Iron castings with cylindrical plate and spherical shapes were cast into metal molds. Some parameters to express average cooling rate and solidification time of castings and a parameter which shows temperature variation of molds were discussed. Graphite structure of cast iron was classified by cooling rate.
  Mold ratio (volume ratio of mold to casting) and metal mold ratio (thickness ratio in cross-section of mold to casting) were not good parameters to express cooling rate V_av. Ratio of (volume V_c/surface A_c)² of casting was good such as shown in the following equation;
      V_av=267.2 (V_c/A_c)^2×(0.90)
This relation is not affected by the shape of casings.
  For the solidification time, (volume/surface area)² ratio was also suitable as a parameter and the solidification time t_f is;
      t_f=1.43(V_c/A_c)??
where, (V_c/A_c)??=(V_c/A_c)²×Y. Y is corrected coefficient : for cylindrical castings Y=1.00, for plate castings Y=1.27, and for spherical castings Y=0.75.
  For temperature variation of molds, mold ratio was good as a parameter. Fine D-type graphIte will probably be obtained at the cooling rate between 12 to 23.5°C/sec.

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  The difference of strength between ferrous alloys (SS41, SCM3, S45C and SUH3) and cast irons (FC25 and FCD45) is the essential factor affecting the character and strength of bonded parts. As the difference of strength becomes larger, more dynamic superplastic flow is needed as far as the optimum bonding conditions are concerned. The present technique of dynamic superplastic solid-state bonding for same and/or different materials seems to embody possibilities for many applications such as partial reinforcement of engine-cylinder head or partial mending of cracks and/or casting defects.

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  Fluid molding sand which was based on special super high early strength cement and included surface active agents and additives was investigated in order to establish fluid molding process having rapid hardening property, little temperature dependence, good stability of mold and excellent collapsibility after casting of metal.
  Surface active agent composed of ester of higher alcohol and sulfonic acid gave good fluidity to fluid sand and improved apparent specific gravity of mold. Surface stabilizer mainly composed of condenstion of β-naphtharin sulfonic acid and formalin, is effective for development of strength and fluidity of sand. Addition of accelerator composed of inorganic oxide (Q agent) gave high initial strength and the effect of the other accelerator composed of calcium aluminate (W agent) was more remarkablees pecially in low temperatures.
  Recommenced proportionings of fluid sand made of special super high early strength cement, water, sand, surface stabilizer, surface active agent and accelerators are established according to molding temerature although they are often influenced by the mechanical characteristics of the mixer. The collapsibility of molded sand depends mainly on the volume density and cement content of fluid sand. Though metal can be poured in the mold without any artificial drying, if it is necessary, drying under low temperature (below 150°C) is suitable in order to avoid drying contraction.

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  The present investigation was carried out in order to obtain further information on the influence of nitrogen on the graphitization, chill depth and formation of nonmetallic inclusion in gray cast iron.
  Nitrogen retards graphitization during solidification and increases chill depth in gray cast iron. Addition of titanium increased nonmetallic inclusions such as TiN and TiC. No influence on the graphite and matrix structures were observed by the increase of any type of nonmetallic inclusions. Nonmetallic inclusions such as MnS, VN, TiN, Al₂O₃, CaO, TiC and AlN were observed with microscopic and EPMA analysis in gray cast iron melted by various type of furnaces such as cupola, low frequency induction furnace and Tammann resistance furnace.

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  A cast iron foundry shop is not a suitable environment for working because of dust and noise produced mainly by molding and shake-out machines. To seek a solution to these problems, a study was carried out to investigate molds using a water-soluble binder to make separation of silica sand from cast iron products easy in water.
  The silica sand mold with under 10percent barium chloride, under 1percent carbohydrate and a small amount of water, gave satisfactory results as a water-soluble mold. The compression strength of this mold rose to about 50kg/cm² and it collapsed promptly in water by the easy dissolution of the binder after dipping, Drying by microwave was most usefull for hardening this mold. When the water-soluble mold containing castings were dipped in water, silica sand separated immediately from castings. The water-soluble mold did not have a harmfull influence on the defect and quality of castings.

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  In order to clarify effects of mold washing on matal penetration, the resistance to metal penetration of cold-setting silica sand mold with various zircon washes has been investigated by means of the laboratory apparatus which is capable of simulating metal penetration, and the wash layer of penetrated sand mold has been observed.
  It is shown that zircon wash is unable to prevent metal penetration and little particular change is recognized even if the wash layer is thicker. The reason for these is that cracks are generated in the wash layer when it comes into contact with molten steel and that molten steel penetrates into sand mold through these cracks.

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