Effect of twinning on microstructure and texture evolutions of pure Ti during dynamic plastic deformation

The microstructure and texture evolution of pure Ti during dynamic plastic deformation were systematically investigated. The dynamic plastic deformation ( ε ̇ =4–6×102 s−1) on cylindrical Ti specimens realized by high-speed impact. The microstructure and texture were examined by electron backscattering diffraction (EBSD) and x-ray diffraction (XRD). Four types of deformation twins were observed at all strains, and twins played an important role in the grain fragmentation and texture evolution. At low strain levels (ε<0.2), the deformation was accommodated by the dominant twinning and the subsidiary dislocation slip. Then deformation twins eventually evolved into a saturation level when strain increased to 0.2. From medium to high levels of deformation (ε=0.3–0.8), slip became predominant and shear bands developed. The initial texture with a bimodal distribution (undeformed) was weakened and transformed into a ring-like distribution by twinning when the strain approached to 0.2, and then further evolved into a basal texture by slip when the strain exceeded 0.4.