Soldagem de revestimento com ligas de níquel empregando o processo MIG/MAG com duplo arame para aplicações em componentes do setor de petróleo e gás natural

• Ano de defesa: 2014
• Autor(a) principal: Pessoa, Edson Frota
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Ciência dos materiais; Ligas; Corrosão
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/11071

The aim of this work was to evaluate the operational (weld geometry and dilution) and metallurgical characteristcs (microstructure, chemical composition, microhardness and corrosion resistance) of Inconel 625 and Hastelloy C-276 nickel-based alloys weld overlay deposited simultaneously by GMAW Double Wire process on steel plate ASTM 516 Gr 60. Initially a previous study was carried out in order to know the early welding parameters and the operational limits of process. Next, single passes welding trials was conducted by applying Taguchi method aiming to select the best parameters of each control factor studied in a reduced numbers of experiments. After, weld overlays were made based on selected parameters. Next, the definitive weld overlays were deposited on steel plates and thus were analysed the geometric features, dilution and metallurgical characterization using optical microscopy and scanning electron microscopy, also a chemical composition analysis was carried out. The profile of microhardness were also performed, as well as analysis of corrosion resistance. The results showed that the minimal global dilution levels measured on definitive weld overlays were 22% approximately. The microstructure of the weld overlays deposited by mixing Inconel 625 and Hastelloy C-276 was constituted generally by a gamma matrix and secondaries phases enriched in niobium, molybdenum and titanium. The chemical composition analysis revealed that the the percentage of Fe on weld increases when dilution levels rises. The increase in Mo, W and reduction in Fe content on the weld metal contributed to the formation of secondaries phases. Regarding the microhardness, no significative differences between first and last weld bead and the microhardness values obtained were appropriate for weld overlays. For corrosion resistance, some of the samples supported Critical Pitting Temperature (CPT) of 80 °C and there were a relation between the controled factors and principals alloy elements presents in the weld overlays