Analysis of Mechanical Properties on Resistance Spot Welded Dissimilar Thick Dissimilar Joints: Effect of Welding Current

Objectives: To study the influence of welding current on shear fracture strength properties of the resistance spot welded (RSW) dissimilar joints. Methods: The study employed the RSW of DP 800 steel and AISI 1040 steel in the context of car chassis applications. In RSW, weld current is considered a variable parameter, while others are constant. The tensile shear fracture test and microhardness analysis performed correlated with base metals. The shear fractured region of the tensile samples was analyzed utilizing scanning electron microscopy (SEM). Findings: The maximum lap-tensile shear fracture load (L-TSFL) and cross-tensile shear fracture load (C-TSFL) achieved were 23 MPa and 19 MPa, respectively. The weld interface exhibits a maximum hardness of approximately 570 HV. The results indicate that an increase in weld current enhances the hardness and shear fracture strength of a dissimilar joint up to a certain threshold, beyond which these properties decrease. Novelty: The joining of dissimilar metals with dissimilar thicknesses by resistance spot welding is an inevitable demand in the modern automotive industry. These research results are more insightful for fabricating automotive frames with dissimilar materials and variable thickness. Keywords: Dual Phase Steel, Medium Carbon Steel, Microhardness, Resistance Spot Welding, Tensile Shear Fracture Strength