Superplastic tensile test was carried out to understand the deformation of TC21 titanium alloys at 1 153

1

193 Kand strain rate of 0.033

0

.000 33s-1.The superplastic tensile deformation activation energy and corresponding stress exponent were calculated.Based on the calculation results

the constitutive equations of strain rate and flow stress was deduced

and it was modified by the software of1 stopt.The results show that the flow stress is decreased with the increase of deformation temperature at a constant strain rate

and it is increased with the increase of strain rate at a constant temperature.With a higher strain rate and a lower deformation temperature

the main softening mechanism of TC21 titanium alloys is characterized by dynamic recrystallization

on the contrary

the main softening mechanism is characterized by dynamic recovery. TC21 titanium exhibits accepatable superplasticity（408.60%）at 1 153 Kand 0.000 33s-1.The superplastic deformation activation energy and the corresponding stress exponent are 329.20kJ/mol and 2.3677

respectively.