To determine the details of the generation of moisture-condensed layer in a mold, a steaming apparatus was made and used to test various specimens.
  Results obtained were as follows :
  (1) The rise of pressure in the mold started slowly after the moisture-condensed layer was saturated and its temperature was 100°C
  (2) When a high pressure steam was passed through the specimen, pressure at the inlet side of the specimen was high and pressure gradient in the specimen was large.
  (3) When the steam was passed through the specimen, the steam condensed, in other words the behavior of the steam passing through the specimen was entirely different compared with air.
  (4) It was found that the moisture and bentonite content affecting the generating speed of saturation zone differed.
  (5) It was confirmed that the steam passing through the specimen formed the condensation zone and then further penetrated into the mold. Moisture content of the condensation zone was calculated and a good approximation was obtained.

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  The solidification of cast iron has been studied by means of remelting small amounts of high purity cast iron in a specially designed high vacuum and high frequency inducation furnace. The meltings were closely controlled to minimize possible influence of impurities and gases. The results show that as the holding temperature of melt raised and the cooling rate of melt increased the spheroidal graphite was formed in Fe-C-Si alloys containing a large amount of silicon, and mottle iron structure (inverse chill) emerging from a two-step eutectic reaction was observed in hypoeutectic alloys. The objective of this study was to investigate the solidification behavior of these two alloys.
  The following conclusions were drawn :
  (1) Eutectic solidification starts with gray in high purity cast iron remelted and solidified in a vacuum with a cooling rate of 10-143°C/min (average cooling rate at a temperature range of 1,170∼1,200°C ).
  (2) In a certain range of cooling rate decided by the composition and the holding temperature of melt the eutectic may solidify with either white or gray. Eutectic solidification which was initially gray transformed to white. The cooling curve indicates two eutectic reactions and inverse chill is formd.
  (3) This range shifts to the high cooling rate side and becomes narrower with either the increase in carbon equivalent or the decrease in the holding temperature of melt.
  (4) In vacuum-melted high purity cast iron, the spheroidal graphite is formed without the usual treatments. The conditions for the formation of spheroidal graphite are similar to that for the inverse chill in relation to the holding temperature and cooling rate of melt.
  (5) The main factor responsible for these phenomena is purity of cast iron.

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  The cause of inverse segregation in the Cu-Sn alloys is a problem still awaiting solution, although there have been a number of brief information on it. In this work, the dependence of absorbed gases in the Cu-Sn alloys on the inverse segregation was systematically investigated on the bases of morphologies of solidified structure and gas analysis. The alloys were molten under a controlled atmosphere and were solidified unidirectionally or bidirectionally. Melting in the reducing atmosphere caused stronger inverse segregation. Hydrogen gas had a strong effect on the inverse segregation. No relation was found between macroporosities and inverse segregation.

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  The static and dynamic elastic moduli and stress-strain properties of cast iron under repeated tensile stress were examined. Longitudinal permanent and recoverable strain by cyclic tensile stress were measured with electrical resistance strain gauge. Both moduli, dynamic and static, under repeated tensile stress proved to be equal intrinsically. The length of the straight line of the repeated stress-strain curve, indicating where the stress and strain was in proportion, decreased to zero or to a certain stress level as the stress-cycle increased. The elastic modulus of cast iron (stress/recoverable strain) also decreased slightly as the stress cycle increased. When the repeated stress was less than about 50% of it's fracture stress, the permanent strain of cast iron per stress cycle decreased. But when more than about 50%, the permanent strain did not decrease to zero and kept a certain value, as Gilbert has elucidated. In the case of the hyper-eutectic cast iron or relatively softer cast iron, this stress limit of about 50% of fracture stress decreased to below 40% and clearly showed downward propensity as the strength of cast iron decreased.

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  The authors have pointed out¹⁾ previously that the differences in the characteristics between induction-melted iron and cupola-melted iron and the modification of properties followed by changing steel ratio in raw materials closely corresponds to the nitrogen content in iron. Furthermore, authors have determined the nitrogen content of various carburizers and found that the nitrogen content varied form a trace amount up to a few percent. From these results, it may be predicted that the properties of iron carburized with different kinds of carburizers alters. The present work was conducted to verify our prediction and to clarify the effect of the various kinds of carburizers on the properties of iron melted.
  In this investigation, electrode graphite (N : trace) and pitch coke (N; 0.63%) were used as carburizers and their influences on a comparably high carbon equivalent, 4.0 to 4.8, induction-melted iron was studied. Melting of 100kg charge with high steel ratio was done in a medium frequency indudtion furnace with magnesia lining.
  The following results were obtained.
  (1) Iron carburized with pitch coke ( hereafter referred to as p-iron) showed higher tensile strength and hardness than the one with electrode graphite (hereafter referred to as e-iron). These differences in strength of the two iron became more evident especially when the holding time of the melt was short. The strength of p-iron was as much as twofold of that of e-iron.
  (2) The chilling tendency was higher in p-iron than in e-iron, the difference of which in-creased as the carbon equivalent became higher.
   (3) As for the thin section castings prepared from a melt held for a long time, e-iron may became harder than p-iron.
  (4) The nitrogen content of p-iron melt was very high when the holding time of melt was short and it decreased with time. On the other hand, the nitrogen content was generally low in e-iron melt and changed little with time. The variation of nitrogen content with time corresponded well with the variation of strength in iron.
  (5) E-iron tended to show a well prolonged A-type graphite structure. On the other hand, p-iron tended to show a mixed structure of A-, D- and E-type graphite.
  (6) P-iron held for a short time in melting tended to show pearlite matrix structure. But p-iron held for a long time and the e-iron showed a ferrite matrix structure.

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