Analysis of texture evolution and variant selection during α→β→α phase transformation of TA1 pure titanium sheet

The texture of titanium and titanium alloy has an important influence on its properties, and it is difficult to eliminate the strong bimodal texture of titanium and titanium alloy by traditional rolling process and recrystallization annealing. The texture distribution of titanium and titanium alloy can be changed theoretically by α→β→α phase transformation annealing, but the texture strengthening phenomenon is usually caused by texture memory effect. In this study, The TA1 sheet with 80% cold rolling deformation was annealed at 500°C for 2 hours and 850°C for 2 hours under different recrystallization degrees, and then subjected to a second annealing at 1100°C for 10 minutes. XRD, EBSD and confocal laser microscopy were used to observe the microstructure and texture of TA1 pure titanium sheets and the migration and merging of β phase at high temperature. Furthermore, an extended annealing treatment at 1100°C for 3 hours was conducted for the sheets annealed at 500°C for 2 hours. it was found that α grains with different initial textures produce different β grain orientation during α→β phase transformation, which alters the subsequent β grain texture and results in different α-phase variant orientations upon β→α cooling., and the texture strengthening effect of 500°C-2h annealing is significantly inhibited.