Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 65, Issue 10
Displaying 1-5 of 5 articles from this issue
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RESEARCH ARTICLE
  • Microstructures and mechanical properties of friction welded joint using a 5052 aluminum alloy small diameter rod
    Yuki Asano, Mitsuteru Nomoto, Masakatsu Maeda, Kazuyoshi Katoh
    Article type: RESEARCH ARTICLE
    2015 Volume 65 Issue 10 Pages 485-491
    Published: October 30, 2015
    Released on J-STAGE: November 30, 2015
    DOIhttps://doi.org/10.2464/jilm.65.485
    JOURNAL FREE ACCESS
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    5052-H34 aluminum alloy with 5 mm in diameter was friction welded using a conventional automatic friction welder. The effect of welding conditions on microstructures and mechanical properties of friction welded joints were investigated. Total loss of welded joints increases with increasing both the rotational speed and friction time. In addition, the total loss was negligibly low when the welding condition was N=6000 rpm and t1=1 s.Macrostructures of welded joints showed symmetrical structure with respect to the weld interface and the rotational axis. A layer with fine-grained microstructure was formed at the weld interface. The layer grew thicker by increasing both rotational speed and friction time. Heat affected zone was formed around the fine-grained layer. It tends to increase with increase of both the rotational speed and friction time. The softened area of the joints reached to about 8 mm from the weld interface. In addition, weld interface was cured under conditions of N=6000 rpm and t1=1 s.The highest tensile strength of thin diameter joints was 209 MPa, which was obtained under the condition of N=6000 rpm and t1=3 s. Its joint efficiency reaches 80% of the base metal.
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  • Hot tearing in direct chill casting ingot of 7000 series aluminum alloys
    Nobuhito Sakaguchi
    Article type: RESEARCH ARTICLE
    2015 Volume 65 Issue 10 Pages 492-497
    Published: October 30, 2015
    Released on J-STAGE: November 30, 2015
    DOIhttps://doi.org/10.2464/jilm.65.492
    JOURNAL FREE ACCESS
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    The initiation mechanism of hot tearing in direct chill casting ingot of 7000 series aluminum alloy was investigated. In 7000 series aluminum alloys, the temperature range between solidus (463°C) and 583°C was classified into brittle range on mechanical properties and deformation behaviors in semi solid state. The brittle range of 7000 series aluminum alloys was larger than that of other general aluminum alloys. In 7000 series aluminum alloy, the healing of the crack which initiated from shrinkage cavity was difficult to occur especially in the center of the direct chill casting ingot which was the last solidification part. Therefore, it was considered that the hot tearing in direct chill casting ingot of 7000 series aluminum alloys was easy to initiate the crack in the center of the ingot.
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  • Enhanced age hardening in an Al–Mg–Si alloy using high-speed compression
    Keitaro Horikawa, Yuki Kitani, Tomo Ogura, Akio Hirose, Makoto Takahas ...
    Article type: RESEARCH ARTICLE
    2015 Volume 65 Issue 10 Pages 498-502
    Published: October 30, 2015
    Released on J-STAGE: November 30, 2015
    DOIhttps://doi.org/10.2464/jilm.65.498
    JOURNAL FREE ACCESS
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    The age hardening of an Al–Mg–Si alloy was examined by the effect of high-speed (105 s−1) compression prior to aging. The enhancement of the age hardening is brought about by the formation of vacancy clusters during high-speed compression. High resolution transmission electron microscopy reveals that these vacancy clusters form stacking fault tetrahedra. Following peak aging, vacancy clusters and aging precipitates coexist in the grain interior. The high aging hardness obtained following high-speed compression is most probably due to the combined effects of vacancy and precipitation hardening.
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