Enhancement of ductility, weakening of anisotropy behavior and local recrystallization in cold-rolled Ti-6Al-4V alloy strips by high-density electropulsing treatment

The effect of high-density electropulsing treatment (EPT) on the microstructure, mechanical properties and fracture behavior of cold-rolled Ti-6Al-4V alloy strip was investigated. The results indicated that EPT accelerated the local recrystallization process tremendously in pre-deformed titanium alloy. The EPT-induced microstructural change resulted in remarkably increasing elongation to failure while remained tensile strength unchanged. In addition, anisotropy behavior of mechanical property is weakened dramatically. A mechanism for rapid local recrystallization in low temperature during EPT was proposed based on the reduction of nucleation thermodynamic barrier and enhancement of atomic diffusion. Uneven fractures of different direction specimens with quasi-cleavage fracture mode were gradually evolved into uniform ductile fracture mode with transgranular dimples under EPT.