TC21钛合金热变形行为

Thermal deformation behavior of TC21 titanium alloy

采用Gleeble−3500热模拟试验机对TC21钛合金进行了高温热压缩变形试验。试验变形温度为890~990℃,应变速率为0.01~10 s−1。通过分析不同热变形条件下获得的应力−应变曲线和微观组织,探究合金在高温变形中的微观组织演变规律。结果表明:TC21钛合金对变形温度和变形速率极其敏感,流变应力随着应变速率的增加和温度的降低而升高。随着变形温度的升高和应变速率的降低,变形中动态回复作用增强,微观组织中动态再结晶晶粒数目减少。此外,应用线性回归方法,建立TC21钛合金的高温本构方程,经过实验验证,该本构模型与实验结果吻合较好;基于Prasad失稳准则,建立了TC21钛合金热加工图,为TC21钛合金锻造工艺的制定提供理论依据。

The high temperature hot compression deformation tests of TC21 titanium alloy were carried out by Gleeble−3500 thermal simulation machine.The test deformation temperature was in the range of 890−990℃and the strain rate was in the range of 0.01−10 s−1.The microstructure evolution of the alloy during high temperature deformation was investigated by analyzing the stress−strain curves and the microstructure obtained under different hot deformation conditions.The results show that TC21 titanium alloy is very sensitive to deformation temperature and strain rate,and the flow stress increases with increase of strain rate and decrease of temperature.With increasing deformation temperature and decreasing strain rate,the dynamic recovery effect in the microstructure is enhanced and the number of dynamic recrystallized grains in the microstructure decreases.In addition,the high temperature constitutive equation of TC21 titanium alloy was established by the regression method.The experimental results show that the constitutive model is in good agreement with the experimental results.The processing map on the basis of Prasad instability criterion was established,which provided a theoretical basis for planning the forging process of TC21 titanium alloy.