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66 巻, 11 号
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研究論文
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小綿 利憲, 堀江 皓, 平塚 貞人, 千田 昭夫1994 年 66 巻 11 号 p. 803-808
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーThe refinement of primary slicon crystals in a hypereutectic Al-20 % Si alloy by the treatment of rare-earth element (RE) was investigated by measuring silicon grain size all over the specimen cast into iron moulds and sand moulds respectively. Silicon crystals were refined in specimens poured into metal mould after modification with RE. The EPMA analysis showed that RE was not detected in primary silicon crystals but in matrix structures of those specimens. A cooling curve obtained from a thermal analysis of these specimens showed that considerable amount of supercooling was observed at the RE-treated specimen. It is suggested that the refinement of primary silicons in the RE-treated hypereutectic Al-Si alloy mainly depended on the supercooling.抄録全体を表示PDF形式でダウンロード (762K) -
旗手 稔, 塩田 俊雄, 炭本 治喜, 中村 幸吉1994 年 66 巻 11 号 p. 809-814
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーLow thermal expansion flake and spheroidal graphite cast irons were produced from high-purity pig iron, steel and electrolytic nickel. The average thermal expansion coefficient (α) in the temperature range from 323 K to 373 K for the cast irons with chemical composition of 35 % Ni-2 % C-1.2 % Si amounts to be 4 × 10-6∼4.5 × 10-6/K and the values of α are considered to be independent of the shape and size of graphite. However, an increase in volume fraction of graphite caused by carbon addition results in an increase in the value of α at 373 K, and results inversely in a decrease in the value of α at the temperatures higher than 473 K. The values of α in low expansion cast irons were found to be dependent on Ni concentration and volume fraction of primary austenite.抄録全体を表示PDF形式でダウンロード (897K) -
松原 安宏, 笹粟 信也, 本田 義興, 武 宏強, 橋本 光生1994 年 66 巻 11 号 p. 815-821
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーMulti-component white cast irons varying in carbon content from 1.7 % to 2.9 % with approximately 5 % of each alloying elements (Cr, Mo, W, V and Co) were produced using a unidirectional solidification method. The morphology of as-cast microstructure was investigated on transverse sections at different solidification rates. From alloy concentrations and X-ray diffraction of carbides, nodular carbide and needle-like or fine lamellar carbide, which precipitate in all the irons, are found to be MC and M2C type respectively. The rod-like carbide which tends to crystallize mainly in the iron with higher carbon content and at lower solidification rate is M7C3 type. MC carbide increases slightly in size and noticeably in number with an increase in carbon content of iron. As the rate of solidification decreases, size of MC carbide enlarges and number of MC one redeuces greatly. M2C carbide changes its morphology from fine lamellar to needle and becomes thicker with increasing carbon content and decreasing solidification rate.抄録全体を表示PDF形式でダウンロード (1165K) -
宋 基敬, 朴 雪鍾, 中江 秀雄1994 年 66 巻 11 号 p. 822-826
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーThe influence of crucible materials and impurities in melt and as well as colling rate on modification rate are very important to clarify the modification mechanism in Al-Si alloy. We investigated the effects of these factors on modification rate of Al-Si-Sr alloy. For the purpose of this experiment, we had to keep the Sr content at the same level during experiments such slow cooling rate as 0.025 K/min. In our research, a self-sealing method was used to prevent the strontium from evaporating and oxidizing. The critical cooling rates for the modification of commercial grade alloys was 0.05 K/min for mullite crucible and 0.025 K/min for alumina crucible respectively. Whereas, the high purity alloy was modified at the slowest cooling rate of 0.025 K/min in these experiments for alumina crucible. These results indicate that the impurities in melt and crucible affected the modification. In addition, many intermetallic compounds of silicide contained both Ca and Sr were found for commercial grade alloys. It is considered that the deterioration in modification rate was caused with the diminution of Sr content by the formation of the intermetallic compound.抄録全体を表示PDF形式でダウンロード (906K) -
永井 恭一, 恵良 秀則, 岸武 勝彦1994 年 66 巻 11 号 p. 827-832
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーImpact fatigue test under four-point bending was carried out on spheroidal graphite cast irons austempered at 573 K and 648 K for 2 hours and an as cast iron with bull's eye structure. The elastic and plastic strain ranges were measured by a strain gage attached on a specimen at the center of four-point bending. Tensile strength of irons austempered at 573 K and 648 K and the as cast iron were 1315 MPa, 920 MPa and 689 MPa, respectively. It has been found that both the elastic and plastic strain ranges of the austempered irons are nearly constant throughout the life, while the plastic strain range of the as cast iron varies during the cyclic impact loading. The impact fatigue life becomes longer with increasing tensile strength of cast irons. The impact fatigue life is linearly related to the elastic or plastic strain range on log-log gragh paper for all the irons tested. It is concluded that the impact fatigue test is a kind of low cycle fatigue tests and the spheroidal graphite cast iron austempered at 573 K has an excellent impact fatigue property.抄録全体を表示PDF形式でダウンロード (660K) -
杉山 好弘, 浅見 克敏, 田畑 修司1994 年 66 巻 11 号 p. 833-839
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーThe characteristics of fatigue crack propagation at stage 2 in austempered ductile cast iron (ADI) were inverstigated from the view points of matrix-microstructure and stress ratio (R = 0.1∼0.8). The obtained results were as follows ; The tensile strength of ADI increased by about three times of that of the as-cast material. But the fatigue crack propagation resistance of ADI decreased remarkably in the low ΔK region under the low stress ratio (for example, R = 0.1) as compared with that of the as-cast meterial. The cause was that the crack closure was suppressed because the matrix-microstructure was changed bainite whose hardness was more than that of ferrite and microstructure was changed bainite whose hardness was more than that of ferrite and microstructure size was smaller. And in ADI too, the more stress ratio increased, the more fatigue crack propagation rate (da/dN) increased. Such a stress ratio effect was also due to the crack closure.抄録全体を表示PDF形式でダウンロード (793K) -
中田 毅, 松本 洋, 春日井 孝昌1994 年 66 巻 11 号 p. 840-845
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーThe purpose of this study is to clarify the continuous cooling transformation behavior of a synthetic weld heat-affected zone and to compare with that of heat treatment for a spheroidal graphite cast iron (FCD 700). For these purposes, two CCT diagrams for welding at maximum heating temperature of 1223 K and 1323 K are made. Ferrite and pearlite transformation regions in CCT diagram of 1323 K shift to a longer cooling time than those of 1223 K. Bainite transformation region exists only in the CCT diagram of 1223 K. Martensite transfomation temperatures of these CCT diagrams are about 530 K. It is considered that these come from carbon distribution in austenite near graphite caused by a dissolution and growth of graphite during heating and cooling. The cooling time range which hardness decreases suddenly with a cooling time obtained from CCT diagrams exists from 10 s to 60 s at both maximum heating temperatures of 1223 K and 1323 K.抄録全体を表示PDF形式でダウンロード (765K) -
楊 忠亮, 佐藤 賢一, 宮本 一道, 田中 雄一1994 年 66 巻 11 号 p. 846-851
発行日: 1994/11/25
公開日: 2011/06/15
ジャーナル フリーIn order to clarify the effect of microstructural factors which strongly influence the fatigue limit, the fatigue tests of spheroidal graphite cast iron were carried out under completely reversed plane bending condition. The fatigue limits of quenched and tempered spheroidal graphite cast iron were related to graphite nodule diameter, matrix hardness and tensile properties. It is observed that fatigue microcracks initiate from the larger graphite nodules prior to others. The fatigue limit is strongly dependent on maximum graphite nodule diameter presumed by using statistics extremes law. On the logarithmic scales, fatigue limit linearly increases with the decrease of maximum diameter. The fatigue limit can be more accurately predicted by the equation : σw = 5924/dmax0.63. Therefore, it is most effective to reduce the graphite nodule diameter as much as possible in order to improve the fatigue limit of quenched and tempered spheroidal graphite cast iron.抄録全体を表示PDF形式でダウンロード (733K)
技術報告
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宮崎 真澄, 奥岡 雅博, 河合 真, 横井 満雄, 小川 雅祥1994 年 66 巻 11 号 p. 852-857
発行日: 1994/11/25
公開日: 2015/01/21
ジャーナル フリーPDF形式でダウンロード (2855K) -
井村 武, 川口 正敏, 田島 宣夫, 小玉 春喜, 山田 信, 大杉 利幸1994 年 66 巻 11 号 p. 858-865
発行日: 1994/11/25
公開日: 2015/01/21
ジャーナル フリーPDF形式でダウンロード (4067K)
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