Interfacial to Pullout Failure Mode Transition in Similar and Dissimilar Resistance Spot Welds of DP600 Dual Phase and AISI1008 Low Carbon Steels

The work here investigates the correlation between microstructural features and mechanical properties of similar and dissimilar resistance spot welds of low carbon steel (LCS) and dual phase steel (DP600) in the tensile-shear test. Correlations between the critical fusion zone size required to ensure pullout failure mode، the weld microstructure and the weld hardness characteristics were developed. Results showed that the critical fusion zone size is a function of hardness profile characteristics (ratio of fusion zone hardness to average hardness of the base metal). Expriments showed that similar DP600/DP600 and dissimilar DP600/LCS welds exhibit the highest and the lowest tendency to fail in interfacial failure mode، respectively. Finally، peak load and energy absorption of similar and dissimilar resistance spot welds are compared.