In this report the quantity of AlN in cast iron melt with varied Si content was investigated. The following results were obtained.
  1) The mechanism of graphitization by Al added to the cast iron melt is related to both its effect to neutralize the chilling tendency by nitrogen and its own effect of enhancing graphitization. The mechanism is independent of the presence of Si.
  2) The quantity of AlN is influenced by the Si and Al contents. Si tends to hinder the formation of AlN.
  3) AlN formed has the tendency to separate from the melt. This tendency becomes marked with increasing Si content.
  4) As the Si content gets higher the formation of AlN reaches a saturation point at a lower Al content and the proportion of N as AlN in the total combined nitrogen gets lower.

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  The work intends to examine the utility of the high frequency capacitance method as a moisture tester of bentonite-bonded sand. The “cylindrical grid electrode” and the Schering bridge were adopted as an electrode and measuring method. The dielectrical index, ΔC_x vs. moisture curve expresses a linear increase when bentonite is not added. The curve, however, becomes a steeply increasing one when bentonite is added at an amount as small as two parts. The curve shifts to the higher moisture side with a further addition of bentonite. Satisfactory measuring sensitivity was obtained only in the lower moisture range. The characteristic increase of ΔC_x at the lower moisture range appears to correspond to the formation of specific numbers of rigid water layer at the interlayer of bentonite particles.

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  Distribution of metal flow in multiple ingate systems for cast iron was studied. The results obtained are summarized as follows.
  1) When all the gates have the same dimensions, more metal passes through the gates at longer distances from the sprue bottom. This tendency becomes remarkable, when the gating ratio is large. In a divergent system, the quantity of metal flowing through ingate at the neighborhood of the sprue bottom is small, which is due to the fact that the runner is not filled with molten metal and the flow is agitated.
  2) Flowrates through ingates are almost proportional to the back pressure of the ingate. This means that the flow behavior is controlled by Bernoulli's law. The metal distribution ratio calculated by use of the coefficient of tube friction: 0.03, and the loss coefficient of bending: 0.7, coincides with that experimentally obtained in a shell mold gating system.

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  Inoculants containing calcium or other elements in the same periodic group are generally used for cast iron, because their chill reducing ability is much higher than that of the inoculants free of elements in the calcium group. To further promote inoculating ability of calcium, the gas bubbling method before inoculation was adopted in order to remove inhibiting substances such as gasses and inclusions in the melts. It was found that this method was superior in effect as pretreatment of iron inoculation. Effectiveness of gas bubbling method was tested under several conditions, i.e. iron melts with various C.E. levels, or those containing chilling elements such as manganese, chromium and sulfur. As the gasses for bubbling, nitrogen, carbon dioxide and air were compared with argon with regard to the chilling tendency. All the test results showed markedly good effects in decreasing cast iron chilling with the exception of high sulfur level melts.

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  In designing metal mold for casting, it is important to estimate the thermal stress generated in a mold. The analysis must take into account non-linearity of mold material, temperature dependence of material properties and thermal history.
  In this paper, thermal stress of semi-infinite cylindrical metal mold was analyzed by a computer program following the finite element method taking the above conditions into consideration. The results revealed the influence of thickness and initial temperature on the thermal stress in mold in a short time range after pouring. The application of the results of the calculation to real situations was discussed.

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  Commercial pure iron, Fe-Cr, Fe-Si and Fe-C alloys were dipped into molten Al-Si alloy baths (JIS AC4C and ADC12) at 800°C and rotated at various speeds for varying length of time. Study of alloy layer formation and the corrosion behavior was made and the results were compared with the results obtained in the static molten Al-Si alloys, static molten pure Al and dynamic molten pure Al baths. The thickness of the alloy layers was almost constant independent of the rotating speed and the dipping time. The major portion of the alloy layer was occupied with FeAl₃. The amount of Fe₂Al₅ was less than that in the case of the static Al-Si alloy baths. The dissolution rate of each alloy increased as the rotating speed increased. As in the static molten Al-Si alloys, as well as static and dynamic molten pure Al baths, the corrosion resistance against molten Al was highest in Fe-C alloy and lowest in Fe-Si alloy. The dissolution process of the commercial pure iron, Fe-Cr, and Fe-Si alloys appears to be controlled by the diffusion of Fe in molten Al. At high rotating speed, the dissolution appears to be further accelerated by mechanical erosion with molten Al, while at low speed, it is accelerated by natural convection. However, the dissolution of Fe-C alloy is presumably retarded by mass transfer or chemical reaction resistance in the alloy layer.

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