The growth of solidifying pure metals and eutectic cast iron on the surface of plate-like and cylindrical mold cavities was theoretically analysed employing the relationship between the heat flow at the metal-mold interface and heat conduction in the molten metal. The solidifying thickness in plate-like castings numerically analysed satisfies an equation experimentally introduced by Ruddle et al except for the solidification start. A simple equation similar to Ruddle's equation for plate-like castings theoretically generalized is introduced to evaluate the growth of solidifying castings in the cylindrical sand mold cavity.

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  A second phase was introduced around graphite nodules in ferritic spheroidal graphite cast iron and graphite steel by induction quenching and tempering at 200°C or 550°C to improve their fatigue characteristics. Completely reversed bending fatigue tests were carried out. The treated irons have the endurance limit superior to that of spheroidal graphite cast irons having ferritic, bull's eye and pearlitic structures. The endurance limit of the treated cast irons and graphite steels rises by increasing the volume fraction of the second phase, but that of the graphite-tempered sorbite steel (1.2%C: with nodular graphite like malleable cast iron) having the second phase volume fraction 40% or more is lower than that of the 10% material. Such an improvement in fatigue characteristics is attributed to the fact that the harder phase introduced around the graphite nodules prevents initiation of fatigue crack at the graphite-matrix interface.

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  Bonding experiments were made using patching cones (the ratio of the prominent height to the radius was 0.2) and conically notched plates both of which were eutectic or grey cast iron. A bonding apparatus having single-faced electrodes which consist of a center electrode and a circular electrode was used. The profile of transformed region and the tensile strength of bonded materials were measured. When the tip angle θ of the patching cone is 120°, the bonding interface is wholly contained within the region of eutectoid transformation, but when it is 90°, part of the bonding interface is not contained within the region. When θ is 120°, the tensile strength of bonded cast iron is affected neither by the heating rate from 2.5°C/sec to 17°C/sec nor by the applied force from 2 kg/mm² to 7 kg/mm², and is between those of the matrix and the material once heated cyclically. Accuracy in handling using the bonding apparatus having single-faced electrodes ensures good solid-state bonding with phase transformation.

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  Malleable cast iron was melted in either vacuum or air and horizontaly cast into a round bar shape. The length of the sound zones in the castings produced by the riser and end effects were examined as a function of eutectic fraction and also numerically calculated basing on Darcy's law. The mathematical analysis suggests that an increase in eutectic fraction leads to widening the sound zones and that castings with low eutectic fraction are accompanied by shrinkage depression. These suggestions are in good agreement with the experiment. The experimental sound zone produced by the riser effect is, however, shorter than the calculated one for castings with eutectic fraction 0.5 or more. Such a disagreement is caused by the fact that the melt with higher eutectic fraction forms a solid skin within a shorter time after pouring into a mold.

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  Impact compression tests were made on high alloyed cast steels containing Mn 12%, C 1.2 to 2.3% and V 0 to 6% heated at 1,050°C for 1 hr and water quenched. The hardness of the work hardened steels is maximum (H_{v, max}) at about 1 mm bellow the edge of the wrought surface and gradually lowers down to the initial hardness (H_{v, base}) as the distance from the wrought surface increases. The cast steel containing the minimum C and V shows 625 of H_{v, max}, and one containing the maximum C and V does 760. V has a less effect on H_{v, max} than C. The V-free steel has H_{v, base} from 195 to 255 depending on the C content, and the V-containing steel shows from 325 to 375. The degree of work hardening ΔH_v (=H_{v, max}—H_{v, base}) is moderated by increasing the V content. Under the same total energy added, for instance, a single impact of 32 kg·m, 8 impacts of 4 kg·m and 16 impacts of 2 kg·m, the distribution patterns of hardness near the wrought surface are almost equal in all the specimens, but the hardness is always higher further down from the surface in the specimen worked by high energy per impact.

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  A heat transfer model in sand molds was derived from modified Kunii's theory for a packed bed. An equation of thermal conductivity is proposed below 600°C where radiative heat transfer is negligible.
    λ=1/[{2/3(1−ε)λ_s}+{1/(3δλ_s+(1−ε−δ)λ_g/φ)]+ελ_g
      δ=0.0996ε^−1.25 W^−0.0106 (λ_s/λ_g)^−0.285 D_p^0.234
      φ=0.937ε^1.32(λ_s/λ_g)^−0.284
      0.385≤ε≤0.494, 0.03≤W≤0.07, 0.0058 cm≤D_p≤0.379 cm
where, λ_s and λ_g : thermal conductivities of silica sand and air respectively, ε : the void fraction, δ : the contact area fraction of silica sand, φ : the ratio of the effective thickness of air film near the contact point to the sand diameter, W : the binder content, and D_p : the diameter of sand in cm. Thermal conductivities of dry sand mold, furan resin bonded sand mold and phenolic resin bonded sand mold are estimative using this equation within the accuracy of ±10%. The thermal conductivity below 600°C is considerably affected by void fraction, but not by the binder content and the sand diameter.

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