Investigation of the effects of welding parameters on mechanical properties and microstructure of triple joined FEP05/DP600/FEP05 steel sheets joined by electrical resistance spot welding

Abstract

Nowadays, resistance spot welding of two or triple joints and of similar or dissimilar sheet metals is widely used in the automotive industry. In the a-, b-, and c-pillars of car bodies, dual-phase (DP) 600 steels and FEP05 steels are commonly welded together. This study investigated the impact of resistance spot welding process parameters such as welding current, welding time, and electrode force on the tensile shear load, elongation, nugget diameter, and indentation depth of triple welded sheet joints (FEP05 + DP600 + FEP05). To determine the mechanical properties of the welded joint, tensile tests and micro-hardness measurements were performed. Microstructural characterization was also used to analyze the weld quality. Additionally, it was demonstrated that welding time, welding current, and electrode force are important factors in triple welded joints. As a result, it has been seen that FEP05 + DP600 + FEP05 sheets can be successfully combined with triple electrical resistance spot welding by choosing the welding parameters appropriately. A shows the relationship of the welding current with the indentation depth and the nugget diameter.