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62 巻, 10 号
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研究論文
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三宅 秀和, 土屋 詔一, 照元 弘行, 岡田 明1990 年 62 巻 10 号 p. 804-809
発行日: 1990/10/25
公開日: 2011/07/27
ジャーナル フリーThe influence of manganese and sulphur on the solidification of primary austenite were investigated by the observation of the degree of undercooling for nucleation, the morphology of solidification and the amount of austenite cells. Though the morphology of solidification tends to become slightly endogenous with the increase of manganese content up to 3%, the undercooling and the austenite cell number hardly vary, respectively. The solidification morphology becomes remarkably endogenous and the austenite cell number increases considerably with the increase of sulphur content up to 0.7%. The nucleation of austenite becomes exceeding easy by the addition of sulphur. The increase of austenite cells with the addition of sulphur is due to that the numerous nuclei simultaneously generated at the start of primary solidification. This is quite different from the mechanism which increase the eutectic cell number with the progressive growth of the nuclei during eutectic solidification.抄録全体を表示PDF形式でダウンロード (1321K) -
山本 浩喜, 計 永毅, 小林 俊郎1990 年 62 巻 10 号 p. 810-815
発行日: 1990/10/25
公開日: 2011/07/27
ジャーナル フリーThe decrease in toughness of austempered ductile cast iron (ADI) with increasing the austempering time is believed to be caused by the formation of carbide like in the austempered high silicon steel with similar transformed structure as ADI. However, it is not yet clear whether carbide formation occurs in ADI structure or not. Therefore, the effect of precipitation of carbide on the loss of toughness with prolonged austempering time is investigated by transmission electron microscope using the ion thinning technique in this study. As a result, it is clarified that the loss of toughness in the lower bainite region and the upper bainite region is due to the formation of χ-carbides and the precipitation of secondary graphites, respectively.抄録全体を表示PDF形式でダウンロード (866K) -
大出 卓, 井川 克也1990 年 62 巻 10 号 p. 816-820
発行日: 1990/10/25
公開日: 2011/07/27
ジャーナル フリーInmold inoculation in the same reaction chamber designed as the gating system of Inmold process was investigated by using Fe-Si alloy. Different dissolution behaviour of the alloy in the chamber was observed with the variation in the amount, the nodule size of alloy and the shape of the chamber. Therefore, the inoculation effect was suggested to be changeable with these factors. Effective inoculation can be achieved by the continuation of convection or agitation of the melt in the chamber. These results were also confirmed by the simulation of water model.抄録全体を表示PDF形式でダウンロード (631K) -
佟 慶平, 加藤 治, 鈴木 俊夫, 梅田 高照1990 年 62 巻 10 号 p. 821-826
発行日: 1990/10/25
公開日: 2011/07/27
ジャーナル フリーInfluence of chemical composition and microstructure on wear resistance was experimently investigated for high chromium cast irons. The experiment was performed by rolling friction of two disks at high temperature.
It was confirmed that the wear resistance depended on the area percentage of eutectic carbides and the Cr/C ratio for alloys with a constant content of Si, Ni and Mo. The irons with area percentage of eutectic carbides of 25-30% and with Cr/C ratio of 5-8 have excellent wear resistance. For 3%C-20%Cr alloy, the wear resistance increased markedly with increasing molybdenum content from 1% to 5% because the amount of fine Mo2C eutectic carbides increased. For alloy with a constant chemical composition, the improvement of wear resistance was confirmed by refining microstructure. The wear mechanism at high temperature was also discussed through the examination of wear surface.抄録全体を表示PDF形式でダウンロード (923K) -
村島 泉, 江越 義明, 北條 信良, 森棟 文夫1990 年 62 巻 10 号 p. 827-832
発行日: 1990/10/25
公開日: 2011/07/27
ジャーナル フリーIn the present work, the heat transfer phenomena at the casting-resin-coated sand core interface and the structure of surface layer in casting have been studied using squeeze method with pressure of 0.230 and 820kgf/cm2. The heat transfer coefficient and the heat flux at casting-core interface were calculated by the heat balance equation. The surface structure of castings was examined with metallographic method.
The heat transfer coefficient at the casting-core interface increased with increasing force of applied pressure. The values of heat transfer coefficient at the interface under gravity, 230kgf/cm2 and 820kgf/cm2 are 0.0005, 0.0015 and 0.0017 cal/ (cm2·s·°C), respectively. The changes of heat transfer coefficient at the interface have been influenced on the condition of contact between castings and core. When the pressure is 0kgf/cm2, the surface of castings is rough. Smooth surface is found when the pressure is raised from 0 to 820kgf/cm2. In case of 0kgf/cm2, the structure of surface layer at the interface are coarse. On the other hand, the microstructure of castings at the interface is fine under pressure of 820kgf/cm2. Solidification rate in the castings is extremely rapid and therefore fine chill surface forms. The heat transfer coefficient at the castings-core interface corresponds well with the structure of surface layer of castings.抄録全体を表示PDF形式でダウンロード (901K)
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