The behavior of Ce and Ca retained in the iron when used as spheroidizer in ductile iron was studied by means of the newly developed elecctron probe X-ray microanalizer. Their locations in the iron relative to those of graphite were investigated and their chemical forms in the iron were determined qualitatively. The speroidizing elements were found near the boundaries of the graphite spheres. They were suspected to exist there as nearly pure elements.

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  In the case of thin plate castings like cylinder liners poured in the perpendicular position, the influence of pouring rate on the soundness of cast iron depending upon the made of feeding during solidification was discussed following equation:
  [Written in non-displayable characters.]
where    ∂q⁄∂y=the gradient of solidification front;
                v=the moving rate of melt surface in the mould cavity;
                t_f=the time between the start of pouring and the start of freezing;
                t₀=the time between the start of pouring and the end of freezing;
                      b(θ_i−θ₀)⁄√π=mould constant.
  It was understood that the soundness of cylinder liner castings are more affected by the freezing rate in the horizontal direction than the mode of feeding at the perpendicular direction.

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  CO₂ Process sands with different fundamental materials and different additives were prepared and their residual strengths after baking were examined. On the other hand, variation of void, free thermal expansion contraetion, and microscopic deformation of bonding structure were examined.
  In this investigation the author tries to clarify the cause of collapse deterioration through analysis of the deformation of bonding structure and plans the improvement of collapsibility.
  The results obtained were as follows.
  (1) Residual strength was maximum at about 200°C, 800°C in baking temperature. The peak on the lower side occurred through vaporization of moisture, and the peak on the upper side did as follows:
  Sand grains were coated with molten binder at high temperature, succeedingly, bonding bridge was narrowed and the contact point increased, during the cool moulding sands were not cracked.
  (2) About CO₂ process sands, the expansion contraction curves were compared with the fundamental type. (Fineness grade No. 6 Silica Sand, Molecular ratio≒2.0 sodium Silicate binder).
  It was found from the contraction state in the curves that the residual strength was decreased when the fluidity of sand grain with molten binder was checked as well as when it was accelerated.
  The former contributes to the separation of bonded point, and the latter is due to the formation of non-uniform structure through severe sintering and void enlargement.
  (3) For an over-all improvement of collapsibility a combination of hygroscopic and mineral additives appears to be the most effective.

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  A new type of testing apparatus capable of studying the mechanism of the wear of metals by means of an abrasive loose-particle condition has been devised.
  The apparatus has such characteristic features as to make the abrasive sands scratch and indent on metals under dry, semi-wet and wet conditions as well as being capable of varying the grain size of sand, the applied load on a specimen and the speed of abrasion. A high reproducibility of the results is obtained rapidly by means of this new machine.
  Also the classifications of the abrasive wear appeared on metals has been given from a new point of view.

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