Estudo da fragilização por hidrogênio em aços maraging 300

• Autor(a) principal: Sarquis, Ivna Nazlé Cavalcante
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/38986
• topic: Aços maraging; Fragilização por hidrogênio; Ensaio baixa taxa de deformação (BTD); Título

This work assessed the effects of hydrogen embrittlement in 18% Ni maraging grade 300 steel in the annealed and aged conditions. Samples were annealed at 840 ºC, 950 ºC, 1050 ºC and 1150 ºC for 1 hour, followed by aging at different temperatures: 480 ºC for 3 hours and 560 ºC for 1 hour. To assess the effects of hydrogen ingress on the mechanical properties of 18% Ni maraging grade 300 steel, slow strain rate tests (SSRT) were performed. The tests were carried out in air and with hydrogen loading. A strain rate of 1.0x10-6 s-1 was applied for the SSRT in air and 1.0x10-5 s-1 for the tests in solution with hydrogen charging. In regards of the tensile tests performed, stress-strain curves could be acquired and analyzed. Changes in fractografic features from ductile dimples to quasi-cleavage and microvoid modes were observed when comparing samples without (air tested) and with hydrogen ingress. The results showed the reduction of ductility and a lower resistance limit for the samples under cathodic polarization in the 3,5% NaCl solution. Samples submitted to the highest annealing temperature (1150ºC) obtained greater hydrogen embrittlement, fracturing around 500 MPa at an aging temperature of 480ºC / 3h. Maraging steel samples aged at 560ºC / 1h showed more mechanical resistance than those aged at 480ºC / 3h.