Soldagem autógena com laser pulsado Nd:YAG da liga de níquel Inconel® 625
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Data
2022-04-01
Autores
Jabur, Fernando Arenas
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Universidade Estadual Paulista (Unesp)
Resumo
As constantes mudanças no cenário global, tanto do ponto de vista econômico quanto tecnológico, forçam uma busca igualmente constante pelo aperfeiçoamento de materiais e processos de fabricação. Dentro desse escopo, destacam-se as superligas, como por exemplo as ligas de níquel: Hastelloy, Inconel, Monel, Incolloy e Nimonic. Essas ligas apresentam uma ou mais propriedades muito acima das ligas convencionais como os aços carbono, aços ferramenta e os aços inoxidáveis. A principal aplicação dessas ligas encontra-se nas indústrias aeroespacial, nuclear, petroquímica, naval e automotiva. A soldagem laser das ligas de níquel, cuja característica é a alta taxa de resfriamento, pode gerar uma microestrutura com alta fração volumétrica de compostos interdendríticos deletéreis, e assim, comprometendo suas características de boa resistência mecânica e resistência à corrosão. O presente trabalho tem como objetivo analisar uma junta de topo soldada com laser Nd:YAG pulsado, na condição autógena, da superliga de níquel Inconel 625, condição presente em muitas situações da indústria química e petroquímica. As soldagens foram realizadas em juntas topo e sem abertura de raiz. A potência de pico, a frequência do pulso e a velocidade de soldagem foram fixadas em 2kW, 9Hz e 1mm/s, respectivamente. A largura temporal do pulso variou de 3,5 ms a 7,5 ms. Dessa forma, as juntas soldadas foram obtidas com energia do pulso de 7J, 8J, 9J, 10J, 11J, 12J, 13J, 14J e 15J. Utilizou-se argônio puro como gás de proteção, com vazão de 15l/min. Foram realizadas análises macrográficas e micrográficas da junta soldada através de microscopia ótica e microscopia eletrônica de varredura. Foram realizados ensaios mecânicos de tração e microdureza Vickers. Os resultados mostraram que a soldagem da liga de níquel Inconel 625 com laser Nd:YAG pulsado gera uma microestrutura com alta fração volumétrica de compostos interdenditricos. A zona termicamente afetada apresentou dimensões muito reduzidas, característica da soldagem laser. As juntas obtidas com energia do pulso de 7J, 8J e 9J romperam no metal de solda enquanto as demais amostras romperam no metal base. Os ensaios de microdureza Vickers mostraram um aumento da dureza na região do metal de solda.
As a result of the constant changes in the global scenario, set by both economic and technological points of view, demand an equally constant search to improve materials and manufacturing processes. Within this scope, the superalloys stand out, such as nickel alloys: Hastelloy, Inconel, Monel, Incolloy and Nimonic. These alloys have one or more properties far above conventional alloys such as carbon steels, hard steels and stainless steels. The main application of these alloys is in the aerospace, nuclear, petrochemical, naval and automotive industries. The laser welding of nickel alloys, whose characteristic is the high cooling rate, can generate a microstructure with high volumetric fraction of deleterious interdendritic compounds, and thus compromising their characteristics of good mechanical resistance and corrosion resistance. The present work is focused on analyze a top joint welded with Nd:YAG pulsed laser, in the autogenous condition, of the nickel super alloy Inconel 625, a condition present in many situations of the chemical and petrochemical industry. The weldments were performed in square butt joints. Peak power, pulse frequency and welding speed were set at 2kW, 9Hz and 1mm/s, respectively. The temporal width of the pulse was ranged from 3.5 ms to 7.5 ms. Therefore, pulse energy deployed at the welded joints were set at 7J, 8J, 9J, 10J, 11J, 12J, 13J, 14J and 15J. Pure argon was used as a protective gas, with a flow rate of 15l/min. Macrographic and micrographic analyses of the welded joint were performed by optical microscopy and scanning electron microscopy. Mechanical tensile and Vickers microhardness tests were performed. The results showed that the welding of the nickel alloy Inconel 625 with pulsed Nd:YAG laser generates a microstructure with high volumetric fraction of interdenditeric compounds. The thermally affected zone presented very reduced dimensions, characteristic of laser welding. The joints obtained with pulse energy of 7J, 8J and 9J had their failure in the weld metal while the other samples ruptured in the base metal. Vickers microhardness tests showed an increase in hardness in the weld metal region.
As a result of the constant changes in the global scenario, set by both economic and technological points of view, demand an equally constant search to improve materials and manufacturing processes. Within this scope, the superalloys stand out, such as nickel alloys: Hastelloy, Inconel, Monel, Incolloy and Nimonic. These alloys have one or more properties far above conventional alloys such as carbon steels, hard steels and stainless steels. The main application of these alloys is in the aerospace, nuclear, petrochemical, naval and automotive industries. The laser welding of nickel alloys, whose characteristic is the high cooling rate, can generate a microstructure with high volumetric fraction of deleterious interdendritic compounds, and thus compromising their characteristics of good mechanical resistance and corrosion resistance. The present work is focused on analyze a top joint welded with Nd:YAG pulsed laser, in the autogenous condition, of the nickel super alloy Inconel 625, a condition present in many situations of the chemical and petrochemical industry. The weldments were performed in square butt joints. Peak power, pulse frequency and welding speed were set at 2kW, 9Hz and 1mm/s, respectively. The temporal width of the pulse was ranged from 3.5 ms to 7.5 ms. Therefore, pulse energy deployed at the welded joints were set at 7J, 8J, 9J, 10J, 11J, 12J, 13J, 14J and 15J. Pure argon was used as a protective gas, with a flow rate of 15l/min. Macrographic and micrographic analyses of the welded joint were performed by optical microscopy and scanning electron microscopy. Mechanical tensile and Vickers microhardness tests were performed. The results showed that the welding of the nickel alloy Inconel 625 with pulsed Nd:YAG laser generates a microstructure with high volumetric fraction of interdenditeric compounds. The thermally affected zone presented very reduced dimensions, characteristic of laser welding. The joints obtained with pulse energy of 7J, 8J and 9J had their failure in the weld metal while the other samples ruptured in the base metal. Vickers microhardness tests showed an increase in hardness in the weld metal region.
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Palavras-chave
INCONEL®, Superligas, Níquel, Soldagem, Laser, Nd:YAG, Superalloys, Nickel, Welding