Correlation between structure and orientation of TC17 titanium alloy during thermal deformation and heat treatment

In the previous studies on the microstructure and orientation of titanium alloys, the microstructural and orientational evolution of typical titanium alloys during thermal compression have been studied in depth. However, studies of the correlation between hot compression and heat treatment processes on microstructural and orientational changes have been few. It is of great significance to further study this correlation during hot treatment. For this study, during hot compression deformation and subsequent hot treatment of TC17 titanium alloy on a thermal simulator using cylindrical specimens, the microstructure, grain size change, and orientation evolution of TC17 were studied using optical microscopy and backscattered electron diffraction analysis. Grain size, texture distribution, pole figure, and reverse polarity were analyzed. Law and the relation between structure and orientation results show that the primary α-content decreases dramatically and size decreases in tandem with deformation temperature. Most of the α phase grains are dispersed and located on the trigeminal grain boundaries of the high temperature β phase grains. After heat treatment, the α phase and β phase had a clear structure and distinct boundary. The primary α phase still exists and tends to be equiaxed, and the metastable β phase changes formed a lamellar β-transformed structure. The hot deformation reduces the density of the α phase texture. Additionally, with increasing temperature, the density value of the α phase texture also becomes small. The α phase is no longer strongly textured after thermal deformation, and the orientation of the α phase grains is considerably influenced by thermal deformation, which clearly improves the uniformity of orientation. The thermal deformation also reduces the texture polar density value of the β phase, but the effect is not obvious. However, there is still a density of orientation, and the uniformity of the orientation is relatively poor.