In this work, resistance spot welding of AISI 201 stainless steel is investigated experimentally and numerically. In the experimental work, based on design of experiments with Box–Behnken design and response surface methodology, effects of process parameters such as welding current, welding time, electrode force and cooling time on tensileshear strength and failure mode of resistance spot welds are investigated. The results show that tensile-shear strength of spot welds is increased with increasing the welding current and welding time due to increase in the generated heat and consequently plastic deformation area. Also, it is concluded from results that tensile-shear strength is increased with increasing the electrode force. However, with increasing the electrode force, electrode indentation in the sheets is increased, and when the electrode force is excessively raised, the cross section of weld metal and consequently the strength of welded joints are decreased. It is obtained from results that tensile-shear strength of spot welded joints is increased with increasing the cooling time. However, when the cooling time is increased excessively, the welded joints strength is decreased. During tensile-shear test, two failure modes were observed, namely pullout and pullout with tearing of the sheet modes. In the numerical simulations, using an electro-thermomechanical analysis, the effect of welding current on fusion zone size is investigated and compared with experimental measurements. The results show that numerical simulations are in good agreement with experimental works. Also, it is concluded that the nugget diameter is increased with increasing the welding current.
