Hot corrosion and air oxidation behavior of pulsed current gas tungsten arc welded and CO2 laser beam welded SMO 254 at 800 °C

Abstract

This research aims to investigate the hot corrosion behaviour of SMO 254 steel samples after PCGTA and CO2 laser beam welding, as well as air oxidation. A salt mixture simulated the waste incinerator environment involving 40 wt. % Na2SO4 + 40 wt. % K2SO4 + 10 wt. % NaCl + 10 wt. % KCl are employed. The hot corrosion tests were carried out for 103.33 h at 800 °C, with a thermogravimetric investigation availed to calculate the impact of corrosion. The weight gain rate for PCGTAW molten salt corroded specimens is greater (33.45 mg/cm2) than the weight gain rate for CO2 Laser molten salt corroded specimens, which is 67.55% higher. The weight of the hot corroded sample rises in the molten salt surroundings due to the creation of compounds including CrS, FeMo2S4, Na2S, Fe2O3, K2S3, Cl4CrNa2. CO2 LBW air oxidation has the lowest rate of corrosion due to the synthesis of beneficial oxides, such as NiCr2O4, NiO, and Cr2O3. Optical microscopy and SEM/EDS were employed on both surface and cross-sectional surfaces to get microstructure at the interface of the fusion region, parent metal, and fusion region using point mapping, line mapping, and X-ray mapping techniques. The corrosion products produced during corrosion were studied using XRD.