Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 53, Issue 7
Displaying 1-6 of 6 articles from this issue
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RESEARCH REPORT
  • Deformation behavior of aluminum alloy sheets in biaxial in-plane tensile stressing
    Motohiro YOSHIMIZU, Toshihiko KUWABARA, Toshio SUGIBAYASHI, Hiroaki IS ...
    2003 Volume 53 Issue 7 Pages 284-289
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.284
    JOURNAL FREE ACCESS
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    A biaxial tensile testing was conducted using cruciform specimens made of an aluminum alloy sheet of the 6000 series, and the testing was successfully kept up to a large deformation in its plastic region. Then, the work hardening exponent n* (n* value) in the central region of the specimens under in-plane biaxial stress was calculated using the strain and the measured value of the load from the device equipped for the testing. Thus, the biaxial tensile testing with cruciform specimens has an advantage over the biaxial testing with a semi-spherical rigid punch, such as the load value can be measured correctly without being affected by bending or friction. Yet, it is very difficult to make the cruciform specimens that make it possible to measure a large strain in plastic region, and there are few reports on the studies about the biaxial stretch forming area using cruciform specimens. In this study, how to make the cruciform specimens which enable the measurement of a large strain, and how to calculate the n* value is explained. Also, the deformation behavior of aluminum alloy sheets of the 6000 series in biaxial stretch forming was attempted to be researched by the experiment on the three stages of strain ratio using the cruciform specimens and two types of devices: a hydraulic type stress control machine and a mechanical type strain control machine.
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  • Semisolid continuous casting of 6070 and 7075 aluminum alloys using an inclined cooling plate
    Fumi TANABE, Tetsuichi MOTEGI, Eiji SUGIURA
    2003 Volume 53 Issue 7 Pages 290-294
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.290
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    Semisolid casting is the most advanced technology for obtaining granular grains in aluminum-alloy cast structures. The conventional semisolid slurry is produced by electromagnetic or mechanical stirring. Both apparatuses that perform these tasks are large and costly. We developed a simple semisolid casting process for 6070 and 7075 aluminum alJoys using an inclined cooling plate. In this process, numerous granular aluminum crystals are nucleated on the inclined cooling plate while flowing downward. The semisolid slurry was held isothermally in the heat-isolating tundish and the granular grains grew inside. The semisolid slurry was then cast into a horizontal continuous casting machine. The resulting billet was 60 mm in diameter and 600 mm in length. For the 6070 aluminum alloy, the casting speed was 3 mm/s. The finest grain size of 56 μm was obtained by casting at 656°C, and by using the inclined cooling plate of 60° and 200 mm.
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  • Continuous observation of tensile deformation of polycrystalline pure titanium by scanning probe microscope
    Yan LI, Takeji ABE, Naoya TADA, Masanori KANAZAWA
    2003 Volume 53 Issue 7 Pages 295-301
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.295
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    Change in the surface plastic deformation of polycrystalline titanium with grain size of about 180 μm is consecutively observed and measured by a scanning probe microscope. It is shown that the surface deformation is mainly due to slip for the plastic strain less than 0.1. After that, a large amount of twins are formed and the secondary slip system becomes active, and accordingly the surface roughness increases. Then, the deformation proceeds with both the slip and the twin in a harmonious way. The surface roughness, the maximum height difference and the averaged slope angle of the microscopic surface profile increase with increase in applied tensile strain. The angle between the slip lines and the loading axis decreases a little with increase in applied strain. It is pointed out that by the use of a scanning probe microscope, the relation between the development of slips or twins in grains and the surface roughness can be clarified in nano-scale.
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  • Grain refinement and stretch forming of AZ31 magnesium alloy sheets
    Hisashi NISHIMURA, Osamu HASEGAWA, Norihisa KOISO, Koji MATSUMOTO
    2003 Volume 53 Issue 7 Pages 302-308
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.302
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    The grain refinement of AZ31 magnesium alloy sheet was attempted by giving various plastic deformation to improve press formability. As a result, no grain refinement was attained in uniaxial and biaxial tension deformation, but the remarkable refinement was achieved in shear and compression. The effect of the grain refinement on the bulging formability was examined. Although the forged sheet with fine grain could not be bulged at temperatures between room temperature and 150°C, it could be bulged at above 200°C. Compared to the as-rolled sheet with coarse grains, the forged sheet could be formed at 100°C lower temperature to get the same bulge height.
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