Up to the present, the forged-steel crank-throw (so-called “crank-pin and webs”) has been used for semi built-up crank shaft for diesel engine. Recently, however, the castings has been taken the place of the forgings.
  Following up this tendency, the authors have made the study on the cast steel crank-throw which had been experimentally manufactured.
  The results obtained are summarized as follows : −
  1) The casting made by the flat method was free from both segregation and shrinkage hole at pin and moreover homogeneous throughout various parts.
  It seemed that the manufacturing cost would be reduced because the weight of castings was much less than that of forgings.
  2) The diffusion annealing and normalization following with tempering gave the better effects on the castings. Consequently the grain size was become extremely fine throughout the section of castings.
  3) In the case of the siutable condition of solidification, the surface of the castings showed considerably high toughness.
  4) The mechanical strength of the castings was uniform at both surface and interior of the castings. Also the castings showed high fatigue strength.
  5) The mechanical strength of the material was based on the M. A. N. specification as shown in Table 1.
    Table 1
[Written in non-displayable characters.].
  After heat treatment trial castings showed the mechanical properties showed in Table 2.
    Table 2
[Written in non-displayable characters.].

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  Several kinds of liquid pig iron were treated with CaCN₂ by amount of 0.5, 1.0, 1.5 and 2.0 pct. The results obtained are as follows : −
  1. Desulphurization of liquid pig iron increases with adding weight of CaCN₂ proportionally.
  2. The lower becomes C. E. value or carbon content of molten pig iron, the more increases desulphurization with equal weight of CaCN₂.
  3. When the initial sulphur content in molten pig iron is high, desulphurization by the same weight of CaCN₂ is great.
  4. With increase of additional CaCN₂, nitrogen content in molten pig iron increases. Proper addition of CaCN₂ improves the tensile strength and hardness of cast iron.
  Next, we discussed the limit of desulphurizing reactions between Fe-C-S or Fe-C-O-S system and solid calcium cyanamide. The reactions considered are as follows : −
    CaCN₂(s)+S=CaS(s)+C+N₂(g) · · · · · · · · · · (a)
    CaCN₂(s)+S+O=CaS(s)+CO(g)+N₂(g) · · · · (b)
  From the results of calculation about the equilibrium constant of these reactions, we can see as follows : −
  1. When there is the excess of solid CaCN₂, initial [S%] in molten pig iron does not affect on the limit of desulphurization.
  2. When other factors are constant, the limit of desulphurization lowers with the decrease of [C%].
  3. When other factors are constant, the limit of desulphurization lowers with the decrease of reaction temperature.
  4. When other factors are constant, the limit of desulphurization decreases as P_N2 becomes smaller.
  5. The limit of desulphurization of reaction (b) decreases with the increase of [0%]/Pco, when other factors are constant.

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  The author has announced the method of determining the surface area of molding sands of a unit weight (specific surface area) in the manuscript appeared in the IMONO. [26 (1954), 9, 472]
  This method consists of the use of ethylen glycol and a centrifuge, and by which it is possible to measure the surface area of molding sands independent of its packing rate.
  Accordingly, if the value of specific surface area of a certain kind of sand is put into the following formula which has heretofore been used generally, then the constant K in this relation may be expressed as a function of packing rate of the said sand.
              S_w²=K⁄F
      where    S_w : specific surface area    F : permeability    K : constant
  The relation between S_w and F is studied experimentally this time and the comparison is made between S_w and the apparent specific weight by using several kinds of molding sands.

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  This paper describes the observed structure of reaction products formed at high temperature on the interface of steel and sand mould and the relationship between this structure and the resulting sand adherence.
  A piece of polished steel and a sand mould, set in contact with each other, were subjected to rapid heating. The experiment was carried out under various conditions of heating atmosphere, temperature, kind of sand and its grain size. As a result three types of sand adherence mechanism could be distinguished.
  The relationship of the state of steel-sand interface to this mechanism can be summarized as follows.
  1) Type 1 is the case of slag infiltrating and adhering to the surface, following the wüstite (FeO) which has been developed on the grain boundary of steel surface before the melting of steel begins. This adherence, though firm, will not occur unless the slag barrier is extremely tenuous or it is slowly cooled. During cooling, in most cases, cracks develop on the interface, causing the barrier to peel off. As a matter of fact, no such adherence will be seen in steel castings.
  2) Type 2 is such adherence as observed when the slag barrier surrounded by the molten steel is subjected to contraction stress after melt-down and the strength of fusion or sintering is very large. Practically it is assumed that it takes place in the core and the re-entrants of products.
  3) Type 3 is what is called penetration. If Type 1 and 2 are chemical adherence, this may be called physical one. It is caused by the formation of discontinuous slag layers containing sand grains.
  The experiment shows that it can sometimes happen despite considerably severe conditions against penetration, i. e. heating under low pressure, large surface tension and contact angle, and a mere 4 cm metal head.
  This is due to an unexpectedly huge void formed by discontinuous layers, developing on the interface, of high-concentrated, high-melting slags of SiO₂ or ZrSiO₄ and the large grains of primary crystals grew in these slags. It will not occur when continuous slag layers are formed. To be good for prevention of penetratien, these layers must be thick if they have low melting point and small viscosity.
  They might be thin, however, if they have high-melting point and large viscosity.

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  In the combusion method of carbon analysis of cast iron, the sample is usually obtained by turning or drilling. In these cases, the size of the chips affects a great influence on the analytical value, because graphite particles in cast iron separate from chips and consequently small analytical value is often obtained. This tendency is the greater in the smaller size of chips, and also the greatest in the case of spheroidal graphite cast iron, next in malleable iron, and the least in flaky graphite cast iron.
  For obtaining, therefore, the most reliable value in the carbon analysis of cast iron, all chips turned or drilled must be used for each analysis.
  The change of carbon content in spheroidal graphite cast iron with the time after the addition of Mg into its melt is studied and discussed.

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