Optimization of spot welding process parameters in dissimilar joint of dual phase steel DP600 and AISI 304 stainless steel to achieve the highest level of shear-tensile strength

Effect of parameters such as current density, welding time, electrodes force and holding time after welding on tensile-shear strength of dissimilar joint were analyzed. Taguchi method was used to design the experiments and Minitab software was used to analyze the effect of parameters and obtain an optimum condition. The microstructure of the optimum condition was analyzed by Scanning Electron Microscope (SEM). The strength of the join was analyzed by tensile-shear test. Fracture mode was assessed by optical microscope. Results showed that current density, holding time after welding, welding time and electrodes force were the most effective parameters hierarchically. Optimum current density of 8 Kamp, holding time after welding of 40 cycle, 16 cycle welding time and 5 kN electrode force were defined as the optimum parameters to join the sheets. Weld nugget (WN) had a martensitic structure containing a relatively high strength and hardness. Its fracture mode was pullout failure.