Investigations on microstructure and grain orientation uniformity of Ti-17 titanium alloy under different hot deformation modes

In this paper, the microstructure and grain orientation uniformity of Ti-17 titanium alloy under high temperature compression and axial upsetting and drawing processing (AUDP) conditions were investigated by light microscopy (LM) and electron backscatter diffraction (EBSD) technique. The relationship between the microstructure and grain orientation evolution in different hot working modes and hot deformation parameters was systematically investigated. The results indicate that grain size of β phase affects the precipitation behavior of α phase, the smaller β grains resulting in a higher grain misorientation angle, thereby improving grain orientation uniformity of the material. AUDP can obtain finer uniformity microstructure, but the homogeneity of β phase grain orientation has not been obviously improved and the anisotropy of the β matrix still exists. Subsequently, when annealing in the (α + β) region, the grain growth and the interface become more clearly, but the annealing process cannot eliminate the macro-zones induced by the β phase with a grain orientation concentrated area.