Soldagem dissimilar autógena com laser pulsado Nd:YAG entre a liga Inconel 625 e o aço inoxidável superduplex UNS S32750
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Data
2021-03-08
Autores
Monteiro, Rairton Barbosa
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O aço inoxidável superduplex e o Inconel 625 são materiais muito importantes tanto economicamente, quando pelas suas aplicações. O superduplex é conhecido por sua microestrutura binária, com frações aproximadas em 50% ferrita e 50% austenita combinando resistência à corrosão com resistência mecânica, quando soldado ocorre o desbalanceamento entra as fases da microestrutura do metal de solda, havendo formação excessiva de ferrita. O Inconel é conhecido por sua ótima resistência a corrosão por se tratar de uma liga de níquel, que possui papel estabilizador de austenita nos aços inoxidáveis duplex. Este trabalho tem como objetivo avaliar a soldagem à laser Nd:YAG pulsado, autógena e dissimilar, do Inconel 625 e superduplex UNS S32750, a fim de analisar a manutenção das resistências a corrosão de ambos materiais. A soldagem foi feita em uma junta de topo, variando a frequência do laser em quatro parâmetros de 2,2 hertz até 9,0 hertz. O gás de proteção utilizado foi o argônio puro, com vazão de 15 l/min. Os ensaios realizados para a pesquisa foram: análise macrográficas, caracterização microestrutural e teste de corrosão. Para revelar os detalhes no metal de solda foi utilizado um ataque químico com o ácido oxálico. As macrografias revelaram que as amostras estão livres de descontinuidades macroscópica no cordão de solda, além de possuir penetração adequada do cordão. As soldas não apresentaram descontinuidades como porosidades e trincas, além de penetração adequada. Os corpos de prova foram submetidos a testes de corrosão em água do mar com eletrólito AMN Guarujá –SP, os testes corrosão se mostraram promissores sendo mais resistente que o superduplex, graças a grande quantidade de níquel e cromo oriundos do Inconel.
Superduplex stainless steel and Inconel 625 are very important materials both economically and for their applications. The superduplex is known for its binary microstructure, with approximate fractions of 50% ferrite and 50% austenite combining corrosion resistance with mechanical resistance, when welded there is an imbalance between the phases of the weld metal microstructure, with excessive formation of ferrite. Inconel is known for its excellent resistance to corrosion because it is a nickel alloy, which has a stabilizing role of austenite in duplex stainless steels. This work aims to evaluate the pulsed, autogenous and dissimilar Nd: YAG laser welding of the Inconel 625 and UNS S32750 superduplex, in order to analyze the maintenance of the corrosion resistance of both materials. The welding was done in a top joint, varying the frequency of the laser in four parameters from 2.2 hertz to 9.0 hertz. The shielding gas used was pure argon, with a flow rate of 15 l / min. The tests carried out for the research were: macrographic analysis, microstructural characterization and corrosion test. To reveal the details in the weld metal, a chemical attack with oxalic acid was used. The macrographs revealed that the samples are free of macroscopic discontinuities in the weld bead, in addition to having adequate bead penetration. The welds showed no discontinuities such as porosity and cracks, besides adequate penetration. The specimens were subjected to seawater corrosion tests with AMN Guarujá –SP electrolyte, the corrosion tests were promising, being more resistant than the superduplex, thanks to the large amount of nickel and chromium from Inconel.
Superduplex stainless steel and Inconel 625 are very important materials both economically and for their applications. The superduplex is known for its binary microstructure, with approximate fractions of 50% ferrite and 50% austenite combining corrosion resistance with mechanical resistance, when welded there is an imbalance between the phases of the weld metal microstructure, with excessive formation of ferrite. Inconel is known for its excellent resistance to corrosion because it is a nickel alloy, which has a stabilizing role of austenite in duplex stainless steels. This work aims to evaluate the pulsed, autogenous and dissimilar Nd: YAG laser welding of the Inconel 625 and UNS S32750 superduplex, in order to analyze the maintenance of the corrosion resistance of both materials. The welding was done in a top joint, varying the frequency of the laser in four parameters from 2.2 hertz to 9.0 hertz. The shielding gas used was pure argon, with a flow rate of 15 l / min. The tests carried out for the research were: macrographic analysis, microstructural characterization and corrosion test. To reveal the details in the weld metal, a chemical attack with oxalic acid was used. The macrographs revealed that the samples are free of macroscopic discontinuities in the weld bead, in addition to having adequate bead penetration. The welds showed no discontinuities such as porosity and cracks, besides adequate penetration. The specimens were subjected to seawater corrosion tests with AMN Guarujá –SP electrolyte, the corrosion tests were promising, being more resistant than the superduplex, thanks to the large amount of nickel and chromium from Inconel.
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Palavras-chave
Superduplex, Inconel, soldagem, Laser, Corrosão, Corrosion, Welding