Weldability of pulse GMAW joints of 780 MPa dual-phase steel

Purpose: This paper assesses the gap bridgeability of pulse GMAW joints of DP 780 for automobile body. Design/methodology/approach: Wire melting was analyzed using a high-speed camera. The impact of EN ratio on the shape of the bead section was examined after analyzing the macrosection of welding which was obtained on a bead-on-plate-welding experiment. Welding conditions that are robust to the gap were suggested through an analysis on tensile strength, macrosection of the weld and fracture appearance of tensile strength testing at the lap joint welding of DP 780. Findings: A relation among the welding current (welding process parameter of AC pulse GMAW), EN ratio, welding speed and bead shape parameters which include bead width, bead height and penetration were computed. Research limitations/implications: The suitable welding conditions proposed in this paper can change because of types of welding joints thickness of base metal and other reasons. Practical implications: In this study, the suitable welding conditions were presented for securing a good weld quality of DP 780 for the automobile body. Originality/value: Through this study, the correlation between the weld bead geometry and the EN ratio in the AC pulse GMAW was confirmed. Though the weld quality assessment, suitable pulse GMAW conditions of DP 780 were suggested.