The relationship between the coefficient of discharge and the gating system for the metal mold casting of cast iron was studied.
  It was shown that the coefficient of discharge varies as much as the variation in the length or the sectional area of the gate. When L/D was defined as followed, it was found that the coefficient of discharge is a function of L/D :
    L/D=L_s/D_s+L_r/D_r+L_i/D_i
where L is the length of gate, D is the equivalent diameter of gate, and subscripts s, r and i refer to sprue, runner and ingate, respectively. Furthermore, an equation for calculating the sectional area of gate for metal mold casting was derived from the coefficient of discharge thus obtained.

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    In order to obtain a more suitable cast iron as brake shoe material for railway use, friction and wear characteristics of several kinds of special cast iron against wheel steel in dry sliding condition were studied. Using a 1⁄4 scale brake tester, a brake shoe specimen was pressed against the outer cylindrical face of a wheel specimen, which was rotating at a constant velocity, and the frictional force as well as the wear amounts of both specimens were measured. The tests were carried out at several sliding velocities, 2.8, 4.8, 9.5 and 16.3m/sec for most specimens. The mean pressure applied on the friction face was 5.5 or 9.0kg/cm². Many kinds of special cast iron-high phosphorous iron, boron containing iron, nodular graphite iron and others-were tested as brake shoe speclmens.
    The results obtained are as follows :
  (1) The friction coefficient of ordinary cast iron with low phosphorous content decreased as the sliding velocity increased. In the case of the high phoshporous cast iron with over 1.0% phosphorous, the friction coefficient and the wear of brake shoe specimen showed a remarkable peak value at the sliding velocity of about 10m/sec.
  (2) At low sliding velocity up to about m/sec, a high phosphorous cast iron showed less wear than a low phosphorous one, but at higher sliding velocity of over 10m/sec or so, the result was reversed.
  (3) Cast iron containing free carbides as well as graphite flakes in its structure, produced with boron addition, showed as little wear as high phosporous cast iron at a low sliding velocity. Moreover, its frictional characteristics were almost identical to those of ordinary low phosphorous cast iron, showing no remarkable peak value of friction coefficient.
  (4) Cast iron containing sufficient amount of hard phases, free carbide and steadite, which can be produced with an addition of proper amounts of boron and phosphorous, showed little wear. The amount of hard phases should be increased with increasing brake pressure.
  (5) Nodular graphite cast iron was more wear-resistant than flake graphite iron. In general, however, the friction coefficient was somewhat smaller than that of ordinary cast iron.
  (6) The temperature at the friction surface is mainly governed by sliding velocity. By the rise in temperature, some physical and chemical reactions-oxidation, phase transformation, melting, etc. take place at the interface. These reactions would cause some changes in friction and wear characteristics.

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  In this report, scaling and growth charactristics as well as mechanical properties of high purity cast iron treated with metallic magnesium containing about 3.5%C, 2.5%Si and up to 7.7%Al were investigated.
  In the scaling test carried out under the heating conditions of 900°C in air for a total of 100 hours the scaling resistance properties of 1.00%Al specimen was slightly superior to the base specimen without Al (0.007%Al), but 1.46%Al and 3.47%Al specimens were remrakably superior.
  In the growth test carried out by a repetition of the heating-cooling cycles 6 times within the temperature range of 600°C to 900°C in the air and measureing the amount of growth in each cycle at 600°C, 1.46%Al specimen showed slight growth, but 3.47%Al and 7.67%Al specimens showed no growth at all. On the permanent growth which appeared when the specimens were air-cooled from 600°C to room temperature after the above mentioned test, the influence of aluminium was quite similar to that the heating-cooling cycle test.
  The mechanical properties of the 2.8%Al specimens which has 54% spheroidization of graphite was tensile strength 40.3kg/mm², elongation 2.5% and BHN about 170. On the other hand, ternary carbide Fe₃AlC_X (ε-phase) appeared in the matrixes of as cast specimens containing above 3.5%Al which remained even after annealing for the heat-resistance test. 1.5%∼3.5%Al specimens which have considerably good mecanical properties, i. e., 40∼38kg/mm² tensile strangth, 3∼2% elongation and 170∼150BHN, showed remarkably good scaling and growth resistant properties.
  These results will be helpful in the production of heat-resistant cast irons.

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  The dynamic Young's modulus of cast iron plays an important role in the design of members for mechanical structures using cast iron. Specifically, the stress-amplitude dependency of dynamic modulus is one of the important factors in discussing dynamic properties of structures in vibration, but little study has been made. Therefore, the authors have examined the stress-amplitude dependency of the dynamic modulus of various gray cast irons with carbon equivalent of 3.6% up to 4.8% and investigated the relation between the dynamic modulus independent of the stress-amplitude, which is one of the useful dynamic characteristic values under very small vibration stress, and (1) the carbon equivalent, (2) amount of free graphite, and (3) graphite shape. Further, the correlation between mechanical properties and dynamic modulus was clarified. The results obtained are summarized as follows :
     (1) The observed dynamic modulus (E_T) of gray cast iron can be separated into two parts : the stress-amplitude independent part (E_I) and the stress-amplitude dependent part (ΔE_H), which can be expressed as follows :
    E_T=E_I−ΔE_H
E_I is, over a wide carbon equivalent range, applicable to the stress region up to about 100g/mm² but the stress region decreases with increase in carbon equivalent.
    (2) E_I decreases as carbon equivalent increases and changes remarkably when carbon equivalent approaches the eutectic composition. Furthermore, E_I decreases as the amount of free graphite increases, however, when the volume of graphite is constant, it depends closely upon the graphite shape.
    (3) The dynamic modulus of stress-amplitude range up to 500g/mm² varies in the same direction as tensile strength, but it has no relation to hardness. Also, E_I is closely related to resonant displacement.

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  This investigation is concerned with the influence of C and Si on tensile strength, elongation, hardness and structure of gray iron cast into metal molds. The effect of variations in composition of C form 2.96 to 4.1% and Si from 1.56 to 3.6% were studied. Various mold ratio and melt treatments were employed to obtain two kinds of gray iron, one with pearlitic matrix and flake graphite structure, and the other with ferritic matrix and fine graphite which were obtained by annealing for either 2 or 3 hours at 900°C.
  In the gray iron with pearlitic matrix and flake graphite, effect of the degree of saturation of saturation of carbon on tensile strength tended to be similar to iron cast into sand molds, but tensile strength of iron cast into metal molds was higher. Increase in the Si/C ratio increased slightiy the tensile strength. Tensile strength was not very much influenced by the area of pearlite occupied in the matrix. Tensile strength and elongation of iron with pearlite matrix and flake graphite were less than 30 kg/mm² and about 0.4%, respectively.
  In the gray iron with ferritic matrix and fine graphite, tensile strength was affected by Si/C ratio through the degree of saturation of carbon was almost the same. The relation between Si/C ratio and tensile strength tended to be similar to the case of pearlite and flake graphite iron but the rate of increase in tensile strength was about three times greater. Tensile strength and elongation of iron with ferritic matrix and fine graphite were about 48kg/mm² and 1.0∼1.4% at Si/C≑1.21, respectively.
  primary austenitic dendrite grew radially from the surface to the center of casting in all specimens. The size of fine graphite was less than 5 or 10μ, but the existence of larger graphite (30∼100μ) widened the dendrite spacing and decreased the tenshile strength.

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