Mechanical response and deformation mechanism of TA1 pure titanium during electrically assisted tension

Abstract

Electrically assisted forming (EAF) is an advanced thermomechanical processing technology that has garnered increasing attention in recent years due to its ability to significantly reduce flow stress and enhance the formability of metals. In this study, electrically assisted tension (EAT) were performed on pure titanium at various current densities. The electro-thermal-mechanical response, along with the evolution of texture, grain orientation, deformation twinning, and dislocation morphology, was systematically characterized using infrared thermal imaging, digital image correlation (DIC), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). These analyses provided deeper insights into the deformation mechanisms of pure titanium under electric current. The results indicate that both flow stress and strain hardening capacity decrease with increasing current density during EAT. Although the total elongation was reduced due to the non-uniform distribution of temperature induced by Joule heating, the local strain remained nearly unchanged. At low current densities, pronounced deformation twins formed within the grains, and twin-twin interactions led to the formation of characteristic high-angle grain boundaries. However, as the current density increased, twinning activity was progressively suppressed. Moreover, the enhancement of the Joule heating effect promotes dislocations annihilation and slip, and the tendency of dynamic recrystallization is obvious, which slows down the accumulation of dislocations and leads to a significant reduction in flow stress. Consequently, dislocation slip became the dominant deformation mechanism with the increasing current density during EAT. This study provides both experimental evidence and theoretical support for the EAF of pure titanium.