The aim of this investigation is to improve the wear characteristics of black heart malleable cast iron.
  The wear resistance under sliding condition of this material containing temper carbon is principally governed by deformation of temper carbon that accompanies plastic flow of the matrix. A hard second phase surrounding temper carbon was introduced by induction hardening as a reinforcement for suppressing deformation of temper carbon. As a result, the amount of sliding wear in the dry condition was efficiently reduced by the second phase surrounding temper carbon and the wear resistance of the irons treated in this manner was markedly improved. It was either the same as or much better than the wear resistance of the high strength malleable cast iron such as JIS-FCMP 55.

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  Sticker caused by hot sand was taken note of and discussed in this paper. Experiments were performed by squeezing hot mulled sand to study the effects of various factors and conditions on the occurrence of sticker. Methods of its prevention were also studied.
  It was found that sticker occurs due to elevation of temperature of the sand especially when the moisture content and the squeezing pressure are low. It was confirmed that sticker is caused by condensation of moisture on the pattern surface. Pattern heating and use of some parting agents proved effective for the prevention of sticker. Painted or varnished wooden patterns should not be used on hot sand, because heavy sticker occurs under all conditions.

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  The structures of Ni-Sn and Ni-Sb alloys of eutectic and near eutectic composition solidified from undercooled melts have been investigated. Specimens were undercooled by glass slag method. The undercooled melts were quenched into water before nucleation of the solid, in order to minimize the anticipated structural change during the recalescence.
  Study of the microstructures thus obtained showed that there exists a range of composition and temperature below the eutectic temperature within which a melt of off-eutectic composition solidifies as quasi-eutectic. The quasi-eutectic structure consists of regions of anomalous eutectic surrounded by regions of normal eutectic. As a general rule, the amount of anomalous eutectic increases with undercooling and the anomalous eutectic growth is associated with recalescence. The shape and position of the quasi-eutectic region are governed by the liquidus lines of the phase diagram just as in organic systems. Specimens outside the quasi-eutectic region solidify with dendrites with various degree of metamorphosis, depending on the amount of undercooling of the two primary phases.

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  Dimensional accuracy and mechanical properties of solid and hollow cylindrical iron castings poured in alumina-base water soluble mold and silica-base CO₂ process mold were studied.
  Because the alumina-base mold has higher hot strength, there is very little wall movement, resulting in better dimensional accuracy and surface smoothness. Because the amount of thermal expansion of the alumina-base and silica-base mold materials are nearly equal at 750°C, castings poured in these molds have similar casting stress.
  The highest tensile strength of casting was obtained in the 30 mm diameter solid cylinder cast in the alumina-base mold, in which the calculated cooling rate was 7 degree/sec. The cooling power of the alumina-base mold is higher and the castings poured in this mold have directional dendrite structure and higher tensile strength. The level of hardness values and the uniformity of the values throughout the casting section were independent of the mold materials used.

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  Electrical resistivity was measured in flake graphite, undercooled graphite, spheroidal graphite and compacted/vermicular graphite cast irons, in order to elucidate the effects of chemical composition, matrix structure and graphite shape on specific resistivity. The results obtained are summarized as follows :
  (1) The specific resistivity of flake graphite and spheroidal graphite cast irons increases linearly with the fraction of pearlite in the matrix,. The difference between the specific resistivity of the pearlite and ferrite matrix is about 8 μΩ·cm.
  (2) The specific resistivity of flake graphite cast iron of pearlite matrix depends linearly on the sum of carbon and silicon weight percent, and increases with degree of coarsening of the flake graphite.
  (3) The specific resistivity of undercooled graphite cast iron is considerably lower than that of flake graphite cast iron at a given sum of carbon and silicon content.
  (4) The specific resistivity of spheroidal graphite and compacted/vermicular graphite cast iron increases linearly with silicon content and is independent of the shape factor of graphite in the shape factor range of 0.3 or more. The resistivity of spheroidal graphite cast iron is independent of the graphite nodule number per unit area.

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  Effects of stress applied along the columnar growth direction and heat treatment on mechanical properties of unidirectionally solidified 18%Ni maraging steel were investigated. The main results obtained were as follows:
  (1) When the stress is applied parallel to the direction of columnar growth, the strength, ductility and toughness are a little higher than those with stress applied to the perpendicular direction.
  (2) A four-step heat treatment including homogenization resulted in increased strength and decreased ductility, whereas the anisotropy of the mechanical properties was reduced.
  (3) A very high Charpy V-notch test value of 20 kg·m/cm² was obtained with specimens parallel to the growth direction after a two-step heat treatment without homogenization.
  (4) Heavy segregation of Mo accompanying dendritic solidification was reduced by the four-step heat treatment. Microhardness difference between dendritic and interdendritic regions remained after the two-step heat treatment, because the segregation effect was retained. Thus, the behavior of the specimens parallel to the growth direction was like that of the “in situ composite” with a ductile phase and a strong phase.

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