Effect of deformation parameters on the precipitation mechanism of secondary α phase under high temperature isothermal compression of Ti-6Al-4V alloy

Isothermal compression tests were conducted for Ti-6Al-4V alloy in the α + β two-phase field, and the effect of deformation parameters on the precipitation of secondary α phase in the subsequent air cooling process following isothermal compression was investigated. The experimental results show that the morphology of secondary α phase transforms gradually from lamellar colony to equiaxed morphology with the increase of strain rate and height reduction and with the decrease of deformation temperature. And the precipitation mechanisms of the secondary α phase under different isothermal compression conditions are explored by noting the effect of the crystal defect (i.e., dislocation, grain boundary and subgrain boundary) density in the β matrix.