MAURILIO PEREIRA GOMES

Projetos de Pesquisa
Unidades Organizacionais
Cargo

Filtros

2018 - 20192
Limpar filtros

Configurações

search.filters.applied.f.ispartof: Materials Research ×

Resultados de Busca

Agora exibindo 1 - 2 de 2
  • Imagem de Miniatura
    Artigo IPEN-doc 26436
    Effect of nitrogen addition to shielding gas on cooling rates and in the microstructure of thin sheets of duplex stainless steel welded by pulsed gas tungsten arc welding process
    2019 - BETINI, EVANDRO G.; GOMES, MAURILIO P.; MUCSI, CRISTIANO S.; ORLANDO, MARCOS T.D.; LUZ, TEMISTOCLES de S.; AVETTAND-FENOEL, MARIE-NOELLE; ROSSI, JESUALDO L.
    The effect of the nitrogen content in the shielding gas and its effect on temperature distributions at the welded zone of thin sheets of duplex stainless steel have been evaluated. The duplex stainless steels have many features due to unique microstructural combination of austenite and ferrite grains. The phase balance can be easily shifted depending on the welding parameters. Two sheets were welded using pure argon and pure argon plus 2% of nitrogen as shielding gas. The thermal profile had shown that N2-supplemented shielding gas lead to higher peaks of temperature using similar welding parameters. Microstructural examination showed that the austenite phase in the weld increased with the presence of nitrogen in the shielding gas. The added nitrogen promoted primary austenite formation and slightly increases the microhardness at the solidified zone. Microhardness mapping and metallographic imaging presented information about microstructures, confirming the formation of secondary phases during thermal cycle in the temperature range 850 °C and 950 °C. Control of ferrite amounts in the welds is essential mainly to improve mechanical properties and corrosion resistance of welding zones.
  • Imagem de Miniatura
    Artigo IPEN-doc 25096
    Heat treatment of sintered valve seat inserts
    2018 - GOMES, MAURILIO P.; SANTOS, IGOR P. dos; COUTO, CAMILA P.; BETINI, EVANDRO G.; REIS, LUIS A.M. dos; MUCSI, CRISTIANO S.; COLOSIO, MARCO A.; ROSSI, JESUALDO L.
    The characterization of sintered valve seat inserts (VSIs) after being subjected to different heat treatment operations has been carried out. The VSIs were obtained from three different alloys by mixing iron powder with AISI M3:2, AISI M2 high-speed steels, and AISI D2 tool steel. After sintering, the VSI were quenched in air followed by double tempering at seven different temperatures. The cooling rate during air quenching was measured by means of a thermocouple type k attached to a data acquisition system. The characterization of the mechanical and physical properties of the VSIs was achieved by measuring relative density, apparent hardness and crush radial strength. The resulting microstructures for the sintered parts were interpreted using the isothermal and continuous cooling transformation diagrams for similar alloys. The VSI obtained with AISI M3:2 and AISI M2 high-speed steels after air quenching and double tempering at 600 ºC showed the best results in terms of apparent hardness and crush radial strength.