TC4-DT钛合金不同热变形条件下流变应力

利用Gleeble-3500型热模拟实验机,研究TC4-DT钛合金在温度850～1 000°C,应变速率0.01～10s-1,变形程度为70%条件下的热变形行为,分析流变应力行为及微观组织演变规律,建立并验证高温应力本构关系模型。结果表明,TC4-DT合金在950°C以下的较低温度变形时应力软化现象非常明显,在950°C以上高温度变形时,低应变速率(如.ε=0.01s-1)促进了动态再结晶行为的发生,而在较高的应变速率(如.ε=10s-1)时,一般只发生动态回复现象;并验证试验合金高温变形时的流变应力规律服从Z参数的双曲对数函数形式,模型预测应力值与实测值之间的平均相对误差为2.23%。

Flow Stress of TC4-DT Titanium Alloy Under Different Hot Deformation Conditions

Hot compressive deformation of TC4-DT titanium alloy is carried out through the hot-simulation machine of Gleeble-3500 under the condition of the deformation temperature ranging from 850 °C to 1 000 °C,the strain rate from 0.01 s-1 to 10 s-1,and the 70% deformation.The deformation behavior and microstructure are analyzed and the constitutive model is set up and proved.The results reveal that the stress softening phenomenon is obvious when TC4-DT alloy deforms at temperatures below 950 °C.The deformation mechanism and deformation activation energy is different from the deformation mechanism high above 950 °C.When the alloy deforms at temperatures above 950 °C,low strain rates(eg.ε·=0.01 s-1) contribute to the occurrence of dynamic recrystallization behavior,while at higher strain rates(eg.ε·=10 s-1),generally only dynamic recovery occurs.Meanwhile,the variation of the flow stress is subject to the hyperbolic form of logarithmic function of Z-parameters,and the average relative error between model predictions and measured values of stress is 2.23%.