Application of Homopolar Pulsed Power to Metals Joining

Homopolar generators (HPGs) presently being developed at the Center for Electromechanics are capable of delivering megampere pulses of electric current in a controllable manner. One application for these machines is as the power supplies for an industrial welding process. During the past five years, several research projects have been carried out to explore the welding capabilities of HPGs. Among the materials that have been welded are carbon and low alloy steels, several varieties of stainless steels, tool steels, nickel-base and molybdenum-base alloys, aluminum, and several dissimilar-metal couples. Among the shapes that have been welded are bars, sheets, plates, tubes, pipe, angle sections, and rails. The largest cross sections that have been welded to date are 9 in. 2 (2.9 tm2), and the smallest have been less than 0.3 in. (0.58 cm). Welding is accomplished in times approximating a second. Unique advantages of the homopolar pulse welding process are that it can be scaled upward to indefinitely large cross sections and that it does not impose a sudden load on the mains.