Optimized designing of process parameters for CP980 steel resistance spot welding based on Orthogonal Test

Abstract

Based on the orthogonal experimental design method, taking CP980 steel as the research object and the tensile sheer force of spot-welded joints as the evaluation index, the effect of different process parameters on the welding performance of resistance spot welding was studied with the extreme variance method. The results indicated that welding current had a significant effect on the shear force, followed by electrode pressure, while welding time had the least effect; the optimal welding parameter of the CP980 spot welded joint was that the welding time was 400 ms, the welding current was 9.5 kA, and the electrode pressure was 3.6 kN. The formation of lath martensite during solidification led to a higher hardness in the nugget region, reaching a maximum of 434 HV. The subcritical heat-affected zone formed a softened zone with an average hardness value of 299 HV as a result of welding thermal cycling.