鋳物
Online ISSN : 2186-0335
Print ISSN : 0021-4396
ISSN-L : 0021-4396
51 巻, 2 号
選択された号の論文の6件中1~6を表示しています
研究論文
  • 与田 亨, 大石 芳宏
    1979 年 51 巻 2 号 p. 71-75
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      Carbon steel castings containing 0.83−0.87%C, 0.27−0.30%Si and 0.31−0.34%Mn were made by solidification under high pressures up to 3,000kg/cm2 using a metallic mold 45mm in diameter. In order to obtain castings that does not have shrinkage cavities, they must be kept under high pressure until they are completely solidified. Castings solidified under pressures over 1,000kg/cm2, showed refined pearlite structures. There was considerable increase in elongation and reduction of area and the impact strength was, also, improved with the increase of the pressure. For castings solidified through a mushy freezing stage, application of pressure is effective for obtaining sound castings.
  • ��田 千里, 坂本 敏正, 伊藤 孝道, 高田 寿
    1979 年 51 巻 2 号 p. 76-81
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      Effect of sulfur on the transition of solidification structure of iron-graphite eutectic were investigated by unidirectional solidification. In the eutectic containing sulfur less than 0.02%, the graphite structure transits from regular lamellar to irregular lamellar, colony, eutectic cell (fine graphite), successively, with the decrease in the ratio of temperature gradient G to growth rate V. In the eutectic containing 0.1%S, the graphite structure transits from irregular lamellar to eutectic cell (flake graphite), eutectic cell (fine graphite), successively, with the decrease in the G/V ratio. But irregular lamellar to eutectic cell transition was not so clear when the sulfur content was very high. Unidirectional solidification structure diagram can be drawn using these experimental results.
  • 福迫 達一, 久保 公雄, 大中 逸雄
    1979 年 51 巻 2 号 p. 82-87
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      Apparent thermal properties of the Vacuum Process Mold were measured for various mold materials by the pouring method. The chilling power (apparent thermal diffusivity) increased in order of silica sand, silicon carbide grit, zircon sand, mixture of steel shot and silica sand, and steel shot. But there was little difference between silicon carbide grit and zircon sand. Commercial pure aluminum was cast in these molds and the solidification times were measured. The solidification times calculated by Adams equation using the obtained apparent thermal properties coincided well with the measured values. The macrostructures and the mechanical properties of the commercial pure aluminum cylindrical castings were not affected very much by the chilling power of the molds examined.
  • 堤 信久, 今村 正人
    1979 年 51 巻 2 号 p. 88-92
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      Retardation of graphitization with bismuth causes the change of structure of synthetic gray cast iron having 1%Si and 3%C to be mottled or white cast iron. Morphological change of graphite in the process was analyzed by scanning electron microscope and quantitative television microscope. It became clear that total area of graphite as well as mottling ratio decreases with the amount of bismuth in cast iron. The graphite carbon content also decreases in the same way. The retardation effect of bismuth on the graphitization of gray cast iron during solidification in stable eutectic system is approximately one sixths of the effect in mottled cast iron. Consequently, it can be assumed that the number of bismuth atom necessary to retard the precipitation of approximately four thousand carbon atom as graphite during solidification is only one. On the other hand, it has been recognized from the experiment of measuring various items, such as area, size, axial ratio, excursion rate of graphite in eutectic cell while increasing bismuth that the form of graphite is always constant but the size of graphite becomes much finer compared with that of normal cast iron.
  • 大和田野 利郎, 岸武 勝彦, 藤井 峰雄
    1979 年 51 巻 2 号 p. 93-98
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      The shape and undercooling of the eutectic solidification front in flake graphite cast iron solidified unidirectionally were investigated by interrupting the solidification. At low growth rates in which graphite flakes were arranged to the overall growth direction, the undercooling at the solidification front increased nearly linearly with the growth rate. At high growth rates, the undercooling deviated from the linearity to a lower value and graphite flakes were curved to be a irregularly arranged structure. The average spacing of graphite flakes λ was expressed by the equation of λ=8.3×10−5R−0.53cm, where R was the growth rate in cm/sec. The graphite flakes were sheathed with austenite at the solidification front and the shape of the sheaths was found to be parabolic. The true radius of curvature at the tip of a sheath was independent of the undercooling and most of the radii fell in the range of 3−6μm. The parabolic shape of the sheath was attributed to the thickening growth controlled by carbon diffusion through austenite from the grooved liquid to the graphite flake in the center of austenite sheath.
  • 森 正平, 谷 耕治
    1979 年 51 巻 2 号 p. 99-104
    発行日: 1979/02/25
    公開日: 2012/06/02
    ジャーナル フリー
      Structural observation on dunite and some characteristics of olivine sand made from this raw ore produced from small scale Imono rocks found among the Higashi Akaishi ultra basic rock zone in Shikoku Island of Japan were studied. This dunite is surpentinized considerably and the ignition loss is approximately 6%. It contains small amount of chromite, magnetite, brucite, spinel and pyroxene. The grain shape is angular and goes up to a maximum value of 1.5 in terms of grain shape number. Endothermic reactions occurring at peak temperatures of about 400, 660 and 760°C and the exothermic reaction at 800°C peak temperature were observed. After 30minutes calcination at 900°C in air, the endothermic and exothermic reactions vanish and the ignition loss falls to less than 0.2%.
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