The hot compression behaviors of BT25 titanium alloys were investigated by Gleeble-3500 thermal simulator at the deformation temperature of 950～1 010℃

strain rate of 0.01～1 s

-1

and maximum height reduction of 60%.The critical damage values were calculated based on the standard Cockcroft-Latham theory.Considering the influence of deformation temperature and deformation rate on the critical damage value

Zener-Hollomon parameter was introduced to establish the critical damage model.By analyzing the damage sensitivity curves

the damage sensitivity rate of 0.03 is taken as the time when the crack is generated

and the damage value at that time is taken as the critical damage factor.The results reveal that the critical damage factor of BT25 titanium alloy is varied in the range of 0.18～0.27 with deformation temperature and strain rate.Meanwhile

the critical damage factor is more sensitive to the strain rate.At the same deformation temperature

the strain rate is increased and the damage factor is decreased.