Navegando por Palavras-chave "Aluminium alloy"

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    High Strength AA7050 Al alloy processed by ECAP: Microstructure and mechanical properties
    (Elsevier B.V., 2011-07-15) Cardoso, K. R. [UNIFESP]; Travessa, D. N. [UNIFESP]; Botta, W. J.; Jorge, A. M.; Universidade Federal de São Paulo (UNIFESP); Univ Vale do Paraiba; Universidade Federal de São Carlos (UFSCar)
    Commercial AA7050 aluminium alloy in the solution heat-treated condition was processed by ECAP through routes A and B-C. Samples were processed in both room temperature and 150 degrees C, with 1, 3, and 6 passes. the resulting microstructure was evaluated by optical microscopy (OM) and transmission electron microscopy (TEM). Only one pass was possible at room temperature due to the low ductility of the alloy under this condition. in all cases, the microstructure was refined by the formation of deformation bands, with dislocation cells and subgrains inside these bands. the increase of the ECAP temperature led to the formation of more defined subgrain boundaries and intense precipitation of spherical-like particles, identified as eta' and eta phases. After the first pass, an increase in the hardness was observed, when compared with the initial condition. After 3 passes the hardness reached a maximum value, higher than the values typically observed for this alloy in the overaged condition. the samples processed by route B-C evolved to a more refined microstructure. ECAP also resulted in significant strength improvement, compared to the alloy in the commercial overaged condition. (C) 2011 Elsevier B.V. All rights reserved.
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    One-sided laser beam welding of autogenous T-joints for 6013-T4 aluminium alloy
    (Elsevier B.V., 2015-01-01) Oliveira, A. C.; Siqueira, R. H. M.; Riva, R.; Lima, M. S. F.; ITA; IEAv; Universidade Federal de São Paulo (UNIFESP)
    Autogenous T-joints for aluminium skin-stringer component performed by one-sided laser beam welding process was conducted using a high power Yb-fiber laser. the influence of the shielding gas, seam angle, beam focal position, and beam positioning relative to weld centerline were investigated regarding to weld microstructural features. the joint mechanical behavior was evaluated concerning to the sheet rolling directions. It was observed that a precise control of the process parameters enabled to obtain weld beads with acceptable dimensional and geometric characteristics and minimizing weld defects. Helium shielding gas produced higher aspect ratio welds than those with pure argon. Although, pores were observed in the fusion zone, they represented only about 5% of the weld bead area. the optimal beam positioning should remain up to 0.2 mm relative to junction line, for seam angles between 10 degrees and 15 degrees. the weld mechanical behavior depended on the sheet rolling direction. Joint efficiency up to 85% were obtained after hoop tensile tests when the weld bead longitudinal-section was perpendicular to skin rolling direction and parallel to the stringer rolling direction. (C) 2014 Elsevier B.V. All rights reserved.