巻号一覧
59 巻, 1 号
選択された号の論文の8件中1～8を表示しています
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研究論文
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小嶋 桂介, 松浦 清隆, 大笹 憲一, 大野 宗一原稿種別: 研究論文
2009 年 59 巻 1 号 p. 2-6
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーIn the present study, it is shown that TiC–20vol%Fe composites can be successfully fabricated by combustion synthesis from elemental powder compacts of titanium, carbon and iron. Particular concern is directed to reduction of the porosity in the product by preheating procedure of the powder compact. There exists 36% of porosity in the fabricated composites without the preheating treatment. However, the preheating treatment leads to the reduction of the volume fraction of porosity to about 10% and, furthermore, a two-step preheating treatment reduces the volume fraction of porosity down to about 5%. Vickers hardness of the TiC–Fe composites fabricated in this study was measured to be around 1300 HV regardless of the preheating condition.抄録全体を表示PDF形式でダウンロード (2495K) -
小橋 眞, 坂本 憲昭, 金武 直幸原稿種別: 研究論文
2009 年 59 巻 1 号 p. 7-12
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーFoaming behavior of 6061 aluminum sheet-type precursor by free foaming or by foaming in die cavity was examined. Projected area of the precursor during foaming process was recorded by two video cameras to analyze the foaming behavior of both vertical (thickness) and horizontal (in-plane) directions. The free foaming behavior of sheet type precursor was extremely unidirectional along the compressed direction of precursor. The specimen expanded only along the vertical direction, and did not expand along the horizontal direction of the sheet type precursor, while pore morphology in the aluminum foam was quite isotropic. Two separate parallel plates were used to investigate the effect of die constraint. The precursor expanded along the in-plane direction when foamed in between the parallel plates. The porosity was not significantly affected by the constraint. The isotropic pore morphology was maintained after foamed in the parallel plates. The mean size of the pores decreased by decreasing the die spacing.抄録全体を表示PDF形式でダウンロード (1910K) -
野田 雅史, 石田 真悟, 船見 国男原稿種別: 研究論文
2009 年 59 巻 1 号 p. 13-18
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーTo develop a fine grain structure on the surface of a magnesium alloy, a multi-axial alternative forged AZ31B magnesium alloy was subjected to hydrogenation treatment using the resultant hydrogen compounds as the trapping source for dislocations, which were induced following the application of the shot peening technique used for surface high strain working and recrystallization treatment. The effect of hydrogenation for grain refinement and the relationship of grain refinement and strength were examined. The storage hydrogen content in forged materials subjected to hydrogenation treatment is 2.1×10−1 mass%, and hydride compounds can be confirmed by X-ray diffraction down to a depth of 0.5 mm beneath the surface. Following the shot peening process, the microstructure of the forged material shows high dislocation density and the average grain size following recrystallization heat treatment is about 1 μm. It was confirmed that the hydrogen absorption process coupled with the shot peening process and recrystallization heat treatment was an effective process to increase surface strength and grain refinement in the material surface.抄録全体を表示PDF形式でダウンロード (4563K) -
熊川 敬亮, 鈴木 寿穂原稿種別: 研究論文
2009 年 59 巻 1 号 p. 19-23
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーThe purpose of the present work is to make clear effect of cooling rate on as-cast microstructure and the formability of AZ31 magnesium alloy. In order to investigate the effect, the AZ31 ingots solidified at 3 kinds of cooling rates were prepared (0.2 K/s, 1.8 K/s and 10.1 K/s) . The grain sizes were measured by microstructure observation using an optical microscope. To estimate the formability, the compression examination and rolling test were performed. As the results, the experimental formula between grain size and cooling rate was obtained. As the cooling rate is faster, as-cast microstructure is refined. Simultaneously, β phases crystallizing at grain boundaries are also refined, resulting in a decrease in holding time of homogenization heat treatment. The formability is improved remarkably in the compressive examination when the grain size is smaller than about 120 μm. For example, maximum reductions enable to compress without surface cracks at 523 K were improved by 100% when using the specimen with a grain size of 121 μm.抄録全体を表示PDF形式でダウンロード (2604K) -
土田 信, 伊藤 清文, 田中 宏和, 金武 直幸原稿種別: 研究論文
2009 年 59 巻 1 号 p. 24-29
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーThe strain and hardness distributions in the drawn cup walls of the cold rolled 3004 aluminum alloy sheet were measured and discussed on the anisotropy and the effect of simultaneous wall ironing during cup drawing. The thickness strain in the cup wall is large along the TD direction of the sheet and is small along the RD direction. This phenomenon is considered to be corresponding to the anisotropy of r value in the cold rolled 3004 aluminum alloy sheet. In RD direction, the ears grow up at the cup wall edge because of the large radial strain balanced with small thickness strain. The sizing work that means ironing a part of the thicker cup wall tends to unify the distributions of thickness strain, and then the ears at the edge of cup wall become to be small. The hardness of the cup wall decreases by drawing to less than the material, and the hardness drop seems to be remarkable especially in TD direction where the thickness strain is large and the sizing work is heavy. The cause of hardness drop is considered to be due to the change of work hardened metal structure that depends on the additive strain through the complex different strain passes during cup drawing.抄録全体を表示PDF形式でダウンロード (1190K) -
小林 正和, 戸田 裕之, 南 恵介, 森 豊和, 上杉 健太朗, 竹内 晃久, 鈴木 芳生原稿種別: 研究論文
2009 年 59 巻 1 号 p. 30-34
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーSynchrotron X-ray microtomography has been utilized for the ex-situ observation of micro-pore growth/annihilation behaviors of a 2024 aluminum alloy at a high temperature. High-resolution experimental configurations have enabled the 3D reconstruction of micro-pore and intermetallic compound particle images with isotropic voxels with 0.088–0.474 μm edges. The variations in micro-pore shape, size and spatial distribution at the high temperature are readily observed, with the tomographic volumes then being provided for the quantitative image analysis of such quantities. It has been clarified that micro-pores, that appear to be nucleated heterogeneously on particles, exhibit the Ostwald growth behavior during the high temperature exposure. Three-dimensional finite element meshes have been generated to monitor distributions of local stress and strain in real materials with such micro-pores. Since micro-pores tend to lie along (former) grain boundary, there seems to be some anisotropic effect on the strain redistribution due to the existence of micro-pores. Since local strain elevation is predicted by 50–200% in the vicinity of micro-pores aligned along grain boundary, it can be inferred that ductile fracture would be promoted considerable by the growth of pre-existing micro-pores.抄録全体を表示PDF形式でダウンロード (1741K) -
筒井 一輝, 久米 裕二, 小橋 眞, 金武 直幸原稿種別: 研究論文
2009 年 59 巻 1 号 p. 35-40
発行日: 2009/01/30
公開日: 2009/03/04
ジャーナル フリーA compressive torsion process, which is one of severe deformation processes, is applied to AZ61 magnesium alloy to control microstructure. This process is composed of relatively low compressive pressure and axial rotation, and can apply huge strain to a work piece without changing in shape during processing. Effect of processing temperature on grain refinement and texture change was investigated. The alloy with initial 10~200 μm grains was refined under 10 μm by this process. The initial grains were refined smaller with lower process temperature, but the refinement was not enough at inner parts of a cylindrical specimen because of geometric strain gradient due to rotational loading. In the case of relatively higher temperature processing, though the refined grains became larger, the grain refinement were uniform all over the specimen even the geometric strain gradient. Axisymmetrical texture of (0002) crystal planes in the starting alloy was changed to the orientations parallel to the basal plane of a cylindrical specimen after this process.抄録全体を表示PDF形式でダウンロード (2119K)
解説
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西村 智志原稿種別: 解説
2009 年 59 巻 1 号 p. 41-48
発行日: 2009/01/30
公開日: 2009/04/30
ジャーナル フリーPDF形式でダウンロード (2424K)
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