Microstructure and Failure Behavior of Dissimilar Resistance Spot Weld of DP600 Dual Phase Steel and St14 Low Carbon Steel

This paper aims at investigating the microstructure and failure behavior of dissimilar resistance spot welds between low carbon steel (st14) and ferrite-martensite dual phase steel (DP600). The effects of welding current in the range of 7.5 to 9.5 kA on the metallurgical and mechanical behavior of the weld were investigated. Microstructural characterization, microhardness tests and the tensile shear tests were conducted. Mechanical properties of spot welds were described in terms of failure mode, peak load and energy absorption. The fusion zone microstructure exhibited martensite, bainite, allotriomorphic ferrite and Widmanst