Journal of Japan Foundry Engineering Society
Online ISSN : 2185-5374
Print ISSN : 1342-0429
ISSN-L : 1342-0429
Volume 85, Issue 7
Displaying 1-9 of 9 articles from this issue
Research Articles
  • Daisuke Shimosaka, Shota Koshikawa, Yohei Harada, Shinji Kumai
    2013 Volume 85 Issue 7 Pages 407-413
    Published: July 25, 2013
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS

      The morphology of eutectic Si particles in Al-11%Si-2.5%Cu alloy was changed by heat treatment and rapid solidification in the aim to study the influence of the morphology of eutectic Si particles on bendability. Eutectic Si particles were plate-like in the as-cast condition of permanent mold cast specimens. The rounding of the plate edges was observed by short heat treatment (500℃-0h). The morphology of the eutectic Si particles became rod-like and globular with increasing heat treatment time. On the other hand, in a twin-roll cast product, the eutectic Si particles were rod-like in the as-cast condition. The aspect ratio of eutectic Si particles in twin-roll cast product was almost the same as that obtained by heat treatment time of 0.5h, and the average eutectic Si particle diameter in twin-roll cast product was the smallest in all specimens. As a result of bending tests, the permanent mold cast specimen (as-cast) was fractured at a bending angle of 45°. On the other hand, heat treated and twin-roll cast specimens were bent to a bending angle of 180°. Broken eutectic Si particles were observed near the bending surface, and cracks in the broken eutectic Si particles were most perpendicular to the bending direction. The size distribution of broken eutectic Si particles was also investigated. When the chill layer was chosen as the bending surface, specimens fractured only at the bending angle of 80°. This is considered due to the dense distribution of fine eutectic Si particles and difficulty of deforming the matrix by the Cu solution.

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  • Toshitake Kanno, Ilgoo Kang
    2013 Volume 85 Issue 7 Pages 414-419
    Published: July 25, 2013
    Released on J-STAGE: April 03, 2017
    JOURNAL FREE ACCESS

      We investigated in detail the effects of Mn and S on the mechanical properties of flake graphite cast iron, specifically ; hardness, tensile strength, elongation, impact value, deflection, and transverse load. We also investigated the causes. With increasing Mn amount for a constant S content, a transition point appears for each mechanical property. That is, hardness, tensile strength, and transverse load become the smallest, and elongation, impact value, and deflection become the largest. The mechanical properties of flake graphite are determined by the intervention of four actions ; MnS nucleation action, interfacial energy action of soluble S, action of soluble S and soluble Mn to eutectic solidification temperature, and pearlitization action of soluble S and soluble Mn. These four actions are thought to be negated by the formation of MnS, resulting in the presence of the transition points. In addition, Mn and S amounts showing transition points demonstrate the best type A graphite shape.

      With increasing Mn amount for various S contents, many transition points appear. When these points are connected, a new transition point appears near S0.03% and Mn0.32%. Excellent mechanical properties are seen at this new transition point. That is, hardness and tensile strength become the highest, and elongation and impact value which conflict with these properties also become the highest. At this new transition point (0.03%, 0.32%Mn), MnS just starts to form ([S] × [Mn] = 0.01), and soluble S is the highest. Here, [S] means soluble S and [Mn] soluble Mn.

      Consequently, in flake graphite cast iron, the best properties are obtained at S0.03% and Mn0.32%, which is just before MnS formation.

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