Characterization of hot deformation microstructure of a near beta titanium alloy Ti-5553

The hot deformation microstructures of Ti-5553 titanium alloy in the temperature range of 750-900 °C and strain rate range of 10 ^-3-10^-1 s^-1 were investigated by hot compressive testing on the Gleeble-3500 thermo-mechanical simulator. Transmission electron microscope (TEM) and electron back scattered diffraction (EBSD) were employed to investigate the effect of deformation conditions on the microstructure and deformation mechanism. The results showed that deformation parameters can significantly affect microstructure evolution, and dynamic recrystallization is more noticeable at temperature 900 °C and strain rate 10^-3 s^-1. Hot deformation dramatically increased the fraction of low-angle grains boundaries (LAGBs), and the misorientation distribution skewed toward low-angle rotations, and also changed the strict Burgers-relationship between α and β phase. Furthermore, thermo-mechanical processing can increase the driving force of phase transformation. The phenomenon of α phase globularization can be explained accurately by β phase wedges model.