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Filho D.F.,Grande Rio University | Ferraresi V.A.,Federal University of Uberlgndia | Scotti A.,Federal University of Uberlgndia
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2010

Ferritic stainless steels are not characterized by good weldability. Wires made of austenitic stainless steels are usually applied to join ferritic materials because of the good mechanical resistance, tenacity, and ductility reached by austenitic weld metal. However, novel ferritic stainless steel wires, stabilized with niobium and titanium, have been developed to tackle the target of matching the required mechanical properties and keeping the costs lower by using ferritic stainless steels. The characterization of these wires concerning weldability aspects (operational and metallurgical) has not been accomplished yet. The aim of the present study was to investigate the influence of the shielding gas composition (pure argon and mixtures with O2 or CO 2) on the chemical composition and microstructure of weld deposits obtained with gas metal arc welding using stabilized ferritic wires (ER430Ti and ER430LNb). The study was made comparatively to a non-stabilized wire (ER430). For each combination gas/wire, three layers of beads were deposited. To prevent interference from base metal dilution, a UNS 43932 was used as support for the layers and only the last layer was analysed. A special experimental approach was applied to permit more reliable comparison among different combinations of wire-shielding gas. Predicted equations for the demanded level of stabilizers in the wire were successfully applied. The results showed that the shielding gas composition played an important role in determining the final chemical composition and microstructure of the deposits, but its effect was dependent on the chemical composition of the deposit as a rule. In general, it was confirmed that the increase in CO2 in the shielding gas augmented the carbon content (and martensite formation) in the weld metal, but wire stabilized with niobium could prevent this detrimental effect but was not able to arrest grain coarsening. There were always losses of alloying elements due to the presence of O2/CO2, but the intensity depended on the amount of titanium/niobium. © 2010 Authors.

Almeida M.C.,Federal University of Itajuba | Ferreira J.R.,Federal University of Itajuba | Luis N.E.,Federal University of Uberlgndia | MacHado A.R.,Federal University of Uberlgndia | And 2 more authors.
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture | Year: 2010

Free machining steel, because of its high levels of sulfur, manganese, and lead, is known for its good machinability. These three residual elements, which act to guarantee easy chip formation, are not, however, acting alone to influence this steel's good machinability. It is their influence, certainly, that is best understood, but researchers have yet to adequately understand the influence of three other residual elements, chrome (Cr), nickel (Ni), and copper (Cu). The present study aimed to determine some measure of the impact of these elements on machinability. In particular their influence on the machinability of AISI 12L14 steel was investigated. Employing the design of experiment (DOE) technique, the tool life was measured for nine batches of steel, each containing, within the tolerable amount, different levels of chrome, nickel, and copper. By analysing the results with statistical tools, it was found that levels of their presence do indeed influence the machinability of AISI 12L14 steel. Therefore, even within the variability allowed by the standards, steel-makers should manage the levels of these residual elements. © 2010 Authors.

Resende N.M.,State University of Rio de Janeiro | Resende N.M.,Federal University of Uberlgndia | De Magalhaes Neto A.M.,State University of Rio de Janeiro | De Magalhaes Neto A.M.,Federal University of Uberlgndia | And 8 more authors.
OMICS A Journal of Integrative Biology | Year: 2011

Physical exercise affects hematological equilibrium and metabolism. This study evaluated the biochemical and hematological responses of a male world-class athlete in sailing who is ranked among the top athletes on the official ISAF ranking list of windsurfing, class RS:X. The results describe the metabolic adaptations of this athlete in response to exercise in two training situations: the first when the athlete was using the usual training and dietary protocol, and the second following training and nutritional interventions based on a careful analysis of his diet and metabolic changes measured in a simulated competition. The intervention protocol for this study consisted of a 3-month facility-based program using neuromuscular training (NT), aerobic training (AT), and nutritional changes to promote anabolism and correct micronutrient malnutrition. Nutritional and training intervention produced an increase in the plasma availability of branched-chain amino acids (BCAAs), aromatic amino acids (AAAs), alanine, glutamate, and glutamine during exercise. Both training and nutritional interventions reduced ammonemia, uricemia, and uremia. In addition, we are able to correct a significant drop in potassium levels during races by correct supplementation. Due to the uniqueness of this experiment, these results may not apply to other windsurfers, but we nonetheless had the opportunity to characterize the metabolic adaptations of this athlete. We also proposed the importance of in-field metabolic analyses to the understanding, support, and training of world-class elite athletes. © 2011 Mary Ann Liebert, Inc.

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