Análise microestrutural do aço maraging 18Ni 300 soldado a laser

• Autor(a) principal: Ferreira, Renan Nascimento [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155423; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-05-02/000883018.pdf
• topic: Solda e soldagem; Aço de alta resistência; Análise estrutural (Engenharia); Aço - Tratamento termico; Solder and soldering

Currently the motor case of the Satellite Launch Vehicle (VLS) is made with high-strength steels 300M. However, the high cost and complexity in the heat treatment of these steels have stimulated the search for alternative materials in this application. The maraging steel has proven to be an advantageous substitute for the simple heat treatment and the mechanical properties. maraging steels are iron-nickel alloys of high mechanical strength and arouse great interest in aeronautics and aerospace industry. These steels have a ductile and tough martensitic phase that has hardness gain by precipitation of alloying elements. When they are heat treated at about 480°C, these steels can reach yield strength between 1700 and 2700 MPa. In this work, were prepared specimens in three groups of thermal treatments: homogenized, solubilized and aged, solubilized and aged and only aged. The specimens were laser welded and subjected to hardness and tensile tests as an assessment of the microstructural and mechanical properties in each case of heat treatment. The micrographs indicate a molten area with dendritic structure and few defects. It was found that heat treatment for homogenization and solubilization eliminate the loss of hardness in the weld bead and generate higher hardness in the material (≈650 HV). Nevertheless, the only aged specimens showed a tensile strength very close to the non-welded steel (≈1960 MPa). The homogenization treatment reduced levels of segregation in the melt zone, however, there was an increase in grain size and tensile strength loss after this heat treatment. The welded specimens showed promising results, with the tensile strength next to the non welded specimens