巻号一覧
51 巻, 6 号
選択された号の論文の6件中1～6を表示しています
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研究論文
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森田 繁樹, 戸田 裕之, 高橋 明宏, 星山 中, 小林 俊郎, 永島 洋2001 年 51 巻 6 号 p. 307-312
発行日: 2001年
公開日: 2007/03/30
ジャーナル フリーThe effects of quenching rate after a solution treatment on strength and fracture toughness of a 6061 aluminum alloy have been investigated, varying the width of PFZ layer and coarse secondary phase particles at grain boundaries by changing the quenching rate utilizing both water quenching and air-cooling. In-situ observation of the fracture toughness tests was also performed to investigate the effects of such microstructural parameters on crack initiation and propagation behaviors. By decreasing the quenching rate, the width of the PFZ layer increases from about 40 to 310 nm, and density and size of the coarse particles increase at the grain boundaries. Mechanical properties such as tensile strength, 0.2% proof stress, elongation, fracture toughness and crack propagation resistance are decreased simultaneously. Especially, the effects of quenching rate on the strength and the crack propagation resistance are remarkable. Such degradation of the mechanical properties is attributed to expansion of the PFZ layer with decreases in quenching rate. It causes localization of plastic deformation, and consequently, transition of fracture mechanisms from grain interior ductile fracture to grain boundary ductile fracture at the PFZ layers. In-situ SEM observation reveals that the effects of the coarse particles at grain boundaries are much less effective than those of the PFZ.抄録全体を表示PDF形式でダウンロード (810K) -
中村 和彦, 大倉 幸伸2001 年 51 巻 6 号 p. 313-317
発行日: 2001年
公開日: 2007/03/30
ジャーナル フリーA newly developed deep drawing method is friendly to environment, because it does not need cleaning and degreasing as after treatment. The properties and the limit of deep drawing process have been investigated using 1100 and 5052 aluminum alloy sheets. On the method, the original sheet is covered by lubricating resin film and then formed by a radial-pressure-assisted hydraulic counterpressure deep drawing method using water as a pressure medium. When a lubricating resin film covers whole area of both sides, the fracture-suppressive effect by friction generated in punch and formed side wall is decreased. So that, the limiting drawing ratio becomes smaller than that of original sheet without lubricating oil. However, if lubricating resin film covers not bottom and punch profile radius, but covers only flange zone, the limiting drawing ratio indicates larger than that of original sheet without lubricating oil. The above method shows good effect of lubricating resin treatment.抄録全体を表示PDF形式でダウンロード (384K) -
古田 昌伸, 中山 栄浩2001 年 51 巻 6 号 p. 318-323
発行日: 2001年
公開日: 2007/03/30
ジャーナル フリーThe effect of the chromium or the manganese addition on the precipitation behavior in the Al–7%Mg alloy was experimentally investigated. The solution treatment was conducted at various temperatures in order to reveal the influences of concentration of solute atoms, size of crystal grains and size and morphology of Al6Mn or Mg3Cr2Al18 phase on the precipitation of metastable β′ and stable β phases. The precipitation of the β′ and the β phases in the chromium or the manganese added specimen was greatly accelerated by a refinement of the crystal grain. In addition, these precipitates were formed in the interface between the matrix and the coarse second phases (Al6Mn or Mg3Cr2Al18). In the manganese added specimen, the precipitation of the β′ and the β phases was slowed down as solutionizing temperature was raised. No clear relationship was obtained between the formation of the β′ and the β phases and the precipitates of Al6Mn and Mg3Cr2Al18.抄録全体を表示PDF形式でダウンロード (657K) -
出村 良広, 北川 和夫, 川添 正孝2001 年 51 巻 6 号 p. 324-328
発行日: 2001年
公開日: 2007/03/30
ジャーナル フリーThe fatigue behavior of the fine-grained 5056 aluminum alloy produced by equal-channel angular extrusion (ECAE) is explored. This material exhibits a slightly enhanced fatigue life at high stress amplitude. However, no improvement in the fatigue limit is observed. Fatigue performance is discussed in terms of fatigue life, crack nucleation and propagation. Structural change during fatigue test is investigated by transmission electron microscopy and DSC. It is shown that the fine structure achieved during processing is unstable and tends to relax with cycling, resulting in local recovery of the pre-deformed material. Structure relaxation during fatigue test is supposed to provoke notable cyclic softening that is particularly pronounced at higher applied stress. It is found that the crack growth rate is greater in the fine grain ECAE material than in the coarse grain counterpart. The improvement of fatigue properties at low-cycle regime is believed to be due to higher resistance to crack nucleation in the fine-grained material having a larger proof stress value.抄録全体を表示PDF形式でダウンロード (557K)
解説
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渡邊 千尋, 藤居 俊之, 加藤 雅治2001 年 51 巻 6 号 p. 329-335
発行日: 2001年
公開日: 2007/03/30
ジャーナル フリーPDF形式でダウンロード (980K)
連載講座
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福田 紀久雄2001 年 51 巻 6 号 p. 336-342
発行日: 2001/06/30
公開日: 2021/06/30
ジャーナル フリーPDF形式でダウンロード (9505K)
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