Experimental Investigation and Mechanical Characterization of Double-Sided Submerged Arc Welding of AISI 304 Austenitic Stainless Steel

Abstract

The austenitic stainless steels are widely used in chemical, metallurgical, conventional, nuclear power plants and industrial applications due to their excellent corrosion resistance and formability. For welding plates of higher thickness, the submerged arc welding is a suitable technique, as it offers higher deposition rate, good bead shape and deeper penetration. To get a sound welded joint without defects, suitable welding parameters should be carefully chosen to weld austenitic stainless steel as they are sensitive to heat input. In this study, austenitic stainless steel plates were joined using double-sided submerged arc welding, and key welding parameters such as voltage, current and welding speed were established to get a defect-free joint. The effectiveness of double-sided welding is evaluated from microstructural and mechanical characterization. From the macroscopic examination, the two weld seams, i.e. initial run and second run intersect at the middle, which is an indication of the defect-free weld. The microstructure of the fusion zone consists of dendritic grains and coarse columnar grains. The microhardness tends to increase in the weld zone for initial weld run followed by second weld run and lowest in the middle of the weld seam. The result of the tensile test indicates that elongation of the welded joint surpasses that of parent metal elongation, and fracture occurs at base zone. The field emission scanning microscopy examination of the broken surfaces of the tensile sample reveals the nature of fracture mode is ductile. In this paper, heat input controlling method was successfully introduced for welding of austenitic stainless steels of higher thickness with a simple double-sided submerged arc welding (DSSAW).