Nitrogen gas was introduced in the molten grey cast iron containing 0.028%Ti. A nitrogen analyzer Thermatic “O-N” was used for nitrogen analysis. The graphite structure was analyzed using an image analyzing computer QTM 720. Fine graphite precipitates during solidification in the cast iron nitrogen treated. Nonmetallic inclusions such as TiN, MnS, SiO₂, TiS and (Ti, Mn)S are found by microscopy and EPMA analysis. Nitrogen less than 100ppm reduces the number of eutectic cells in hypoeutectic cast iron. Nitrogen, however, does not have any influence on the primary graphite in hypoeutectic cast iron.

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  Effective utilization of waste molding sand and dust was tried as an alternative to the usual CaCO₃ filler material for a pavement asphalt mixture. Marshall Stability Test was conducted. The foundry dust is a useful asphalt filler material.

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  An Al-Si-Mg alloy (AC4A) was cast in a metal mold having such cores as alumina-base water soluble core, oil sand core and plaster core. The alumina-base core has excellent cooling property. The casting poured in the metal mold having alumina-base core has a fine structure, high density and good mechanical properties. Improved temperature distribution during solidification and better feeding effect of molten metal can be expected in the casting poured in the metal mold in which a core having high cooling ability is inserted.

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  The pressure gradient and temperature distribution in the green sand mold, the amount of gas evolved from the mold and the rate of moisture evaporation were measured. The permeability at different zones in the green sand mold such as the initial zone and the moisture condensed zone was calculated. The gas pressure measured in the mold continuously changes after pouring remarkably near the metal. This change can be well explained by Darcy's law. A close agreement lies between observed and calculated values of the gas pressure change. The influence of various factors such as pouring temperature, additional materials to green sand and squeeze pressure on gas pressure was also examined. The gas pressure is independent of the amount of gas or steam generation, but it changes with the permeability of the mold.

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  Three self-hardening organic binders, low-nitrogen furan, oil-urethane and phenol-urethane were tested. Test apparatuses were developed to measure hot surface stability and hot compressive strength. The furan binder shows higher hot strength at 600°C than the urethane binders because of the level of carbon precursor generating after decomposition of the binder. When the temperature of the mold surface is raised to 1,000°C, the urethane binders give higher hot strength than the furan binder. This fact can be explained by the adhesive force of carbon precursor to the sand.

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