Navegando por Assunto "Welding"

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Acesso aberto (Open Access)
Estudo da técnica de enchimento de chanfro do aço naval pelo processo GMAW-CW
(Universidade Federal do Pará, 2011) BARBOZA FILHO, Lúcio da Silva; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
In this work studied the operational viability and the characteristics economic and geometric of technique of the process welding GMAW -CW (additional alimentation of a cold wire) in comparison Gas Metal Arc Welding (GMAW). The alimentation system of cold wire was designed and adapted to welding gun GMAW. Used an electronic source of multiple processes adjusted in constant voltage and DC+, the gas shield was a mixture 75% Ar+25% CO2 and commercially pure CO2. The wire used was Class ER70S-6 with diameter of 1.2 mm for the electrode wire and 1.0 mm for the cold wire, the both wires were fed in heads independent. The input operating variables were the feed speed of wire energized at three levels, 4, 6 and 8 m / min and the wire feed speed in cold 50%, 60% and 70% of the wire feed speed energized . The welds were automated in simple deposited in the pushing direction and the positioning of the cold wire in a single level, Tandem in chamfer "U" steel plate ASTM 1020. The variables of response used were: superficial inspection of the cords, analysis of the geometry (width, penetration, reinforcement and dilution) and economic solder (melting rate, deposition rate, yield and operating cost). The results indicated that for surface analysis, using the AR25% CO2 gas to the surface of the strands were more homogeneous with respect to CO2 and less splash index for the analysis of economic characteristics, the process always GMAW-CW was superior to the conventional process, the operating costs the conventional process was lower, but without filling of the chamfer, which occurred with the use of GMAW-CW.
Acesso aberto (Open Access)
Estudo do comportamento dos aços ferramentas soldados em fadiga
(Universidade Federal do Pará, 2011-02-28) MONTEIRO, Alberto de Castro; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Knowing that fatigue is a gradual reduction of the carrying capacity of the component by slow and gradual breakdown of the material. And this defect arises from the infinitesimal advance of microcracks that form inside the material, imperceptible to the naked eye, it is also clear that the presence of alloying elements in steels, allows changes in metallurgy and mechanical properties of the material, applied to work. On the other hand, when he underwent processing of diverse, they all zones deform elastic, plastic, and after break up. Emphasizing the goal of this study, intended to address the welded joints, in stages that are subjected to high temperatures and cools without control, even at room temperature. In the end, are requested by cyclic alternating or constant. In particular, it is expected to detect structural changes deep in the Heat Affected Zone - ZTA, suffered because of overheating, both near the midpoint of the weld pool and in the region and located in the neighborhood. As we do not have enough parameters and necessary to control these changes, we propose to analyze the HAZ of the welded joint in order to evaluate the metallurgical behavior and its implications caused by gas-metal interactions. To analyze the effects of the triangle formed by the base material AISI / SAE 4340, SAE 1020 and chamfered V-coated electrode E-6013. Structure analysis will be performed by testing techniques using the metallographic optical microscopy - MO which is widely circulated in technical and scientific communications, through which, the transformations distinguish multiphasic. These transformations, distinguished by direct transformation of austenite to martensite without passing through the ferrite and pearlite. With these identities, metallography can characterize and predict the future responses of the structures by analyzing the requests, which may besubmitted. To analyze the fatigue behavior of materials in question, it is adopted as a parameter ancillary testing the Charpy pendulum. Therefore, the results obtained, we conclude that structures are compromised by tensions 05/05/2011 internal consequently weaken, but welding procedure can be adopted, followed annealing for stress relief, if not make cracks.