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49 巻, 8 号
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研究論文
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鷹取 正六, 太田 祥隆1977 年 49 巻 8 号 p. 471-477
発行日: 1977/08/25
公開日: 2012/07/10
ジャーナル フリーLow carbon steel pipes of 10mm thickness, 170mm external diameter and 2.3m in length and similar pipes with a flange attached at one end were cast by water shower cooled metal mold centrifugal casting process under different conditions, and relations between these conditions and tear on cast pipes were studied. The experiments were carried out in the range of average thickness 0.06-0.6mm of refractory coating on the inner surface of mold and number of times gravity 30-125.
The thinner the coating, the higher the spinning speed, the lower the thermal conductivity of coating, and the more the amount of bentnite in coating is, the more the tear is apt to occur. The tears were only circumferential hot tears on the outer surface of pipes at the longitudinal position where metal has solidified finally. Circumferential hot tear is caused by the restriction on the longitudinal thermal contraction of solid skin along the outer surface of the full length of cast pipe. Centrifugal force raised this restriction in relation to the behavior of fine refractory particles in the coating. The easier the longitudinal movement of fine refractory particles is, the more loosened is the restrictions, then the tear is not apt to occur.抄録全体を表示PDF形式でダウンロード (741K) -
尾崎 良平, 岡田 明, 三宅 秀和1977 年 49 巻 8 号 p. 478-482
発行日: 1977/08/25
公開日: 2012/07/10
ジャーナル フリーThe ability of the catalysts to nucleate the graphite-γ eutectic is judged by considering simultaneously the nucleation temperature, at which the most powerful catalysts generate the nuclei, and the number of nuclei grown before recalescence. The nucleation temperature is to be indicated by the temperature of initial arrest revealed just after the crystallization of primary γ on the cooling curve and the number of nuclei is indicated by the number of eutectic cells in samples quenched at the minimum temperature before recalescence in the eutectic solidification. Fe-C, Fe-C-Si, Fe-C-S and Fe-C-Ti alloys were, respectively, molten and solidified as gray cast iron in a SiC-resistance furnace under accurately reproducible conditions. Thermal analysis was carried out during the cooling. The number of eutectic cells was counted in samples quenched at various stages during cooling.
Under the experimental conditions, the nucleation temperature appeared clearly on the cooling curve, but no cells appeared in samples quenched at the minimum temperature in the eutectic solidification, excect Fe-C-Ti alloy. The number of nuclei, however, was indicated by the number of cells in the furnace-cooled castings, except for the alloy containing surface active elements such as sulfur. In the case of an Fe-C-S alloy, it was complicating to express the number of nuclei experimentally because it was not indicated by the number of eutectic cells in the casting.抄録全体を表示PDF形式でダウンロード (551K) -
中村 幸吉, 炭本 治喜1977 年 49 巻 8 号 p. 483-488
発行日: 1977/08/25
公開日: 2012/07/10
ジャーナル フリーThe chilling of the gray cast iron is generally dependent on the composition of the molten iron. When the same base metal (pig iron) was added to the molten iron and then casted, we observed that the chill depth of the gray cast iron decreased remarkably. The addition of the pig iron that decreased the chilling tendency without any change in the composition of the iron could be called as a kind of “the pig iron inoculation”. The amount of pig iron inoculation usually ranges from 3% to 20% and the inoculating effect is independent of the size and structure (gray or whtie) of the pig iron. Though the pig iron inoculation decreased the chilling tendency, it did not improve the strength of the cast iron.
Perhaps the following reasons developed the above phenomena. First, the temperature of the melt decreased due to the pig iron addition, then the graphite in the pig iron melted rapidly to form a carbon nucleus like a carbon micro-group which decreased the chilling tendendy. The stopping of the chilling tendency by the pig iron addition is very strong. Therefore, this means is very effective in decreasing the depth of the chilling tendency of the melt in the low frequency furnace melting and in the metal mold casting.抄録全体を表示PDF形式でダウンロード (726K) -
岩淵 義孝, 鈴木 是明, 中田 進一1977 年 49 巻 8 号 p. 489-494
発行日: 1977/08/25
公開日: 2012/07/10
ジャーナル フリーThe effect of quality heat treatment condition on the mechanical properties and temper embrittlement of 2¼Cr-1Mo cast steel for turbine cylinder castings are presented in this paper. Mechanical properties after quality heat treatment were shown as a function of the cooling rate from austenitizing temperature and Larson-Miller's tempering parameter.
When the cooling rate was faster than 20°C/min, uniform bainite or mixture of bainite and martensite with no blockish ferrite, which caused excellent mechanical properties, was obtained and tensile and impact properties were improved with the increase of tempering parameter. The degree of temper embrittlement 2¼Cr-1Mo cast steel is affected by chemical composition and heat treatment. It has been proved that the lower temper embrittlement parameter and the cooling rate faster than 30°C/hr from tempering temperature are necessary to obtain excellent notch toughness.抄録全体を表示PDF形式でダウンロード (703K) -
相馬 詢, 長岡 金吾1977 年 49 巻 8 号 p. 495-500
発行日: 1977/08/25
公開日: 2012/07/10
ジャーナル フリーIn order to investigate the effect of the shapes of graphite on the growth of forged spheroidal graphite cast iron with flattened graphite nodule was cyclically heated to 950°C and examined. Both as-cast and grown irons were forged with the forging ratio of 25% and 50%. The growth of spheroidal graphite iron increased by forging, and especially in grown iron, the growth characteristics which had declined recovered extremely.
The growth of spheroidal graphite iron increased by about 20% with the forging ratio of 25%, and by 10%, with the forging ratio of 50%. At the tip of the graphite nodule which was flattened by forging, there was a preferential reprecipitation of graphite after cyclic heating. Though the microstructure of the matrix did not change by forging, specific gravity and hardness of grown iron increased remarkably. Growth rate of iron decreased after previous 10% growth in air, but increased more than 2.0 times by forging with reduction of 25% compared with the unforged specimen. The characteristics of the growth of iron can be explained generally by the mechanism of irreversible migration of graphite. The recovery of growth by forging in grown iron may be due to the increase of graphite migration due to the mechanical reduction of grown voids.抄録全体を表示PDF形式でダウンロード (763K)
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