Succeeding to the previous report on the segregation in aluminum alloy castings, experiments on the segregation in copper alloy castings, i. e. aluminum bronze, yellow brass, and tin bronze were made by the local spectrographic analysis method.
  The results obtained are as follows:
  (1) Excepting yellow brass, the shapes of segregation in copper alloy castings were mostly similar to the type in aluminum alloy castings.
  (2) Relation between the thickness of castings and the manner of segregation, influences of pouring temperature and mold material to the shape of segregation agreed also with the tendency in aluminum alloy castings.

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  Rote and his colleagues in A. F. S. have suggested the fracture test to estimate melt quality of 85-5-5-5 red brass, and a few criticism is informed by some authers. The authers have already shown probable correlations between melt quality and fracture appearances of chill-blocks in the previous papers, and also indicated close relationships between fracture characteristics and amounts of dissolved gases in the metal.
  In the present work, influences of casting conditions on the fracture appearances are deterimined to define the fracture testing process which will be applicable. Fracture appearances may be susceptible to variation in amounts of dissolved gases in the melt. Neverthless, depths of columnar and blue-grey patterns which are the most important variables in estimating the melt quality are affected by a little contamination of harmfull element such as aluminum and silicon, and this causes incorrect estimotion of the melt quality. A simple test to detect contaminations of alumlnum and silicon by means of observation of the surface apearances of cast blocks is also described.
  A preferable way in which the melt quality may be evaluated includes observation of the surfaces of cast blocks to detect contaminatios and, if the melt is uncontaminated, fracture testing to determine amounts of dissolved gases in the melt.

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  Durability of calcium effect (spheroidizing of graphite) to the molten iron was studied by using calcium silicide as the calcium agent.
  When calcium was satisfactorily reacting with the molten iron, durability of its effect was over 20 minutes in the industrial scale and was of the same order as that of magnesium effect. Calcium effect was observed even with a small quantity of calcium, but, in this case, its durability was little, and it increased with the increaseing content of calcium.
  Although characteristics of molten iron treated with calcium was changed by keeping in molten state, contents of silicon, sulphur and oxygen did not show distinct changes. On the contrary the changes of the contents of carbon and residual calcium, which did not strictly correspond to the change of the structures of castings, showed the tendency to decrease, and it was considered that the changes of the contents of both elements fundamentally controlled the changes of characteristics of molten iron.
  At the beginning, when the effect of calcium was still present, the obvious super-cooling was observed on the solidification process, and, when the effect of calcium decreased and the form of graphite changed from the spheroidal form to the flaky one, super-cooling disappeared. As mentioned above, the super-cooling considerably corresponded to the changes of structure, but the degrees of super-cooling did not correspond to it. A cause of spheroidizing of graphite, therefore, was thought not to be the super-cooling, but the purification of molten iron which caused the super-cooling.

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  The effects of chemical compositions on the formation of residual stress in iron castings were investigated by strain hindering method which was reported previously. The formation of residual stress in white pig iron castings as well as the effects of silicon added to white pig iron and phosphorus added to grey pig iron on the residual stress formation were examined.
  The results obtained are as follows;
  1. The process of residual stress formation in castings of white pig iron resembles to that of grey cast iron but differs in the growing rate of stress below the transformation temperature, i. e., the stress development in the former is much larger than in the latter. This difference may be attributed, to a large extent, to the difference in Young's modulus.
  2. So far as these experiments are concerned, the stress relaxation by plastic deformation is not detectable in white pig iron castings below the transformation temperature, so about 650°C is considered to be so-called “critical temperature”.
  3. Addition of silicon in white pig iron decreases the residual stress as the silicon content increases up to 3.8%, but further increase up to 7% has no effect.
  4. Increase of phosphor content in grey cast iron rather increases the residual stress, though in a little amount.

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  The cast iron in vacuum melting as well as that contains titanium has structure of undercooled graphite and dark-black fracture which could be expected that they are somewhat related each other in the mechanisms of these formations. Synthetic cast irons of Fe-C, Fe-C-Si, Fe-C-Ti, Fe-C-Si-Ti and Fe-C-Si-S alloy systems with hypo and hyper eutectic compositions of carbon were melted under reduced atmospheric pressures of vacuum, 200, 400, 600, and 760mm Hg. The sizes of the graphite flakes were measured in these specimens, and the maximum size was found at certain pressure range related to the compositions of the specimens.
  In hypo eutectic iron, the pressure which got the maximum size of flake graphite in Fe-C-Si- S alloy existed near the vacuum side and approached to the pressure of 760mm Hg in Fe-C, Fe-C-Si and in Fe-C-Si-Ti alloy one after another. In hyper eutectic iron the same tendency was found in the ordering of Fe-C and Fe-C-Ti alloy. The formation temperatures of the oxide films on the molten surfaces of the cooling specimens were measured by an optical pyrometer, which depressed gradually by reducing the atmospheric pressure and raised by titanium addition, and the temperatures were higher in hypo eutectic than in hyper eutectic irons. The oxygen content of Fe-C-Ti alloy melted in atmospheric pressure decreased gradually by cooling but sharply at about 1300°C.
  By the experiments mentioned above, it is considered that the eutectic graphite structure in the cast iron containing titanium was attributed to the deoxidation of titanium. By this consideration, the next experiment was done to find some difference between the obstruct action of sulphur and titanium in the spheroidal graphite formation of the magnesium treated iron. It was found that in the magnesium treated iron containing sulphur the quasi-flake graphites were separated from eutectic austenite cell while in the iron containing titanium the graphite formed in spheroidal austenite had some irregular type and very fine threadlike graphite was formed at the boundary of the austenite at the end of the eutectic solidification.

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  Author have studied on the Olivin Minerals as a raw material of molding sand using Differential Thermal Analysis.
  As following results have obtained.
  ① Recognized many differences on the curve between these minerals.
  ② Products of Hokkaido, Ehime, Akita Prefecture have show nearly linear curve on the Differential Thermal Analysis curve and recognized that these minerals are Forsterite by X-Ray Analysis.
  ③ Serpentine Minerals have a charge at 600°∼700°C on the Differential Thermal Analysis curve and these minerals change to Forsterite crystoline structure after heating at 700°C.
  ④ Recognized that the change at 600°∼700°C on the Differential Thermal Analysis is due to dehydrate in of the mineral by measuring heating weight loss.

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