The present research was made to see the influence of the super-heating of the molten cast iron on its properties. After 13 charges of the preliminary research melting, 28 charges were melted in one ton basic electric furnace, using cast iron turnings as the principal raw material. The total carbon content of iron varied from 2.6 to 3.6% by the adddition of steel scrap and electrode carbon, and silicon content was fixed between 1.6 and 1.8% using ferro-silicon.
  The first slag in good consistency by the addition of lime and spar produced in the melt down period was skimmed from the furnace and the second carbide slag was made by charging 30kgs of lime, 5kgs of spar, and 5kgs of coke. The temperature of the bath was measured directly, insertnig the Pt-PtRh thermocouple or by an optical pyrometer when the temperature of the bath exceeds 1600°. The test pieces were cast at constant casting temperature viz 1350° into dry sand mould from a small hand ladle into which a sufficient amount of molten iron was poured from the furnace at the melt down stage before the skimming of the first slag and at 1450°, 1550°, 1600° and 1650° in the refining period.
  The tensile strength, the bending strength, the amount of bending and the Brinell hardness were measured on these specimens and finally their microstructures were observed. The results obtained are as the following.
  1) those irons containing an amount of total carbon between 2.8 % and 3.2 % have highest strength, and medium toughness, 2) a suprer-heating of iron to 1500° is necessary and sufficient to gain highest gaulity of iron. 3) the size of graphite flakes become larger as the carbon content increases, it becomes finer with the degree of super-heating 4) the dendritic structure becomes apparent with the degree of super-heating. 5) the so-called “Kikume structure” which designates the curved graphite flakes in medium size can be easily obtained with the above composition and the degree of super-heating.
  Further researches are required to get firm conclusion on the superiority of the two slags method and of the basic furnace instead of acid furnace.

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  The main difficulty of oil sands is that although it is very strong after drying, it is very weak subsequent to drying. Substances whose addition will help to increae the strength are clay, bentonite, flour, water, etc. Addition of water to oil-sand bonded with linseed oil is especially effective. Green bond is also somewhat increased by the addition of flour. Clay and bentonite will increase the green bond but its addition has a drawback of causing weakness after drying.

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