超高强TB8钛合金高温塑性变形流变应力分析与本构方程

Flow stress analysis and constitutive equation of super-strength TB8 titanium alloy during high temperature plastic deformation

在Gleeble-3000热模拟试验机上进行等温恒速率热压试验(变形温度800~950℃,应变速率0.001~1.0 s-1),研究了TB8合金的高温塑性变形流变应力变化规律,建立了一个包含应变量的本构方程。结果表明,流变应力随变形温度的升高和应变速率的降低而减小;当ε·≤0.1 s-1时,TB8合金高温热压流变曲线为动态再结晶型流变曲线;热变形激活能Q、材料常数n、α、及ln A均与变形量有关;所建立的本构关系能较好的反应TB8合金高温低应变速率下的流变特征。

Hot compression tests of the titanium alloy were performed on Gleeble-3000 thermal simulator at the temperature range from 800 ℃to 950 ℃and at the strain rate range from 10 -3 s-1 to 1 s-1 .The flow stress was studied and the flow stress constitutive equation considering the effect of true strain was established for TB8 titanium alloy during high temperature plastic compression.The results show that the flow stress of TB8 titanium alloy decreases with decreasing of strain rate and increasing of deformation temperature.The flow stress curves obtained from experiments at the strain rate below 0.1 s-1 are typical of the recrystallization rheological curves. The hot deformation activation energy Q and the other material parameters are strain-dependent.It is proved that the model reflects the real deformation feature of TB8 alloy comparing with experimental results.