Effect of annealing temperature on microstructure and mechanical properties of TA22 alloy pipe

This study investigated the microstructure, texture and mechanical properties of TA22 alloy tubes annealed at 500~800 °C. The alloy was composed by equiaxed α-phase, lamellar α-phase and fine β phase. The cold rolling and subsequent annealing converted part of lamellar α-phase to equiaxed α-phase, whose grain size increased with annealing temperature. The β-phase grew in size with higher temperature, while α-phase was gradually segmented. The β-phase is mainly distributed at equiaxed α-phase grain boundaries, due to higher energy and faster atomic diffusion at grain boundaries. In addition, the cold working-induced dislocations gradually annihilated with increasing annealing temperature. The texture type was adjusted by subsequent annealing. It demonstrated 600 °C annealing formed a (10-10) texture, while 800 °C annealing led to a (11-20) texture and more high-angle grain boundaries. Schmidt factor analysis indicated that high-temperature annealing enhanced prismatic and pyramidal slip activity and homogenized the slip distribution. Mechanical properties showed yield strength and tensile strength decreased, while plasticity increased with temperature, attributed to the synergistic effect of β-phase evolution, dislocation annihilation, texture softening, and improved slip coordination. The TA22 alloy after annealing at 800℃ exhibits the highest strength-ductility product, indicating its optimal comprehensive mechanical properties.