Investigation of mechanical properties of spot welded dual-phase steel sheets used in automotive industry

Dual-phase steel is a high-strength steel which is heat treated to contain both a ferrite and martensite microstructure for extra strength. It's highly formable and has a low alloy content and high strength. In this study, Dual-phase (DP 600 type) steel sheets having different thicknesses like 1 mm and 1,2 mm were welded in different combinations by electrical resistance spot welding method. Welded joints were prepared in 4, 5, 6, 7 and 8 kA welding currents and in 5, 10, 15, 20 and 25 cycles welding times. The tensile-peel and tensile-shear tests of these joints were performed and mechanical and microstructural properties of them were investigated, and also advise were given to users showing the optimum welding parameters.