Effect of DC Current on the Formability of 6Al 4V Titanium

Abstract

Recent research has demonstrated that the mechanical properties of metallic materials are altered when an electrical current is passed through the material. These studies suggest that titanium, due to its low formability and potential for dramatic improvement, should be subjected to additional study. The research presented herein further investigates the use of electricity to aid in the bulk deformation of 6Al-4V titanium under tensile and compressive loads. Extensive testing is presented that documents the changes that occur in the formability of titanium due to the presence of an electron wind at varying current densities. Using carefully designed experiments, this study also characterizes and isolates the effect of resistive heating from the change due to the electrical flow alone. The results demonstrate that the presence of an electrical current within the material during deformation can greatly decrease the force needed to deform titanium while also dramatically enhancing the degree to which it can be worked without fracturing. Isothermal testing further demonstrates that the changes are significantly beyond that which can be accounted for due to increases in the titanium’s temperature. The results are also supported by data from tests using pulsed and discontinuously applied current. Furthermore, current densities are identified that cause an apparent superplastic behavior to occur. Overall, this work fully demonstrates that an electrical current can be used to significantly improve the formability of 6Al-4V titanium and that these improvements far exceed that which can be explained by resistive heating.