TA32 increases enormously and strength decreases clearly as temperature rises to 800℃ . At the mean time, the steady stage of stress occurs. The constitutive model of Arrhenius-type was constructed by using a specific correction method based on statistic and regularization. The comparison shows a more accurate flow predicted stress through modified model against to the conventional least squares model.