The dependence of the number of eutectic cell on the content of Ti and S coexisting in high purity grey cast iron was considered on the basis of the results obtained from investigating the influence of these two elements on the production of nucleating catalyst and the physico-chemical properties of eutectic melts both of which factors affect graphite nucleation during eutectic solidification.
  Of the various elements present in the eutectic melt formed during the eutectic solidification of cast iron containing Ti and S, it was considered that C, Si, Mn, P, Ti, S, N and O may participate in the formation of compounds probably acting as nucleating catalyst or, otherwise, may dissolve in the melt without forming compounds and influencing the physico-chemical properties of eutectic melts.
  It was considered from the related data available and thermodynamic calculations that Mn, P, Si, N and O have no influence on the change of nucleation with the change of content of Ti and S. It was also considered from the equilibrium concentration curves for crystallization of TiC and Ti₂S at eutectic solidification temperature, that C, Ti and S are related to the degree of nucleation in the forms of TiC, Ti₂S and dissolved S.
  The relation between the eutectic cell number and these components affecting nucleation of graphite in cast iron was considered as follows:
  The cell number decreases as the precipitation of TiC increases. This phenomenon seems to be due to the fact that the catalytic function in the nucleation of graphite of the some forms of carbon group decreases by forming TiC with Ti, and consequently, the degree of nucleation of graphite decreases.
  Regardless of the amount of precipitated Ti₂S, the cell number increases as the amount of dissolved S increases. This seems to be due to the fact that Ti₂S does not act as a nucleating catalyst, and both the catalytic ability of carbon group and the growth of graphite are disturbed by the surface active element, dissolved S, and increases the degree of nucleation as a result.

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  It is difficult to make heavy ferritic casting of, for example, 120mm thickness, in the as cast condition with the industrial grade spheroidal graphite cast iron usually produced.
Thick sections of ferritic casting can be produced with low manganese high purity iron in the as cast condition, But the mechanical properties in the thick section are inferior to the industrial one and show a discrepancy, because of the presence of chunky graphite.
  Casting of the same thikness with much better mechanical properties can be produced in the as cast condition if low manganese high purity iron with tellurium or bismuth addition is used because of the absence of chunky graphite and ferritic matrix.
  The relationship between mechanical properties and casting thickness is slso described in this paper.

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  It is metal penetration that especially disturbs shake out of large steel castings. One of the important factors which have an influence on metal penetration is wettability between molten steel and mould. In order to investigate influences of mould conditions on wettability in this experiment, we measured contact angles between molten steel and moulds by the sessile drop method. As contact angles obtained are influenced by roughness of mould surface and interaction between molten steel and mould, they are not true, but apparent contact angles. The results obtained were summarised as follows:
  (1) Contact angles between molten steel and cold-setting moulds of silica sand, zircon sand and chromite sand were 116°, 122° and 84°, respectively.
  (2) The contact angle increased by the addition of sand flower or by the use of finer sand.
  (3) The contact angle depended upon the kind of binders and additives. The contact angle increased when adding clay and Fe₂O₃, and decreased when adding waterglass. But furan phenolic resin did not influence contact angle.
  (4) Zircon wash increased the contact angle.

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  Shrinkage cavity is one of the greatest defects in spheroidal graphite cast iron. In order to find out the formation mechanism of the cavity, we must first quantitatively measure the volume change of molten spheroidal graphite cast iron. For this reason, the authors calculated in this experiment the volume change of this alloy by measuring its density at the molten state. Experiments have been made with hyper-eutectic composition, because this is the general kind of alloy, and calcium-silicide or Fe-Si-Mg alloy was added as spheroidal graphite reagent. The residual calcium content was 0.02 to 0.03% and the residual magnesium content was 0.06 to 0.08%. In general, the volume of molten alloy at temperature T_x is calculated by the following equation.
      [Written in non-displayable characters.]
  V_TX : calculated volume at T_x temperature.
  V_T0 : voume at eutectic temperature standard volume.
  Δ_V1 : volume change from eutectic temp. to liquidus line temp.
  Δ_V2 : volume change from liquidus line temp. to T_x.
  T_x : measured temperature.
  T₁ : liquidus line temperature.
  T₀ : eutectic temperature.
In our experiments with the calcium-silicide reagent, the values of dV₁⁄(dV₁) and dV₂⁄(dV₂) were as follows.
  [Written in non-displayable characters.]
  The most important experimental results are summarized as follows.
  1) Volume change of molten spheroidal graphite cast iron, to which calcium-silicide has been added as spheroidal graphite reagent, was 1.8%/100°C.
  2) Volume change of molten flaky graphite cast iron-with the same composition as the former-was 1.5%/100°C.

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  Quite a number of papers have been published classifying the types of temper carbon into spheroidal, compact and aggregated forms. But this classification is not satisfactory at all. In the first stage of graphitization of pure white cast iron given various conditions, the authors have obtained snow-flaky or star-like graphite and fine graphite, in addition to spheroidal, compact and aggregated graphites. By controlled solidification of white cast iron, spheroidal graphite can be obtained without any addition of spheroidizing elements. Snow-flaky graphite precipitates by the graphitization at higher temperature or by the addition of graphitizing elements. The formation of fine graphite is observed on those white cast iron which solidified rapidly or which were forged with high forging ratio after usual solidification. The authors suggest a new classification of five types of temper carbon by the present investigation. In addition, the nucleation and growth of temper carbon was directly observed under the high-temperature microscope.

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