巻号一覧
60 巻, 1 号
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研究論文
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櫻井 健夫, 松元 和秀, 小松 伸也, 河野 紀雄原稿種別: 研究論文
2010 年 60 巻 1 号 p. 2-6
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーHole expanding limit, λ, measured as an index of stretch flange-ability of 6022 aluminum alloy was severely decreased by slow cooling (forced air: 10 K/s) after solutionizing at 823 K for 15 s, in 0.5% Cu added Al–0.6%Mg–0.9%Si alloy sheet which ingot was homogenized at a high temperature, 823 K. Whereas by fast cooling (water quenching: 500 K/s), 1.5 mm thick sheets of both alloys showed the λ higher than 50%. Influences of homogenizing temperature and cooling rate after solution treatment on the λ were investigated by semi-quantitative metallography. Ingot homogenization at higher temperature decreases amount of Mg–Si precipitates and increases solute concentration. Judging from measured conductivity (IACS%) , almost all of added Cu seems to remain in solid solution. Even after hot rolling, cold rolling, solution treatment and T4 treatment for more than 600 ks at room temperature, IACS% of the T4 sheets was in nearly same order as ingots. The severe decrease of the λ in the Cu added alloy sheets homogenized at 823 K and slowly cooled after solution treatment will be explained by coarse Si precipitates on grain boundaries formed during the slow cooling. The Cu addition and high homogenization temperature will lead to a high degree of solute supersaturation and elevate temperature for precipitation starting. Region of high dislocation density was observed nearby the coarse Si precipitates by transmission electron microscopy after the hole expanding test.抄録全体を表示PDF形式でダウンロード (2951K) -
外山 和宏, 松浦 清隆, 大野 宗一, 佐藤 大樹, 中山 昌紀原稿種別: 研究論文
2010 年 60 巻 1 号 p. 7-11
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーEffects of hot rolling on microstructure and mechanical properties of a cast Al–Si alloy have been investigated. The hot rolling was carried out at 330°C with rolling reductions ranging from 0 to 80%. With increase in the rolling reduction, the shrinkage cavity decreases in size and volume fraction, and also the eutectic Si particles decreased in size and distance between the particles. In the hot rolled samples, the Al matrix phase consisted of recrystallized grains of which size is comparable to the distance between the eutectic Si particles. Ultimate tensile strength of hot rolled sample increased nearly 33% compared to the one without hot rolling. Elongation of hot rolled sample was about 4.5 times higher than the one without hot rolling.抄録全体を表示PDF形式でダウンロード (4548K) -
足立 大樹, 会田 哲夫, 田中 昭衛, 楠井 潤原稿種別: 研究論文
2010 年 60 巻 1 号 p. 12-18
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーIt is well known that Al3Zr and Al3(Sc, Zr) particles precipitate in the matrix by adding Zr and Sc to aluminum alloys and these particles inhibit a static recrystallization by pinning the grain boundary. In this study, 1.33%Zr, 0.4%Sc–0.8%Zr and 0.8%Sc–0.4%Zr (in mass%) were added to 7000 series aluminum alloys in supersaturation by using powder metallurgy. By applying rapidly solidified powders of these alloys to a heat treatment at 773 K, Al3Zr and Al3(Sc, Zr) particles were precipitated in high density. Subsequently, hot extrusion was carried out at 773 K. During extrusion, continuous dynamic recrystallization (DRX) occurred and fine DRX grains with a diameter of 1 μm were formed. Continuous DRX is generated since the particles pin the grain boundaries and the mobility of the grain boundary lowers. So, the number of DRX grains are strongly related to the pinning force calculated by the average diameter of Al3Zr and Al3(Sc0.5, Zr0.5) particles precipitated in 1.33%Zr added alloy and 0.4%Sc–0.8%Zr alloy, respectively. Though, in 0.8%Sc–0.4%Zr added alloy, since Al3(Sc0.5, Zr0.5) and Al3(Sc0.86, Zr0.14) particles were precipitated concurrently, the diameter of particles exhibits a bimodal distribution and shows a widely dispersed distribution. As a result, the pinning force can't be accurately calculated by using the average diameter of particles and the number of DRX grains are weakly related to the calculated pinning force in 0.8%Sc–0.4%Zr added alloy.抄録全体を表示PDF形式でダウンロード (1871K) -
大﨑 修平, 前田 悦宏, 森田 到, 中井 学, 藪田 均原稿種別: 研究論文
2010 年 60 巻 1 号 p. 19-25
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーFor medium-strength aluminum alloys 7003 and 7N01 having average (symbolized with S) or upper limit (symbolized with H) in the contents specified in JIS, SSRT tests were carried out in humid air with 90% relative humidity by using a smooth tensile specimen machined from the alloy plates with temper T5, T6 or T7. The susceptibility to hydrogen embrittlement (HE) was evaluated and the relation between the crack extension and microstructural factors was discussed. The following four materials were found to satisfy the useful combination in properties between a low HE susceptibility and yield strength σYS≧320 [MPa]; 7003H-T5, 7N01S-T5, -T6 and -T7. It is supported from microstructural observations that the relatively high HE susceptibility in 7003S-T6 or 7N01H-T6 results from a heterogeneous distribution or a smaller size in grain boundary precipitates to favor intergranular cracking (IGC) , while the low susceptibility in 7003S-T7 or 7N01S-T6 is attributed to the grain boundary hydrogen accumulation reduced by trapping effects of matrix precipitates, dispersoids or second phase inclusions, leading to retardation of IGC extension.抄録全体を表示PDF形式でダウンロード (6039K) -
磨田 直人, 鑓田 征雄原稿種別: 研究論文
2010 年 60 巻 1 号 p. 26-30
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーMagnesium alloys have the lowest density among metals in practical use and have properties such as high specific strength and good vibration damping. However, there has been little use of these materials in metal forming because of their poor plastic deformability at normal temperature and high cost of production. To promote sheet products manufactured by metal forming, rolling technologies enabling the production of thin sheets with good surface qualities, mechanical properties and sheet formability at normal temperature are strongly required. In this study, rolling experiments using cone-shaped rolls are conducted to investigate the effects of asymmetric rolling and the thrust force on the mechanical properties and sheet formability of AZ31 magnesium. Hot-rolled AZ31 magnesium sheets were experimentally warm-rolled and reduced a thickness from 2.5 mm to 0.6 mm (a total reduction of 76%) by 11 passes at a sheet temperature of 573 K and roll temperatures of 353 K. Rolling force and axial force were measured. The grain structures and orientations of the rolled materials were also examined. Their mechanical properties such as tensile strength, 0.2% proof stress, total elongation and Lankford value (r-value) were measured by tensile tests. To investigate the sheet formability at normal temperature, conical cup tests were conducted and the sheet formability by asymmetric rolling were compared with that by symmetric rolling. The material rolled by asymmetric rolling exhibits greater elongation than that rolled by symmetric rolling. Asymmetric rolling can improve the sheet formability. However, magnesium alloys rolled by asymmetric rolling have poor sheet formability compared with mild steel sheet.抄録全体を表示PDF形式でダウンロード (2892K) -
山田 浩之, 堀川 敬太郎, 小林 秀敏原稿種別: 研究論文
2010 年 60 巻 1 号 p. 31-35
発行日: 2010/01/30
公開日: 2010/02/28
ジャーナル フリーIn order to elucidate the mechanism of the high temperature embrittlement of Al–5 mass%Mg alloys containing traces of sodium, microscopic observation of grain boundaries during quasi-static and impact tensile deformation was carried out. The high temperature embrittlement during the quasi-static deformation was caused by a combination of grain boundary sliding and grain boundary serration. On the other hand, the high temperature embrittlement during the impact deformation was caused by the localization of stress concentration at the grain boundaries. This localization was due to planar slips.抄録全体を表示PDF形式でダウンロード (3302K)
解説
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奥田 浩司, 落合 庄治郎原稿種別: 解説
2010 年 60 巻 1 号 p. 36-40
発行日: 2010/01/30
公開日: 2010/04/30
ジャーナル フリーIntroduction to small-angle X-ray scattering (SAXS) and ultra small-angle X-ray scattering (USAXS) is presented. SAXS is useful for microstructure analysis of age-hardenable alloys containing precipitates with several to several tens of nanometers in size. On the other hand, USAXS is appropriate to examine much larger microstructural heterogeneities, such as inclusions, voids, and large precipitates whose size is typically around one micrometer. Combining these two scattering methods, and sometimes also with diffractions, it is possible to assess the hierarchical structure of the samples in-situ and nondestructively, ranging from phase identification, quantitative analysis of precipitation structures upto their mesoscopic aggregates, large voids and inclusions. From technical viewpoint, USAXS requires some specific instrumentation for its optics. However, once a reasonable measurement was made, the analysis for the intensity is the same as that for conventional SAXS. In the present article, short introduction of conventional SAXS is presented, and then, the analysis is applied for a couple of USAXS data obtained for well-defined oxide particles whose average diameters are expected to be about 0.3 micrometers.抄録全体を表示PDF形式でダウンロード (871K)
連載講座
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真鍋 健一2010 年 60 巻 1 号 p. 41-51
発行日: 2010/01/30
公開日: 2021/06/15
ジャーナル フリーPDF形式でダウンロード (1755K)
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