Joining of austenitic AISI 310-ferritic AISI 430 stainless steels through electric resistance spot welding and investigation of mechanical properties

The aim of this study is the investigation of the effect of some welding parameters changed during the joining of ferritic and austenitic stainless steels through electric resistance spot welding method; on the mechanical and microstructural properties. In this study, AISI 430 ferritic and AISI 310 austenitic types of stainless steels, 1 mm in thickness and 45x105 mm in sizes, first among themselves and then with each other were joined by resistance spot welding method by using different parameters. The welding process were carried out at 6 kN electrode force, 4.5, 5.5, 6.5, 7.5, 8.5 kA welding currents and 5, 15 and 25 cycle welding times, a total of 15 different parameters. In order to determine the strength of the welded joints, tensile-shearing tests were applied to the welded specimens. The weld nugget diameters of the welded specimens were measured by digital caliper. Also, microhardness and microstructural examinations were done on the welded regions of the welded specimens.The experimental results showed that increasing of welding current and welding time increased the weld nugget diameter and electrode dept intensity. These, in turn, increased the tensile-shearing of the welded specimens. Hardness measurement results indicated that weld nugget had the highest hardness and the heat effected zone (HAZ) and the base metal followed this. As a result of microstructural examinations, it is obeserved that the grains existence of welded nugget expanded because of heat input.As a conlusion, the proper parameters are determined for electric resistance spot welding of ferritic and austenitic stainless steel sheets. Also it was shown that the changed welding parameters affected the mechanical properties.