Impact welding creates arguably the strongest welds between wide varieties of metallic materials without formation of a heat affected zone. However, both the incumbent impact welding techniques, explosive welding and magnetic pulse welding, have serious limitations. Explosive welding cannot be practiced in a conventional factory environment and magnetic pulse welding suffers from actuator longevity issues while welding strong structural materials. Vaporizing Foil Actuator Welding (VFAW) enables impact welding of structural alloys in traditional factory settings. An adaptation of VFAW for spot welding of aluminum to steel sheets is presented here. Dual phase steel and aluminum sheets, 1.2 mm and 1 mm thick respectively, were welded using the accelerating pressure from a fugitive aluminum foil that was vaporized with a maximum input energy of 2.6 kilojoules. The velocity of impact between the flyer and target sheets with a standoff distance of 3mm was measured to be approximately 500m/s. Upon mechanical testing in lap shear mode, the samples either failed in the parent aluminum at an approximate load of 6.4 kN leaving behind a 12mm diameter nugget or along the weld interface at an average load of 5.7 kN. The details of the experimental results, the welding device and the power supply are discussed.
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