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51 巻, 6 号
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研究論文
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中野 幸紀, 川野 豊1979 年 51 巻 6 号 p. 315-321
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーRelation between magnetic properties and microstructures of both spheroidal and flake graphite cast irons was studied varying the metallurgical operation of cast irons. The form of graphite has a major effect on magnetic induction and differential permeability in 400 Oe., while the matrix affects initial permeability and coercive force. In the ferrite-matrix spheroidal graphite cast iron, increasing the silicon content will lower magnetic saturation and decrease hysteresis loss, and high purity raw pig iron also decreases hysteresis loss. Nearly rectangular loops are observed in materials annealed in the austenite temperature range. These magnetic changes become obliterated when varying silicon content and purity of raw pig iron changes microstructures in as-cast stage. By means of the Principal Component Analysis of the general movement of hysteresis loop, the three principal components such as magnetic softening, magnetizing difficulty and rectangularity of the hysteresis loop were obtained. With reference to the magnetizing mechanism, it is recognized that the graphite form reasonably influences the range of rotation magnetization, the change of matrix structure and purity of raw iron influence the range of displacement of magnetic domain boundaries and silicon directly affects the magnetizing behavior of both.抄録全体を表示PDF形式でダウンロード (736K) -
吉田 千里, 坂本 敏正, 伊藤 孝道, 森 隆資, 高田 寿1979 年 51 巻 6 号 p. 322-326
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーThe electrical resistivity which was related to the graphite structure, was measured parallel and vertical to the direction of solidification in the lamellar graphite structure of Fe-C-Si alloy unidirectionally solidified under rate of less than 1cm/hr. Since these resistivities were 50∼80μΩ·cm in both directions, there was unexpectedly no anisotropy in this specimen. This was because the graphite was arranged at random in a vertical plane to the direction of solidification. On the other hand, a rolled or forged lamellar graphite structure of the alloy was layered even in a vertical plane. The electrical resistivity in a vertical direction was about 10∼20 times as much as one in a rolled or forged direction. There was large anisotropy of electrical resistivity in this layer graphite Fe-C-Si alloy.抄録全体を表示PDF形式でダウンロード (689K) -
尾崎 良平, 岡田 明, 三宅 秀和1979 年 51 巻 6 号 p. 327-332
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーDifferential thermal analysis (DTA) was made in white cast iron of Fe-C system by heating it above 1,100°C at a constant rate and the structures of the iron were examined after water-quenching from different heating temperatures. When the heating rate was small, endothermic, exothermic and endothermic reactions were observed on the DTA curves as the temperature became higher. The first endothermic reaction corresponds to the fusion of the cementite-austenite eutectic and exothermic reaction results from the solidification of the graphite-austenite eutectic from the melt. The last endothermic reaction is due to the fusion of the graphite-austenite eutectic. The amount of the graphite-austenite eutectic solidifying on heating the iron increases as the heating rate is reduced. When white cast iron without silicon is heated in the range between both the temperatures of cementite-austenite and graphite-austenite eutectic, it causes the fusion of the cementite-austenite eutectic followed by the solidification of the graphite austenite eutectic. Addition of silicon to the iron promotes nucleation on the solidification of the graphite-austenite.抄録全体を表示PDF形式でダウンロード (900K) -
山本 善章, 岩堀 弘昭, 米倉 浩司, 中村 元志1979 年 51 巻 6 号 p. 333-338
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーGas defects such as pin-holes are often observed in cast steel and malleable cast iron, cast in molds of Olivine sand. The gas pressure in shell mold cores made of Olivine sand which had been previously dried in the temperature range of 200°C to 1,000°C was measured. The gas pressure in cores during casting at 1,400°C was 15—20% lower in Olivine sand dried at 1,000°C compared to undried sand. However, gas pressure in Olivine sand shell mold cores during casting at 1,540°C was much higher than that at 1,400°C, despite the fact that there was no difference in gas pressure in the shell mold cores made of quartz sand in the range of casting temperature from 1,400°C to 1,540°C. But, even in casting at 1,540°C, use of Olivine sand pre-dried above 800°C decreased the gas pressure to a half of that of undried Olivine sand. For casting at 1,540°C with the same casting plan, the gas pressure in shell mold cores of Olivine sand pre-dried below 600°C exceeds the hydrostatic pressure of the molten metal, resulting in gas blowing, one of the main causes of gas defects in castings. The difference in gas pressure between the two cores pre-dried above 800°C and below 600°C can be attributed to vaporization of combined water in the serpentine (3MgO·SiO2·2H2O) involuted in Olivine sand, as confirmed by X-ray analysis, chemical analysis of combined water and measurement of evolved gas volume.抄録全体を表示PDF形式でダウンロード (666K) -
堤 信久, 松川 安次1979 年 51 巻 6 号 p. 339-344
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーWith a view to investigating the occurrence of inverse chill in spheroidal graphite cast iron castings, the influence of carbon equivalent value, pouring temperature and cooling rate on the inverse chill were investigated by using the directional solidification. Two forms of inverse chill, the wide band inverse chill and the concentrated inverse chill, which have been reported by other investigators were observed. Chemical analysis and EPMA of specimen showed no detectable segregation in the wide band inverse chill. Undercooled graphite was found in the wide band inverse chill area. Wide band inverse chill tendency was promoted by elevating the pouring temperature and by decreasing the carbon equivalent value. These behaviors of the wide band inverse chill occurrence can be explained by the undercooling theory. Concentrated inverse chill was more stable in decreasing the cooling rate compared with the wide band inverse chill. A segregation of manganese was recognized in the concentrated inverse chill area.抄録全体を表示PDF形式でダウンロード (750K) -
小松 康彦, 杉本 繁利, 北川 久善, 谷村 凞1979 年 51 巻 6 号 p. 345-350
発行日: 1979/06/25
公開日: 2012/06/02
ジャーナル フリーIn order to develop spheroidal graphite cast iron with a good heat resistance for automotive parts, the influence of silicon content on mechanical and anti-oxidation properties of the iron was investigated. The specimens containing from 2.4%—5.0%Si were heated at 700°C and 850°C for 100hrs, then the amount of oxides eliminated by means of shot blast treatment were measured. On the other hand, tensile strength, elongation and hardness from room temperature to 700°C and impact value from −70°C to 200°C were measured. The reasons why adding Si contributes to improvement of anti-oxidation are considered to be that Fe2SiO4 content increases in the oxide layer, and that decarburization reaction is accelerated as the upper point of eutectoid transformation temperature rises. The higher the temperature, the smaller the effect of Si content on the tensile strength is. Adding Si is not effective in improving the strength over 500°C. As the elongation at 500°C abruptly declines at 4.7%Si in the annealing specimens and at 4.4%Si in the as-cast specimens, improved elongation is detained by annealing. The relation between strength and hardness is drawn by a straight line from room temperature to 300°C.抄録全体を表示PDF形式でダウンロード (686K)
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