High carbon steel has attractive properties such as high strength and good wear resistance. However, the welding of these steels often includes the undesirable results of low ductility and high hardness, which has to be corrected by relatively expensive heat treatments. In this work, resistance spotwelding (RSW) process of eutectoid steel (AISI 1075) sheet is studied experimentally. The effects of process parameters such as welding current, electrode force, welding cycle and cooling cycle on the tensile-shear strength of resistance spot welded joints are investigated using response surface methodology (RSM). Two failure modes such as interfacial and partial interfacial modes are observed in the tensile tests of resistance spot welded joints. The variation of tensile-shear strength with process parameters is mathematically modeled by using the regression analysis method and a closed form equation is derived. The results show that tensile-shear strength is increased with increase in welding current and welding cycle. Also, it is demonstrated from results that tensile-shear strength is decreased with increase in electrode force and cooling cycle
