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65 巻, 8 号
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研究論文
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高橋 利夫, 多田 周二, 阿部 利彦1993 年 65 巻 8 号 p. 615-620
発行日: 1993/08/25
公開日: 2011/06/22
ジャーナル フリーAustempered ductile cast iron (ADI) has excellent mechanical properties both in strength and toughness, but Young's modulus of ADI is lower than that of steel because ADI contains much graphite. Spheroidal graphite cast steel containing less graphite by volume was selected to be austempered in order to get better mechanical properties than ADI. Young's modulus of the austempered spheroidal graphite cast steel (AGS) is 200 GPa, which is comparable to steel. The retained austenite volume of the sample containing 2.4 % Si varies with the austempering conditions in a manner similar to ADI, but that of the sample containing 1.4 % Si decreases in a shorter austempering time. These results show that Si influences stability of the retained austenite. Charpy impact value increases with increasing retained austenite volume when the volume is above 15 %. The impact value of AGS with 40 % retained austenite is over twice as large as that of ADI austempered under the same conditions. The mechanical properties of AGS such as Young's modulus and impact characteristics are superior to those of ADI.抄録全体を表示PDF形式でダウンロード (683K) -
張 世江, 手塚 裕康, 神尾 彰彦1993 年 65 巻 8 号 p. 621-626
発行日: 1993/08/25
公開日: 2011/06/22
ジャーナル フリーExperiments were carried out under a wide range of solidification conditions to make clear the growth mechanism of non-dendritic primary crystals under stirring. Crystals were difficult to grow dendritically in the slowly cooled and violently stirred semi-solid Zn-22 mass % Al alloy. The crystal was formed in a morphology of rosette at high cooling rate or of colony of spherical and cellular particles at low cooling rate. A formation mechanism of non-dendritic structure was also shown.抄録全体を表示PDF形式でダウンロード (889K) -
岩渕 義孝, 小林 勲1993 年 65 巻 8 号 p. 627-632
発行日: 1993/08/25
公開日: 2011/06/22
ジャーナル フリーEffect of the heat treatment in the ferrite-austenite region (α + γ), aiming to obtain the varying amounts of the reverted austenite, on the such toughness degradation as temper embrittlement of JIS SCS 5 steels, 13 % Cr-4 % Ni soft martensitic stainless steels was studied by means of metallurgical observation and mechanical examination. When (α + γ) heating temperature was increased, the martensitic embrittlement was remarkable for the non-embrittled specimens because the most part of the reverted austenite transformed to the fresh martensite during the cooling. Temper embrittlement due to the isothermal heating at 823 K seemed to be suppressed when (α + γ) heating temperature was increased. There was the good relation between the degree of toughness degradation and the magnitude of the corrosion loss indicating that the temper embrittlement was accompanied by the carbide precipitation along the prior austenite grain boundary. “Pine cone fracture” was observed for the embrittled specimens containing a large amount of reverted austenite.抄録全体を表示PDF形式でダウンロード (749K) -
笹栗 信也, 松原 安宏, 大城 桂作1993 年 65 巻 8 号 p. 633-639
発行日: 1993/08/25
公開日: 2011/06/22
ジャーナル フリーHypoeutectic, eutectic and hypereutectic high chromium cast irons containing from 10 to 30 mass % Cr and mild steel were brazed using pure copper filler, and the effect of chromium and carbon contents in cast iron on microstructural variations and behaviors of alloying elements in the bonded zone have been investigated. The length of rod-like crystal precipitated at the cast iron-copper interface and the width of bonded zone decrease with an increase in Cr/C value of cast iron. This is because diffusion of iron from steel to cast iron becomes less due to the decrease of difference in chemical potential of iron between the cast iron and the steel sides.抄録全体を表示PDF形式でダウンロード (877K) -
笹栗 信也, 松原 安宏, 大城 桂作1993 年 65 巻 8 号 p. 640-643
発行日: 1993/08/25
公開日: 2011/06/22
ジャーナル フリーBonding of hypoeutectic, eutectic and hypereutectic high chromium cast irons containing chromium from 10 to 30 mass % and mild steel was carried out by means of copper brazing, and relationships between bond-strength and chromium, carbon contents in cast iron were clarified. Bond-strength (τB) is closely related to Cr/C value of cast iron, and it decreases with an increase in Cr/C value. τB lowers as filler metal thickness increases under the same Cr/C value. From the relation between microstructure and bond-strength, τB is found to change depending on the ratio (GA) of the length of rod-like crystal to the width of bonded zone which are varied by chemical compositions in cast iron and filler metal thickness. The relation of τB vs GA is approximately given by an equation, τB (MPa) = 1.80 × % GA + 157.抄録全体を表示PDF形式でダウンロード (527K)
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