Static and fatigue behavior of plug-welded dissimilar metal welds between carbon steel and austenitic stainless steel with different thicknesses

Background Plug welding was used on the parts of the structure in which spot welding cannot be implemented, such as the complex structure and the construction with the profile stiffener. The objective of the present work is to define the static and fatigue behaviors of the plug-welded dissimilar metal welds between carbon steel and austenitic stainless steel with different thicknesses because the detailed recommendations on it were limited. Methods Carbon steel SS400 with a thickness of 3.0 mm and 1.0-mm-thick austenitic stainless steel SUS304 were plug welded using varied hole diameter in a range of 7 to 13 mm where the welding current and the diameter of welding wire were kept constant at 80 A and 1.0 mm, respectively. The welding joints were exposed to tensile shear tests, and the transition of interfacial fractures to tearing fractures was defined as the optimum condition. Tensile peel, fatigue, and corrosion fatigue tests were carried out on the optimum specimens. Results The optimum plug welding joints were obtained at the hole diameter of 8 mm where the tensile peel and tensile shear load bearing capacity were 8.6 and 17.2 kN respectively. The endurance limit of fatigue conducted in air was 2 kN, whereas corrosion fatigue samples at this load fail at about 1,000,000 cycles. Conclusion AWS's formula for plug weld can be applied to the plug-welded dissimilar metal welds between carbon steel and austenitic stainless steel with different thicknesses. Endurance limit of this joint in corrosive environments is about half of the endurance limit in normal environments.