Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 62, Issue 7
Displaying 1-4 of 4 articles from this issue
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RESEARCH ARTICLE
  • Effect of shot peening on mechanical and fatigue properties of AZ31 magnesium alloy processed by multi-axial alternative forging
    Masafumi Noda, Yuki Ichihara, Kunio Funami
    Article type: RESEARCH ARTICLE
    2012 Volume 62 Issue 7 Pages 265-271
    Published: July 30, 2012
    Released on J-STAGE: August 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.265
    JOURNAL FREE ACCESS
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    To improve the fatigue properties of AZ31 magnesium alloys, two technical approaches were used to reform the material structure. The first approach is grain refinement of the material structure by multi-axial alternative forging (MAF) to reduce anisotropy and to improve the strength. The second approach created an inclined recrystallized surface layer by shot peening to retard crack initiation on the surface layer and the propagation rate in the tissue layer of the fine-grained structure. The relationship between the microstructures and fatigue properties was examined. As a result, by combining MAF and heat treatment the endurance limit increased by 15%. Moreover, shot peening at medium temperatures formed a recrystallized submicrometer grain size microstructure in the surface layer and an inclined structure to a depth of over 100 μm below the surface, and the fatigue properties increased by about 30%. From measurement of the crack propagation rate, it was found that the improvement in fatigue properties led to the delay in crack initiation in the fine-grained surface layer and decreased the crack propagation rate in the residual strained layer.
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  • Effect of Cu addition on mechanical properties of Mg–Gd–Zn–Zr casting alloy
    Tomomichi Ozaki, Yasunori Kuroki, Hiroyuki Hoshikawa, Kentaro Yamada, ...
    Article type: RESEARCH ARTICLE
    2012 Volume 62 Issue 7 Pages 272-277
    Published: July 30, 2012
    Released on J-STAGE: August 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.272
    JOURNAL FREE ACCESS
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    Mg–Gd–Zn–Cu–Zr cast alloys were developed for high strength casting products. Effects of Cu addition on microstructures and tensile properties of these alloys were investigated. Depending on Cu content different compound phases existed at grain boundaries in cast sample after solution treatment. In low Cu content alloys, these phases were identified as mainly Mg5Gd with minor amount of LPSO phase. In other alloys, the LPSO phase forms principally along with Mg12(Cu,Zn)Gd. The type of its phase was 14H-type structure in all fabricated alloys. In addition, age-hardening occurred around 473 K after solution treatment. T6-treated alloys including the LPSO phase predominantly exhibited excellent ductility and work hardening. Mg–3.2Gd–1.0Cu–0.5Zn–0.2Zr (mol%) alloy, in which volume fraction of the LPSO phase was about 45%, indicating ultimate tensile strength of 370 MPa and elongation to failure of 10%. On the other hand, low Cu content alloys with few LPSO phase showed lower tensile strength due to scarce elongation regardless of remarkable age-hardness. Eventually, the LPSO phase increased ductility and tensile strength.
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  • Fabrication of ADC12 porous aluminum with graded porosities and pore structures
    Takao Utsunomiya, Kazuya Takahashi, Hiroki Kato, Yoshihiko Hangai, Soi ...
    Article type: RESEARCH ARTICLE
    2012 Volume 62 Issue 7 Pages 278-284
    Published: July 30, 2012
    Released on J-STAGE: August 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.278
    JOURNAL FREE ACCESS
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    Porous aluminum has received much attention in various industrial fields due to their high energy absorptivity together with their superior lightweight. In this study, using aluminum alloy die casting ADC12, the porous aluminum changing the pore structures in one individual was tried to fabricate by FSP (Friction Stir Processing) route precursor method. At first, the effects of the contained gases and the amount of added blowing agent on the porosities and pore structures of ADC12 porous aluminum with uniform pore structure were examined. On the basis of the results, the fabrication possibilities of two types of ADC12 porous aluminums changing the pore structures were discussed. One of the porous aluminums has two different porosities and average diameters of pores and the other has two different porosities with almost same average diameter of pores. It was shown that the two types of ADC12 porous aluminums with graded porosities and pore structures were practically fabricated by using the FSP route precursor method, through the observations of pore structures by X-ray computed tomography of the fabricated porous aluminums.
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