巻号一覧
50 巻, 8 号
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研究論文
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岩澤 秀, 才川 清二, 富田 剛利, 林 勝三, 鎌土 重晴, 小島 陽2000 年 50 巻 8 号 p. 371-375
発行日: 2000年
公開日: 2007/03/30
ジャーナル フリーMicrostructure and mechanical properties of Al–7 mass%Si–0.5 mass%Mg 357 alloys produced by thixocasting and permanent mold casting process were investigated. The microstructure of the thixocast specimen consists of the spherical α–Al phase particles and fine eutectic Si phase, and cross section macrograph of the thixocast specimen exhibits no segregation and defects. The average size and volume fraction of the α–Al phase particles are about 58 μm and 64%, respectively. The tensile strength, 0.2% proof stress and elongation of T6–treated thixocast specimen aged at 443 K for 18 ks are 363 MPa, 313 MPa and 12%, respectively. These values are about 30 MPa in tensile strength, 40 MPa in 0.2% proof stress, and 6% in elongation higher than those of permanent mold cast specimen. The absorbed energy of the as-cast and T6–treated thixocast specimens are 102 and 53 kJ/m2, respectively. These values are far superior to those of T6–treated permanent mold cast specimen. The fatigue strength of the T6–treated thixocast specimen at the 107 cycles is 140 MPa. Such an good tensile properties, impact value and fatigue strength of thixocast specimen may be caused by high cooling rate during solidification, resulting in effective refining of eutectic Si phases and Al–Fe system intermetallic compounds, compared with permanent mold casting process.抄録全体を表示PDF形式でダウンロード (722K) -
藤田 武志, 小村 章吾, 堀田 善治, Terence G. LANGDON2000 年 50 巻 8 号 p. 376-380
発行日: 2000年
公開日: 2007/03/30
ジャーナル フリーThis paper describes grain refinement of an Al–3%Mg–0.2%Sc alloy using the equal-channel angular pressing (ECAP) technique at room temperature. It is shown that a grain size of 0.2μm is obtained with this technique. The paper also presents the results of tensile tests for the fine-grained Al–3%Mg–0.2%Sc alloy over a wide range of strain rates. Elongations of more than 1000% are attained at a temperature of 673 K in a high strain rate range of more than 10−2 s−1. Transmission electron microscopy and scanning ion microscopy are employed for microstructural observations before and after tensile testing. The results are compared with those of a cold-rolled Al–3%Mg–0.2%Sc alloy. It is demonstrated that grain refinement using the ECAP technique is useful for the production of Al alloys exhibiting high strain rate superplasticity.抄録全体を表示PDF形式でダウンロード (587K) -
鈴木 信行, 高津 正秀, 田辺 重則, 東 健司2000 年 50 巻 8 号 p. 381-385
発行日: 2000年
公開日: 2007/03/30
ジャーナル フリーA new superplastic blow forming procedure for 7475 aluminum alloy sheets to provide the optimum distribution of thickness to a slender pan. The procedure adopts a preliminarily machined blank with different thickness locally before a superplastic forming (SPF). The figure and thickness for machining is calculated by a numerical analysis method developed for the pan to be formed with the optimum shape, size and thickness. This procedure also contains a friction between a sheet and a die, and work hardening of a blank material during SPF. It feeds the optimum pressurization schedule to the preliminarily machined blank to be formed with the maximum strain rate. A SPF of 7475 aluminum alloy sheets machined preliminarily to be formed a rectangular pan, in the ratio of the bottom to wall thickness is 2:1, according to the numerically calculated pressurizing schedule. The distribution of thickness in the formed pan was coincident with that of expected one.抄録全体を表示PDF形式でダウンロード (460K) -
高橋 明宏, 小林 俊郎, 戸田 裕之, 水谷 道2000 年 50 巻 8 号 p. 386-391
発行日: 2000年
公開日: 2007/03/30
ジャーナル フリーEffect of temperature on mechanical properties of an 5083 aluminum alloy has been investigated for various testing temperatures from 10 to 773 K. For that purpose, the static tensile, dynamic fracture toughness test and fractography are carried out, and stop block method is employed to characterize fracture behavior at cryogenic temperatures. Mechanical properties such as 0.2% proof stress and ultimate tensile strength increase with decreasing temperature. The high temperature embrittlement, which has been often reported for 5000 series alloys having high Mg content, was not observed in the present study. The dynamic fracture toughness value, Jd, and dynamic crack extension toughness, Tmat, at 20 K are approximately 57% and 74% lower than that at 150 K, respectively. Fracture toughness at cryogenic temperatures shows strong dependence on formation of delamination cracks. The delamination cracks are initiated at grain boundaries. According to a SEM-EDX analysis, Mg is detected adjacent to the delamination cracks. Therefore, it is concluded that the formation of delamination cracks are concerned with β(Al3Mg2) phase at the grain boundaries.抄録全体を表示PDF形式でダウンロード (794K) -
福本 信次, 波々伯部 朋子, 椿野 晴繁2000 年 50 巻 8 号 p. 392-397
発行日: 2000年
公開日: 2007/03/30
ジャーナル フリーMicrostructures of various aluminum dross generated from the aluminum scraps of 1000, 5000 and 6000 series alloys that were recovered individually were observed by an optical microscope, an electron probe microanalyzer (EPMA) and a transmission electron microscope (TEM). Various oxides such as MgO, Fe3O4 and SiO2 in addition to metallic Al, AlN and Al2O3 were identified in the dross by X-ray diffraction analysis. Particularly, the formation of MgO and Al2MgO4 were marked in the 5000 and 6000 dross since Mg and Si are main additional elements in 5000 and 6000 aluminum alloys. Comparatively large blocks whose size was several tens mm were mainly composed of aluminum. Some inclusions such as Al6Fe, Al3Fe and α–Al–Fe–Si and a lot of filmy oxides and porosities were formed in the block. In the case of small particles in 1000 dross whose size was below several mm, Al2O3 was formed at the surface and AlN layer was formed in the interior side of Al2O3 layer. In 5000 dross, there was MgO or Al2MgO4 at the outermost layer of the dross powder.抄録全体を表示PDF形式でダウンロード (712K)
解説（軽金属学会賞受賞）
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「企業における研究開発: 私の体験より」馬場 義雄2000 年 50 巻 8 号 p. 398-408
発行日: 2000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 (1186K)
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