Improving and Monitoring the Magnetic Pulse Welding Process between Dissimilar Metals

The success of conventional fusion welding technologies for dissimilar metal welding is often limited due to the differences in the thermo-physical properties and formation of brittle intermetallic phases. The latter phenomenon does not occur during pressure welding processes such as magnetic pulse welding (MPW). Due to the short process durations in the range of a few microseconds, this joining technique proves to be attractive for line production. At the same time, this advantage challenges the process observation, inline-quality assurance hardware and the design of the tool coils. The paper presents two strategies to reduce the energy input during MPW and consequently to increase the lifetime of the tool coils. Firstly, a reactive nickel interlayer between steel and aluminum leads to a significant energy reduction. Compared to aluminum samples joined by laser welding, the load-bearing capability of the hybrid MPW driveshaft samples is higher in static torsion tests and similar in cyclic tests. Secondly, a novel process monitoring system helps to analyze the characteristic light emission and enabling MPW with low energy input. The same tool supports the MPW process for the manufacturing of a part that consists of three different tube materials: stainless steel, aluminum and copper.