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

• Published in: Welding international Vol. 36; no. 7; pp. 394 - 413
• Main Authors: P, Roshith, M, Arivarasu
• Format: Journal Article
• Language: English
• Published: Cambridge Taylor & Francis 03.07.2022; Taylor & Francis Ltd
• Subjects: Base metal; Carbon dioxide lasers; Corrosion products; Corrosion rate; Corrosion tests; Gas metal arc welding; Hot corrosion; Incinerators; Laser beam welding; Lasers; Mapping; Molten salts; Optical microscopy; Oxidation; PCGTA welding; Potassium sulfate; Pulsed current; Sodium sulfide; thermogravimetric method
• ISSN: 0950-7116; 1754-2138
• DOI: 10.1080/09507116.2022.2089608

This research aims to investigate the hot corrosion behaviour of SMO 254 steel samples after PCGTA and CO 2 laser beam welding, as well as air oxidation. A salt mixture simulated the waste incinerator environment involving 40 wt. % Na 2 SO 4 + 40 wt. % K 2 SO 4 + 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/cm 2 ) than the weight gain rate for CO 2 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, FeMo 2 S 4 , Na 2 S, Fe 2 O 3 , K 2 S 3 , Cl 4 CrNa 2 . CO 2 LBW air oxidation has the lowest rate of corrosion due to the synthesis of beneficial oxides, such as NiCr 2 O 4 , NiO, and Cr 2 O 3 . 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.