LUIS AUGUSTO MENDES DOS REIS

LUIS AUGUSTO MENDES DOS REIS

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 11

Study of recycling process viability of zirconium alloys chips for melting in VAR furnace
2017 - REIS, L.A.M.; ALENCAR, M.; GOMES, M.P.; PEREIRA, L.A.T.; MUCSI, C.S.; ROSSI, J.L.
Cavacos de ligas de zircônio (M5, Zirlo, Zircaloy) são gerados em elevadas quantidades na confecção de tubos e tampões das varetas que compõem o elemento combustível de reatores de potência refrigerados a água pressurizada (PWR). Essas são ligas importadas e por isso é mostrado interesse pela indústria de reciclagem na sua reutilização. Este trabalho apresenta os estudos de um processo de reciclagem e a obtenção de eletrodos prensados para serem fundidos em um forno VAR (Vacuum Arc Remelting). O processo se inicia com uma separação magnética, lavagem do fluido de corte que é solúvel em água, utilização de um desengraxante industrial, seguido por um enxágue com fluxo contínuo de água em alta pressão e secagem por fluxo de ar quente. Para a obtenção de eletrodos, os cavacos foram prensados em uma matriz de seção quadrada 40x40 mm² com 500 mm de comprimento, resultando num eletrodo com 20% da densidade aparente da liga. A fusão foi feita um forno VAR de laboratório no CCTM-IPEN, gerando um lingote maciço de 0,8 kg. A fusão dos cavacos é possível e viável em um forno VAR o que reduz em até 40 vezes o volume de armazenamento desse material.
Influence of air quenching on apparent hardness of valve seat inserts obtained with AISI M2 high-speed steel powder
2017 - GOMES, M.P.; SANTOS, I.P.; REIS, L.A.M.; CIONE, F.C.; COLOSIO, M.A.; ROSSI, J.L.
The aim of this work consisted of evaluate the influence of heat treatment on sintered valve seat inserts (VSI) obtained with the AISI M2 high-speed steel powder. The AISI M2 high-speed steel powder was mixed with iron powder and additives such as manganese sulphide, zinc stearate, graphite and carbides. The heat treatment of the VSI consisted of air quenching followed by double tempering it in seven different equidistant temperatures, from 100 °C until 700 °C. The mechanical property was measured regarding the VSI apparent hardness. The results indicated that the VSI obtained with the AISI M2 high-speed steel powders mixtures showed the best results regarding its apparent hardness after air quenching and double tempering it at 600 °C.
Effect of the cooling rates on heat-affected zone of UNS S32304 duplex stainless steel welded by pulsed GTAW process
2017 - BETINI, E.G.; GOMES, M.P.; REIS, L.A.; MUCSI, C.S.; ALENCAR, M.C.; ORLANDO, M.T.D.; LUZ, T.S.; AVETTAND-FENOEL, M-N.; ROSSI, J.L.
Two thin plates of UNS 32304 of duplex stainless steel were joined by pulsed gas tungsten arc welding (GTAW) using a mixture 98% of argon plus 2% of nitrogen as shielding gas or pure argon as purging gas at the bottom of the plate without filler metal. The temperature profile close and away from the weld pool was measured using K type (Ni-Cr) thermocouples, connected to a digital data acquisition system. The thermal cycles was recorded in the heat-affected zone (HAZ) at a distance in between 1 and 3 mm from the joint line. The cooling rate and holding time were studied with respect to the used purging gas. Experimental thermal profiles are in good agreement with literature values. The joints welded without any purging gas revealed high peak temperature and cooling rates. The present investigation showed that temperature peaks are comprised in the phase transformation temperature ranges for the welded duplex stainless steel.
Characterization of sintered valve seat inserts obtained with AISI M2 high-speed steel after air quenching
2017 - GOMES, MAURILIO P.; SANTOS, IGOR P. dos; REIS, LUIS A.M. dos; COUTO, CAMILA P.; MUCSI, CRISTIANO S.; COLOSIO, MARCO A.; ROSSI, JESUALDO L.
The aim of this work was to heat treat and characterize sintered valve seat inserts (VSI). The powder metallurgy route was the only way found to substitute cobalt and lead, used in the VSI original alloy, due to their high cost and toxicological effect, respectively. The studied VSI was obtained with AISI M2 high-speed steel powder mixed with iron powder and other additives such as manganese sulphide, graphite, zinc stearate, carbides and copper, which was added by metallic infiltration. All the VSI were air quenched and double tempered, for one hour each, at seven different equidistantly temperatures, ranging from 100 °C up to 700 °C. The physical and mechanical properties were evaluated by means of the VSI apparent density, apparent hardness and crush radial strength. The chemical composition was determined through gas analysis, for the light elements such as carbon and sulfur, and energy dispersive X-ray fluorescence spectrometry for other elements. Microstructural characterization was performed with the support of scanning electron microscopy and energy dispersive spectroscopy. Regarding the VSI final application, the best results were achieved with the inserts air quenched and double tempered at 600 °C.
Study on welding thermal cycle and residual stress of UNS S32304 duplex stainless steel selected as external shield for a transport packaging of Mo-99
2019 - BETINI, E.G.; GOMES, M.P.; MILAGRE, M.X.; MACHADO, C.S.C.; REIS, L.A.M.; MUCSI, C.S.; ORLANDO, M.T.D.; LUZ, T.S.; MARTINEZ, L.G.; ROSSI, J.L.
Thin plates of duplex stainless steel UNS S32304 were welded using the pulsed gas tungsten arc GTAW process (butt joint) without filler addition. The used shielding gas was pure argon and 98% argon plus 2% of nitrogen. The thermal cycles were acquired during welding, in regions near the melting pool. This alloy is candidate for the external clad of a cask for the transport of high activity radiopharmaceuticals substances. For the residual stress measurements in austenite phase an X-ray diffractometer was used in a Bragg-Brentano geometry with CuKα radiation (λ= 0.154 nm) and for ferrite phase was used a pseudo-parallel geometry with CrKα radiation (λ= 0.2291nm). The results of residual stress using sin2 methodology showed that the influence of the high welding temperature leads to compressive stresses for both phases of the duplex steels mainly in the heat-affected zone. It was observed a high temperature peak and an increase of the mean residual stress after addition of ni-trogen to the argon shielding gas.
Valve seat insert: air quenching and characterization of components obtained with AISI M3:2 high-speed steel
2018 - GOMES, M.P.; SANTOS, I.P.; REIS, L.A.M.; COUTO, C.P.; BETINI, E.G.; MUCSI, C.S.; COLOSIO, M.A.; ROSSI, J.L.
The development of components ecologically correct is something more and more necessary. The first developement of valve seat inserts (VSI) take in account the use of cobalt and lead in its chemical composition. Such elements are avoided in the current applications due to its high cost and toxicological effects, respectively. In the present work was used VSI developed with a new chemical composition. The aim of this work were to air quench and characterize such components. The studied VSI were obtained with AISI M3:2 high-speed steel admixed with iron powder and another additives such as manganese sulphide, graphite, zinc stearate and carbides. All the air quenched VSI were double tempered, for one hour each, at seven equidistant temperature from 100 °C until 700 °C. The air quenched components had its mechanical and physical properties determined by means of its apparent density, apparent hardness and crush radial strength. The chemical composition was measured through the gases analyses and energy dispersive X-ray fluorescence spectrometry techniques. Microstructural and phase characterizations were performed with the support of optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Regarding the VSI required properties, the best results were obtained with the components air quenched and double tempered at 600 °C.
Recycling process viability from zirconium alloys scraps of lathe melted in the vacuum arc remelting (VAR) furnace
2018 - REIS, L.A.M.; ALENCAR, M.C.; GOMES, M.P.; PEREIRA, L.A.T.; BARBOSA, L.P.; MUCSI, C.S.; ROSSI, J.L.
Pressurized water reactors (PWR) commonly use U235 enriched uranium dioxide pellets as a nuclear fuel, these are assembled and cladded in zirconium alloy (M5, Zirlo, Zircaloy) tubes and end caps. During the machining of these components, large amounts of turning lathe chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry has shown interest in its recycling due to its strategic importance of these scraps. This paper presents the steps on the recycling processes and the results for the search of an efficient way on the cleaning, quality control, manufacturing, and melting of electrodes for Vacuum Arc Remelting (VAR) furnace. The process starts with cutting oil washout and this step consists of a water dissolution followed by a degreasing process, the water rinse by continuous flow of water and finally drying in hot air. Process evaluation was first made by means the X-ray fluorescence tests in order to define the quality of the scraps that after washing were pressed in 20 mm diameter briquettes, melted and subjected to such analysis. The next step consists in the pressing with a die square section with 40 mm2 and 500 mm long, producing an electrode with 20% of the Zircaloy bulk density. The electrode was melted in a laboratory scale VAR furnace located at the CCTM – IPEN producing a 0.8 kg ingot. The microstructural and macro structural characterization is being done by analyzes performed in the optical microscope and scanning electron microscope (from portuguese Microscópio Eletronico de Varredura - MEV). Gas analyzes were carried out with the intention of evaluating possible gases resulting from the melting and evaluating their influence. X-ray diffraction analyzes were also performed to identify the phases present in the material after the melting process The authors conclude that the samples obtained from the fuel element industry can be melting in a VAR furnace reducing 40 times the storage volume, however, it is necessary to remelt the ingots by correcting their composition intended for reuse.
Study on the viability of the recycling by electric arc melting of zirconium alloys scraps aiming the scalability of the process
2018 - MUCSI, C.S.; REIS, L.A.M. dos; GOMES, M.P.; PEREIRA, L.A.T.; ROSSI, J.L.
Turning chips of zirconium alloys are produced in large quantities during the machining of alloy rods for the fabrication of the end plugs for the Pressurized Water Reactor (PWR) fuel elements parts of Angra II nuclear reactor (Brazil – Rio de Janeiro). This paper presents a study on the search for an efficient way for the cleaning, quality control and Vacuum Arc Remelting (VAR) of pressed zirconium alloys chips to produce a material viable to be used in the production of the fuel rod end plugs. The process starts with cutting oil clean out. The first step in this process consists in soaking a bunch of chips in clean water, to remove soluble cutting oils, followed by an alkaline degreasing bath and a wash with a high-pressure flow of water. Drying is performed by a flux of warm air. The oil free chips are then subjected to a magnet in order to detect and collect any magnetic material, essentially ferrous, that may be present in the original chips. Samples of the material are collected and then melted in a small non consumable electrode vacuum arc furnace for evaluation by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRFS) in order to define the quality of the chips. The next step consists in the 15 ton hydraulic pressing the chips in a die with 40 mm square section and 500 mm long, producing an electrode with 20% of the Zircaloy bulk density. The electrode was finally melted in a laboratory scale modified VAR furnace located at the CCTM–IPEN, producing 0.8 kg ingots. The authors conclude that the samples obtained from the fuel element industry can be melting in a VAR furnace, modified to accommodate low density electrodes, allowing a reduction up to 40 times the original storage volume, however, it is necessary to remelt the ingots to correct their composition in order to recycle the original zirconium alloys chips. in a process to reduce volume and allow the reutilization of valuable Zircaloy scraps.
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.
Recycling and melting process of the zirconium alloy chips
2017 - REIS, LUIS A.M. dos; MUCSI, CRISTIANO S.; TAVARES, LUIZ A.P.; ALENCAR, MAICON C.; GOMES, MAURILIO P.; BARBOSA, LUZINETE P.; ROSSI, JESUALDO L.