巻号一覧
57 巻, 7 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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寺脇 翼, 山本 厚之, 椿野 晴繁2007 年 57 巻 7 号 p. 269-273
発行日: 2007年
公開日: 2007/08/30
ジャーナル フリーSurface modification by combining high purity (h.p.) magnesium coating intermediate layer and the fluoride treatment has been applied to AZ31B magnesium alloy. The h.p. magnesium coating on AZ31B alloy was formed by vacuum evaporation method. Specimens with and without the h.p. coating are dipped into molten NaBF4 at 693 K for 10.8 ks to form fluoride layer. Diffraction measurements and residual stress analysis were carried out at synchrotron radiation facility SPring-8, BL-24XU (Hyogo prefecture beam line). The surface layer after the fluoride treatment was composed of NaMgF3 and MgF2 phase. Compression residual stress was detected, and the h.p. intermediate layer effectively decreased the compression stress. The fluoride treatment layer on the h.p. magnesium showed high corrosion resistance. The combined surface modification with the h.p. coating and the fluoride treatment improved corrosion resistance by a factor of one half in 0.1 N HNO3 solution, and by a factor of two in 0.02 N HCl solution, comparing with the fluoride-treated AZ31B alloy without the h.p. magnesium intermediate layer. Because Al–Mn compound, which might precipitate in AZ31B alloy and disturb the formation of the surface fluoride layer, were covered by the h.p. magnesium layer, the corrosion resistance seemed to be improved by the combined surface modification.抄録全体を表示PDF形式でダウンロード (3014K) -
松本 良, 小坂田 宏造2007 年 57 巻 7 号 p. 274-279
発行日: 2007年
公開日: 2007/08/30
ジャーナル フリーThe upsettability test and backward extrusion are carried out to investigate forging limit of a commercial AZ31 magnesium alloy (Mg–3%Al–1%Zn) with controlled grain size at temperatures of 293–673 K. To change the grain size of the AZ31 specimen, the specimens are annealed at temperatures of 473–773 K before forging. By annealing at higher than 673 K, the grain size of the specimen becomes large, and the anisotropy of the specimen is reduced. In forging at lower than 473 K, forging limit without fracture of the specimen annealed at 773 K is higher than that of the specimen annealed at 473 K. On the other hand, in forging at higher than 473 K, the forging limit of the specimen annealed at 773 K is lower than that of the specimen annealed at 473 K. Thus, it is considered that the refinement of the grain size is effective on the forging limit in warm forging, and the controlling of the anisotropy of the specimen is effective on the forging limit in cold forging.抄録全体を表示PDF形式でダウンロード (1376K) -
中山 栄浩, 吉田 翔, 野村 享平2007 年 57 巻 7 号 p. 280-285
発行日: 2007年
公開日: 2007/08/30
ジャーナル フリーIt is well known that a pre-strain such as skin pass rolling is effective for the prevention of a strain marking accompanied by the forming. However, it has been pointed out that the formation of the strain marking depends on the time and the temperature history until the forming. In the present study, therefore, a 5083 aluminum alloy plate was tensile deformed and aged in order to investigate the influence of the strain aging on the stress fluctuation. Stress fluctuation resulted from the strain marking was generated with the lapse of strain aging time at any aging temperature, while the time required to the onset of stress fluctuation became long along with the rise in aging temperature. The amount of an increasing flow stress due to the strain aging increased monotonously with the rise in aging temperature and with the lapse of aging time. On the other hand, the critical strain required to the onset of stress fluctuation in the serration region decreased clearly when the strain aging was carried out at near 328 K, while there was no quantitative relation between the degree of time and strain of the strain aging and the amount of a decrease of the critical strain.抄録全体を表示PDF形式でダウンロード (627K) -
山口 毅, 斉藤 研, 河村 能人2007 年 57 巻 7 号 p. 286-292
発行日: 2007年
公開日: 2007/08/30
ジャーナル フリーThe authors examined the properties of Mg96Zn2Y2 alloy bars made through continuous consolidation of chip using a newly developed single screw extrusion machine designed for magnesium alloy chip. Surface conditions as well as microstructure of the consolidated Mg96Zn2Y2 alloy varied depending on the die conditions. With a die inner diameter of 49 mm and die temperature of 723 K, severe plastic deformation in the die produced a fine-grain microstructure in the consolidated Mg96Zn2Y2 alloy bar. The compounds such as Mg12YZn and Mg3Y2Zn3 in the bar were also dispersed finely. Owing to its randomized crystal orientation, a secondary extruded bar made from the consolidated Mg96Zn2Y2 alloy bar showed a higher ductility than that of ingot-extruded bar. The fine-grain consolidated Mg96Zn2Y2 alloy bar exhibited an elongation of 308% at 723 K. Furthermore, the deformation characteristics were examined with the consolidated Mg96Zn2Y2 alloy bar for the purpose of determining its suitability as hot-processing material billets. The fine-grain consolidated Mg96Zn2Y2 alloy bar was compressed without cracking up to 623 K while Mg96Zn2Y2 ingot cracked. It was found that smaller grain diameter made the m-value higher.抄録全体を表示PDF形式でダウンロード (2385K)
解説
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石田 章2007 年 57 巻 7 号 p. 293-300
発行日: 2007年
公開日: 2007/10/30
ジャーナル フリーPDF形式でダウンロード (2672K)
連載講座
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高辻 則夫2007 年 57 巻 7 号 p. 301-310
発行日: 2007/07/30
公開日: 2021/06/30
ジャーナル フリーPDF形式でダウンロード (3182K)
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