Characterization of the Welding Zone of Automotive Sheets of Different Thickness (DP600 and DP800) Joined by Resistance Spot Welding

Abstract

Automotive industry in recent years, has gained great importance. In line with this, DP600 and DP800 dual-phase steels and the electrical resistance spot welding method were used in the study. During the experimental trials, different welding currents (6, 7, and 8 kA) were selected and all other welding parameters were kept constant. The effects of the welding parameters on microstructure, hardness, tensile-shear, and cross-tensile strength were analyzed. In the phase measurements, 27.06–29.97% martensite and 70.73–73.85% ferrite phases were found. When the hardness values in the HAZ regions were examined, it was seen that the highest hardness values were 356 ± 5 HV in the DP600 and 451 ± 5 HV in the DP800 with a current intensity of 6 kA. Consequently, it was determined that tensile-shear and cross-tensile strengths had increased in parallel with the increase in the welding current and the highest values were determined as 8 kA–15.91 kN in tensile shear and 8 kA–4.91 kN in cross-tensile strength. © 2021, The Indian Institute of Metals - IIM.