Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 57, Issue 2
Displaying 1-7 of 7 articles from this issue
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RESEARCH REPORT
  • Magnetic pressure seam welding for aluminum and various metal foils
    Makoto MIYAZAKI, Keigo OKAGAWA, Tomokatsu AIZAWA, Masaki KUMAGAI
    2007 Volume 57 Issue 2 Pages 47-51
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.47
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    This paper deals with a new foil welding method and its experimental results. When an impulse current from a capacitor bank passes through a flat one-turn coil, a magnetic flux is suddenly generated in the coil. Eddy currents are induced in two insulated metal plates and overlapped foils (for example, aluminum and copper) between the plates in the coil. These foils could be welded both by the magnetic pressure applied onto them and by Joule heat generated in them. The bank energy required for welding of 20 mm in length was less than 2 kJ.
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  • Texture control of commercial pure aluminum sheets by cross rolling with an idle roll
    Shinobu KANEKO, Kouki MORI, Hiroshi UTSUNOMIYA, Tetsuo SAKAI, Norio FU ...
    2007 Volume 57 Issue 2 Pages 52-56
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.52
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    Recently, the authors proposed a continuous spreading method for thin strips by cross rolling. This method employs a flat platen and an idle tapered roll moving over the material width. So the continuous widening of strip width could be virtually realized by repetition of material feeding in the longitudinal direction and reducing thickness between a platen and a roll. It is also aimed to control textures or lower the anisotropy of sheets by changing strain path during deformation. A commercial pure aluminum sheets were used to investigate the mechanical properties, microstructures and textures of the materials fabricated by the above method. The influence of three different angles of tapered rolls on texture evolution was especially focused. As a result, the rotation of orientations from the as-received texture is enhanced by smaller roll taper angle and higher reduction in the rolling textures of the as-rolled sheets. Conversely, the asymmetry of the texture around TD-axis particularly evolves in the case of higher reduction and larger taper angle of roll. In the recrystallization textures, Cube orientation strongly dominates in the cases of larger taper angle. The rolling conditions are optimized to obtain the sheet with smaller planar anisotropy.
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  • Microstructures and corrosion resistance of surface layers formed on fluoride-treated magnesium alloys
    Atsushi YAMAMOTO, Hidekazu INAOKA, Harushige TSUBAKINO
    2007 Volume 57 Issue 2 Pages 57-61
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.57
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    A fluoride-treatment has been applied to various magnesium alloys, such as 3N-Mg, AZ31, AZ61, AZ91E and Ca-added AM60 alloys. The specimens of the alloys are dipped into molten NaBF4 at 673 to 723 K for 0.3 to 86.4 ks. Surfaces of the specimens were successfully coated with surface layer by the treatment. Diffraction measurement in the synchrotron radiation facility SPring-8, BL-24XU (Hyogo prefecture beam line) showed that the surface layer was composed of NaMgF3 and MgF2 phases. The surface fluoride layer exhibits a superior corrosion resistance even in an immersion test using a 1% HNO3 solution, filiform-like corrosion was suppressed for 1 to 3 ks in the solution depending on the alloy. Aluminum contents in the substrate alloys would affect the corrosion resistance by changing the microstructures in the fluoride layer.
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  • Performance evaluation of extrusion die surface modified by electro-spark deposition
    Norio TAKATSUJI, Kenji MATSUKI, Tetsuo AIDA, Kazuo MUROTANI, Ryuji MAS ...
    2007 Volume 57 Issue 2 Pages 62-66
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.62
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    The electro-spark deposition (ESD) processing method is a kind of the electric discharge machining method. It is a method of generating not the processing on a liquid inside but the spark discharge in the atmosphere, and stiffening and coating the surface of the metallic substrate with the deposition of the electrode material. In this research, the surface modification on the extrusion die bearing by the ESD processing method is tried, and the performance is evaluated. In addition, it is investigated the correlation between the abrasion of the electrical discharge coating layer and the surface properties of hot-extruded 5056 high strength aluminum alloy. As a result, it has been understood that the ESD processing of the super-hard alloy whose WC, TiC, and Co are principal ingredients is effective in the extension at the tool life and the prevention of the tearing (crack) of the extrusion material.
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  • Refinement of recrystallized grains of AZ31 magnesium alloy sheets by asymmetric rolling
    Yusuke NAKAURA, Akira WATANABE, Koichi OHORI
    2007 Volume 57 Issue 2 Pages 67-73
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.67
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    For the purpose of grain refinement of AZ31 magnesium alloy sheets, influences of asymmetric rolling conditions such as the roll temperature and the mismatch speed ratio on microstructures and texture were examined, and compared with those of conventional rolling sheet. Grain size of the annealed sheets processed at a roll temperature of 80°C and the rolled sheets processed at a roll temperature of 250°C decreases with increasing mismatch speed ratio. And at a mismatch speed ratio of 1.5, the grain size of 4.2 and 2.4 μm are obtained in the former and the latter, respectively. There is not an obvious difference in textures between the conventionally rolled and the asymmetrically rolled sheets. Proof stresses on the sheets annealed after rolling at 80°C and on the sheets rolled at 250°C increased with decreasing the grain size. Hall-Petch plot for both the sheets showed a good linearity expressed with σ0.2%95+0.20d−1/2. The grain refinement by asymmetric rolling at a roll temperature of 250°C seems to result from the promotion of a continuous recrystallization by a simultaneous action of two deformation mode, namely compression and additional shear deformation.
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  • Hydrogen embrittlement properties of notched-aluminum alloy plates in humid air
    Shuhei OSAKI, Jun IKEDA, Katsuyuki KINOSHITA, Koji ICHITANI, Yoshio TA ...
    2007 Volume 57 Issue 2 Pages 74-79
    Published: 2007
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.74
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    For 6061-T6 and 7075-T6 aluminum alloy plates, SSRT (slow strain-rate technique) tests in humid air with 90% relative humidity were carried out using a notched tensile specimen to evaluate the susceptibility to hydrogen embrittlement and to appreciate the role of notch in the process of HEAC (hydrogen-environment-assisted cracking). 7075-T6 showed a significant embrittlement due to intergranular cracking more inspired by the existence of notch, while in contrast, 6061-T6 exhibited a trend of an enhanced plastic deformation by hydrogen effects, accompanied with a trace of nonconventional TTS facet in fracture surface and an increase in notch opening displacement in the early stage of still low stress level. The SSRT behaviors of these alloys are explained to result from the mechanism of hydrogen-enhanced localized plasticity, where the process of hydrogen population is supported to include both effects of trapping at microstructural defects such as inclusions and stress-induced diffusion at macroscopic defects such as notch.
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