巻号一覧
63 巻, 12 号
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研究論文
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上村 岳之, 大澤 泰明原稿種別: 研究論文
2013 年 63 巻 12 号 p. 439-445
発行日: 2013/12/30
公開日: 2014/01/31
ジャーナル フリーAn analysis on plastic instability theory together with some constitutive equations involving strain, strain rate and temperature leads to simple conclusion, which suggests an increase of uniform strain range by falling off temperature intentionally during the process. To evaluate the above prediction, the concept of temperature descent is provided and the usefulness of cooling down with the process temperature is shown by the comparison with constant temperature. Experiments were carried out in uniaxial tensile test, methods of cooling with using natural cooling and air blow cooling. It was observed that temperature descent during forming process causes a significant rise of the uniform strain. In the case of air blow cooling, significant increase of uniform strain was seen because temperature descent rate was larger than natural cooling. The result may be applied to any other metal, being independent of metal class, thus generalized concept seems to be reached to extension in uniform strain range of metals with poor formability.抄録全体を表示PDF形式でダウンロード (1327K) -
久米 裕二, 磯村 圭祐, 小橋 眞, 金武 直幸原稿種別: 研究論文
2013 年 63 巻 12 号 p. 446-451
発行日: 2013/12/30
公開日: 2014/01/31
ジャーナル フリーPorous aluminum alloys prepared by a precursor method inherently develop a thin solid layer, also known as the skin layer, on their surface. Formation of a skin layer is a characteristic feature of the precursor method, and it affects certain compressive properties of the alloy. Furthermore, investigating the effect of changes in the aluminum alloy composition on the compressive properties is important. In this study, the effects of the skin layer on several compressive properties were investigated for two different porous aluminum alloys developed by the precursor method: AA6061 and Al–7mass% Si. The plateau stress and energy absorption of both alloys increased with increasing bulk density, irrespective of whether the skin layer was present or not. In the case of the porous AA6061 alloy, the skin layer did not affect the plateau stress; however, the plateau strain increased under large deformation because the skin layer peeled off under relatively small deformations in the compression test, causing a decrease in the relative density of the specimen. In the case of the Al–7%Si alloy, the skin layer affected stress oscillation and the plateau stress became unstable. Peeling of the skin layer also increased the plateau strain, resulting in increased energy absorption.抄録全体を表示PDF形式でダウンロード (1483K) -
山本 裕介, 浅野 峰生, 吉田 英雄, 小林 正和, 戸田 裕之原稿種別: 研究論文
2013 年 63 巻 12 号 p. 452-457
発行日: 2013/12/30
公開日: 2014/01/31
ジャーナル フリーThe crack initiation and the propagation during bending have been considered to be affected by second phase particles with micro-voids and shear-band. However, the effect of second phase particle distribution on formation of micro-voids, and the effect of micro-voids on crack initiation and propagation during bending have not been fully investigation. In this study, the effect of second phase particle distribution on formation of micro-voids, and the effect of micro-voids on crack initiation and propagation during bending were investigated by using the largest synchrotron radiation facility “SPring-8” and FE-SEM/EBSD. With increasing the bending ratio, micro-voids were increased around coarse particles nearby outer surface. In particular, coarse micro-voids were formed around coarse particles with high aspect ratio on shear-bands. At large cracking part, the coarse micro-void was observed at outmost layer section as crack initiation site, and coarse micro-voids and sheared fracture surface were observed at crack propagation site. At small cracking part with no propagation, Cube orientation grains were located under the small crack. It was considered that these cube orientation grains inhibited the formation of shear-bands, therefore propagation of cracks did not occur at small cracking area.抄録全体を表示PDF形式でダウンロード (3560K)
解説
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長谷川 靖洋原稿種別: 解説
2013 年 63 巻 12 号 p. 458-460
発行日: 2013/12/30
公開日: 2014/03/30
ジャーナル フリーPDF形式でダウンロード (2096K)
連載講座
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倉田 博基2013 年 63 巻 12 号 p. 466-473
発行日: 2013/12/30
公開日: 2021/06/15
ジャーナル フリーPDF形式でダウンロード (1425K)
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