In this work, dissimilar resistance spot welding of austenitic stainless steel sheet (304 grade) and ferritic stainless steel sheet (409 grade) is studied experimentally. For this purpose, the effects of process parameters such as welding current, welding time and electrode force on tensile-shear strength of resistance spot welded joints are investigated with response surface methodology (RSM). Also, microstructural evolutions during resistance spot welding process of AISI 409 and AISI 304 stainless steels are evaluated by optical microscopy. It is concluded from results that the tensile-shear strength of spot welds is increased with increasing the welding current, welding time and electrode force. It is shown that widmanstatten ferrites have been grown in the weld metal of dissimilar resistance spot welds of AISI 304 and AISI 409 stainless steels.
