鋳物
Online ISSN : 2186-0335
Print ISSN : 0021-4396
ISSN-L : 0021-4396
59 巻, 4 号
選択された号の論文の7件中1~7を表示しています
技術報告
研究論文
  • 毛利 勝一, 柳本 智明, 森 和胤
    1987 年 59 巻 4 号 p. 205-210
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      Molten 9%Ni cast steel being stirred electromagnetically was solidified in furan molds having cavities 100 and 150mm in thickness, and the steel containing Zr was solidified in the same manner in a mold having a cavity 90mm in thickness for preventing intergranular cracking. Both castings 90mm in thickness stirred and unstirred are insusceptible to cracking. Castings 100mm in thickness stirred are insusceptible to cracking, but those unstirred are susceptible. Fine cracking occurs both in castings 150mm in thickness stirred and unstirred. The fracture surface analysis shows that an embrittling solute significantly segregates toward grain boundaries and that electromagnetic stirring during solidification has an effect of moderating grain boundary segregation.
  • 小林 俊郎, 山本 浩喜, 高林 幸央
    1987 年 59 巻 4 号 p. 211-216
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      Static and dynamic crack initiation resistance toughness (JIC, JId) and crack propagation resistance toughness (J-Δa curve, Tmat) of austempered low alloy ductile iron were evaluated by direct current electrical potential method and instrumented Charpy impact test with compliance changing rate and key-curve analyses. The compliance changing rate and key-curve analyses are effective for evaluating dynamic crack initiation and propagation resistance toughness in this type of iron. QB' treatment [quenching in oil bath after holding in the γ-phase region for a short time and austempering after holding in the (α+γ) region] and B' treatment [austempering after holding in the (α+γ) region] improve crack initiation and propagation resistance toughness of Mn and Ni added iron.
  • 阿部 利彦, 藤田 克輔, 明石 起之助, 井川 克也
    1987 年 59 巻 4 号 p. 217-221
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      Ultrasonic methods were applied to measuring thickness and calculating stress concentration coefficient induced by graphite. Thickness of cast iron measurable by the ultrasonic mathod is limited by noise echo scattered at flaky graphite in gray cast iron. The maximum thickness TL (mm) measured by 5MHz probe is proportional to the sound velocity v(m/s) in gray cast iron as : TL=0.022v-58.9. The thickness less than 20mm is unmeasurable in severely corroded cast iron because the incident ultrasonic beam is strongly scattered at the corroded and waved interface. The measureable thickness is limited up to 100mm both in CV and ductile cast iron. This limitation is yielded not by the graphite origin noise echo but by the echo reflected at any planes other than the object bottom plane. Stress concentration coefficients induced by graphite are calculated through ultrasonic sound velocity, tensile strength, Brinell hardness and pearlite area fraction as 1.6 to 4.8 for gray cast iron, 1.25 for CV graphite iron and about 1 for ductile cast iron.
  • 西村 章, 川野 豊, 藤田 健治
    1987 年 59 巻 4 号 p. 222-227
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      Correlation between grain forming characteristics and factors governing grain size was discussed from the viewpoint of grain distribution and the grain forming time estimated by a simple solidification model. The factors include molten metal stirring, Ti addition, cooling rate and purity of aluminum. New grain formation in high purity aluminum proceeds till the later stage of static solidification than that in low purity aluminum. Most of grains form both in low and high purity aluminum nearly at the same time in the early stage of solidification when they are stirred. Stirring has an opposite effect on aluminum containing 0.2%Ti. When the cooling rate is accelerated, a number of grains form, and the formation of new grains proceeds over the prolonged period throughout the solidification in aluminum being stirred or not.
  • 神戸 洋史, 錦織 貞郎, 本間 梅夫, 雄谷 重夫
    1987 年 59 巻 4 号 p. 228-232
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      The residual liquid in solidifying Al-5mass%Si and Al-3mass%Mg alloys was forced to flow into a tube at different fractions solid by compressing. The apparent permeability of residual liquid was calculated from the flow rate of liquid and pressure in Darcy's equation. The interdendritic fluid flow proceeds at fractions liquid within a range from 0.6 to 0.2. The apparent permeability is nearly proportional to the cube of fraction liquid. When slender dendrites are growing in Al-5mass%Si alloy, the apparent permeability is lower at the same fraction liquid. When shorter and rounded dendrites are growing in Al-3mass%Mg alloy, on the other hand, the apparent permeability is higher. Independent of alloy systems, the apparent permeability is almost proportional to the 2.5th power of the hydraulic radius which depends on the geometory of dendrites.
  • 粟野 洋司, 清水 吉広
    1987 年 59 巻 4 号 p. 233-238
    発行日: 1987/04/25
    公開日: 2011/09/23
    ジャーナル フリー
      When Al-Si alloys contaminated with Fe were superheated above 800°C and cast, Chinese scripts of an AlFeSi compound crystallized instead of needle-like compounds T2 or β-AlFeSi. In oder to clarify this phenomenon, effects of superheating temperature, thermal histry of the melt after superheating and solidification time on the crystallized structure of AlFeSi compounds and crystallizing prosess were examined. Chinese scripts of AlFeSi compounds crystallize in the Fe-enriched residual liquid through nonequilibrium solidification and are insusceptible to thermal history of the melt after superheating. Minor impurities have significant effects on the crystallized structure of AlFeSi compounds.
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