There are a number of reports on the formation of plate-like eutectic carbide in white cast iron but few have probed into the details of its formation, composition or cooling condition.
  In this paper a close investigation was made on the ralation between Cr and C content and cooling velocity of some 40-gram furnace-cooled hypo-eutectic white cast iron specimen.
  The results are as follows :
  (1) In eutectic solidification of hypo-eutectic Fe-C-Cr alloy, plate-like eutectic carbide appeared when intense undercooling and very rapid recalescence occured at the beginning of eutectic solidification.
  (2) The degree of undercooling and recalescence ralated to the growth of this plate-like eutectic carbide depended on Cr and C content, melting temperature and cooling velocity.
  (3) When a plate-like eutectic carbide was observed in the ledeburite structure, the surface of primary austenite dendrite was irregular.
  (4) The distribution of steadite produced by the addition of P to Fe-C-Cr alloy with a plate-like eutectic ledeburite structure was apparently different from that with a rod-like eutectic ledeburite structure.

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  The purpose of this study was not only to statistically analyse the origin of the casting blow-hole formation for zinc and aluminum alloys but also to consider preventive methods for it. The multiple correlation analysis was used in the statistical examination.
  From the analysis of the experimental results it was found that the factors influencing the formation of casting blow-holes were pouring time, pouring temperature, amount of parting agent, thermal decomposition ratio, thermal decomposition rate and injection conditions. The multiple correlation coefficient for these factors obtained from the amount of gas in the cavity, the amount of parting agent and the injecting condition was estimated to be 0.9 regardless of the kinds of alloys.
  The air and gas in the cavity did not disperse outside because they were wrapped up in the molten metal being injected with high speed and high pressure, and resulted in the formation of the casting blow-hole. Thus it was considered that to prevent these troubles a flow of these gases should be lead out towards a certain direction. Three methods to take the gas in the cavity out which are the pressure reduction method, the blowing gas method and the method combining the two previous methods were employed in this die-casting experiment for ZnDC 2 and ADC 12 alloys.
  In the case of the pressure reduction method, gas in the cavity flowed into the pressure reducing tank connected to the vent hole of dies. In the flowing gas method, gas in the cavity flowed outside through the vent hole passing a constant flow of gas from the pouring hole. In the method combining the two methods, the gas flowing into cavity were immediately evacuated with the pressure reducing tank.
  The results obtained by these developing techniques of die-casting in this experiment are summarized as follows.
  (1) As compared with an conventional die casting method, it was easy to prevent the die-casting blow-hole formation with this method.
  (2) The tensile strengh of castings produced by this method was 10-15% higher than that by a conventional method.
  (3) The castings produced was confirmed to withstand heat treatment and facilitate surface polishing.

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  It is usually believed that nitrogen in cast iron is a stabilizing element of cementite, but the cementite-stabilizing effect differs with the state of nitrogen in the cast iron.
  In the present paper, the state of nitrogen in cast iron from the molten state to room temperature was studied. Most specimens were cast in graphite mould of various temperatures and quenched in water after a fixed holding period. Several specimens were made by sucking out the melt by quartz tube, and some were cast in dry sand moulds. Most of these specimens were electrolyzed for the isolation of cementite. The nitrogen content was analysed by JIS distillation mdthod. The results are as folllows :
  (1) Nitrogen addition in the melt leads to some formation of Si₃N₄ but most of the nitrogen dissolves in the melt. The proportion depends on the silicon content and the temperature of melt.
  (2) When the melt solidifies to gray iron, a part of the dissolved nitrogen is degassed, but the remaining nitrogen moves into the austenite. Some nitrogen in the austenite dissolves in the eutectoid ferrite by a eutectoid reaction, but the remaining nitrogen moves into the eutectoid cementite. With the lowering of the temperature Si₃N₄ is formed both in the cementite and the ferrite, and by further lowering of the temperature some dissolved nitrogen changes to either Fe₁₆N₂ or Fe₄N, and the remaining nitrogen continues to dissolve in the cementite and the ferrite.
  (3) When the melt solidifies into white iron, during the eutectic solidification some nitrogen in the melt moves into the cementite, but the others are dissolved in austenite. The behaviour of nitrogen depends on the cooling rate of the casting. The behavior of nitrogen after solidification is very similar to that of gray iron.

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  Graphitic steels are those steels which are in the hypereutectoid range and have spheroidal graphites in the as-cast state. This research can be summerised as follows :
  (1) Gray cast irons with the largest graphitizing tendency have oxygen and sulfur contents in the range of 20-30 and 150-300 ppm, respectively. It can be assumed that the contents of those of the graphitic steels are equal to those of the gray cast irons having the largest graphitizing tendency.
  (2) Use of carbide slag before and after melt down of raw iron materials effectively decreases oxygen contents of these steels and improves the behaviours of graphtization, that is, form of graphite is more spheroidal, nodules are increased and sizes become smaller than when carbide slag is not used.
  (3) Concerning the fading phenomena after inoculation, there is almost no degradation in spheroidal form of graphite and sizes of graphite become smaller with lapse of time.

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  The straightening of the distortion in steel castings is done by hot-working at the locally heated part. The purpose of this study is to clarify the changes in the structure and mechanical properties of normal carbon steel casting (SC 46) during hot-working under extreme experimental conditions.
  The results are as follows ;
  (1) At the working-part, the yield-strength increased from 24-25 kg/mm² to 25-36 kg/mm² and the elongation decreased from 18-19% to about 13%.
  (2) The impact-value and hardness increased.
  (3) The micro-structure changed to normalized-structure.

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