鋳物
Online ISSN : 2186-0335
Print ISSN : 0021-4396
ISSN-L : 0021-4396
48 巻, 9 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
  • 宇佐美 正, 鈴木 敏光, 小原 文夫, 芹田 陽
    1976 年 48 巻 9 号 p. 557-562
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      This paper is one of the serial investingations on the structure of white cast iron. This paper focuses on the relationship between the structure and the solidification conditions of eutectic and neary eutectic Fe-C-3.0%Cr and Fe-C-3.0%Cr-3.0%Mo alloy solidified unidirectionally under controlled conditions. Round castings of the alloys, 8.5mm diameter and 30mm length were melted and solidified unidirectionally by downward motion at constant speeds in a vertical furnace. The solidification rates were controlld within the range of 101.3 to 3.0 mm/hr.
      As the solidification rate decreased, the ledeburitic eutectic structure of F-C-Cr alloy, which were almost rod-like, became coarse and chrysanthemum-shaped. This structure change was also observed by adding Ni and V to this alloy. The formation of chrysanthemum-shaped eutectic structue was also affected by the temperature gradient in the liquid ahead of the solid-liquid interface. As for Fe-C-Cr-Mo alloy, the change into chrysanthemum-shaped eutectic structure was hardly observed. The chrysanthemum-shaped eutectic structure was closely related to the shape of the primary austenite.
  • 大和田野 利郎, 鳥越 清, 神崎 郁美
    1976 年 48 巻 9 号 p. 563-567
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      Solidification of spheroidal graphite iron of Fe-C and Fe-Si-C eutectic alloy systems was analytically investigated by means of quantitative metallography. Small specimens, some of which were inoculated, were cooled and solidified at varied rates and quenched at about 1,000°C. The volume fraction of graphite VG and the number of graphite nodules in a unit area NA were measured in a longitudinal section of each specimen. Growth rate constants of austenite spheres in liquid K were computed by
        V-1/3NAKtS=0.33,
    where tS denoted the conventional time for complete solidification at an average temperature. The values of K thus determined were all in good accordance with those Fe-C and Fe-Ni-C eutectic alloys reported previously. The above equation and the temperature dependent values of K explained the small undercooling in Fe-Si-C and inoculated alloys with increased nodule numbers. A chart for computation of NA, which is one of the important matrix controlling factors, from temperature and time of solidification was also shown.
      As the maximum value of K determined was approximately 4×10-7cm2/sec, VG-1/3NAtS should be larger than 8.25×105 sec/cm2 in order for solidification to be completed by diffusion controlled gowth of austenite spheres under consideration. Otherwise, a different mechanism must be considered in the solidification process of ledebulite formation among austenite spheres, which occured in the later stages of solidification when Fe-C alloy was cooled relatively fast.
  • 高瀨 孝夫, 中村 康彦, 高田 良規
    1976 年 48 巻 9 号 p. 568-573
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      The dry wear resistance of liquid nitrided (Tuftride Process) spheroidal graphite cast iron with ferritic and bull’s eye’s matrices were investingated by Amsler wear testing machine. Perfect rolling, perfect sliding and rolling accompanied by a small amount of sliding were repeated on the surface of the specimens.
      Under perfect rolling and sliding conditions, the wear resistance of nitrided irons was higher than that of non-nitrided irons. It was found that ferritic iron offered the most effective wear resistance by nitriding. The wear resistance of nitrided irons is high due to the specially superior property of the Fe nitrided surface layer against wear resistance and the increase of fatigue strength at the diffusion zone. Under rolling with sliding, it was found that nitrided irons always exhibited a higher wear loss than those of non-nitrided irons owing to the decomposition of Fe nitride by the higher shearing stress concentration at the surface compound layer.
  • 森 正博, 乾 仙之助
    1976 年 48 巻 9 号 p. 574-578
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      With respect to optimum molding sand control in high pressure molding, the meaning of “mold-ability” and “compactability” was examined. Formulation of molding sand characteristics with the molding sand composition changed is also a necessary step in electronic data processing of system sand operation. A multiple regression analysis (by a stepwise procedure) was successfully carried out for 9 molding sand characteristics on 14 kinds of molding sand mixtures. Molding characteristics with the same meaning proved to have a similar form of equation.
  • 小幡 錬
    1976 年 48 巻 9 号 p. 579-584
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      A riser equation considering the solid volume solidified during pouring is derived as follows :
        [Written in non-displayable characters.]
    where; Fct=Act/Vc2/3, shape factor of casting, Act=total surface area of casting including riser-casting contact area, Vr, Vc=Volume of riser and casting, K=(height of riser) / (diameter of riser), β=Fraction of solidification contruction (0.05 for steel), Vf=solidified volume in the casting during pouring.
      It is found that the adequate volume of riser decreases as the volume solidified during pouring increases. For a cube shape steel casting, pouring so as to make the ratio Vf/Vc be equal to 0.3, the riser determined from the equation behaved as the optimum riser. A riser equation is derived on a condition of pouring additional melt to fill the shrinkage cavity formed in the riser after the first pouring. The required volume of riser for additional pouring decreases by increasing the volume of solid solidified in the casting befere additional pouring.
  • 山内 勇, 大中 逸雄, 福迫 達一
    1976 年 48 巻 9 号 p. 585-591
    発行日: 1976/09/25
    公開日: 2012/09/13
    ジャーナル フリー
      Numerical simulation was made on such casting parameters govering the solidification profiles as the level of meniscus, holding period in an intermittent casting operation, casting speed and mold diameter by the conventional forward explicit difference method considering two dimensional heat flow. If the meniscus level is low or the mold diameter is small, ring-like defects are easily formed on the internal surface of a pipe. This may be caused by prefered solidification at the meniscus where conduction heat loss to the upper solid shell or convection and radiation to the atmosphere play important roles. If the meniscus is higher than the mold height, defects are reduced but the solid shell is reheated near the melting point and then broken often. These predictions are experimentally confirmed.
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