A statistical investigation was carried out to clarify the relations among the various factors influencing the conditions of cupola operation.
  In this experiment a water cooled hot blast cupola was operated in basic condition and specially selected steels with uniform contents were charged. The operating conditions were maintained unchanged during the operation.
  The data on various factors were obtained continuously extending over 2 hours during an operation.
  From the results of the process analysis, several influencing factors were found to be the height of coke bed, CO₂ content in top gas and the tapping speed and temperature as the information factors, and to be the temperature of hot blast as the controlling factor.

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    The mechanical properties of black heart malleable cast iron are superior to those of grey cast iron. The former has, however, the disadvantage that it needs a long annealing time at high temperatures. To shorten the annealing time various additions of alloy elements have been studied so as to promote graphitization. Among them addition of silicon alloys is most common.
    On the other hand, it is known that nitrogen present in molten iron has a tendency to retard the graphitization, resulting in decreasing the number of graphite nodules and increasing their size. To reduce such retarding effect of nitrogen addition of titanium to molten metal has been investigated. For this purpose the authors employed titanium-silicon alloys as a denitriding element. The chemical composition of the alloys was :
    Alloy      Ti%      Si%      Fe%      Al%      C%
      A           6.8       69.6      17.1       5.0
      B         20.48     66.0        9.4       3.28      0.23
White cast iron used for the experiments was made by melting electrolytic iron, electrode graphite and metallic silicon. It was cast into sand mold and metallic mold, and the addition of titanium-silicon alloy to molten metal was made just before casting. The specimens were annealed in high vacuum. The graphitization of primary cementite was shown as an expansion curve by means of a displacement measurement apparatus.
    The results thus obtained were :
  1) Both alloy A and B promoted graphitization extensively, the effect of alloy B being more significant than that of alloy A.
  2) The form, distribution and size of graphite nodules were changed by the addition of Ti-Si alloy. The graphite nodules looked like broken snowflakes.
  3) The time length of graphitization was remarkably reduced by adding Ti-Si alloy.
  4) The amount of expansion caused due to graphitization depended upon both form of graphite nodules and microporosity produced by the graphitization.

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  The effect of feldspar on the interfacial reaction between mold and liquid steel of 0.2% carbon was studied by varying the content of feldspar in silica sand bonded with sodium silicate, bentonite or fireclay. The mold sand was made by mixing pure silica sand with alkali feldspar both of which had a similar grain size. Tbe products caused due to mold reaction were examined by using a polarizing microscope, metallographic microscope, electron prove microanalyser and X-ray diffractometer. The results obtained were:
  1) As shown in Fig. 1, mold-metal interfacial reaction was retarded by the addition of feldspar. The same tendency was found with increasing the size of sand grains.
  2) In the case of pure silica sand mold the reactant products consisted of fayalite, cristobalite and eutectic of a fine structure. The eutectic consisted of Fe-Si-Na-O compounds when sodium silicate was used as a bonding material, while it consisted of Fe-Si-Al-O when bentonite or fire clay being used.
  3) The additon of feldspar to silica sand promoted the formation of Fe-Si-Al-Na-K-O eutectic of fine structure.
  4) The resultant products were easy to make silica sand particles wetable to form a iron rich fused surface layer.
  Generally, the products formed at the interface between mold and liquid steel consisted of iron silicate and easily penetrated into gaps between sand grains due to capillary attraction. In this case, the addition of feldspar had the advantage that it caused a reduction of the surface tension of irsn silicate and increased its viscosity, and that it resulted in sintering of sand grains to produce a barrier to the penetration of the fused products.

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  The redistributing behaviors of tin in the Cu-20%Pb-2 or 5%Sn bronzes during freezing wered etermined by means of the X-ray microanalysis. Cosiderable release of tin from the alpha solid during freezing results in extreme condensation in the remained liquid as much as 20% at the end of the monotectic reaction. The ratios tin concentration in the solid to that in the liquid are 0·08 to 0.13 and 0.14 to 0.20 respectively in the Cu-20%Pb-2 and 5%Sn bronzes and are the least at the initial stage of nucleation for alpha dendrites. The growing alpha solid is often surrounded with the (L₁+L₂) liquid. The lead-rich L₂ phase which is easily aggregated leads to coarse and irregular distribution of lead. Tin once condensec in the liquid is inversely released from the lead-rich liquid and disolved into the alpha solid accompanying with coring in it. Less condensation of tin in the remained liquid is found in the bronzes containing 2% nickel and silver. 0.5% silicon has an inverse effect.

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