999 resultados para Solidos - Propriedades eletricas


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This work aims to study the Dual-Phase 600 and 780 steels, which are part of technology development project materials for the automotive industry. It is worth underscoring the antagonistic properties as the Dual-Phase steel assemble, high mechanical strength and elongation due its microstructure, ferrite and martensite. These properties are obtained by a intercritical heat treatment which facilitates the formation of a hardness metastable microstructure shaped plates of low carbon steels. The applicability of Dual Phase steel in the structure of vehicles is huge and its production is already on a commercial scale, so the study and development of this material implies lower cost in automobile manufacturing processes. The dual phase steels DP600 and DP780 underwent tensile, hardness and metallographic analysis to evaluate and comparing its properties. The results indicate that the DP780 steel has higher strength and hardness than the DP600 steel and its microstructure consists of martensite higher fraction which accounts for the higher resistance and hardness. However, the DP600 has higher conformability to DP780 steel

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pressure vessels are equipments that require a great care because of their high cost and human life risk in case of fail, and its fabrication methods are different for each manufacturer. Normally, pressure vessels and its parts are fabricated by welding, which may change local properties of metals. The head of a pressure vessel is a very important structural component and it is fabricated by welding and mechanical conformation. Because its excellent mechanical properties, de steel A-516 Grade 70 is often used in manufacturing of large pressure vessels that are subjected to high pressure and temperature, but was verified that its mechanical resistance is decreased when submitted to a tension relief heat treatment. By experience it was defined that before mechanical conformation of the head of a large pressure vessel, the steel should be submitted to a stress relief heat treatment in order to facilitate the mechanical conformation, but there is no quantitative analysis to prove this method and study its possible risks. In the present work the steel A-516 Grade 70 demonstrated a decrease of its mechanical resistance when submitted to a stress relief heat treatment, but keeping above the minimum limit defined in the literature. By other side its ductility was substantially increased, being possible to deduce that the stress relief heat treatment before mechanical conformation is a viable e recommended technique, but with reservations. With the data acquired during the fabrication e preparation of the specimen and the result of the tests, it was possible to elaborate a welding procedure that provides the same results obtained in this present work

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Pós-graduação em Química - IQ

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Pós-graduação em Engenharia Civil - FEIS

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Pós-graduação em Química - IQ

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)