Fabrication of 2000 series aluminum lap joint sheets by magnetic pulse welding and their interfacial microstructure observations

Lap joint sheets of 2017-T3/2017-T3 and 2024-T3/2024-T3 were fabricated by magnetic pulse welding (MPW). Tensile shear tests were performed on the welded sheet, and a good lap joint was achieved at a discharge energy more than 3.0 kJ for both lap joint sheets. Weld interface showed wavy morphology when the bonding at an adequate amount of discharge energy. Weld width of the lap joint sheets tend to increase with increasing of discharge energy. Collision speed calculated from collision time was 211 m/s and estimated 1.5 GPa of the collision pressure at discharge energy of 3.5 kJ. SEM and EDS results showed that the weld interface exhibited no significant contrast of intermediate layer and oxides. A Metal jet was observed as aggregates of fine particles with size of less than 100 nm at the outside of bonded area. From TEM observation at the bonding interface, Al phases between flyer and parent sheets had direct contact without the intervention of the oxide, and localized melting was not recognized. From these obtained results, good lap joint is attributed to true-contact of Al phases, an increasing of weld width, the anchor effect, and work hardening at weld interface. © 2017 The Japan Institute of Light Metals.