Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 54, Issue 2
Displaying 1-7 of 7 articles from this issue
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RESEARCH REPORT
  • Evaluation method of surface texture by the surface colors of aluminum alloys
    Makiko YONEHARA, Koichiro KIHARA, Hiroaki ISONO, Akira KIJIMA, Toshio ...
    2004 Volume 54 Issue 2 Pages 45-50
    Published: 2004
    Released on J-STAGE: February 20, 2007
    DOIhttps://doi.org/10.2464/jilm.54.45
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    In this paper, we carried out an experimental research for establishing the evaluation of metal's surface texture by analysis of surface color. The materials of samples used in the experiment were aluminum alloys (A2017, A5052), stainless steel (SUS304) and copper alloy (nickel silver C7541). The surfaces of samples were burnished by use of waterproof abrasive papers. The surface roughness of samples evaluated by arithmetical mean Ra, root mean square slope RΔq and mean width of the profile elements RSm. The experimental results showed strong correlation for three different roughness parameters. Consequently, “Ra” was used as roughness parameter. As Ra decreased, the glossiness exponentially increased. The evaluation method of surface color was applied to CIELAB. The lightness L* in CIELAB decreased as Ra decreased. Thus, it showed that relationship between L* and Ra inverse correlation between glossiness and Ra. Moreover, surface color of four different materials showed that the chromaticness of blue increased as Ra decreased.
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  • Evaluation of serration using the fast Fourier transform method
    Masanobu FURUTA, Yoshihiro NAKAYAMA
    2004 Volume 54 Issue 2 Pages 51-56
    Published: 2004
    Released on J-STAGE: February 20, 2007
    DOIhttps://doi.org/10.2464/jilm.54.51
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    Fast Fourier Transform (FFT) method was applied in order to evaluate a repeated load drop (serration) observed in the load-time curves in the tensile test. 5083 aluminum alloy plates were tested in tension at temperatures between 203 K and 333 K using an Instron type tensile test machine. Changes in repeated load drops with the deformation temperature were characterized by a conventional method (mean amplitude ΔLm and number N of load drops) and FFT method (maximum amplitude Cmax and peak frequency fp derived from the Fourier spectrum). Cmax and fp were compared with ΔLm and N, respectively. The comparison showed the reasonable agreement between fp and N, as well as that of Cmax and ΔLm. In evaluation of the serration using FFT method, there was no artificial reading error and reliable analysis could be carried out in a short time. Therefore it suggests that FFT method is suitable for the investigation of the serration.
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  • Shearing of light metal sheets using hard-film-coated tools
    Ratchanee PAISARN, Kazunari HATO, Nobuhiro KOGA
    2004 Volume 54 Issue 2 Pages 57-61
    Published: 2004
    Released on J-STAGE: February 20, 2007
    DOIhttps://doi.org/10.2464/jilm.54.57
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    In shearing process, such as blanking or piercing on the sheets of both aluminum and magnesium alloys, there are problems that large burrs generate and the accuracy of cut surface is worse after a few repetitions of these processes. Therefore, in this study, we investigated the cause and solution of these problems. We found that the cause was not the deterioration of the tool edge due to wear or chipping, but that materials of the sheared sheets which adhered to the side of the tool shaved the cut surfaces of the sheets during shearing or adhered to the cut surfaces and induced partial plastic deformation. We also found that a hard-carbon-film-coated tool is effective in preventing the generation of adhesive materials, thereby preventing both the generation of large burrs and the decrease in the accuracy of cut surfaces.
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  • An electronic approach to the G.P. zone formation requirement in magnesium and aluminum light metals
    Moritaka HIDA, Kazuo TAKAO, Akira SAKAKIBARA, Yoshito TAKEMOTO
    2004 Volume 54 Issue 2 Pages 62-68
    Published: 2004
    Released on J-STAGE: February 20, 2007
    DOIhttps://doi.org/10.2464/jilm.54.62
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    The characteristics in electronic states were investigated by DV-Xα method, which could describe the cluster models for both solid solution (cluster model I) and for G.P. zone (cluster model II) of Mg/Al alloys, Mg–M (M; Al, Ag, Zn) alloys and Al–M (M; Mg, Ag, Zn) alloys. The bond order in the cluster model II for G.P. zone increased more than that in the cluster model I for solid solution in the specific alloy systems where the formation of G.P. zone was detected experimentally. Furthermore, the net charge in the cluster model I for solid solution indicated the significant different characteristics from that in the cluster model II for G.P. zone. By changing the bonding length of each cluster model, the local density of the states around the vicinity of Fermi energy varied high sensitively in FCC cluster models (I and II) of Al–Mg alloy, but not so much in HCP cluster models (I and II) of Mg-Al alloy. The energy gap between HOMO and LUMO was recognized from the consideration of the bond contraction of the cluster model II for G.P. zone, which suggesting the increment in electrical resistance because of the formation of G.P. zone.
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  • Relationship between stress corrosion resistance and microstructure of rapidly solidified Al–Zn–Mg alloys
    Hiroki ADACHI, Kozo OSAMURA, Jun KUSUI
    2004 Volume 54 Issue 2 Pages 69-74
    Published: 2004
    Released on J-STAGE: February 20, 2007
    DOIhttps://doi.org/10.2464/jilm.54.69
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    The stress corrosion cracking (SCC) resistance of hot-extruded P/M Al–Zn–Mg alloys, Mesoalite, was investigated as compared with that of I/M Al–Zn–Mg alloys and the correlation between stress corrosion resistance and microstracture was studied. SCC resistance about P/M alloys was high as compared with that of I/M alloys and when the solute concentration increased, reduction of SCC resistance about P/M alloys was not observed. The difference in width of PFZ, distribution of precipitates on grain boundary, the amount of metastable phase precipitated in the matrix, tilt angle of grain boundary, grain size and shape was investigated as a cause of the difference of SCC resistance. The large change in the size and shape of grain among these factors was observed. In the P/M alloys, the fiber-like grain elongated to the extruded direction was observed to the equi-axial grain having been observed in the I/M alloys. When stress was applied parallel to elongated grains, the stress perpendicular to the grain boundary was low. Since the SCC resistance is improved when the applied stress perpendicular to the grain boundary is small, it is concluded that the SCC resistance of the P/M alloys which has the fiber-like grain elongated to the ED became large.
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