Magnetic pulse spot welding of bimetals

•We developed a new approach to spot weld bimetals using electromagnetic energy.•The process is named as “magnetic pulse spot welding”, a solid-state, rapid joining process.•A requirement of ensuring distance between two sheets to be welded is avoided by this approach.•The weld interface shows typical wavy surfaces that are in two opposite directions from the center of the weld.•Increasing the discharge energy up to certain limits increased the area of the spot weld. One of the main parameters in magnetic pulse welding (MPW) is the requirement of certain distance/spacing called “air gap” between the two sheets or tubes to be welded. This work presents means to alleviate this constraint through stamped humps in one of the sheets. The sheets remain in contact all over except at humps where a local air gap is sufficient to generate impact velocity required to produce spot welds using electromagnetic energy. The developed approach has been validated on the heterogeneous assembly of AA1199 aluminum to EN 355 steel. The microstructural analysis revealed that the weld interface is wavy and the waves are in two opposite directions from the center. Quasi-static tension–shear tests validated the joint efficiency of spot welds.