Effect of GTAW remelting on the corrosion performance of AISI 316L cladding

• Published in: Materials and corrosion 2021-01, Vol.72 (1-2), p.141-153
• Main Authors: Malhotra, Dikshant, Shahi, Amandeep S., Gupta, Kamal
• Format: Article
• Language: English
• Subjects: Arc deposition; austenitic stainless steel 316L cladding; Austenitic stainless steels; autogenous gas tungsten arc welding; Carbon steels; Chromium; Corrosion; Corrosion effects; Corrosion resistance; Electrochemical impedance spectroscopy; Electron probe microanalysis; EPMA; Gas metal arc welding; Gas tungsten arc welding; Melting; Molybdenum; Nickel; passive film; Penetration depth; Photoelectrons; pitting corrosion; sensitization; Spectroscopic analysis; Spectrum analysis
• ISSN: 0947-5117; 1521-4176
• DOI: 10.1002/maco.202011666

Gas tungsten arc welding (GTAW) process was used for remelting of the top clad layers of austenitic stainless steel 316L deposited on low‐carbon steel using gas metal arc welding (GMAW) process. Different electrochemical techniques were used for assessing and comparing sensitization and pitting corrosion performance of these clads (both in the as‐welded as well as aged condition), besides comparing their passive film characteristics. Top clad layer remelting was influential upto a penetration depth of around 2.34 mm. Aging of clads at 750°C/24 hr accelerated the precipitation of carbides, which suppressed partially due to their remelting as indicated by electron probe microanalysis studies. Due to this GTAW remelted clads exhibited a relatively lesser degree of sensitization and higher pitting corrosion resistance as compared to the conventional GMAW clads. X‐ray photoelectron spectroscopy studies revealed a relatively higher concentration of O, Cr, Ni, and Mo in the passive film of remelted clad surfaces than the conventional ones, which accounted for enhanced protectiveness of passive film on remelted surfaces as indicated by electrochemical impedance spectroscopy studies. Surface remelting of AISI 316L clads using the GTAW process improved their resistance to sensitization and pitting corrosion by modifying their passive film composition, thereby enhancing its protective properties. As remelting resulted in the suppression of precipitation of chromium carbides, this technique can be used for improving corrosion performance of conventional 316L.