Ti60近α钛合金的热变形行为和组织演化

Thermal deformation behavior and microstructure evolution of nearαTi60 titanium alloy

通过热压缩模拟试验和微观组织表征研究了Ti60钛合金在变形温度为975~1080℃、应变速率为0.001~1 s^(-1)下的流变行为和微观组织演化规律。结果表明,Ti60钛合金在高应变速率变形时热效应导致的温升明显,并存在不连续屈服现象。随着变形温度由975℃增加到1080℃,Ti60钛合金变形组织发生混晶组织双态组织全针状组织的转变。α单相区变形时,硬取向α晶粒几乎不发生变形和转动,软取向α晶粒在大变形后发生动态再结晶。Ti60钛合金在两相区变形时材料发生αβ相变,当应变速率小于0.1 s^(-1)时,即形成全针状组织,而在应变速率为1.0 s^(-1)时,变形时间短,相变不充分,形成双态组织。此外,α相再结晶机理为不连续动态再结晶,再结晶晶粒尺寸随应变速率的增加而逐渐降低,再结晶晶粒的取向较随机,主要的织构成分为CD//{1210}(CD为压缩方向),最大织构强度约为1.42,且强度随应变速率的升高略有增强。

The rheological behavior and microstructure evolution law of Ti60 titanium alloy at the deformation temperature of 975-1080℃and strain rate of 0.001-1 s^(-1) were studied by hot compression simulation tests and microstructure characterization.The results show that the temperature rise of Ti60 titanium alloy caused by thermal effect is obvious and discontinuous yield phenomenon exists when Ti60 titanium alloy is deformed at high strain rate.With the increase of deformation temperature from 975℃to 1080℃,the deformation microstructure of Ti60 titanium alloy undergoes a transition as mixed-grain structure duplex structure whole acicular structure.During the deformation inαsingle-phase region,the hard-orientedαgrains hardly deform and rotate,while soft-orientedαgrains undergo dynamic recrystallization after large deformation.Theαβphase transition occurs when the titanium alloy is deformed in the two-phase region.When the strain rate is below 0.1 s^(-1),the whole acicular structure is formed.However,when the strain rate is 1.0 s^(-1),the deformation time is short and the phase transformation is insufficient,which results in the duplex structure.In addition,the recrystallization mechanism ofαphase is discontinuous dynamic recrystallization,and the recrystallization grain size decreases gradually with the increase of strain rate,and the recrystallization grains show random orientation texture with the main texture component CD//{1210}(CD indicates the compression direction),the maximum texture strength is about 1.42,and the strength increases slightly with the increase of strain rate.