Electro-plastic effect in Ti-6Al-4V: An experimental and numerical study

Abstract

Electric pulse aided deformation is gaining importance in plastic deformation processes because of its ability to form difficult-to-form materials like Ti-6Al-4V at much lower temperatures than hot/superplastic forming processes. Applying electric pulses with suitable parameters during plastic deformation reduces the flow stress near instantaneously (stress-drop) due to thermal (expansion and softening) and electro-plastic effects. To quantify the electro-plastic effect, one needs to predict thermal effects accurately. In the present work, electrically assisted uniaxial tensile tests on Ti-6Al-4V are carried out both in elastic and plastic regions. Flow stress reduction due to thermal effects are predicted using finite element analysis. Comparison of predicted thermal effects with that of experimentally measured in elastic region revealed that they are in excellent agreement, as it is well known that thermal expansion only plays a role in the elastic region. In the plastic region, a considerable difference between measured (thermal and athermal) and predicted (only thermal effects) stress-drop values is observed, and this difference is due to the electro-plastic effect. The effect of different process parameters on electro-plastic effect is studied, and the same is quantified.