Efeito da adição de níquel e nitrogênio na microestrutura e propriedades mecânicas de juntas de aço superduplex UNS S32750 soldadas com Laser Pulsado Nd:YAG
Carregando...
Data
2018-07-03
Autores
Bonuti, Robert de Souza
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O presente trabalho consistiu em uma análise da influência da adição de elementos gamagênicos, estabilizadores da austenita, no processo de união autógena do aço superduplex UNS S32750, soldados com Laser Pulsado Nd:YAG. Os corpos de prova foram soldados utilizando duas técnicas: introdução de nitrogênio gasoso na atmosfera protetora, e adição de uma liga de níquel (Inconel 625 e Hastelloy C-276) na junta a ser soldada, tendo-se como objetivo a avaliação das propriedades mecânicas e microestruturais da junta soldada, como microdureza e tração. Todos os dados foram obtidos nos laboratórios da área de Materiais e Processos de Fabricação e no Laboratório de Soldagem da UNESP – Universidade Estadual Paulista Júlio de Mesquita Filho, Campus de Ilha Solteira, SP. O processo de soldagem foi realizado com a máquina de solda a laser UW 150A. Para a revelação dos detalhes dos cordões de solda foi utilizado o reagente Behara modificado. As medidas geométricas dos cordões de solda, como largura e profundidade, foram realizadas no microscópio Estéreo Zeiss Discovery V8. O MEV (Microscópio Eletrônico de Varredura) foi utilizado para a obtenção dos detalhes microscópicos dos cordões de solda. Os ensaios de tração foram realizados na Máquina Universal de Ensaios, e os valores de microdureza Vickers foram obtidos com o apoio do ultramicrodurômetro digital Shimadzu, modelo DUH 211S. Os resultados da microdureza Vickers, e dos ensaios de tração, nos corpos de prova obtidos com o uso dos gases de proteção Argônio e Nitrogênio, durante o processo de soldagem autógena, demonstraram semelhança de valores. Fato este que comprovou que o uso do gás inerte (Argônio) e do gás ativo (Nitrogênio), causou baixa influência na constituição do metal de solda. O uso das ligas Inconel 625, e Hastelloy C276, que mesmo tendo alto teor de Níquel, não contribuíram significativamente para elevar os valores de microdureza e de resistência mecânica no metal de solda, se comparados às do metal base.
The present work consisted in an analysis of the influence of the addition of gamma - genic elements, stabilizers of austenite, in the process of autogenous union of the superduplex steel UNS S32750, welded with Nd: YAG Pulsed Laser. The specimens were welded using two techniques: introduction of gaseous nitrogen into the protective atmosphere and addition of a nickel alloy (Inconel 625 and Hastelloy C-276) in the joint to be welded, with the objective of evaluating the mechanical properties and microstructural weld joints, such as microhardness and tensile strength. All data were obtained from laboratories in the area of Materials and Processes of Manufacture and at the Welding Laboratory of UNESP - Paulista State University Júlio de Mesquita Filho, Campus de Ilha Solteira, SP. The welding process was performed with the UW 150A laser welding machine. For the development of details of the weld beads, the modified Behara reagent was used. The geometric measurements of the weld beads, such as width and depth, were performed on the Zeiss Discovery V8 Stereo Microscope. SEM (Scanning Electron Microscope) was used to obtain the microscopic details of the weld beads. The tensile tests were performed in the Universal Testing Machine, and the Vickers microhardness values were obtained with the support of the Shimadzu digital ultramicrodurometer, model DUH 211S. The results of the Vickers microhardness and the tensile tests on the specimens obtained with the protection gases Argon and Nitrogen during the autogenous welding process showed similar values. This fact proved that the use of the inert gas (Argon) and the active gas (Nitrogen), caused little influence on the constitution of the weld metal. The use of the Inconel 625 and Hastelloy C276 alloys, which although having a high Nickel content, did not contribute significantly to increase the microhardness and mechanical strength values in the weld metal compared to those of the base metal.
The present work consisted in an analysis of the influence of the addition of gamma - genic elements, stabilizers of austenite, in the process of autogenous union of the superduplex steel UNS S32750, welded with Nd: YAG Pulsed Laser. The specimens were welded using two techniques: introduction of gaseous nitrogen into the protective atmosphere and addition of a nickel alloy (Inconel 625 and Hastelloy C-276) in the joint to be welded, with the objective of evaluating the mechanical properties and microstructural weld joints, such as microhardness and tensile strength. All data were obtained from laboratories in the area of Materials and Processes of Manufacture and at the Welding Laboratory of UNESP - Paulista State University Júlio de Mesquita Filho, Campus de Ilha Solteira, SP. The welding process was performed with the UW 150A laser welding machine. For the development of details of the weld beads, the modified Behara reagent was used. The geometric measurements of the weld beads, such as width and depth, were performed on the Zeiss Discovery V8 Stereo Microscope. SEM (Scanning Electron Microscope) was used to obtain the microscopic details of the weld beads. The tensile tests were performed in the Universal Testing Machine, and the Vickers microhardness values were obtained with the support of the Shimadzu digital ultramicrodurometer, model DUH 211S. The results of the Vickers microhardness and the tensile tests on the specimens obtained with the protection gases Argon and Nitrogen during the autogenous welding process showed similar values. This fact proved that the use of the inert gas (Argon) and the active gas (Nitrogen), caused little influence on the constitution of the weld metal. The use of the Inconel 625 and Hastelloy C276 alloys, which although having a high Nickel content, did not contribute significantly to increase the microhardness and mechanical strength values in the weld metal compared to those of the base metal.
Descrição
Palavras-chave
Gamagênico, Soldagem autógena, Inconel, Hastelloy, Soldagem laser, UNS S32750, Autogenous welding, Laser welding