鋳物

研究論文

発泡鋳型による精密鋳造法の研究

安達秀男, 北野隼男, 表修

1966 年 38 巻 10 号 p. 691-700
発行日: 1966/10/25
公開日: 2012/10/10

DOIhttps://doi.org/10.11279/imono.38.10_691

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  In order to get small bubbles dispersed in the muddy mold materials (=slurry), the small amount of bubbling powder was added into the slurry mixture of refractory materials colloidial silica with basic or acid gelatinizer as a binder. The mold was made by pouring the molding materials the small bubbles dispersed into the pattern, and was kept to be hardened, The pattern was removed while the mold was still in plastic condition. The mold has to be kept more to be hardened. Many small cracks were grown between these small bubbles on leaving, and less dimension change occured, It is known that the common muddy material have big cracks on hardening by absence of bubbles and big dimension change occured.
  In show process mold dimension is kept constant owing to the number of cracks produced in impact heating. However, this method gave many small cracks spontaneously. Many small bubbles in the mold was effective not only for the accurate dimension of the mold, but to prevent from the heterogeneous state of mold caused by the difference of grading and gravity of the refractory materials and improve the fluidity of it.
  It was possible to get the smooth casting surfaces of mold if the unti-bubble reagent with seperating effect was dressed on the pattern.

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逆チルの発生について

植田昭二, 菊永牧男

1966 年 38 巻 10 号 p. 700-706
発行日: 1966/10/25
公開日: 2012/10/10

DOIhttps://doi.org/10.11279/imono.38.10_700

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  The object of the present paper is to introduce the proposed mechanism by which inverse chill forms.
  With respect to inverse chill, the majority of investigators have expressed the view that the high content of sulphur, oxidized iron and the absorption of hydrogen promote the defect and the inverse nature of the chill is due to the segregation effects of their elements. But the results of chemical analysis have seemed far from conclusive and the segregation has not been observed by many foundrymen.
  The proposed mechanism is mainly based on the constitutional supercooling which would take place in the solidification of primary austenite, without taking the segregation effects into account.
  The summary of the mechanism is as follows :
  With the growth of primary austenite from a liquid the concentration of solute in the liquid at the interface will rise and the liquid adjacent to the interface would become constitutionally supercooled.
  If this instability causes the interface to break down into an array of austenite dendrites and the solute redistribution in the liquid forms just before the eutectic solidification starts, the liquid will be more greatly supercooled with respect to the second phase because the concentration of solute in the liquid is sharply increased, and this will create a tendency for carbide nucleation to occur.
  This consideration is verified by the observation of microstructural features in the inverse chill.

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2t MBC キュポラの溶解特性に関する研究

生井享, 牧口利貞, 菊地政郎, 村松晃, 持田忠明, 馬場孝

1966 年 38 巻 10 号 p. 707-716
発行日: 1966/10/25
公開日: 2012/10/10

DOIhttps://doi.org/10.11279/imono.38.10_707

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  The authors constructed 2-ton MBC cupola which was unlined, water cooled and able to be operated with hot blast above 500°C. The furnace was used for the following two purposes.
  1) To determine the optimum operating conditions of the furnace.
  2) The examination of the operating characteristics of the furnace.
The experimental results obtained using optimum operating conditions were summarized as follows.
  In this furnace the decrease of silicon and manganese was very little, but occasionally a slight increase in silicon was observed.
  From these results it was considered that the atmosphere in the furnace was reducing and consequent reduction of semi-reduced iron ore and the like would be expected.

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Al-Si系合金の凝固過程に関する研究

津田昌利, 江川勝一

1966 年 38 巻 10 号 p. 716-727
発行日: 1966/10/25
公開日: 2012/10/10

DOIhttps://doi.org/10.11279/imono.38.10_716

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  With a view to comprehend the basic properties of a metal in itself, it is important to investigate the properties of the metal by it’s solidification process.
  This works, using the hypo-eutectic, eutectic and hyper-eutectic compositions of Al-Si system alloys, have involved an inquiry of the solidification process by quenching method.
  The microstructure of a metal is mainly lead to change with the phase transformation. Similarly in Al-Si system alloys, the microscopic change with the eutectic reaction has been remarkable and it has been comfirmed that the proeutectic and the eutectic structure had been resulted in abrupt coarsening at the temperature slightly above the eutectic. So it is considered that the degree of the reduction of crystal coarsening tendency is in relation to the proeutectic refinement.
The results obtained were as follows :
  (1) Little effect of the duration of time in liquid state on microscopic changes was observed.
  (2) As the temperature comes down slightly above the eutectic, the proeutectic silicons in hyper-eutectic alloy become very fine.
  (3) The phenomenon of crystal coarsening at the temperature slightly above the eutectic was so remarkable that it would be considered that the degree of the coarsening depended upon the cooling rate through this temperature range.
  (4) After eutectic solidification, the dendrite of α-phase, the eutectic and the proeutectic silicon made gradual coarsening.

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