Research on underwater wet manual SHS welding

Based on self-propagation high-temperature synthesis technology (SHS technology) and principle of underwater wet electric-arc welding, a new wet manual SHS welding is proposed and investigated. It could be used in rapid repairing underwater metal structures. The rod and coating of electrode was developed for underwater welding. The welding was performed and microstructure and properties of the welding joint were tested. The results show that underwater metal structures could be welded successfully with this welding method on the condition of no electric, no gas and no other equipment. Welded joints, which were one-side welded with back formation, were obtained and the tension strength reached 267 MPa, the impact energy was 13.8 J. SEM and EDS revealed that the weld metal was composed of matrix of α-Cu solid solution and massive second phase enriched with Fe precipitates. The epitaxial nucleation was found between base metal and weld metal, which formed gradient fusion welding. The tensile fracture occurred at weld metal or fusion zone. There were a great number of dimples in the fracture, which confirmed that the fracture is the mode of ductile fracture.