Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 51, Issue 9
Displaying 1-6 of 6 articles from this issue
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RESEARCH REPORT
  • Practical use of hard-carbon-coated tools in deep drawing of AZ31 magnesium alloy sheets
    Nobuhiro KOGA, Ratchanee PAISARN
    2001 Volume 51 Issue 9 Pages 441-445
    Published: 2001
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.51.441
    JOURNAL FREE ACCESS
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    In order to solve the lubricant-related problem, which is considered to be the most serious problem in the deep drawing of the AZ31 magnesium alloy, we have proposed a method of using hard-carbon-coated tools. Furthermore, through oil-free deep-drawing experiments with the AZ31 magnesium alloy using these hard-carbon-coated tools, we also demonstrated that the use of these tools is extremely effective in improving the formability and preventing flaws of the products. The purpose of this study is to verify the practical applicability of our method. We carried out a continuous deep drawing experiment with an AZ31 magnesium alloy sheet using hard-carbon (WC/C)-coated tools and an inexpensive solid-film prelubricant, the degreasing process of which is relatively easy compared to that of other lubricants. The results indicate that our deep drawing method enables the processing of products with high precision in a stable manner. The practical applicability of our method is demonstrated.
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  • Effect of pre-sintered structure on sintering rate in the final stage of HIP process for pure titanium
    Takashi OKI, Kazuhiro MATSUGI, Tomei HATAYAMA, Osamu YANAGISAWA
    2001 Volume 51 Issue 9 Pages 446-451
    Published: 2001
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.51.446
    JOURNAL FREE ACCESS
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    The sintering rate in the final stage during HIP has been investigated by measurement of relative density of compacts which were preliminary sintered in vacuum. The activation energy of the final stage HIP-sintering rate Qh of 218 kJ/mol and the stress exponent nh of 4.5 are obtained for the pure titanium compact with an equiaxed structure and Qh of 213 kJ/mol and nh of 4.7 are obtained for that with a non-equiaxed structure. These values are approximately equal to the creep parameters, Qc and nc, obtained from creep experiments. The sintering rate of the pure titanium with the equiaxed structure is larger than that with the non-equiaxed structure under the same condition of temperature and pressure in the HIP process, which is influenced by the structure of compacts pre-sintered in vacuum. This is mainly due to the variation of A value in the equation of power-law creep influenced by the microstructure. The control of presintered structure is important for the followed HIP process.
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  • Shearing and shaving of AZ31 magnesium alloy sheets
    Nobuhiro KOGA, Kazunari HATO, Ratchanee PAISARN
    2001 Volume 51 Issue 9 Pages 452-456
    Published: 2001
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.51.452
    JOURNAL FREE ACCESS
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    Attention has recently been focused on press forming, such as deep drawing and forging of AZ31 magnesium alloy sheets. In press forming, blanking, which yields blanks of desired shapes from a plate, and shearing, such as trimming and piercing of a formed shape, are indispensable. This study investigates the properties of shearing under cold and warm processing of AZ31 magnesium alloy sheets, which have not been studied so far, and the possibility of fine shearing by shaving using the same samples. The shearing mechanisms of AZ31 magnesium alloy sheets and the influence of tool clearance and heating temperature of samples on the precision of the sectional surface are elucidated. Furthermore, results of this study clarity that shaving is effective as a method of fine shearing of AZ31 magnesium alloy sheets and demonstrate that a high-precision sectional surface is efficiently obtained when piled shaving, in which blanking and shaving are performed within one stroke of the press, is used.
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  • Effect of anodized coating on fretting fatigue characteristic of 6063 aluminum alloy
    Tomohisa NISHIDA, Junnosuke MIZUTANI, Yoshiharu MUTOH, Masatsugu MAEJI ...
    2001 Volume 51 Issue 9 Pages 457-463
    Published: 2001
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.51.457
    JOURNAL FREE ACCESS
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    Wear, scratch, plain fatigue and fretting fatigue tests were carried out using aluminum alloy JIS 6063–T5 specimens with anodic film and lubricating anodic film. Though the surface hardness of lubricating anodic film was lower than that of anodic film, lubricating anodic film had excellent wear resistance and crack resistance compared to anodic film. Plain fatigue strength of the specimen with anodic film was lower than that of the specimen with lubricating anodic film, which almost coincided with that of the specimen without film. Fretting fatigue strength of the specimen with lubricating anodic film was higher than that of the specimen with anodic film, which was higher than that of the specimen without film. The lubricating anodic film had the lowest coefficient of friction and a higher cracking resistance, which contributed to the late crack initiation and the low crack growth rates. The anodic film also had low coefficient of friction compared to the specimen without film and prevented metal-contact, which may result in higher fretting fatigue strength compared to the specimen without film. The lubricating anodic film is of significant benefit to fretting fatigue strength without degradation of plain fatigue strength.
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