Abstract:The dynamic phase transformation of Ti-5Al-5Mo-5V-1Cr-1Fe alloy during hot compression below the β transus temperature was investigated. Strain-induced α-to-β transformation is observed in the samples compressed at 0-100 K below the β transus temperature. The deformation stored energy by compression provides a significant driving force for the α-to-β phase transformation. The re-distribution of the solute elements induced by defects during deformation promotes the occurrence of dynamic transformation. Orientation dependence for the α-to-β phase transformation promotion is observed between {100}-orientated grains and {111}-orientated grains. Incomplete recovery in {111}-orientated grains would create a large amount of diffusion channels, which is in favor of the α-to-β transformation. The effects of reduction ratio and strain rate on the dynamic phase transformation were also investigated.

Key words: titanium alloy; hot compression; phase transformation; orientation dependence