Magnetic pulse welding (MPW) is widely used in the connection of dissimilar metals. The welding process involves the coupling of the electromagnetic field and structural field, which is a high-energy transient forming process. Based on the current experimental methods, it is difficult to capture the relevant data in the process of magnetic pulse welding, and the transient forming mechanism of magnetic pulse welding needs to be further studied. Taking the magnetic pulse welding of an Al-Mg sheet as an example, based on the Ansoft Maxwell and ANSYS finite element simulation platform, the loose coupling method was used to analyze an electromagnetic field generated by the discharging capacitor bank and structural field of the Al-Mg sheet under the action of electromagnetic force. The discharge period of the magnetic pulse welding capacitor bank was 62 μs. The current direction in the aluminum sheet changed once half a cycle, and the direction of the electromagnetic force was always consistent with the Z-axis. Under the skin effect, the magnetic induction intensity on the lower surface of the aluminum sheet was the largest. At 16 μs, the induced current, electromagnetic force and magnetic induction intensity in the aluminum sheet reached the peak values, which were 7.89 A/m2, 4.58 N/m3 and 12.6 T, respectively. The maximum electromagnetic force and velocity in the structural field were 2400 KN and 300 m/s. The structure field simulation reproduces the transient forming process of magnetic pulse welding, and clarifies the formation mechanism of the “intermediate zone rebound uncomposite zone-welding bonding zone-unbound zone”. Based on the numerical simulation technology, the research on the transient forming mechanism of magnetic pulse welding under multiphysics simulations can promote the development and application of magnetic pulse welding technology and better guide engineering practices.

In this investigation, 1060Al/AZ31B welded joints were obtained by magnetic pulse welding technique. In order to test the microstructure and mechanical properties of the joints, the welded joints were annealed at different temperatures and then examined by optical microscopy (OM), scanning electron microscopy (SEM), energy spectrum analysis (EDS) and mechanical properties testing. The testing results of the welded joints annealed at different temperatures showed that the Al-Mg MPW welded joints were well bonded. The changing of the microstructure and mechanical properties of Al/Mg welded joints was not apparent under the temperature of 200 °C. However, Al12Mg17 intermetallic compound layer formed at 200 °C. Al12Mg17 and Al3Mg2 intermetallic compound layers formed at the temperature of 300 °C. The diffusion rate of Mg and Al elements is proportional to the annealing temperature and the intermetallic compounds layer is gradually formed. The microhardness near the interface decreased first and then increased on account of the brittleness of intermetallic compounds. In the tensile shear tests, the fracture mechanism of Al/Mg MPW welded joints were analyzed. When the temperature was lower than 200 °C the joints did not crack. At 200 °C and 250 °C, the joints fracture along the Al12Mg17-Al interface. The joint cracks along the interface of Al12Mg17-Al3Mg2 at the temperature of 300 °C.