变形方向对TiAl合金二次热变形行为的影响

Effect of Direction on Flow Behavior of TiAl Alloy in Secondary Hot Deformation

通过等温热压缩实验研究变形方向对经一次锻造后的Ti-46.2Al-2.5V-1.0Cr-0.3Ni合金热变形行为的影响,所选定的二次热变形方向垂直或平行于一次锻造应力轴方向,试样初始组织状态分别为锻造态、去应力退火态和双态组织。结果表明:变向二次热变形均加快了三种热处理状态钛铝合金加工硬化率的衰减过程;对于其中具有双态组织的钛铝合金继续施加变向或不变向二次热变形均有利于减小流变软化程度,提高二次热变形后的组织均匀性。进一步的微观组织观察表明,变向二次热变形与不变向二次热变形相比,更有利于合金的残余层片分解和动态再结晶的进行。

The flow behavior of already forged Ti-46.2Al-2.5V-1.0Cr-0.3Ni alloy by the isothermal compression experiments was investigated.The direction of secondary hot deformation was taken to be vertical or parallel to the former forging axis（reversed or unreversed deformation）.Specimens have three kinds of starting microstructures,as-forged,relief annealed and duplex.The results show that reversed deformation can accelerate the decline of work hardening rate.And compared with other two microstructures,the duplex microstructure has the lowest softening degree in reversed or unreversed secondary hot deformation.According to the results of microstructure observation,the reversed secondary hot deformation can be favorable to the breakdown and dynamic recrystallization of remanent lamellar structure.