TA15钛合金β热变形中的动态再结晶形核

Nucleation of dynamic recrystallization of titanium alloy TA15 during hot deformation process in β field

利用Thermecmaster-Z型热模拟试验机在β相区对TA15钛合金进行了热压缩试验,采用金相显微镜及EBSD取向差分析技术,研究了TA15钛合金β热变形中动态再结晶形核。结果表明,随内、外界条件的不同,TA15钛合金存在两类典型的动态再结晶形核地点,即晶界周围及变形带。相应地,随应变速率增大,存在两种动态再结晶形核机制,在较低应变速率下,晶界弓弯形核是动态再结晶的主要形核机制,晶界、三岔界是主要形核地点;在高应变速率下,动态再结晶不仅可以在晶界、三岔界附近形核,还可以借助变形带形核。此时的动态再结晶形核为晶界弓弯与亚晶旋转机制共同作用。

Hot compression tests of titanium alloy TA15 in β field were conducted on a Thermecmaster-Z hot simulation test machine,and nucleation of dynamic recrystallization was investigated by means of OM and EBSD.The results indicate that the nucleation of dynamic recrystallization occurs at,deformation band and around grain boundaries.At low strain rates,the nuclei of dynamic recrystallization form by bulging of initial grain boundaries,and the nucleation occurs on sites of grain boundaries and triple junctions.At high strain rates,the nuclei of dynamic recrystallition form not only at grain boundaries and triple junctions but also at deformation bands,with nucleation mechanism of bulging of initial grain boundaries and subgrain rotation.