Discontinuous Yielding in High Temperature Deformation of Ti-5553 Alloy

The discontinuous yield behavior of Ti-5Al-5Mo-5V-3Cr-0.5Fe alloys, a new metastable β titanium alloy, was tested at 800∼860 °C and in strain rate range of 0.1∼10 s−1 on a Gleeble-1500 thermal Simulation testing machine. Results show that discontinuous yielding appears at the highest strain rate (10 s−1), and the magnitude of discontinuous yielding increases with increasing of the temperature. The above mentioned phenomenon is in agreement with Johnston and Gilman's dynamic yield theory, that is to say, the discontinuous yield behavior is related to the sudden multiplication of a great quantity of mobile dislocations in the alloy.