Metallic Forging Using Electrical Flow as an Alternative to Warm/Hot Working

Manufacturing processes (e.g., forging, rolling, extrusion, and forming) rely on heat to reduce the forces associated with fabricating parts. However, due to the negative implications associated with hot working, another more efficient means of applying energy is desired. This paper investigates material property changes of various metals (aluminum, copper, iron, and titanium based alloys) in response to the flow of electricity. Theory involving electromigration and electroplasticity is examined and the implications thereof are analyzed. It is shown that, using electrical current, flow stresses are reduced, resulting in a lower specific energy for open-die forging. It is also shown that an applied electrical current increases the forgeability of materials, allowing greater deformation prior to cracking. Moreover, the changes caused by the flow of electricity are significantly greater than those explained by resistive heating. Additionally, elastic recovery is decreased when using electrical flow during deformation. Finally, for most materials, these effects were dependent on strain rate. Overall, this work demonstrates that substantial increases in the forgeability of metals are achieved by deforming the material while applying an electrical current. These improvements exceed those achieved through comparable increases in workpiece temperature and demonstrate that this method provides a viable alternative to warm/hot working.