AN OXIDATION BEHAVIOUR OF DISSIMILAR WELDMENTS IN THE PRESENCE OF MOLTEN SALTS AT 1123K

In order to investigate the effect of Inconel 718 and ASS 316 dissimilar (thickness of 3mm) weldments made by Gas Tungsten Arc welding in the presence of molten salts at 1123K in the air. To assess the performance of the weldments in the real time environment, at various zones of the welded coupons was subjected to hot corrosion studies. The coupons used for corrosion studies was mirror polished down to 1 m before the corrosion run. Cyclic hot corrosion studies were performed on different zones of the weldments by exposing in the molten salt environment of Na2SO4- 48% Nacl mixture at 1123K. Hot corrosion studies were performed on different zones of dissimilar weldments of INCONEL 718 and ASS 316. to estimate the corrosion behavior for 50 cycles (each cycle consists of 1 h heating followed by 20 min of cooling to room temperature) at 1123K. A coating of uniform thickness with 3–5 mg/cm2 of Na2SO4- 48% Nacl was applied using a fine camel hair-brush on the samples. The salt coated samples were first heated and dried at 200°C in the oven. Each cycle consists of 1 hour heating followed by 20 min of cooling in the room temperature. The weight changes are measured for all the regions for each cycle using electronic weighing balance with a sensitivity of 1 mg. The weight gain or loss of the spalled scale was also included at the time of measurement to determine the rate of corrosion. The corroded samples of various regions were characterized for XRD and SEM analysis.