Microstructural and Corrosion Behavior of Thin Sheet of Stainless Steel-Grade Super Duplex 2507 by Gas Tungsten Arc Welding

Super duplex stainless steel (SDSS) is a type of stainless steel made of chromium (Cr), nickel (Ni), and iron (Fe). In the present work, a 1.6 mm wide thin sheet of SDSS is joined using gas tungsten arc welding (GTAW). The ideal parameter for a bead-on-plate trial is found, and 0.216 kJ/mm of heat input is used for welding. As an outcome of the welding heating cycle and subsequent cooling, a microstructural study revealed coarse microstructure in the heat-affected zone and weld zone. The corrosion rate for welded joints is 9.3% higher than the base metal rate. Following the corrosion test, scanning electron microscope (SEM) analysis revealed that the welded joint’s oxide development generated a larger corrosive attack on the weld surface than the base metal surface. The percentages of chromium (12.5%) and molybdenum (24%) in the welded joints are less than those in the base metal of SDSS, as per energy dispersive X-ray (EDX) analysis. Corrosion modeling is done using the COMSOL Multiphysics software. Electrochemical corrosion modeling is used to determine the electrolyte potential (i.e., 0.09 V) and current density (i.e., 0.2 A/m2 to 1.8 A/m2). An entire mesh model contains 6240 elements. The largest and smallest element sizes are 4 mm and 0.1 mm, respectively. The maximum element rate of growth is 1.2.