Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 61, Issue 6
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
  • Relationship between the generation of deformation band and the preceding inhomogeneous deformation in tensile deformed 5083-O aluminum alloy sheet
    Yoshihiro Nakayama, Masahiro Maeda
    Article type: Research Report
    2011 Volume 61 Issue 6 Pages 240-245
    Published: June 30, 2011
    Released on J-STAGE: July 30, 2011
    DOIhttps://doi.org/10.2464/jilm.61.240
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    5083-O aluminum alloy sheet was subjected to tensile deformation at 318 K to investigate the state of deformation-band generation in terms of the generation position, generation order, etc. In the previous report, it was shown that the edge of the latter deformation band overlapped partially with that of the former deformation band. Furthermore, the tendency of the deformation bands to form successively in the same direction was suggested. In this study, a more detailed examination on the generation state of deformation bands was conducted. The results of this study are as follows. A slight stress variation in the stress-time curve was observed just before the onset of the deformation-band generation. The strain measurement conducted using strain gauges established that this stress fluctuation was related to the propagation of the inhomogeneous deformation region. The first deformation band was generated in front of the inhomogeneous deformation region and the subsequent deformation bands were successively generated in the same direction. Since the magnitude of strain increase and strain velocity related to the propagation of the inhomogeneous deformation region increased with time, it was suggested that the deformation scale of inhomogeneous deformation became large toward the onset of the deformation-band generation.
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  • Effect of surface modification on characteristics in Ti–10 mass%Cr–(0, 3, 6) mass%Al alloys for medical applications
    Takahiro Kinoshita, Shouta Hatanaka, Rui Kawano, Masato Ueda, Masahiko ...
    Article type: Research Report
    2011 Volume 61 Issue 6 Pages 246-249
    Published: June 30, 2011
    Released on J-STAGE: July 30, 2011
    DOIhttps://doi.org/10.2464/jilm.61.246
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    Two types of surface modifications such as chemical-hydrothermal and NaOH heat treatments were carried out in Ti–10Cr–0, 3 and 6 Al alloys. The effect of heat treatment accompanied by the modifications on several properties of substrates was also investigated. The Ti alloys were chemically treated with H2O2/HNO3 solutions at 353 K for 2 h. The specimens were then hydrothermally treated with an aqueous Ca(OH)2 in an autoclave at 453 K for 12 h. Homogeneous CaTiO3 films could be obtained on all substrates. On the other hand, TiO2 and Na2TiO3 composite films could be obtained by the NaOH heat treatment. After the chemical-hydrothermal treatment, the hardness of substrates was hardly changed though a small amount of isothermal ω was confirmed to form in Ti–10Cr–0 and 3 Al alloys. In contrast, all the present alloys were hardened due to α phase precipitation after the NaOH treatment. A small amount of hydroxyapatite precipitation could be observed on the non-surface modified substrates after 4 days immersion in simulated body fluid. In contrast, the precipitation was confirmed to occur in only 2 days on the CaTiO3 films. Thus, the combined chemical-hydrothermal treatment promoted the deposition of hydroxyapatite on the surfaces while maintaining the original properties of substrates.
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  • Nanoindentation measurement of interfacial reaction layers in 6000 series aluminum alloys and steel dissimilar metal joints with alloying elements
    Tomo Ogura, Keisuke Ueda, Yuichi Saito, Akio Hirose
    Article type: Research Report
    2011 Volume 61 Issue 6 Pages 250-254
    Published: June 30, 2011
    Released on J-STAGE: July 30, 2011
    DOIhttps://doi.org/10.2464/jilm.61.250
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    Nanoindentation measurements were successfully applied to the interfacial reaction layers in dissimilar metal joints of 6000 series aluminum alloys containing alloying elements to steel in order to characterize their mechanical properties. The nanoindentation hardness of the reaction layer formed at the aluminum side was lower than that formed at the low carbon steel (SPCE) side of the investigated joints. At the aluminum side, the nanoindentation hardness changed by the addition of alloying elements. The hardness of the resulting Al12Fe3Si intermetallic compound (IMC) (and the same IMC containing Cu) was lower than that of Al3Fe. In comparison with the hardness values obtained from bulk Al–Fe binary series IMCs, it is considered that hardness changes of interfacial reaction layers are derived from the crystal structural changes produced by the alloying elements. The result of micro-testing of Al–Fe series IMCs indicates that the modification of the interfacial reaction layer by alloying elements contributes to higher ductility and the improvement of joint strength through crystal structural change.
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  • Experimental observation of elasto-plasticity behavior of type 5000 and 6000 aluminum alloy sheets
    Shohei Tamura, Satoshi Sumikawa, Takeshi Uemori, Hiroshi Hamasaki, Fus ...
    Article type: Research Report
    2011 Volume 61 Issue 6 Pages 255-261
    Published: June 30, 2011
    Released on J-STAGE: July 30, 2011
    DOIhttps://doi.org/10.2464/jilm.61.255
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    Elasto-plasticity behavior of type A5052-O and AA6016-T4 aluminum alloy sheets was examined by performing several experiments of uniaxial tension, biaxial stretching and in-plane cyclic tension–compression. Both sheets exhibit apparent r-value planar anisotropy, especially for AA6016-T4 it is extremely strong, while their flow stress directionality under uniaxial tension is not so significant. Both the sheets show strong cyclic hardening with weak Bauschinger effect. Such material behavior is well described by Yoshida–Uemori kinematic hardening model combined with an appropriate choice of anisotropic yield function.
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  • Effect of cooling rates during solidification of Al–5.5%Mg–2.3%Si–0.6%Mn and Al–13%Mg2Si pseudo-binary alloys on their secondary-particle morphology and tear toughness
    Daisuke Shimosaka, Shinji Kumai, Federico Casarotto, Shuichiro Watanab ...
    Article type: Research Report
    2011 Volume 61 Issue 6 Pages 262-268
    Published: June 30, 2011
    Released on J-STAGE: July 30, 2011
    DOIhttps://doi.org/10.2464/jilm.61.262
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    Al–5.5%Mg–2.3%Si–0.6%Mn alloy and Al–13%Mg2Si pseudo-binary alloy were cooled at various cooling rates during solidification. Morphological change of secondary particle was examined. Solidified structure of Al–5.5%Mg–2.3%Si–0.6%Mn alloy consisted of primary α–Al dendrites, Al–Mg2Si eutectic structure and Al6Mn particles. The most significant morphological change was from lamella Al–Mg2Si eutectic structure in the permanent mold cast and the die-cast product to refined and globular Mg2Si phase in the high-speed twin-roll cast product. In contrast, no morphological change was observed for Al6Mn particles. In order to investigate the effect of morphological change of Mg2Si phase on tear toughness, tear toughness tests were performed for Al–13%Mg2Si pseudo-binary alloy cast products produced by permanent mold casting and high-speed twin-roll casting. Unit crack propagation energy (UEp) of the high-speed twin-roll cast products was 5 times higher than that of permanent mold cast products. For permanent mold cast specimens, crack propagation occurred along the interface of plate-like Mg2Si/matrix of the eutectic solidified region and in Al-matrix. But fracture surface of high-speed twin-roll cast specimens was covered with fine dimples. Such difference of fracture mode is due to morphological change of Mg2Si phase from plate-like to globular by rapid cooling.
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