TC4-DT钛合金高温热变形行为研究

Study on Hot Deformation Behavior of TC4-DT Titanium Alloy

利用Gleeble-3500型热模拟实验机,研究了TC4-DT损伤容限型钛合金在温度850℃～1000℃、应变速率0.01～10s-1、变形程度为40%～70%条件下的热变形行为,分析了该合金的流变应力行为及微观组织演变规律,并建立了本构关系模型。研究结果表明,TC4-DT合金在950℃以下的较低温度变形时应力软化现象非常明显,变形机制和热变形激活能不同于950℃以上的较高温度变形机制;在950℃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,动态再结晶行为受抑制。

Hot compressive deformation of TC4-DT titanium alloy was carried out with the hot-simulation machine of Gleeble-3500 over the range of deformation temperature from 850 ℃ to 1000℃,strain rate from 0.01s-1 to 10s-1,and the deformation from 40% to 70%.The deformation behavior and microstructure have been analyzed;meanwhile the constitutive model has been set up.The results reveal that TC4-DT alloy deforms at temperatures below 950 ℃ when the stress softening phenomenon is very obvious,the deformation mechanisms and deformation activation energy are different from the deformation mechanism above the temperture of 950 ℃.When the alloy deforms at temperatures above 950 ℃,low strain rates（such as=0.01s-1） contribute to the occurrence of dynamic recrystallization behavior,while at higher strain rates（such as =10s-1）,only the phenomenon of dynamicrecovery generally occurs.The dynamic recrystallization is inhibited.