Effects of non-metallic inclusions on the mechanical properties of cast steel, especially elongation, reduction of area and impact value, were reported. From normal running melt 30 charges were extracted, which were molten by 2-ton electric arc furnace. The number of inclusion was measured in the test pieces cast in every charge, and the relationship between inclusions and mechanical properties was investigated. The quantitative determination of number and size of inclusion was carried out by means of the point-counting method with a microscope of 400 magnifications. Size of inclusion was divided into three classes in as-cast samples : >5μφ, 3∼5μφ and 3μφ>. In samples forged into 13 mm from 30 mm diameter, inclusions were classified into undeformed granular inclusion and elongated inclusion, and the size of inclusion of the latter was divided into three classes: >15μ 10∼15μ and 10μ>. Samples had chemical composition consisting of 0.19∼0.33%C, 0.25∼0.53%Si, 0.45∼0.60%Mn, 0.009∼0.022%S and 0.020∼0.037%P and were fully annealed under the same condition.
  The results obtained were summarized as follows:
  (1) More numbers of measurement in the cast samples was needed than in the forged samples; 90 in as-cast samples 60 in forged samples. Because the distribution of inclusions was not uniform in the as-cast samples.
  (2) The number of inclusions over 5μφ in as-xast samples was not related to elongation, reduction of area or impact value, but elongation and impact value tended to lower with the increase of number of inclusions under 5μφ.
  (3) The granular inclusions in forged samples were not connected with elongation, reduction of area or inpact value in forged samples, while the elongated inclusions were related in all sizes of inclusion.
  (4) From the results of X-ray microanalysis, it is considered that the elongated inclusions are composed principally of (Fe, Mn) S type, and the granular inclusions mostly of SiO₂ type and partly Al₂O₃ type inclusion.
  (5) From these results, it was found that the fine non-metallic inclusions lowered elongation, reduction of area and inpact value, and its effect was remarkable in the elongated inclusion, (Fe, Mn) S, while no effect of SiO₂ type inclusion was noticeable.

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  Generally, spheroidal graphite cast iron is superior in heat resistance to normal gray cast iron with flake graphite. The use of spheroidal graphite cast iron at elevated temperatures has been restricted for many years to temperature pu to 350°C. Long-term stress-rupture values are most important for estimating heat resistance of materials for turbine parts, pressure vessels application and so on. The spheroidal graphite cast iron has great strength and ductility as carbon steel, and yet is inferior to it in elevated temperature creep-rupture properties. For higher temperature services, therefore, plain carbon or alloy steels have been used. But creep-rupture properties of spheroidal graphite cast iron can be improved by alloying.
  Ferritic spheroidal graphite cast irons, FCD 40, and two alloyed, ferritic and ferritic-pearlitic spheroidal graphite cast irons, one of which contains 1% molybdenum-1% nickel and another 1% molybdenum-0.3% chromium, were tested for a period of about 10,000 hours at temperatures up to 550°C. From a Larson-Miller master rupture curve, creep-rupture properties were compared on various materials, including these spheroidal graphite cast irons, low carbon steel and 0.5% molybdenum-alloyed steel, of which data were obtained from the literature. The rupture stresses for long-term 10⁵-hrs were estimated, and influences of the ferritizing annealing on creep-rupture properties were investigated.
  The results of the experiment were summarized as follows :
  (1) Alloyed Spheroidal graphite iron indicated better stress-rupture properties than low carbon steel or FCD 40. Molybdenum-chromium-alloyed, ferritic-pearlitic cast iron was best of them all and its properties approximately equaled to that of the 0.5% molybdeum-alloyed steel. The 10⁵-hrs stress-rupture values at 450°C were estimated to be approximately 15kg/mm².
  (2) After the creep rupture test there were no microstructural changes, that is, residual pearlite in the ferritic-pearlitic, molybdenum-chromium-alloyed one did not decomposed and was stable at temperatures up to 550°C.
  (3) For ferritizing annealing, full annealing including high temperature treatment is more desirable from the view point of ductility rather than from that of creep-rupture properties.

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  This study was undertaken to determine the effects of some variables, such as aluminum content, pouring temperature, mold temperature and addition elements, on the fluidity of Zn-Al alloys by the spiral-form metallic mold testing apparatus.
  The results obtained are summarized as follows :
  (1) For Zn-Al binary alloys, the fluidity value is approximately in inverse proportion to the freeziing range, and alloy containing about 30%Al shows the lowest fluidity value.
  (2) The coarse porosities appear in the fluidity specimen having narrow freezing range such as pure metals and eutectic composition, the microporosities dispersed in the alloys having long freezing range.
  (3) The relations between fluidity value and superheat of pouring temperature and mold temperature may be shown as the following equation :
          L=A⋅ΔT+B
where, L is fluidity value in cm, T is superheat of pouring temperature or mold temperature in °C, A is constant in cm/°C, B is constant in cm.
  (4) For the effects of addition elements on the fluidity of high Al-Zn alloy with long freezing range, the fluidity may be improved by adding Mg, Si, V and Cu, and decreased by adding Cr, Zr, Ti, Ni and Mn in the range of less than 0.5%.
  (5) In Zn-22% Al-1% Cu and Zn-22% Al-3% Cu alloys, the fluidity value may be increased by adding Si, and decreased by adding Mg. In Zn-22% Al-3% Cu-1% Mg alloy, the fluidity valuie decreases by adding Si more than 0.5%.

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  The ferritic cast iron has good machinability and stable properties at elevated temperatures. This report is one of the basic studies of a series on ferritic cast iron. The purpose of this investigation is to produce ferritic cast irons as cast. In this work, the cooling rate on certain temperature during the cooling process after freezing in shell mold was measured. The relations between the cooling rate, various silicon contents in cast iron containing a certain carbon content and the ratio of ferrite in the matrix structure were examined.
  The results obtained were as follows :
  (1) The ratio of ferrite in the matrix structure decreased with increase of cooling rate in the solid state range after freezing. Between the ratio of ferrite (F) and the cooling rate (V), a relation of F=a√V+b is established (a, b : constant).
  (2) The ratio of ferrite increased with the increase of eutectic reaction time and eutectoid transformation time. Between the ratio of ferrite (F) and eutectic reaction time or eutectoid transformation (t), a relation of F=A√t+B is established (A, B : constant).
  (3) The degree of effect of cooling rate on the ratio of ferrite in matrix decrease with increase of silicon content.

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  There are many investigations on the effects of several elements on the spheroidal graphite formation in cast iron, but only a few investigations concerning when and how these elements have a harmful influence on the spheroidal graphite formation, have been reported.
  In this paper, to clarify the points mentioned above, the experiments which were carried out to study the inhibitory effects of copper on the spheroidal graphite formation were reported. The base metal, composed of electrolytic iron and electrode graphite, was melted in a high frequency induction furnace and then was cast into an iron mold. 50 grams of alloy having a carbon content of 4.35% was melted in a fused silica crucible by a resistance furnace, and copper up to 4.0% were added to the melt. At 1,350°C, the melt was treated with Fe-Si-Mg (21.4%) alloy and cooled while the cooling curve was plotted. At the various predetermined temperatures, the specimen was quenched into ice water to interrupt the solidification process and then the graphite nodule number and the amount of solidified part in the eutectic were measured microscopically in these specimens. Also, X-ray micro-analysis was carried out on some of the quenched specimens to determine the distribution of copper.
  The experimental results are as follows :
  (1) Copper has adverse effect on the formation of spheroidal graphite and forms a quasispheroidal graphite at the first stage of the eutectic solidification.
  (2) It is considered that in specimens containing copper more than 2.5%, growth of the primary and eutectic spheroidal graphite are prevented by copper-rich melt which piled-up around both graphite nodules.
  (3) Copper does not accelerate the fading of magnesium.
  (4) According to the previous classification of harmful elements in the spheroidization of graphite, i. e. sulpher group, titanium group and lead group, copper is classified into the titanium one.

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