Microstructure Evolution and Recrystallization of Ti6246 Alloy in Hot‐Rolling and Annealing Processes

Abstract

Herein, the Ti‐6Al‐2Sn‐4Zr‐6Mo (Ti6246)‐casted alloy is treated with two different hot‐rolling processes (3‐pass and 5‐pass), and the as‐rolled alloy is subsequently annealed at different temperatures (780 and 850 °C). During hot rolling, obvious changes in the morphology and microstructure of the Ti6246 alloy occur. A large number of dislocations are generated in the rolling process, and their movement plays an important role in the microstructure evolution of the alloy. The 3‐pass hot rolling results in a smaller grain size (0.43 μm) than that of the 5‐pass rolled sample (0.68 μm), which can be attributed to the larger deformation degree of the single pass in the 3‐pass rolling process. However, the larger deformation degree of the 3‐pass rolling leads to higher dislocation density (34.29% of LM above 1) and more microstructure defects in the Ti6246 alloy, which further result in easier initiation of the prismatic and pyramidal slips of the alloy. The 5‐pass procedure can provide more deformation passes to promote the dynamic recrystallization (DRX) of the Ti6246 alloy and the fraction of DRX can reach 33.27%. In contrast, with the increase of the annealing temperature, the degree of recrystallization increases and the number of microstructure defects decreases.