Artigos Científicos - FEM/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2552

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Navegando Artigos Científicos - FEM/ITEC por Periódicos "Soldagem & Inspeção"

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    Efeitos do comprimento de reversão e do ângulo de ataque sobre a estrutura de solidificação do cordão em soldagem MIG/MAG com "Switch Back"
    (Universidade Federal do Pará, 2012-06) ALMEIDA, Hélio Antônio Lameira de; MOTA, Carlos Alberto Mendes da; SCOTTI, Américo
    The welding technique denominated switch-back technique consists in a torch oscillation in the welding direction rather than transversally. However, there is not much information in literature about the solidification structure of the bead when this technique is applied. Therefore, in this work is presented a study on the effect of the torch leading angle and of the reversion course length over the bead solidification structure. Welds were carried out with Pulsed MIG/MAG Process on plain carbon steel plates. The results showed that the parameters under analysis modify the solidification mode of the bead. In general, when the angle of torch leads to pushing-pulling movement, equiaxial grains near the fusion line is favored. In relation to the course length, its increase leads to finer solidification structure.
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    Influência dos procedimentos e modos de transferência no processo MAG na redução de deformações em painéis de estruturas navais
    (Associação Brasileira de Soldagem, 2013-11) CABRAL, Tarcio dos Santos; BRAGA, Eduardo de Magalhães; MENDONÇA, Everton Augusto Maciel; SCOTTI, Américo
    The Growth in the Brazilian shipbuilding industry brought on numerous problems in the production line. Some of these problems are related to the manufacturing process, welding process, due to residual stress and distortions. In the present paper, the influence of the welding procedure (sequence and direction of welding and the use of back weld) was studied. Different welding processes with different transfer modes (GMAW-CC, GMAW-TT and GMAW-CW) were also used. These changes were made to observe the influences on the amplitude of the distortions. All the welds were made using the ER70S-6 electrode and pure CO2 as a shielding gas with the short circuit transfer mode. The results showed that the most important variable is the direction of welding, which is related to the level of restriction of the panels welded. The effect of the welding sequence presented on the values of distortion produced were minor. The panels produced using the back welding procedure presented small values of distortion however, the procedure showed to be inefficient. It was also observed that the level of distortion for the processes GMAW-CC and GMAW-STT showed similar values. On the other hand the values of distortion in the panel welded using the GMAW-CW process presented the lowest values.
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    Revestimento de níquel depositado pela soldagem MIG e MIG com arame frio
    (Universidade Federal do Pará, 2016-12) MOTA, Carlos Alberto Mendes da; NASCIMENTO, Alexandre Saldanha do; GARCIA, Douglas Neves; SILVA, Diego Almir Silva da; TEIXEIRA, Felipe Ribeiro; FERRARESI, Valtair Antônio
    This paper presents a study about the operational, geometrical and microstructural characteristics of GMAW and GMAW-CW (GMAW Cold Wire) welds applied on a coating of steel AISI 1020 plate, with a nickel superalloy ER NiCrMo-4, Hastelloy 276C type. The welding was automated in flat position, and executed with an electronic source on DC+ and having instantaneous acquisition of the welding voltage and current oscillograms. The input variables were the speeds of the electrode and cold wires and the welding speed. It was evaluated the operational processes and the effect of heat input on the geometrical characteristics (reinforcement and width), dilution, microstructure and microhardness of the coating. The results indicated a good operating performance, the absence of defects in single passes and in the GMAW-CW coatings. Furthermore, it has been found the lowest level of dilution.
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