It is important to analyse the behavior of metal penetration into the sand mould and to prevent the adherence of sand especially in steel castings.
  The Behaviors of metal penetration into sand moulds were investigated by means of a flexible laboratory apparatus capable of simulating the practical conditions of temperature, pressure and chemical reactions between metal and mould. In this report, the comparison of the resistance to penetration into the typical sand moulds for large steel castings was described. The following results were obtained :
  (1) It was recognized that the resistance to metal penetration could be determined by evaluating “penetrating pressure” and the observation of penetrated mould specimens after the test.
  (2) Though the resistance to penetration was the highest in the lin-seed oil sand mould, there was still a possibility of heavy penetration in larger steel castings.
  (3) In the dried mould, the resistance to penetration was medium and there may be less anxiety of deep penetration.
  (4) Though the resistance to penetration was low in the CO₂ mould, it could be considerably improved by the addition of a reagent to glassify such as ferric oxide to the mould.

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  When iron and steel parts are case hardened by induction or flame, the surface layers of the parts are heated and cooled very rapidly. In this report, the author made an attempt to explain the effects of main alloying elements on the phenomena of rapid heating and cooling in cast iron.
  Inoculated irons, which contained various amounts of silicon, manganese and phosphorus, were used in the following experiments. Small cast iron specimens, 3×3×15 mm of dimensions, were dipped into the thermal bath which was held at various quenching temperatures, and were quenched into the water. The hardness of the quenched pieces were measured in Rc scale, and hardness variation curves effected by the temperatures of the lead bath and the dipping period were obtained.
  Summing up the results of the experiments, it can be noted as follows.
  (1) Specimens containing high silicon have rather longer in cubation periods in austenizing.
  (2) Low silicon irons have a tendency of retaining austenite when they are quenched at high temperature.
  (3) High manganese specimens quenched at high temperature have a large amount of residual austenite in the hardened structure.
  (4) Phosphorus slightly raises the transformation point of the matrix of cast iron.
  (5) High hardness is easily obtained by the quenching of spheroidal graphite cast iron, but cares should be taken in the hardening of the spheroidal graphite cast iron containing high silicon content.
  (6) Cupola melted grey cast iron having low strength as FC 14 can also reach to a high hardness, but high strength cupola melted iron such as FC 27 have a tendency of retaining austenite by over-heating and quenching, because of it's low silicon content.
  (7) The results of the thermal bath quenching experiments seemed to be related to the characteristics of the induction hardening of cast iron.

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  The mechanism of the formation of eutectic cells have been reported in the early experiment⁽¹⁾ of A. Boyels who found the existence of the cells, and it was also investigated by Fujita,⁽³⁾ and Ikawa⁽⁴⁾. The present authors made quenching tests during the solidification of Fe-Calloys, and the following results were obtained.
  (1) Eutectic cells nucleated successively during the eutectic reaction. And they did not glow over a certain size. Therefore the solidification was proceeded by the nucleation of the new cells and the conbination of them.
  (2) In the hypo-eutectic alloy, the location of nucleation of cells existed in the interface between the primary austenite and eutectic liquid or in its neighborhood.
  (3) The glowth of graphite flakes depended on remarkably on the distribution of the primary austenite in the hypo-eutectic alloy.
  (4) There was no difference in their mechanism of the cell formation in Fe-C, Fe-C-S and Fe-C-P alloys.

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  Stream of molten metal changes its direction by 90° at sprue base where it becomes confused and the flow velocity is lowered. The shape of the sprue base is, therefore, desired to be such that the stream smoothly changes its direction with little resistance. It has been tried, in this study, to obtain a proper shape of sprue base by means of hydrodynamically analyzing the flow resistance of various sprue bases. Suitabilities of the shapes of sprue bases were evaluated by comparing the velocity coefficient or the loss coefficient due to bend calculated from the following equations :
      v=C√2gh ········(1)
    C=velocity coefficient, v=flowing velocity, h=metal head
      C=1/√(1+K)  or  C=1/√{1+K+λ(1/d)}····(2)
    K=loss coefficient due to bend, λ=coefficient of fluid friction,
    l=length of stream, d=diameter of stream
  Experimental Procedures : CO₂ moulds with a fixed metal head (h=205mm) were made of which the sprue bases were variously altered. Metal was poured into the mould, the weight of metal flowed out and the flowing time were measured, thus the flowing velocity v was obtained by the following equation :
      v=W/a·ρ·t ········(3)
  a=sectional area of outlet of sprue base, ρ=density of metal
  Thus obtained values of v were inserted into the equation (1) and the values of C or K were calculated from the equation (1) or (2)
  Metal used for the experiment was ordinary commercial grey cast iron of which density ρ was assumed to be 7.0g/cm³. Pouring temperatures were adjusted to 1,380-1,400°C.
  Experimental Results :
  (1) When metal is poured into mould cavity through the gate directly from the sprue, a rounded inside corner of the connecting area of sprue and gate is extremely effective. Deep bottom of the sprue base also gives a favourable effect.
  (2) When a runner is connected to the sprue, it is effective to decrease the flowing velocity of the metal just entering the runner by widening the sectional area of the runner. To choke the gate or half way of the runner is also effective. Rounded inside corner of the connecting area also gives more favourable effect in this case, however, even when the inside corner is not rounded the unfavourable effects are somewhat relieved.
  (3) When the length of runner increases, the friction of runner decreases the loss due to the sprue base of no rounded inside corner, while in the case of rounded corner, the loss due to bend and the loss due to the friction of runner occur independently.

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