Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 64, Issue 7
Displaying 1-3 of 3 articles from this issue
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RESEARCH ARTICLE
  • Effect of heat treatment conditions on the elongation of 1200 aluminum sheets
    Mineo Asano, Takuro Nakamura, Hideo Yoshida
    Article type: RESEARCH ARTICLE
    2014 Volume 64 Issue 7 Pages 279-284
    Published: July 30, 2014
    Released on J-STAGE: August 30, 2014
    DOIhttps://doi.org/10.2464/jilm.64.279
    JOURNAL FREE ACCESS
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    It has been reported that the elongation of the 1050-H26 sheet annealed at 200°C is lower than that of the 1050-H18 sheet. In this study, the effect of the annealing time at 250°C on the elongation of 1200 aluminum sheets was investigated, and the cause of the low elongation was discussed by observing the change in the microstructures before and after tensile deformation. The elongation of the samples annealed at 250°C for less than 50 min was below 1%, and this elongation was lower than the elongation of the as-rolled and the annealed ones at 250°C for more than 150 min. In the samples annealed for a short time, the subgrains with a diameter of about 0.5–2 µm formed, and Fe and Si, which were a solid solution, became segregated at the sub-boundaries. These samples were locally deformed in a stress concentrated area during the deformation, and there was no significant increase in the dislocation density near the fracture part after the deformation. The cause of the low elongation was considered to be due to the dynamic recovery that locally occurred in a stress concentrated area during the deformation, because dislocations introduced into the subgrains by the deformation easily moved to the sub-boundaries due to the low solute levels within the subgrains.
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  • Effect of precipitation of impurities during annealing on the rate of recovery and recrystallization in 1050 aluminum hot-rolled sheets
    Hideo Yoshida, Yoshimasa Ookubo
    Article type: RESEARCH ARTICLE
    2014 Volume 64 Issue 7 Pages 285-291
    Published: July 30, 2014
    Released on J-STAGE: August 30, 2014
    DOIhttps://doi.org/10.2464/jilm.64.285
    JOURNAL FREE ACCESS
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    It is well known that the recovery and recrystallization of pure aluminum are influenced by the dissolved impurities, iron and silicon. In this study, we assumed that the dissolved impurities precipitate on the cell boundaries and subgrain ones during annealing and control the rate of recovery and recrystallization in the pure aluminum and adopted a new rate equation developed by Yamamoto, which contains the term of particle number that exponentially changes. It was found that the entire reaction was divided into two reactions, i.e., the recovery process and recrystallization one analyzed by this equation. The entire reaction was expressed by superimposing the two processes. In the recovery process, the value of the time exponent is 0.5, which means the control of the dislocation pipe diffusion, by which impurities precipitate on the dislocation cell boundaries. For the recrystallization process, the value of the time exponent is 1, which means the control of the grain boundary diffusion, by which impurities precipitate on the subgrain boundaries. Therefore, our assumption was verified by this new equation. From the activation energy, we consider that the precipitation of silicon during the recovery process and that of iron during the recrystallization one control the reaction rate.
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