CAMILA PUCCI COUTO
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Artigo IPEN-doc 27114 The use of scanning vibrating electrode technique to evaluate the effect of hot stamping on the corrosion resistance of 22MnB5 press-hardened steel electroplated with Zn-Ni2019 - COUTO, CAMILA P.; COSTA, ISOLDA; VIVEIROS, BARBARA V.G. de; ALENCAR, MAICON C. de; COLOSIO, MARCO A.; PANOSSIAN, ZEHBOUR; ROSSI, JESUALDO L.Carmakers must achieve the worldwide targets for lightweight materials, safety and reducing the fuel consumption. The use of press-hardened steel (PHS), in vehicle structures has been contributing with these requirements. This type of steel is widely used for the hot-stamping which consists in heating the steel blank to total austenitization temperature and then transferring it from the furnace into the die tool where the steel is formed and quenched at the same time. PHS is usually protect with metallic coatings in order to avoid both steel oxidation and decarburization. Hot-dip Al-Si coating is currently the main used in this application. However, alternative coatings, like zinc-based, are under investigation. This work aims at evaluating the corrosion resistance of the 22MnB5 grade PHS, electroplated with Zn-Ni, before and after hot stamping, using the scanning vibrating electrode technique (SVET). Results from SVET showed that samples prior to hot stamping, the corrosion mechanism was uniform over the exposed surface, and was mainly related to selective dissolution of zinc from the coating. On the other hand, hot stamped samples showed localized corrosion mechanism with decrease in current with time of immersion due to the formation of corrosion products on the exposed surface.Artigo IPEN-doc 25096 Heat treatment of sintered valve seat inserts2018 - 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.