The graphitizatin of white cast iron takes place in solid solution, and Si-concentration in the solid solution plays an important rôle in the graphitization.
  Therefore, the variation of Si-concentration in solid solution due to graphitization of C-content in white cast iron gives a change to the rate of graphitization. Once graphite is precipitated, the solid solution in the vicinity of graphite becomes to be a stable-phase, and graphite in solid solution promotes the graphitization of the cementite.

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  In the low pressure diecasting process, such casting defects as misrun, shrinkage and cold shut are mostly attributed to the way in controlling the rate of pressure increase of the operating air.
  The present authors have recently developed an automatic device for the pressure control.
  Using water instead of molten metal in a low pressure casting machine equipped with this controling device, it was found :
  1) Sprashing and bubbling accur in the case of a too fast increment rate of pressure.
  2) The proper increment rate for mild flowing condition depends upon the area-ratio
(= Sectional area of stalk outlet⁄Surface area of molten in a crucible) and the shape of stalk outlet.
  3) Vent hole of die is one of the important factors to affect the flowing condition.

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  The present work is relating to the nature of oxidation in the liquid state of copper and copper-tin, copper-zinc and copper-lead alloys. The experiments include oxidising copper and these binary copper-base alloys in the liquid state, concentrating the oxides during centrifuging, extracting these oxides in the centrifuged castings, and electron-microsceopy and diffraction of the oxides. These procedures lead to the morphology of oxidation of copper and copper-base alloys in the liquid state. The behaviors of the oxides are also discussed.

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  The research was done to improve the impact properties of the black heart malleable cast iron by adding small amount of special element to it. In this report which is the second report of the series, the effects of addition of B, Al, Ni, Zn, Zr, Sn, Te and Bi were investigated.
  The results were summarized as follows. B, Al, Ni and Sn decrease the impact properties of the malleable cast iron, so the amounts of these additional elements should be low from this point of view. Very small amount of Te does not affeect the impact properties and Zn, Zr and Bi to certain amount improve the impact properties of this iron respectively. Especially the effect of Zr is the most remarkable which may promise the practical application.

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