Comparative Evaluation of Self-Shielded Flux-Cored Wires Designed for High Strength Low Alloy Steel in Underwater Wet Welding: Arc Stability, Slag Characteristics, and Joints’ Quality

In this work, four types of self-shielded flux-cored wires which include two ferritic wires and two nickel-based wires were specifically designed to improve the quality of underwater wet welded E40 steel joints. The effect of different wires on arc stability and the metal transfer process was examined. The slag obtained in the wet welding process with flux-cored wires was collected, milled, and subsequently analyzed. The microstructural features, mechanical performance and susceptibility to cold cracking of underwater wet welded joints were comparatively evaluated. The results showed that all the welds presented acceptable bead appearance. The arc stability of the ferritic wires with TiO₂-based slag system was found to be superior to that of the Ni-based wires with CaF₂-based slag system. Further, different flux-cored wires did not alter the typical metal transfer modes, however, they changed the relative proportion of the metal transfer modes. The underwater wet welded joints were free from cold cracks, which were indicated by the Y-groove restraint test. The developed self-shielded flux-cored wires possessed superior performance in terms of strength and toughness in shallow water.