Avaliação de resistência à corrosão e à fadiga do aço API 5L X70

• Autor(a) principal: Gomes, Vinícius Mota da Cruz [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/11449/155431; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-05-02/000883103.pdf
• topic: Corrosão por fadiga; Aço de alta resistência; Ligas de aço; Steel, High strength

IThe objective of this research was to study the fatigue behavior of a high-strength, API grade 5L X70 microalloyed steel (used in oil and gas runoff pipelines), before and after exposure to aggressive corrosion environment by saline mist, according to recommendations Of ASTM E466 and ASTM B117, respectively, in order to simulate the conditions to which offshore structures and installations are subjected in a marine environment. Cyclic stresses of low frequency, common in these marine environments, can favor and facilitate the corrosive action of the environment (which is time dependent), whose synergistic corrosion-fatigue action can result in catastrophic fracture of the whole installation, unexpectedly and in Short time, with large economic and environmental consequences. And due to such evil aspects to these risers, bodies of evidence of this steel in corrosion and fatigue were tested. The corrosion results were of an average loss of 0.224 mass% after cleaning of the corroded layer, which resulted in a surface roughness Ra = 3.55 μm, Rz = 23.58 μm and Rt = 35.77 μm extremely roughness High, if compared to Ra = 0.169 μm, Rz = 1.79 μm and Rt = 2.76 μm, resulting in a sensitization of the steel in the fatigue test, reducing its load capacity by 22% and its life In fatigue for the same voltage from 30000 cycles to 1225 cycles, thus corroborating the hypothesis of corrosion reducing its life in fatigue, due to its attack on the surface