Flow behavior and plasticity of Ti–6Al–4V under different electrically assisted treatments

Both electrically assisted tension (EAT) and electrically assisted pre-treatment tension (EAPT) were conducted to compare different effects on improving deformation resistance and ductility of Ti–6Al–4V. It is found EAPT obviously enhanced the ductility of Ti–6Al–4V compared with that obtained in EAT. In order to decouple the thermal effect from electro-plastic effect, thermally assisted tension (TAT) as well as thermally assisted pre-treatment tension (TAPT) were also conducted. The result indicates deformation mechanism of alpha phase with h.c.p crystal structure in Ti–6Al–4V was insensitive to electric current when current duty is less than 20%. However, the elevated temperature alone is insufficient to account for additional stress drop in the initial yielding stress observed in EAT and EAPT when current duty is higher than 20%. According to XRD investigation on specimens treated in original state, TAPT and EAPT, it is found electric current accelerates the annihilation of alpha phase and formation of beta phase in Ti–6Al–4V more effectively than the rising temperature does and such microstructure evolution also throws light on the improvement of flow stress and ductility observed in EAPT both experimentally and theoretically.