Microstructure Characteristic and Texture Evolution of TB18 Titanium Alloy during Hot Compression in the β Phase Zone

Abstract

In the present study, microstructure characteristic and texture evolution of TB18 titanium alloy were studied by isothermal hot compression under different strain with strain rate of 0.001 s⁻¹ and 0.1 s⁻¹ in the β phase zone. Electron Back-Scattered Diffraction (EBSD) and XRD were used to characterize the microstructure and macrotexture. Microstructure characteristic demonstrated that coarse β grains flatten and elongated to the compression direction as strain increased. The dynamic recrystallization mechanism is continuous dynamic recrystallization (CDRX) at lower strain rate, while discontinuous dynamic recrystallization (DDRX) at higher strain rate. The deformation is strongly dependent on the dislocation density, geometrically necessary dislocations density increased with strain at different strain rate. The limited faction of dynamic recrystallization has little effect on texture evolution, and the texture evolution is ascribed to the strain induced boundary migration and activity of slip system. At lower strain rate, the lower activity of {110}〈111〉 slip system and higher activity of {123}〈111〉 enhanced the 〈110〉 texture and weakened the 〈111〉 texture; at higher strain rate, the higher activity of {123}〈111〉 slip system modified the 〈111〉 β texture intensity and enhances the 〈110〉 texture.