Avaliação dos parâmetros de nitretação por laser de CO2 no aço maraging 18Ni (300) para melhoria da resistência à oxidação
Evaluation of CO2 laser nitretation parameters on maraging 18Ni steel (300) to improve oxidation resistance
João Paulo Giacomelli, Filipe Estevão de Freitas, Adriano Gonçalves dos Reis, Aline Capella de Oliveira, Vanessa Ribeiro dos Santos, Danieli Aparecida Pereira Reis
Resumo
O objetivo deste trabalho foi a avaliação dos parâmetros de nitretação por laser para o aumento da resistência a oxidação do aço Maraging 300 solubilizado. Para verificar as mudanças em suas propriedades, as amostras foram nitretadas por laser. Para a caracterização e análise fractográfica do material foram utilizadas técnicas de termogravimetria (TGA), microscopia óptica, difratometria de raios X e dureza, antes e após o tratamento de nitretação, a fim de comparar os ganhos em propriedade mecânica e térmica do material. As amostras foram nitretadas com laser de CO2 com comprimento de onda de 10,6 μm e uma máxima potência de 100 W, com velocidade de 10 mm/s e 20 mm/s. Os resultados foram positivos quanto à formação de uma camada nitretada, menor índice de oxidação além de um real ganho em resistência a oxidação quando submetidas a análises termogravimétricas, especialmente para a amostra nitretada com velocidade de 20 mm/s no laser e sobreposição de 50% entre os passes, onde o ganho de massa (devido à oxidação) ficou na ordem de quatro vezes menor que a amostra controle.
Palavras-chave
Abstract
The objective of this study was to validate the laser nitriding process to increase the oxidation resistance of solubilized Maraging 300 steel. In order to verify changes in their properties, specimens were laser-nitrided, with a laser beam. For the characterization and fractographic analysis of the material techniques of thermogravimetry, optical microscopy, X-ray diffraction, and hardness were used before and after the nitriding treatment in order to compare the gains in mechanical and thermal property of the material. The samples were treated by CO2 laser with 10.6 μm wave-length and 100 W of power, the speeds used were 10 mm/s and 20 mm/s. The results were positives in relation to the formation of a nitrided layer, less oxidation rates in addition to a improvement in oxidation resistance when subjected to thermogravimetric analysis, especially for the sample submitted to nitriding in a laser speed of 20 mm/s with 50% overlap between passes, where the mass gain (due to oxidation) was in the order of four times smaller than the control sample.
Keywords
References
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Submitted date:
06/04/2020
Accepted date:
11/05/2020
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