Journal of Japan Foundry Engineering Society
Online ISSN : 2185-5374
Print ISSN : 1342-0429
ISSN-L : 1342-0429
Volume 88, Issue 4
Displaying 1-5 of 5 articles from this issue
Research Article
  • Mayuki Morinaka, Michihiro Toyoda
    2016 Volume 88 Issue 4 Pages 185-191
    Published: April 25, 2016
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS

      Hypereutectic Al-Si alloy is an industrially important alloy because of its excellent wear resistance. However, since the molten metal temperature of this alloy at the time of casting is high, there are problems such as gas absorption and oxide formation. Therefore, in this study, attempts were made to cast the alloy by reducing the amount of P in the Al-17%Si alloy extremely to as small as 25ppm, together with lowering the molten metal temperature to 720℃. As a result, the primary Si phase was found to be refined. The reason for this can be explained by the solidification sequence of AlP and primary Si phase. In addition, the formation and growth of the primary Si phase, α-Al phase, and eutectic cell are discussed from the viewpoint of constitutional undercooling and heterogeneous nucleation.

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  • Sadatoshi Koroyasu
    2016 Volume 88 Issue 4 Pages 192-197
    Published: April 25, 2016
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS

      The effect of the coat permeability on the melt velocity of molten aluminum alloy in the expendable pattern casting (EPC) process was investigated experimentally. For eight kinds of coats, the linear relationship between the inter-coat differential pressure and the airflow rate was obtained. Coat permeabilities conforming to JIS were determined from the gradient of the linear relationship. Using the eight kinds of coats, aluminum alloy plates were cast by the EPC process for three kinds of expansion ratios of expendable polystyrene (EPS) pattern, in the case of bottom pouring and without reduced pressure. The arrival time of the molten metal was measured and the melt velocity was obtained. The use of high expansion ratios of EPS pattern or high permeability coats led to higher melt velocities. In the high coat permeability region, the melt velocity did not increase so much, even when the coat permeability increased. The effects of the pouring temperature and casting thickness on the melt velocity were also examined. The application of high pouring temperature or large casting thickness, led to higher melt velocity. The experimental values of the melt velocity were compared with the calculated values based on the mold filling model used in the previous study. The experimental values were in relatively good agreement with the calculated values, except for when the coat permeability was high and the casting thickness was small.

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