Investigation of Spot Resistance Welding Performance of Galvanized Steels Used in Automotive Industry with AZ31B Magnesium Alloy

This study investigates the weldability and weld joint performance of AZ31B magnesium alloy, AA1050 aluminum alloy, and EN 10346 DX52D + Z (Erdemir-1312 quality) galvanized steel sheets, which exhibit disparate metallurgical properties, through spot resistance welding, a widely utilized technique in the automotive industry. In order to apply spot resistance welding in an oxygen-free environment, the welding operation was conducted in an argon gas atmosphere within the designated welding cabin. The optimal welding parameters for achieving the highest strength were identified as 250 kgf electrode force, 25 cycles of squeeze time, 8 cycles of weld time, and a weld current of 7.6 kA. To facilitate comparison, it was seen that a higher strength could be achieved in the joint made with magnesium compared to the welded joints made with AA1050 aluminum sheets. It was observed that the joints prepared in accordance with the standard and applied under spot resistance welding under room conditions were unable to create joints that exhibited consistent strength values due to the presence of oxidation on the magnesium plate surface. It was determined that the weld nugget structure was both unsymmetrical and irregular with respect to the plate axes, and that the Zn element on the surface evaporated due to galvanization and formed pores in this area.