Miniaturized S-shaped flexible magnetic pulse welding coil design for engineering applications

Magnetic pulse welding (MPW) as a new solid-phase welding technology in the manufacturing field has vast application prospects. However, the application of MPW in engineering is severely limited by the large working area required for existing coils resulting in poor flexibility of the process. In this paper, a highly flexible, miniaturized S-shaped stereoscopic coil was proposed to reduce the working area required for the MPW process. The required working area was reduced to 32 x 30 mm. Numerical simulations were performed to determine the most suitable coil cross-section size. In addition, the feasibility of the coils was verified by welding AA5052 aluminum alloy and 316 L stainless steel through the new stereoscopic coils. Quasi-static tensile testing, laser microscopy, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS) were used to characterize the mechanical properties of the joints, weld interface morphology and element diffusion, respectively. It was revealed through simulation that the impact velocity of the new stereoscopic coil during MPW (342 m/s) was slightly higher than that of the conventional flat coil (327 m/s) at the same discharge energy. This indicated that the coil could achieve reliable welding. The AA5052-316 L joint welded by the new stereoscopic coil was demonstrated to be reliable by experiments. Furthermore, microscopic observation revealed that two effective bonding regions were formed at the interface. In addition, continuous interfacial waves and element diffusion were observed at the welding interface. Finally, the typical parts of Al-Fe double-cap beam structure were successfully welded by using a new stereoscopic coil. The coil is beneficial to broaden the application field of MPW.