Estudo de revestimentos de aço inoxidável 308L obtidos por soldagem MIG com e sem posterior refusão por TIG

Abstract

In this work, the results obtained from the application of 308L stainless steel coatings on 304 stainless steel substrates by the MIG welding process, with and without subsequent TIG remelting, are presented. The main objective of the study was to evaluate the performance of the coatings under the severe conditions typically found in industrial environments, characterized by the presence of corrosion and cavitation. Nine experimental samples were produced: three with only MIG welding, three subjected to one TIG remelting pass, and three with two remelting passes. The deposition process was carried out using four parallel weld beads and a protective gas mixture composed of 90% argon and 10% carbon dioxide. The investigation included the analysis of the formed microstructures, metallurgical homogeneity, and defects that appeared during the welding procedures. The results showed that the TIG remelting stage plays a decisive role in the coating quality, promoting surface re-liquefaction, microstructure homogenization, and a more continuous and stable transition between the coating and the substrate. Micrographic analyses indicated that the coatings obtained only by the MIG process exhibited an austenitic matrix with carbide precipitation at grain boundaries, while the samples subjected to remelting showed greater structural refinement and better performance characteristics. The results reinforce the relevance of integrating welding techniques and remelting treatments as an effective strategy for developing more resistant, durable, and economically viable solutions, contributing to the protection and reliability of industrial equipment in aggressive environments.