TB17钛合金β相区动态再结晶行为及转变机理

Dynamic recrystallization behavior and transformation mechanism in β-phase region of TB17 titanium alloy

通过Gleeble-3800热压缩模拟试验机对TB17钛合金β相区进行热压缩实验,研究该合金β相区的动态再结晶行为及转变机理。结果表明:TB17钛合金在β相区变形时会发生动态回复(DRV)与动态再结晶(DRX)。不同应变速率下存在两种动态再结晶形核位置,低应变速率下主要在晶粒内部形核,高应变速率下主要在晶界附近形核。通过EBSD和TEM分析可知,在低应变速率下发生连续动态再结晶(CDRX),其发生的主要形式为亚晶合并转动。高应变速率下发生不连续动态再结晶(DDRX),发生的主要形式为晶界剪切伴随着亚晶转动。尽管两种动态再结晶的转变方式不同,其本质都是通过位错的增殖、滑移和胞状结构演化形成新的动态再结晶晶粒。

The thermal compression experiment of TB17 titanium alloy in theβphase region was carried out by Gleeble-3800 hot compression simulator.The dynamic recrystallization behavior and transformation mechanism in theβphase region of the TB17 titanium alloy were studied.The results show that the dynamic recovery(DRV)and dynamic recrystallization(DRX)occur in theβ-phase region during deformation process of the TB17 titanium alloy.There are two dynamic recrystallization nucleation sites at different strain rates.At low strain rate,it mainly nucleates inside the grains,and at high strain rate,it is near the grain boundary.According to EBSD and TEM analyses,the main mechanism happened at low strain rate is continuous dynamic recrystallization(CDRX)which mainly is controlled by sub-grain rotation.Discontinuous dynamic recrystallization(DDRX)occurs at high strain rates,the main form of deformation is grain boundary shear accompanied by sub-grain rotation.Although the two dynamic recrystallizations are transformed in different ways,the essence is to form new dynamic recrystallized grains through the propagation,slip and cell structure evolution of dislocations.