Dynamic Recrystallization of Ti-6Al-4V Alloy During Hot Compression

The stress-strain curves of Ti-6Al-4V alloy during hot deformation by applied strain rate within the range of 5×10-4~5×10-2 s-1 at 870~960℃ were measured via single-pass isothermal compression test. The dynamics characteristics of rheological stress, critical strain capacity and structure evolution of the alloy during dynamic recrystallization were systematically illustrated by means of KM model, Poliak-Jonas model, and Avrami model. Then a concept of volume fraction of the microstructure transformation, i.e., the portion of the alloy that has been underwent microstructure transformation during dynamic recrystallization, was introduced into the so called prasad power dissipation rate model, thus the energy variation of the alloy during dynamic recrystallization was acquired. Further, taking both of the acquired energy variation and the observed microstructure evolution characteristics together into consideration, the dynamic recrystallization mechanism of Ti-6Al-4V alloy may be revealed. It follows that the critical strain capacity of Ti-6Al-4V during dynamic recrystallization decreased and the structural transformation volume fraction increased following the rise of deformation temperature or the decline of strain rate. The power dissipation rate upon complete dynamic recrystallization is larger than 0.34, and the forming mechanism is a dislocation-induced arcuation nucleation mechanism. © 2021, Editorial Office of Chinese Journal of Materials Research. All right reserved.