Relation between short-term creep and stress relaxation of titanium alloy at high temperature

Creep or stress relaxation is considered as a main mechanism of reducing the springback of titanium alloy sheet during thermal forming process. So far, the difference and relation between the two phenomena have not been clearly explored. In this paper, tests of short term creep and stress relaxation of Ti6Al4V alloy were conducted at high temperature. The microstructure of the tested alloy was observed by using TEM. Effects of temperature, stress and time on creep and stress relaxation behavior were studied, respectively. The correlation and difference between the two phenomena were compared based on relations of creep strain - time and strain rate - time. Results show that creep behavior is controlled by atom diffusion at low temperature under low stress; by dislocation slide and climb at high temperature under high stress. The stress relaxation behavior is mainly governed by dislocation climb. The predicted stress relaxation behavior based on the creep data shows a good agreement with the experiment.