Competition between dynamic recovery and recrystallization during hot deformation for TC18 titanium alloy

The competition between dynamic recovery (DRV) and recrystallization (DRX) during hot deformation has been investigated in the present paper. Isothermal compression experiment of TC18 titanium alloy was conducted for verification. The hot deformation mechanism for TC18 alloy has been identified as dislocation evolution from the stress exponent correspondence. Suitable descriptions to dislocation evolution under DRV/DRX have been obtained and validated by stress variation with DRX critical strain as the transition. Work-hardening behaviors correspond to the competition between DRX/DRV and segmented functions were constructed to describe the variation. The influence of α/β phase transformation and DRX evolution on dislocation evolution and work-hardening behaviors has been characterized with the Kocks-Mecking model developed. Power dissipation efficiency and microstructure observation were utilized to demonstrate the dependence of dynamic softening mechanism. The β necking phenomenon in DRX grains has been associated with the periodic competition between DRX and DRV.