The present work aims to study the hydrogen embrittlement process in API 5L X60 and API 5L X80 steels. The tests were performed using two kinds of hydrogen sources to work with two conditions of hydrogen damage: environmental hydrogen embrittlement and internal hydrogen embrittlement. The mechanical behavior of API 5L X60 and API 5L X80 steels in tensile tests, with and without hydrogen, were studied. Under environmental hydrogen embrittlement conditions, the API 5L X60 steel presented a softening process observed by the decrease in yield strength and increase in its deformation. The API 5L X80 steel was more susceptible to the phenomenon due the deformation decrease of hydrogenated samples. In notched samples, both steels were susceptible to embrittlement as shown by the decrease in elongation. Under internal hydrogen embrittlement conditions, in both steels the changes in deformation were significant and can be attributed to changes in the hydrogen trapping due to the hydrogenation process used, the chemical composition and microstructure. It was observed that the fracture surface morphology of hydrogenated samples of both steels was ductile by microvoids coalescence, and that the distribution of dimples per unit area was higher in the API 5L X60 steel. It can be concluded, as reported in the literature, that the reversible hydrogen trapping observable in environmental hydrogen embrittlement is more damaging than irreversible hydrogen trapping, observable in internal hydrogen embrittlement.
Esse trabalho teve o objetivo de inspecionar os parâmetros microbiológicos da água de cisternas nas escolas públicas de Pocinhos-PB. As amostras de água destinadas para as análises microbiológicas foram coletadas diretamente das cisternas em garrafas de vidro (500 ml) com boca larga, protegidas com papel laminado, previamente esterilizadas em autoclave a 121 oC, por 30 minutos, e foram encaminhadas para o Laboratório do Centro de Formação Profissional do Instituto Albano Franco de Tecnologia de Couro e de Calçado (CTCC) em Campina Grande/PB. Os parâmetros analisados e os métodos de análises foram: coliformes totais, coliformes termotolerantes, Escherichia coli e bactérias heterotróficas. Por motivos éticos, os nomes das referidas escolas foram mantidos em sigilo, sendo as amostras coletadas nas mesmas, identificadas como amostras 1, 2, 3, 4 e 5. Observou-se que, entre as amostras analisadas, três delas (1, 4 e 5) apresentaram quantidade de coliformes totais, totalmente fora dos limites estabelecidos pela portaria vigente. Todas as amostras apresentaram coliformes termotolerantes. Não se evidenciou a presença de Bactérias heterotróficas. A presença da bactéria E. coli, considerada indicativo de contaminação fecal, foi evidenciada em apenas duas amostras. Conclui-se que todas as amostras estão em desacordo com as recomendações estipuladas pela Portaria do Ministério da Saúde de nº 5, de 28 de setembro de 2017, pois apresentaram coliformes totais, coliformes termotolerantes e/ou E. coli, necessitando, portanto, de tratamento prévio antes de serem fornecidas para consumo humano.
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