Avaliação microestrutural via técnicas EBSD/EDS de revestimentos em Inconel 625 e do Inox 309L soldados pelo processo GMAW aplicados a dutos para transporte de petróleo, gás natural e biocombustíveis

Abstract

Regions of oil exploration are prone to corrosion, which can lead to failures in pipelines and cause significant economic and environmental damage. To prevent these failures, a common solution consists of applying internal and/or external cladding to the pipelines, with welding being a widely used cladding process in the petroleum industry. Among the types of welding, Gas Metal Arc Welding (GMAW) is a technique used to join dissimilar materials with high deposition rates and high speed. Nickel and chromium alloys are often employed for anti-corrosion cladding, due to their high corrosion resistance, fatigue resistance, mechanical properties, and good weldability. However, variations in welding parameters can significantly affect the properties of the cladding, especially in the interface region between the cladding and the base metal. In this regard, this study aims to investigate the final microstructure of the weld interface region by varying the welding parameters with active and inert gas, single and double layers, of Inconel 625 and Inox 309L claddings deposited on low carbon steel. For this purpose, microstructural analyses were conducted in the Heat Affected Zone (HAZ) using Electron Backscatter Diffraction (EBSD) analysis in parallel with chemical analysis (EDS) and Vickers microhardness testing to identify the influence of microstructure on the region's final mechanical properties achieved. The results show that welding parameters significantly affected the desired final mechanical properties, and that the EBSD analysis technique is an important tool for assessing the microstructure of the welding interface region. Therefore, this study highlights the importance of considering welding parameters and using microstructural analysis techniques to optimize the welding process and improve the quality of anti-corrosive metallic claddings applied in the oil industry pipelines.