Recently it has been empirically known that the gray cast iron with the plate like steadite (Balken, Karbidinsel) has an excellent resistance to sliding wear. As a preliminary investigation to make clear the condition and mechanism of formation of this structure, an examination is made on the influence of several alloying elements and cooling velocity on the structure of Fe-Fe₃C-Fe₃P eutectic alloys. Firstly, the potentiostatic etching condition which allows the metallo-graphic identification of the phases in the alloys is determined in 10n-NaOH aq. solution.
  The results obtained are summarized as follows;
  (1) It is known to be able to etch preferentially Fe₃C and Fe₃P at −300mV and +100mV respectively vs. Hg-HgO reference electrode.
  (2) As the cooling velocity increases, the primary Fe₃P shows a lamellar structure instead of its characteristic tabular form, but morphology of primary Fe₃C is not so changed.
  (3) It is shown that Fe₃C crystallizes primarily by small addition of Ce, B and Mn, on the other hand Mo facilitates the formation of Fe₃P. V and Te exhibit an intermediate behaviour between the above two groups when added relatively small, however they form other phases regarded as special carbides, besides Fe₃C, Fe₃P and austenite when the amounts added increase. C in the alloy tends to aggregate as flaky graphite by addition of Si. It should be noted that a part of C in these alloys coagulates as spheroidal graphite by addition of Mg even when added at and below 1,100°C.
  (4) Changes of microhardness of Fe₃C and Fe₃P in these alloys correspond on the whole to their structural changes caused by alloying additions.
  These changes in structure may be accounted for by the view that the eutectic point of Fe-Fe₃C-Fe₃P is shifted by the alloying additions and suggest that the plate-like steadite in low alloyed cast irons may be able to occur not only from the eutectic reaction in Fe-Fe₃C system but also as a primary Fe₃C of this ternary eutectic depending on the microsegregation of alloying components.

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  A study to clarify the various factorial factor relations having influence on the cupola operating conditions is statistically made.
  In this study, it is nessesary to know the time lags between variation of chemical composition in molten iron and the factors obtained from instruments atached to cupola with artificial changes in its operations. But a determination of the time lags of resultants of cupola operation of a steady state is very troublesome. More various statistically analysing practices revealed that the time lags of factorial factors during cupola operation are determined with the multicorrelation analysis method in consideration of the self-legressions of deta of factorial factors and the metallurgical engineering.

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  The machine parts of hydraulic equipment are hard worn by solid particles such as sand muds contained in fluid stream.
  This wear is generally called sand erosion, and the mechanism of sand erosion is considered to consist of abrasive wear and corrosive wear. But, therelation between sand erosion resistance of materials and their microstructure has not been cleared. Then we have studied on this relation of practical metals and high carbon high chromium ferrous alloy by a sand erosion testing apparatus which has simple mechanism. The results obtained are as follows.
  1. Sand erosion resistance of practical metals is generally in propotion to their hardness but there is a finite value of the resistance in evey microstructure.
  2. The best sand erosion resitance of practical cast materials was found in high carbon high chromium cast alloy and sanderosion resistance is controlled by composition of carbides formed in casting.
  3. The excellent sand erosion resistance of high carbon high chromium ferrous alloy is due to very hard carbide formed as (Cr. Fe)₇C₃.
  4. 3%C-20%Cr series ferrous alloy, Containing chromium Carbide (Cr. Fe)₇C₃ as main carbide, has more excellent sancl erosion resistance than 24% chromium Cast iron used as practical wear resistance alloy casting. Besides, the sand erosion resistance of 3%C-20%Cr series ferrous alloy is improved remarkably by adding 1% of vanadium.

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  Recently, it has been demanded self curing for foundry mold. As self curing binders, sodium silicate, cement, and furan resin etc, have been used. When the self curing sands are employed for mass production mold, they must be provided the sands with green strength. In this paper, sodium silicate was employed as the self hardening binder, and bentnite was emploved for the second binder to give the green strength.
  As the properties of self hardening mold employed sodium silicate are influenced from concentration and mol ratio of the binder, we have tested the mold properties when concentration and mol ratio of the binder were changed.

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