It is clear that cupola control may be operated in some of the fundamental conditions based on blast volume and pressure, but fundamental knowledge indicating relationships between the combustion conditions and some of the important metallurgical reactions is required.
  The author operated the acid-lined cupola to continue the standard melting for cast iron by addition of steel scrap or all steel scrap for a considerable time to investigate the relative relations of operating conditions.
  In this paper, he reports the details of the operation of chromium cast iron melting based on the results obtained from steel scrap melting by cupola.
  The results of this experiment are summarized as follows :
  It is possible to melt the high chromium cast iron (10∼25%Cr) by the use of cupola alone when the operation is performed under the reasonable and theoretical control to govern the combustion condition which is obtained from the experimental data.
  At 1450°∼1550°C, the behaviour of chromium under the condition of cupola operation may differ from that of steel making conditon, and when the temperature is low, the better migration of chromium from molten iron takes place, and at a higher temperature this is decreased.
  Influences of temperature and FeO content of the slag for migration of chromium are clear, and as the FeO content is lower the temperature change will be more effective.
  By the addition of chromium to molten pig iron, it's carbon content will be increased, but if low carbon content iron is desired, the oxygen blowing method in the ladle may be effective for decarburization the iron without much loss of chromium.

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  The process of the formation of undercooled graphite in cast iron has recently been discussed again by many investigators as Morrogh and Williams¹⁾ Berman²⁾, Shaw and Kondic³⁾, Hultgren's group⁴⁾ and Scheil⁵⁾. The argument is that whether the undercooled graphite is a decomposition product of ledeburite or it solidifies directly from the melt.
  The present paper dealt with the problem on the line and is composed of five experiments, that is, (a) an investigation of a solidification mechanism of Fe-C-Bi alloy, (b) chill test of commercial charcoal pig iron by additions silicon, (c) sand cast test of the pig iron with a little addition of bismuth, (d) graphitization of Fe-C-Si alloy just under the eutectic temperature, and (e) heating ledeburite successively to its formation from the melt.
(a) : Flake graphite structure in Fe-C alloy converted into undercooled graphite and inverse-chilled structure with increased bismuth. Thermal analysis and interrupted quenching was applied and it was to be noted that the formation of undercooled graphite was followed by the ledeburite formation.
(b) : Fracture of cast iron containing a certain amount of silicon had a dusky layer adjacent to chilled white zone, the constitution of which was coarse undercooled graphite with small amount of ledeburite. This was ascertained to be the graphitization product of columner ledeburite by interrupted quenching.
(c) : Fractures of sand cast specimens containing a small amount of bismuth revealed undercooled graphite both in outer and in central parts, but it seemed to be developed in a different way. Near the surface, ledeburites crystallized first and fine undercooled graphite deposited between them from the melt while the former decomposed to graphite which was quite similar to the latter. In the inner parts, fine undercooled graphite deposited from the melt with spherical crystallization fronts.
(d) : White iron was graphitized completely in a time comparable to that of the eutectic reaction on solidification when it had rather high silicon as more than 0.6% and heated just below the eutectic temperature.
(e) : When solidifying Fe-C-Te or Bi alloy was heated at the eutectic temperature immediately after ledeburite was formed, there appeared coarse undercooled lump, quasi-flaky and/or Widmannstätten graphite accompanying with residual acicular cementite.
  It was concluded from the results mentioned above that the undercooled graphite generally solidified directly from the melt prior to ledeburite formation. But when the iron contained some graphitizing elements such as silicon, similar graphite could appear as a decomposite product of ledeburite. Strictly speaking, these were different and could be distinguished each other, but in some cases they had quite a resemblance which might make a confusion.

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  Two test bars with six steps were prepared from cupola melt. They were common gray cast iron having normal flaky graphite structure. After fracture test, microstructure examination and hardness measurement were carried out, it was confirmed that mass effect of S-H cast iron is far less than that of common gray cast iron for structure and hardness.

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  Segregation in castings is very complicated and the method of its determination by chemical analysis is almost inappropriate because of the sampling difficulties. The authors established the local spectrographic analysis method to meet the difficulties of sampling, and by means of this method, they carried out the experiment on the determination of segregation of silicon, manganese and magnesium in cast iron.
  The results obtained by the experiment have already announced in Repts. 1 and 2. Succeeding to the previously carried out experiment, the segregation in copper alloy castings was determined this time. Newly developed C. R. L. type universal source unit for local spectrographic analysis was used in this experiment. By means of this unit, good results have also been obtained for copper alloy castings.
  The determination was made on three different systems of alloys such as Cu-Sn, Cu-Ni and Cu-Pb.
  In the rapid-cooled Cu-Sn alloy castings, inverse segregation appeared at the outer and inner layers and normal segregation in the intermediate layer.
  Among these, inverse segregation at the outer layer would not appear gradually when the cooling rate was not fast enough and in this case, normal segregation appeared over the outer to intermediate layers. In cases of Cu-Ni and Cu-Pb systems, normal and inverse segregations were appeared in the outer and inner layers respectively.
  However, normal segregation was seen in the extremely inner layer in case of Cu-Pb alloy castings.
  The experimental results and the detailed theoretical considerations on the phenomena shall be stated in this report.

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  An equation of the combined permeability of facing and backing sands is introduced and as its application, the relationship between permeability and surface roughness of castings was studied.
  Main conclusions obtained were as follows :
  1) The combined permeability of molding sands is calculated by the following equation
            [Written in non-displayable characters.].
      where H is height of each layer, K is permeability.
  2) The above equation can be applied extensively to values of the permeability with a good accuracy.
  3) The surface roughness of castings takes a minimum to a value of the combined permeability, which is changed by the mold surface or sand grain size, that is, with finer surface roughness of the mold the value declines to lower permeability. (Fig. 3) Therefore, in order to obtain fine surface roughness of castings, the combined permeability of facing and backing sands should be controlled properly according to mold surface roughness or sand grain size.

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