PURPOSE: To join a steel material and an aluminum material without variations in strength by simultaneously forming uniform nugget on the contact surfaces of steel with each other or aluminum with each other by one time of energization.
CONSTITUTION: The oxide films, on the aluminum side surface of the material 3 for joining different metals which is the Fe/Al double layered steel plates of 30×30×0.8mm consisting of a cold rolled steel plate (steel layer) 1 of 0.4mm and aluminum plate (A1050) (aluminum layer) 2 of 0.4mm and the surface of the plate 5 of the aluminum material which is a material to be welded are removed and thereafter, the materials are subjected to a heat treatment for two hours in an atm. furnace kept at 350°C in order to form the oxide films on the surface of the aluminum and are cooled in the atm. The material 3 for joining different metals which is the Fe/Al double layered steel plates is thereafter so disposed between the cold rolled steel plate 4 of 30×60×0.8mm and the aluminum plate (A5052) 5 of 30×60×1.0mm in such a manner that the different materials face each other, then these materials are spot welded.
SAITO TORU
NAGASE TAKAO
UENO SHINJI
