Hot Deformation Behavior, Dynamic Recrystallization, and Texture Evolution of Ti-22Al-25Nb Alloy

The hot deformation behavior, dynamic recrystallization, and texture evolution of Ti-22Al-25Nb alloy in the temperature range of 950-1050 degrees C and strain rate range of 0.001-1s(-1) is investigated by plane-strain compression testing on the Gleeble-3500 thermo-mechanical simulator. The results show that the flow stress decreases with the increase of temperature and decrease of strain rate. Besides, the flow curves appear a serrate oscillation at a strain rate of 0.1s(-1) for all the temperature ranges, which may result from instability such as flow localization or micro-cracking. The flow behavior can be expressed by the conventional hyperbolic sine constitutive equation and the calculated deformation activation energy Q in the ((2)+B2) and B2 regions are 631.367 and 304.812kJmol(-1), respectively. The microstructure evolution is strongly dependent on the deformation parameters, and dynamic recrystallization (DRX) is the dominant softening mechanism in the ((2)+B2) region, including discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX). In addition, the (bcc)-fiber of {110} <001> is the dominant texture component in deformed Ti-22Al-25Nb alloy. It is observed that the weakening of the deformation texture is accompanied by the occurrence of DRX, which can be attributed to the large misorientation between DRX grains and neighboring B2 matrix induced by the rotation of DRX grains toward the preferred slip systems.