This study has examined the cooling rate, the mechanical strength and the number of eutectic cells for round, square and plate castings. Also discussed was their relationship to the casting modulus. It has been made clear that the mechanical strength, the number of eutectic cells and the cooling rate vary with the change of sectional area and the difference of forms, and they become smaller in the order of round, square and plate castings. The cooling rate (V_S) of all castings can be represented by a function of the casting modulus (M) and be given by the general form V_S=BM^−nf, in which B is a constant and f=1 in each case. The experimentally evaluated value of n-th were 2.0 for round bar, 2.3 for square bar and 2.4 for plate castings. The relationship of the mechanical strength (σ_B), the number of eutectic cell (N) and the cooling rate is expressed by the following equations: σ_B=C₁V_S^f, N=GV_S^f, where C₁ and G are constants.
  The mechanical strength and the number of eutectic cells are given by the following forms which are reciprocals of casting modulus: σ_B=K₁[1/(V/S)]ⁿ, N=D[1/(V/S)]ⁿ, where K₁ and D are constants. The values of n-th obtained were 2.0 for round bar, 2.3 for square bar and 2.4 for plate castings. While, values of K₁ and D vary with the mass and the material quality. The strength relates to the number of eutectic cell accompanying the variation of forms and sectional area, and the relationship is expressed by the following equations: σ_B=J₁N^f, H_B=J₂N^f, where J₁ and J₂ are constants. It is revealed that the experimental values of the casting modulus, the mechanical strength and the number of eutectic cells which depend on the change of sectional area, agree well with their experimental equations.

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  To clarify the influence of destabilization heat treatment on martensitic transformation of high chromium cast iron, specimens with 6.5 to 26% chromium and with 1.5 to 4% carbon were annealed at 900, 1,000 or 1,100°C for 20 to 1.8×10⁴ min and then rapidly cooled down to room temperature. When specimens containing chromium and carbon in the ratio of 3 : 1 are annealed, carbides precipitate from supersaturated austenite and distribute uniformly in a short time. With the progress of precipitation of carbides, Ms point rises to the temperature determined by equilibrium chromium and carbon concentration in austenite. In the specimens containing chromium and carbon in the ratio of 6 : 1 or 8.5 : 1, the precipitation of carbides initiates from the immediate vicinity of the eutectic carbides, and delays that of the central part of primary dendrite. With cooling, austenite transforms to martensite only in the region where chromium and carbon were depleted by the precipitation. Annealing more than 6×10³ min is required to homogenize the austenite. Ms temperature of homogenized specimen rises both with the decrease in annealing temperature and with the increase in the ratio of chromium to carbon.
  When the specimens are homogenized at 1,000°C, the hardness of matrix becomes larger with increase of the ratio of chromium to carbon. Conversely, the hardness of specimens homogenized at 900°C decreases with increase of the ratio, because the hardness depends on the carbon concentration in martensite as well as on the amount of martensite. The marix is mostly composed of austenite in the specimens homogenized at 1,100°C.

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  Eutectic solidification is accompanied by an increase in volume due to graphite crystallization. The swell or the increase of mold cavity due to its expansion is often observed in ductile iron castings. To investigate the relation between the value of iron expansion and the external restraining forces in effect, cylidrical test castings, 60 mmφ × 120 mm in size with 5 mm thickness, were poured in various rigid molds. Increasing the rigidity of the mold decreases the amount of expansion during eutectic solidification, but it was difficult to supress the amount defined in this test casting to 0.4% even with the most rigid mold in general use. The movement of the external wall of mold during eutectic solidification is very small, therefore adding the external restraining forces to the external wall of mold dose not cause a considerable decrease in the amount of expansion. The expanding iron exerts pressure on the surrounding mold and reaction forces from the mold determine the expansion of the cast iron. The expansion rate of the cast iron varied between 0.4% and 0.8%, and the expansion pressure varied between 2.5 kg/cm² and 0.5 kg/cm² in the usual molds.

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  The contraction and strength in liquid-solid coexisting zone of Al-Zn-Mg alloys were investigated. The liquid-solid zone may be divided into two stages by the strength boundary. One stage of higher temperature was called strength minimum zone and another of low temperature was strength increase zone. In Al-5%Zn-Mg alloys, the strength increase zone was increased considerably at less than 2%Mg, and the strength minimum zone was increased at more than 2%Mg. The strength minimum zone was increased and the strength increase zone was decreased by the individual addition of Ti, 0.5%Zr and 0.2%Be to Al-5%Zn-2%Mg alloy. The reverse tendencies were recognized by addition of Mn, Cu and Cr. The strength increasing rate of Al-Zn and Al-5%Zn-Mg alloys decreased with the increase of Zn and Mg content, that of Al-5%Zn-2%Mg alloy increased by the addition of Ti, 0.5%Zr and 0.2%Be. Al-Zn alloys with low Zn and Al-5%Zn-Mg alloys with high Mg decreased the linear contraction rate and the elongation. Those of Al-5%Zn-2%Mg alloy decreased by addition of Ti, 0.5%Zr and 0.2%Be and increased by addition of Mn, Cu and Cr.

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  A study on sea water corrosion of grey cast irons was carried out under the most critical conditions conforming to the splash zone, and the influence of fundamental component, graphite form and matrix structure of cast iron was clarified. The fundamental components, in particular, C and Si content have a major influence on corrosion resistance. When C content decreases or Si content increases, corrosion resistance is improved. The influence of graphite form of corrosion is governed by the difference in the continuity of graphite. The progressive corrosion occurs quickly in the iron of higher graphite continuity, and corrosion rate decreases in the order of lower graphite continuity (FCD<CV<FC<Eutectic). Furthermore, influence of matrix structure is also large. The most corrosion resistant structure was white cast iron with ledeburite matrix, the next was grey cast iron with ferrite matrix. When pearlite content increases, corrosion resistance declines.

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  Undercooling behavior and the structures of specimens solidified from undercooled melts of iron-phosphorus alloys containing up to 15%P have been investigated. A series of specimens having up to 3%P were readily undercooled by as much as approximately two tenths of the melting point. Further increasing phosphorus content up to 10.5% led to difficulties in undercooling and melts with more than 6%P normally solidified with almost no undercooling. In alloys containing more than 10.5%P of eutectic composition, undercooling was very marked again. Primary α did not undercool but undercoolings of primary Fe₃P and Fe₂P were very marked. Maximum degrees of primary Fe₃P and Fe₂P obtained in Fe-12.6%P alloy specimens were 280 and 132 degree, respectively. And those of stable α+Fe₃P and metastable α+Fe₂P eutectic obtained in Fe-10.5%P alloy specimens were 105 and 41 degree, respectively. The two eutectic structures changed from rod-like to anomalous eutectic structure by increasing undercooling. A great portion of α+Fe₂P eutectic solidified in metastable system changed to stable α+Fe₃P eutectic during solidification and cooling.

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