The transition from strain rate insensitivity to sensitivity of Ti–6Al–4V alloys deformed at cryogenic temperature

Abstract

The aim of the present study is to elucidate the strain rate (ε˙) dependency of Ti–6Al–4V alloys under cryogenic deformation conditions, inspired by our recent observations of strain rate insensitivity in pure titanium as well as the temperature effect on the stacking fault energy. Unlike the pronounced strain rate sensitivity at ambient temperatures, a strain rate insensitivity when ε˙ < 10−2 s−1 and strain rate sensitivity when ε˙ > 10−2 s−1 were observed during cryogenic deformation. Subsequent analyses underscored the pivotal role of stacking faults in modulating the transition from strain rate insensitivity to sensitivity with increasing strain rates. The present study therefore enriches the existing knowledge on the mechanism of cryogenic deformation, offering guidance for the engineering of high-performance titanium alloys.