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采用应变速率循环法在超塑拉伸机上对TC21钛合金进行5组高温超塑性拉伸实验,变形温度范围860℃~940℃,应变速率循环范围10-5s-1~10-3s-1。通过对拉伸实验数据分析,计算出TC21钛合金动态再结晶激活能Q,利用Arrhenius模型构建TC21钛合金高温条件下的超塑性本构方程,并通过1stOpt软件进行非线性回归拟合进行修正,得到了更为精准的超塑性本构方程。实验结果表明,当变形温度不变时,流动应力随着应变速率的增大而增大,且高应变速率时,流动应力对应变速率的敏感性要大于低应变速率时,可判定TC21钛合金属于正应变速率敏感材料。TC21钛合金在860℃附近时的超塑性较好,综合延伸率可达366.6%。
Five high temperature superplastic tensile tests on TC21 titanium alloy were carried out on the superplastic stretching machine by the strain rate cycling method. The deformation temperature range was 860 ℃ ~ 940 ℃ and the strain rate circulation range was 10-5s-1 ~ 10-3s-1. The dynamic recrystallization activation energy Q of TC21 titanium alloy was calculated through the experimental data of tensile test. The superplastic constitutive equation of TC21 titanium alloy under high temperature was established by using Arrhenius model and modified by the nonlinear regression fitting of 1stOpt software. Get a more accurate superplastic constitutive equation. Experimental results show that when the deformation temperature is constant, the flow stress increases with the increase of strain rate, and when the strain rate is high, the sensitivity of flow stress to strain rate is greater than that of low strain rate. It can be determined that TC21 titanium alloy Belongs to the positive strain rate sensitive material. The superplasticity of TC21 titanium alloy near 860 ℃ is good, the comprehensive elongation rate can reach 366.6%.