Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 66, Issue 2
Displaying 1-8 of 8 articles from this issue
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TECHNICAL REPORT
REVIEW
RESEARCH ARTICLE
  • Synchronized monitoring between hydrogen gas release and progress of atmospheric hydrogen embrittlement in 7075 aluminum alloy
    Keitaro Horikawa, Shunsuke Hokazono, Hidetoshi Kobayashi
    Article type: RESEARCH ARTICLE
    2016 Volume 66 Issue 2 Pages 77-83
    Published: February 28, 2016
    Released on J-STAGE: March 30, 2016
    DOIhttps://doi.org/10.2464/jilm.66.77
    JOURNAL FREE ACCESS
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    A testing apparatus, which can simultaneously monitor the hydrogen gas release and the progress of fracture, was newly developed in order to clarify the behavior of hydrogen atoms on hydrogen embrittlement in aluminum alloys. This apparatus is composed of a tensile testing machine equipped with two mass spectrometers and a high-speed microscope placed in an ultrahigh vacuum (UHV) chamber. By using this apparatus, we have succeeded in detecting hydrogen (deuterium) gas evolution dynamically during grain boundary fracture in a 7075 aluminum alloy indicating hydrogen embrittlement. Concentration of hydrogen atoms at the grain boundary associated with hydrogen embrittlement was estimated to be more than 3.0×10−7 mol/m2. It was also clarified that deuterium atoms introduced from the testing atmosphere were released not only at the moment of fracture but also at the plastic deformation.
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  • Evaluation of hydrogen release routes on the microstructure of 6061 aluminum alloy surface by means of repetition in hydrogen microprint technique
    Keitaro Horikawa, Yuka Takahashi, Hidetoshi Kobayashi
    Article type: RESEARCH ARTICLE
    2016 Volume 66 Issue 2 Pages 84-89
    Published: February 28, 2016
    Released on J-STAGE: March 30, 2016
    DOIhttps://doi.org/10.2464/jilm.66.84
    JOURNAL FREE ACCESS
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    Hydrogen microprint technique (HMT) was repeatedly applied to Al–Mg–Si base alloys without and with containing iron as an impurity element. A special jig was made to perform the repeated HMT, which can keep a constant loading using one specimen. By using this testing jig, we could verify the hydrogen emission behavior in the same microstructure of the Al–Mg–Si base alloys during deformation. It was shown that hydrogen atoms were released at grain boundaries in the early stage of the plastic deformation. When the applied strain was then increased, hydrogen atoms were released at the periphery of iron based intermetallic inclusions. Based on this, it was believed that hydrogen-trapping force by the inclusions was higher than that by grain boundary during deformation.
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  • Effect of high strain rate deformation on hydrogen desorption behavior of 6061 and 7075 aluminum alloys
    Keitaro Horikawa, Tomo Ogura, Yui Miyakawa, Go Endo, Makoto Takahashi, ...
    Article type: RESEARCH ARTICLE
    2016 Volume 66 Issue 2 Pages 90-95
    Published: February 28, 2016
    Released on J-STAGE: March 30, 2016
    DOIhttps://doi.org/10.2464/jilm.66.90
    JOURNAL FREE ACCESS
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    Hydrogen desorption behavior in 6061 and 7075 aluminum alloys was studied by means of thermal desorption analysis using a semiconductor hydrogen sensor in the gas chromatograph. Effect of high strain rate deformation (105 s−1) on the hydrogen trapping state in the alloys was examined in particular. It was found that hydrogen atoms were released at lower temperatures when both alloys were plastically deformed. The tendency was more obvious in the 6061 alloys deformed with a high strain rate. In comparison with the previous reports, the difference of the hydrogen desorption behavior in the case between high speed and low speed deformation would be related to the difference of the hydrogen trapping effects by the different type of lattice defects.
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