Study on mechanical properties and microstructural feature of magnetic pulse welding joint between Cu and Al sheets

In this paper, mechanical properties and microstructural feature of magnetic pulse welding joint between Cu and Al sheets were investigated. The qualities of Al/Cu (Al acted as a flying plate) and Cu/Al (Cu acted as a flying plate) joints were analyzed by lap-shear tensile test and microstructure observations. The welding process was simulated by LS-DYNA to observe the changes in physical parameters such as collision speed and current density. The morphologies of the welding interface were established by smoothed particle hydrodynamics (SPH). The results showed that Al/Cu joints had a better lap-shear load value than Cu/Al joints at the discharge energies of 30 kJ and 35 kJ. The lap-shear load of Al/Cu joint was over 3.5 kN when the energy reached 30 kJ and the Al plate was broken. The Al/Cu joints easily formed more regular interface waves than Cu/Al joints from 25 to 35 kJ. The orientations of interface wave in Al/Cu joints (identical to the welding direction) and Cu/Al joints (opposite to the welding direction) were different. The orientation of interface wave was relevant to the densities of welding metals. Besides, the orientations of other metal joints interface wave were predicted by the flow of metallic material on the welding surface.