The Mechanical Properties Of Underwater Wet Weldedjoints

To expend its utilization in the field of underwater building and repairing,underwater welding, as a key technology, has been paid more attention in recentyears. In this paper, experiment on wet welding of E40material was performed. Inwhich different joints were obtained either in the seawater or in the freshwater.Moreover, the effect of water depth on quality of the joint was researched as well.The microstructure, hardness, mechanical properties and fracture morphology of thewelded joints were analyzed in detail. The results obtained in this research are asfellows:According to the results of experiments in the seawater and freshwater，it isfound that the microstructures of weld joints in both conditions are analogous.Such defects as pores of bead and cracks of heat affected zone in the seawaterwelding joints were much more than the ones in freshwater joint. The depth ofseawater (less than7m) had a few effects on the microstructure and surfacingequality of welded joints, i.e., microstructure and surface shape of weld joints didnot change much with the depth of seawater.The tensile strength of weld joint in freshwater experiment was higher than thatin the seawater environment. The metallurgical process in the seawater is complex,and welding defects were generated easily, for which the joint tensile strengthreduce greatly. So welding in the seawater maybe need better protection. The waterdepth had large effects on the tensile strength of the butt joints, defects in the jointare easily formed with the increasing of water depth.