巻号一覧
後続誌
62 巻, 7 号
選択された号の論文の9件中1～9を表示しています
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技術報告
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片岡 義博, 宮﨑 俊行, 村井 香一, 中崎 一之1991 年 62 巻 7 号 p. 499-504
発行日: 1991/07/25
公開日: 2015/01/22
ジャーナル フリーFe-C alloys (Fe-3%C, Fe-3%C-2%Si) are made in Tamman furnace from electrolytic iron, electrode graphite and metallic silicon as raw materials and are cooled rapidly in water at 1200℃. Relationship between secondary dendrite arm spacing and cooling rate of surface structure irradiated pulsed with YAG laser beam is obtained.
Results are summarized as follows:
(1) Secondary dendrite arm spacing of the irradiated structure of Fe-3%C alloy is 1.7μm at a cooling rate of 1.0 × 107℃/min, and that of Fe-3%C-2%Si alloy is 1.3μm at a cooling rate of 1.1 × 107℃/min.
(2) Secondary dendrite arm spacing of the irradiated structure of Fe-C alloys becomes finer with silicon addition.
(3) Relationship between secondary dendrite arm spacing (d) and cooling rate (V) is given by d ＝ 300・V－1/3.抄録全体を表示PDF形式でダウンロード (3164K)
研究論文
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伊藤 公雄, 田中 照司, 福迫 達一1990 年 62 巻 7 号 p. 505-509
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーThe authors investigated the features, formation mechanism and prevention of HfO2 surface defects peculiar to directionally solidified materials which result from high temperatures of mold and melt, as well as from highly active Hf in melt. It was made clear that improper moldmaking process tends to cause formation of SiO2 films on fired mold surface, which readily react with Hf in melt, bringing about formation of linear surface defects, and that the defects can be prevented by suppressing formation of the films.抄録全体を表示PDF形式でダウンロード (893K) -
井ノ山 直哉, 川瀬 欣也, 山本 悟, 川野 豊1990 年 62 巻 7 号 p. 510-516
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーThe mechanism of pearlite stabilization of additional elements such as Mn, N, Sn, Sb, As, S, P and Cu has been investigated by elucidating of the characteristics and behaviour of such elements during solidification or annealing process in cast irons.
Both manganese and nitrogen are more enriched in eutectoid cementite than in eutectic cementite. Therefore, eutectoid cementite is more stabilized than eutectic cementite and the development of pearlite structure is promoted when Ar1 transformation occurs.
The addition of tin, antimony, arsenic, or sulfur promotes the pearlite formation because each element forms covalent intermediate phases around cementite or at ferrite-grain boundary. Each element prevents the diffusion of C-atoms onto graphite and suppresses the growth of graphite.
Phosphorus in ductile iron is enriched at spherical graphite/γ-iron interface or at the ditch of γ-iron shell during solidification and exists as a phosphide. In such a case, phosphorus prevents the growth of graphite and promotes the formation of pearlite structure in similar way as in the case of Sn, Sb, As, or S addition. On the other hand, phosphorus is easily dissolved into γ or α iron during slow cooling or annealing. Therefore, if phosphide is decomposed and dissolved into γ or α iron by annealing, the formation of pearlite structure is not promoted.
Copper is usually used as a pearlite-stabilizer although copper itself is a graphitizer. As for the reason, when copper and manganese coexist, the concentration of manganese is higher in eutectoid cementite than in eutectoid cementite when manganese alone exists, which results in the stabilization of eutectoid cementite.抄録全体を表示PDF形式でダウンロード (1807K) -
青山 正治, 小林 俊郎, 松尾 國彦1990 年 62 巻 7 号 p. 517-523
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーIn this study, effects of silicon content, section thickness and the special austempering treatment consisting of prequenching from the γ range followed by austempering from the (α+γ+Graphite) range on the toughness were evaluated by using instrumented Charpy impact testing machine. The ductile cast irons in the three levels of silicon contents in ranging from 1.5 to 3.5wt% with or without nickel and manganese were used.
Comparing with the standard austempering treatment, impact values in the special austempering treatment showed no remarkable change over a austempering temperature range from 250 to 400°C, and it was possible to obtain high impact value in a short austempering time too. The proper content of silicon was also suggested ; the sample containing 2.1wt%Si showed a high dynamic fracture toughness value.抄録全体を表示PDF形式でダウンロード (893K) -
殷 樺, 沢本 章, 村井 典子, 大城 桂作1990 年 62 巻 7 号 p. 524-529
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーTo clarify the hardenability of high chromium-niobium cast iron, the precipitation process of secondary carbide, the austenite retention and the hardness were systematically studied for irons with 2.5%C, 15%Cr, 0 to 4.5%Nb, 1 to 2.5%Mo, 0.6%Si and 0.8%Mn. They were destabilized at 800 to 1200°C for 120 min and then quenched into oil bath. As the destabilizing temperature rises, the secondary carbides corsen and decrease. The effect of niobium on the precipitation process is small, though columnar M23C6 and M7C3 precipitate in Nb-free iron and Nb-containing iron, respectively. The rise in destabilizing temperature increases the carbon content of austenite and hence increases the amount of retained austenite. Niobium slightly decreases retained austenite. The hardness of quenched iron takes the maximum value at a certain destabilizing temperature, as the hardness depends on both the amount and the hardness of martensite. The maxium hardeness is almost unchanged by the addition of niobium, though niobium tends to raise the destabilizing temperature for the maximum hardness. The hardness of tempered iron is also scarecely affected by niobium. These little influences of niobium are attributable to the very small values of partition coefficient of this element to primary and eutectic austenite.抄録全体を表示PDF形式でダウンロード (826K) -
香川 明男, 嶋本 芳久, 井手 康一1990 年 62 巻 7 号 p. 530-535
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーThe hot formability of iron-carbon-chromium alloys was examined by high temperature tension test. On the basis of the results obtained in the tension test, the alloys were hot-forged at temperatures higher than 900°C. The influence of hot-forging on the Elinvar characteristics of the alloys was investigated by Young's modulus measurement performed in the temperature range up to 250°C. The alloys containing carbon up to 4wt% had an excellent formability at temperatures higher than 1000°C. The alloys heavily hot-forged and followed by heat-treatment of quenching and tempering showed improved tensile properties at room temperature. Hot-forging caused an averaged elastic behavior of cementite which has anisotropic Young's modulus and its temperature dependence in as-cast alloys. It resulted in the separated temperature range where the alloys showed Elinvar characteristics. The critical composition where Elinvar characteristics was observed was demonstrated to be functions of forging-ratio and forging-direction.抄録全体を表示PDF形式でダウンロード (851K) -
岩田 靖, 米倉 浩司, 山本 善章1990 年 62 巻 7 号 p. 536-542
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーA computer system for analyzing the molten metal flow in die cavity of a plate shaped die castings has been developed. The molten metal flow in the die cavity was simulated by solving reformed 2D Navier-Stokes equations considering the thickness of the flow. The apparent kinematic viscosity of the actual flow in the simulation, 2cm2/s which conformed to the actual flow was obtained. With the simulation system using this coefficient, the molten metal flow in the die cavity of the plate shaped die castings having the gas defects was analyzed, enabling the decrease of the defects.抄録全体を表示PDF形式でダウンロード (818K) -
鹿毛 秀彦, 平岡 武, 上出 英彦, 田中 雄一1990 年 62 巻 7 号 p. 543-548
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーIt has been studied the role of graphite nodule size on the tensile properties of the austempered spheroidal graphite cast iron (ADI) from the standpoint of the matrix struture, particularly reacted and unreacted retained austenite.
The reacted high carbon and the metastable unreacted retained austenite were identified by the heat tinting technique, i. e., the reacted austenite was shown in purple color and unreacted austenite in light blue which appears in the eutectic cell boundary area due to solute segregation. Both the ultimate tensile strength and elongation were remarkably improved with decreasing the nodule size in accord with decreasing the amount of unreacted retained austenite. The unreacted austenite tended to transform to strain induced martensite during tensile deformation. The formation of martensite as a consequence of the formation of large amount of unreacted austenite caused a premature initiation of micro-cracks due to the higher notch effect of the particles such as non-metallic inclusion.
Therefore, it is concluded that high strength and high elongation in ADI are obtained by controlling the segregation of alloying elements at cell boundary, that is, by increasing the eutectic cell boundaries or by increasing the graphite nodule counts.抄録全体を表示PDF形式でダウンロード (897K) -
星野 和義, 坂井 卓爾, 黒澤 達也, 大谷 利勝1990 年 62 巻 7 号 p. 549-554
発行日: 1990/07/25
公開日: 2011/07/27
ジャーナル フリーSolidification of 37%NH4Cl aqueous solution under vibration in a clear acrylic resin mold is investigated to simulate the solidification of metals under vibration. In order to obtain constant power of vibration, the amplitude and the frequency of vibration are adjusted. Results obtained are as follows.
Wave height of the solution surface in the mold has biggest influence on the solidification structure of the solid. Resonance vibration is effective for a fine grain formation under a constant power of vibration. Temperature gap of the solution during solidification between at the surface and at the bottom is lowered by the vibration which has a high wave height. Vibration of the solution during solidification has little influence on structure of the solid in the corner part of the mold.抄録全体を表示PDF形式でダウンロード (870K)
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