EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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2 resultados
Resultados da Pesquisa
Item Effect of thermal aging on the microstructure and mechanical properties of stainless steel UNS S31803.(2020) Costa, Junia Maria Gândara; Lacerda, José Carlos de; Godefroid, Leonardo Barbosa; Cândido, Luiz CláudioDuplex stainless steel UNS S31803 exhibits high mechanical strength with high corrosion properties, due to its microstructure composed of ferrite and austenite phases, in equal proportion. When the UNS S31803 steel is submitted to high temperatures, some precipitations can occur, such as nitrites, carbides, and third phases (e.g. sigma phase -σ, and alpha prime - α'). These phases are deleterious in relation to the mechanical properties and corrosion resistance, and their effects are analyzed regarding the properties of the steel. In order to evaluate the precipitation of this deleterious phase, isothermal treatment was done at 500°C for 144 hours (α' phase) and at 850ºC for 80 minutes (σ phase). The results were obtained through the microstructural analysis and tensile tests. The presence of sigma phase was verified in the grain boundary, an increase in the mechanical resistance with a loss of toughness. There was as well as an increase in mechanical resistance with the precipitation of α', with less loss of ductility than that observed in the experiments involving the presence of sigma phase.Item Effect of niobium on microstructure and mechanical properties of a hypereutectoid steel.(2022) Pessoa, Ricardo Amorim; Porcaro, Rodrigo Rangel; Cândido, Luiz Cláudio; Pereda, Beatriz; Lopez, BeatrizHigh-carbon steels have been used to high-strength steel wire and strands for prestressing concrete. The necessity of high-strength levels at increasingly larger diameters of wire rods is a technological challenge. Two steels with and without Nb were obtained in a steel mill, submitted to detailed microstructural (previous austenitic grain size, pearlite interlamellar spacing and colony size) and mechanical characterization through tensile tests and hardness. Hot torsion and dilatometry tests were performed to simulate steels processing and to verify the influence of Nb on phase transformation. Adding Nb to steel resulted in a refinement in austenitic grain size and pearlite colonies but had no effect on pearlitic interlamellar spacing. There was a decrease at the start transformation temperature austenite/pearlite and therefore an increase in the hardenability of the Nb-added steel. Finally, Nb addition proved to be a technical and economical way to increase tensile strength and to reduce the variability of the mechanical properties.