Being excited by Meehanite Metal, foundrymen in our country recently pay attention to the melting process in the use of much steel scrap by which a superior iron casting is obtained. In viewpoint of enabling this process to be easy by trying to melt iron at a higher temperature, authors investigated properties of cast iron under the various operational conditions by using the midget cupola of the internal diameter 200 mm.
  The results obtained are as follows:
  (1) Under the best operational condition, the specimen was carburized to 3.1∼3.2%C, and had the tensile strength 38 kg/mm², good fluidity, a fine structure and good resistance in pressure test.
  (2) For obtaining the above good properties it is necessary that the used ratio of steel scrap should be high and also the tapping temperature should be about 1500°C. When the used ratio of steel scrap is less than 50 per cent, cast iron is carburized too much and has not a good properties because of showing a bad effect of raw material.
  (3) In order to rize the tapping temperature above 1500°C, coke of good quality and the coke ratio 25∼30 per cent were used, and therefrom the volume of blast was increased. It will be suitable that the coke ratio of the large cupola is about 20 per cent.
  (4) Inoculation of calcium siliside is necessary for cast iron not to chill easily. The adequate addition is 0.35 per cent. It was accertained by the analysis of oxides that acceleration of graphitization of calcium siliside is due to deoxidation of molten iron.

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  By investigating the sand adhering phenomena on the foundry products and the laboratory specimens, the chief causes were analysed and therefrom the factors of its prevention were determined.
  “Burn-on”, the phenomenon which is generally called for “Hard adherence of sand or core”, in Japanese foundries can be cl ssif ed into two types; one is the adhesion of fused and sintered sand on the casting surface, and the other is caused by the penetration of metal into the mould surface. The adhesion phenomena mostly found in foundries belong to the latter type, which was chiefly investigated in this work.
  Macroscopic and microscopic examinations show that the slag formation between cast metal and the mould surface is an effective factor of preventing penetration, provided that the casting temperature, the solidifying time, the static pressure of metal, etc., are not extremely severe.
  The oxidation of the interface between the metal surface and the mould is violent, and the penetrated metals are much decarbonized. Some examples of selective oxidation of Mn and Fe are listed-up by analysing the slag layer.
  For the static pressure of molten metal, the result of the laboratory test and calculation show that the metal penetration is very remarkable when the blacking, slag formation and the back pressure do not exist.
  From the thermochemical point of veiw concerning the process of penetration, it is concluded that the fundamental natures of moulding sand, that is, the high purity, good refractoriness and the round shape are the most important factors of preventing penetration.
  In addition, required factors of preventing penetration in the foundry practice are summarized.

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  Following the last report we have studied the specific gravity, apparent specific gravity, porosity, permeability and green compressive strength of granules of mould sand, and have got the relations among these values, water and clay content reported in the last report. Results are shown in the figures in this report.

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  In this test, we used Feedex No. 3 (Foseco in England), which was made for the purpose to use in a steel casting. The sleeve used was made of 5% H₂O and Feedex. Its density was 1.34 gr per cc.
  The quantitive of Feedex was determined by applying Lazendorfer's calculation formulas, which is written in “An Exothermic Feeding Compound” in the Iron and Steel, June, 1952.
  According to the results of calculation, we were able to save the volume of the riser by 57∼74% by using Feedex-in other word, the recovery of products was improved to the extent 13∼24%.
  As the price of Feedex is very high, the casting weight needs to be comparatively large.
  We applied this heat insulator (Feedex) to the high manganese steel casting tyre and obtaimed the good result.

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