Per: haitao jiang (University of Science and Technology Beijing), guihua zhang (UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING), wenqi guo (UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING), SHIwei tian (UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING)
Abstract:
The evolution of microstructure and texture of Ti6Al4V alloy developed by cold rolled followed by annealed treatment at thickness reduction ratio of 15%-70% were investigated by scanning electron microscopy and X-ray bulk texture measurement technique. It is found that during cold rolled deformation process, the grains were severely broken up and elongated, and the degrees of the mechanical anisotropy of the Ti6Al4V alloy were increased. For cold-rolled samples, recovery and recrystallization occurred during annealed treatment. After the thickness reduction ratio of 10% and 30%, the microstructure still retained the structural features of the cold rolled. When thickness reduction ratio reached 50%, the deformation band structure disappeared. This is related to the large residual internal stress in the microstructure under the condition of severe deformation. Compared to the cold rolled samples, the mechanical anisotropy of the annealed samples was weaker and it was mainly related to the texture components. The intensity of the {0001} basal texture and <10-10> fiber texture were strengthened by cold rolled, (0001)<10-10>, (-12-10)<10-10> and (11-25)<10-10> components dominated the texture of the cold rolled samples. Among them, (-12-10)<10-10> and (11-25)<10-10> texture components inherited the as-received microstructure and the intensity of that was increased with thickness reduction ratio increased. But the intensity and volume fraction of the texture (-12-10)<10-10>component rapidly increased and the intensity of the texture (11-25)<10-10> and (0001)<10-10> components were weakened by the annealed treatment. At high temperature condition, the elongated slipped region start recrystallizing faster and starts growth, the prismatic scatter grains have more severe deformation (higher stored energy) compared with the prismatic tilt grains and preferential nucleation may happen in the region having texture of prismatic scatter. This eventually leads to grain having texture component (-12-10)<10-10> orientation is gradually strengthened by consuming other scatted orientations. In addition, it can be found that an increase in the intensity and volume fraction of (-12-10)<10-10> texture component has a positive effect on improving the mechanical anisotropy of the Ti6Al4V alloy. So it can promote optimizing the process treatment of the Ti6Al4V alloy by studying characteristic of the texture components.
