As a result of an investigation carried out on the effects of copper content on the properties such as mechanical ones and corrosion resistance in die-casting alloy of No.12 type (Japanese Industrial Standard) the following results were found:
  (1) Tensile strength, 0.2% yield strength, and hardness increase proportionally with the copper content as it increases to 1.31%, 2.18%, 3.25%, and 4.13%.
  (2) Elongation and impact value decrease with the increase of copper content up to Cu 3.25%, but when copper content exceeds 3.25%, decreasing rate of elongation and impact value become small.
  (3) Anode potential (Saturated calomel potential) increased slightly in the order of samples D (Cu 4.13%), B (Cu 2.18%), C (Cu 3.25%) and A (Cu 1.31%).
  (4) Considering the alloy from the view point of application for die-casting, the range of copper content in the revised standard appears to be appropriate in general although tensile strength and hardness are somewhat different.

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  The temperature distribution of test piece of spheroidal and flake graphite Cast iron at solidification has been investigated.
  The obtained results were as follows.
  1) The solidification time of spheroidal graphite cast iron is longer than that of flake graphite cast iron at equal pouring temperature.
  2) The solidification shell of hypo-eutectic flake graphite cast iron develops along mold-wall. On the other hand, the inside shape of solidification shell is parabolic.
  3) The spheroidal graphite cast iron solidifies by mushy type, however flake graphite cast iron solidifies by mushy type plus skinformation type. Therfore massfeeding in flake graphite cast iron is easier than in spheroidal graphite cast iron.

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  The reason why oxygen contents in grey iron scatter greatly seems to be caused by adsorption of gases in atmosphere, therefore, the mechanism of adsorption was investigated in CO and H₂O+Ar atmospheres.
  The results obtained were summarized as follows:
  1) If grey iron was treated thoroughly by degassing hold in vacuum of 10^-5 mmHg at 900°C, oxygen contents turned to the values corresponding to those of white iron.
  2) Increase of oxygen content in grey iron with increase of holding time was deduced by adsorption of gas to graphite presented in matrix and diffusion of adsorbed gas into the graphite.
  3) Moisture in the air was adsorbed selectively in the early stage of adsorption.
  4) The reason that even in the same sample oxygen contents in the part of grey iron are higher than those of white iron part participates in the precipitation mechanism of graphite, the difference of directional growth of graphite crystal and thermal expansion, and micro gap between matrix and graphite.

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