Microstructural aspects of adiabatic shear failure in annealed Ti6Al4V

This work reports a comprehensive examination of the microstructural evolution in Ti6Al4V subjected to high-strain-rate deformation. The sequence of microstructural rearrangements leading to adiabatic shear banding is presented. A detailed microstructural comparison between two types of specimens, one that failed by adiabatic shear and the other that was strained to half its failure strain, is carried out. The main observation is that for this material, the microstructure of the two types of specimens is qualitatively identical, indicating that from approximately half the failure strain until adiabatic shear failure, no additional micromechanism is observed to develop and operate. Overall, the microstructure undergoes a significant refinement with the increasing strain until the formation of dynamically recrystallized grains. It is therefore suggested that the evolution of the volume fraction of recrystallized grains should be characterized from its early onset until final failure by adiabatic shear banding.