Optimization process of resistance spot welding for high-strength low-alloy steel using Taguchi method

Resistance spot welding (RSW) is considered as predominant welding technique that is used in the manufacturing of modern automobile structures. The automobile structure is made of high-strength steel which is preferred by the car industry companies due to its high strength-weight ratio. This work presents an optimization method for RSW of high-strength low-alloy steel DOCOL 500 LA. Tensile test and microstructure analysis for base material (BM) were carried out to get the mechanical properties of BM and to specify the rolling direction. Taguchi method, a high efficiency technique, was applied using Minitab19 software to achieve the optimization process. The tensile shear test was carried out to evaluate the strength of the welding nugget, absorbed energy and failure mode. The results showed that the optimum parameters were 8,800 A for the current, 30 cycles for the welding time and 2,230 N for the electrode force and two types of failure modes could be observed which were interfacial and full pullout mode.