铸态TB6钛合金β热变形中的动态再结晶行为

Dynamic Recrystallization Behavior of As-Cast Titanium Alloy TB6 during the β Process

利用Thermecmaster-Z型热模拟试验机在β相区对铸态TB6钛合金进行了热压缩试验,并对其动态再结晶行为进行了研究。结果表明,合金在β热变形过程中主要存在两类形核位置:原始β晶界附近及β晶粒内部,相应地存在两类动态再结晶机制:不连续动态再结晶和连续动态再结晶。在较高应变速率(≥0.01s-1)时,以不连续动态再结晶机制为主,但动态再结晶发生的程度较低,不能通过此机制使组织获得明显细化;在低应变速率(≤0.001s-1)和高变形温度(≥950℃)时,以连续动态再结晶机制为主。此时,合金动态再结晶晶粒直接由亚晶转变而成,组织均匀、细小。

Hot compression tests of as-cast titanium alloy TB6 were conducted using the Thermecmaster-Z hot simulation test machine in the β process, and its dynamic recrystallization （DRX） behavior was investigated. The results indicate that there are two kinds of typical nucleation sites, namely, grain interiors and near grain boundaries. Accordingly, there are two kinds of dynamic recrystallization mechanism： discontinuous and continuous dynamic recrystallization. The operation of discontinuous dynamic recrystallization （DDRX） as predominant mechanisms is anticipated in case of strain rate higher than 0.01 s^-1, which leads to a low degree of DRX and thus does not to marked grains refinement. And the operation of continuous dynamic recrystallization （CDRX） by mechanism of subgrain rotation, leading to grains refinement, is observed in case of strain rate no more than 0.001 s^-1 and temperature higher than 950 ℃.