Aplicação de cobre e níquel puro como metais de adição na soldagem de chapas de aço superduplex UNS S32750 com Laser Pulsado Nd: YAG
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Data
2021-10-04
Autores
Cardoso, Matheus Singh
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Universidade Estadual Paulista (Unesp)
Resumo
Os aços Inoxidáveis superduplex (AISD) são materiais que apresentam elevados valores de resistência mecânica, aliados com altos níveis de resistência à corrosão, sua microestrutura é bifásica, consistindo em: ferrita (δ) e austenita (γ), uma matriz ferrítica com ilhas de austenita nas mesmas proporções, estrutura que garante as suas propriedades. Entretanto, a utilização dos AISD apresenta uma dificuldade com relação à processos de soldagem. Isso acontece devido à quebra das proporções de austenita e ferrita, pois quando submetido a um processo de soldagem, a microestrutura resultante é predominantemente ferrítica, devido as altas velocidades de resfriamento. Dessa forma a adição de elementos gamagênicos para a formação de austenita na soldagem, garantindo o balanço de fases, é de extrema importância na utilização dos AISD. Tendo isso em vista, o objetivo deste trabalho é estudar a influência do cobre e do níquel puro, separadamente, na soldagem a laser pulsado ND: YAG, do aço superduplex UNS S32750, analisando o balanceamento de fases na junta soldada, de forma que os metais de adição ajam como estabilizador da austenita, alterando as propriedades do material. Foram estudadas cinco condições de soldagem para o níquel e três para o cobre, comparando com a soldagem autógena (sem metais de adição). A adição de níquel foi feita com tiras finas do material entre as juntas soldadas e para o cobre a adição foi feita com revestimento eletrolítico. Para a adição de níquel, houve uma melhora na soldabilidade, possibilitando o balanço de fases e consequentemente boas propriedades e resistência à corrosão. Para a adição de cobre concluiu-se que o elemento não possui um potencial gamagênico alto, com formação apenas de austenita secundária nos contornos de grão e o aparecimento de trincas e poros no cordão de solda, diminuindo a soldabilidade
Superduplex Stainless Steels (SDSSs) are materials that have high values of mechanical strength, allied with high levels of corrosion resistance, its microstructure is biphasic, consisting of: ferrite (δ) and austenite (γ), a ferritic matrix with austenite islands in the same proportions, structure that guarantees its properties. However, the use of SDSS presents a difficulty in relation to welding processes. This is due to the breaking of the proportions of austenite and ferrite, because when subjected to a welding process, the resulting microstructure is predominantly ferritic, due to the high cooling rates. Thus, the addition of gamma-genic elements for austenite formation in welding, ensuring phase balance, is extremely important. Therefore, the objective of this work is to study the influence of copper and nickel separately on pulsed laser beam welding Nd: YAG, of UNS S32750 superduplex steel, analyzing phase balancing on the welded joint. Five welding conditions for nickel and three for copper were studied, comparing with autogenous welding (without addition metals). The addition of nickel was made with metallic foils of the material between the welding joints, and the copper addition was made with electrolytic coating. For the addition of nickel, there was an improvement in weldability, enabling the balance of phases and consequently good properties and corrosion resistance. For the copper addition it was concluded that the element does not have a high gamma-genic potential, with formation only of secondary austenite in the grain contours and the appearance of cracks and pores in the weld bead, decreasing weldability.
Superduplex Stainless Steels (SDSSs) are materials that have high values of mechanical strength, allied with high levels of corrosion resistance, its microstructure is biphasic, consisting of: ferrite (δ) and austenite (γ), a ferritic matrix with austenite islands in the same proportions, structure that guarantees its properties. However, the use of SDSS presents a difficulty in relation to welding processes. This is due to the breaking of the proportions of austenite and ferrite, because when subjected to a welding process, the resulting microstructure is predominantly ferritic, due to the high cooling rates. Thus, the addition of gamma-genic elements for austenite formation in welding, ensuring phase balance, is extremely important. Therefore, the objective of this work is to study the influence of copper and nickel separately on pulsed laser beam welding Nd: YAG, of UNS S32750 superduplex steel, analyzing phase balancing on the welded joint. Five welding conditions for nickel and three for copper were studied, comparing with autogenous welding (without addition metals). The addition of nickel was made with metallic foils of the material between the welding joints, and the copper addition was made with electrolytic coating. For the addition of nickel, there was an improvement in weldability, enabling the balance of phases and consequently good properties and corrosion resistance. For the copper addition it was concluded that the element does not have a high gamma-genic potential, with formation only of secondary austenite in the grain contours and the appearance of cracks and pores in the weld bead, decreasing weldability.
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Palavras-chave
Aço superduplex UNS S32750, Cobre e níquel como metais de adição, Soldagem laser Nd:YAG, Superduplex steel UNS S32750, Copper and nickel as addition metals, Nd: YAG laser bean welding