巻号一覧
48 巻, 4 号
選択された号の論文の9件中1～9を表示しています
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研究論文
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松木 賢司, 近藤 琢年, 會田 哲夫, 高辻 則夫, 楠井 潤, 村上 哲1998 年 48 巻 4 号 p. 157-162
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーAir atomized 2024Al–3Fe–5Ni alloy powder was mechanically alloyed (MA) for 0~154.8 ks in an argon atmosphere. Subsequently, hot compacted at 673 K, and then hot pressed to 2 mm thickness plates at temperatures of 673 K~793 K and at initial strain rates of 5 ×10−1~10s−1. The effect of MA time on the microstructure and hardness of MA powder, hot compacted blocks and hot compressed plates has been investigated in the light of improvement of ambient and high temperature strength of the alloy plates. Vickers hardness of MA powders and compacted blocks increased with increasing MA time up to 57.6 ks. Thus, the hot compressed MA alloy was stronger than the non MA alloy at temperatures up to about 573 K. The results of DSC, XRD and TEM revealed that the primary and eutectic intermetallic phases such as Al9FeNi compounds were finely dispersed and finally the transition elements in some parts of compounds were super-saturated in matrix by the high energy of MA. The supersaturated elements were precipitated as finely and thermally stable dispersed particles at the temperature higher than about 673 K. Improvements in the ambient and elevated temperature strength are mainly attributed to the presence of extremely fine grain structure and finely dispersed particles which were introduced during MA and consolidation process.抄録全体を表示PDF形式でダウンロード (1059K) -
北澤 君義, 守国 栄時1998 年 48 巻 4 号 p. 163-167
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーA new CNC incremental process with ORIGAMI method in which a shell is formed from a flat blank by means of pre-bending process (ORIGAMI process) and subsequent incremental stretch-expanding process has been proposed in order to prevent the thinning phenomena. Although the process has the advantage of preventing the thinning phenomena, a method for preventing the forming defects, such as wrinkling, remains unknown. In this study, the forming defects occurred in the process have been experimentally investigated. Aluminum and its alloy blanks were bent into a shape inscribed in an automobile trunk-lid-type panel, and then stretch-expanded to the panel shape, and the deformation behavior was examined. It was found that formability of the process is dependent not only on the degree of surface distortions of the panel, such as wrinkling and puckering, but also on the remainder of pre-bent shape caused by elastic deflections during the stretch-expanding process. Experimental results showed that these distortions and the remainder of pre-bent shape can be overcome by employing the stretch-expanding process with reciprocating tool-path.抄録全体を表示PDF形式でダウンロード (1187K) -
鎌土 重晴, 北口 豊, 播磨 克忠, 小島 陽, 谷池 茂弘, 関伊 佐夫1998 年 48 巻 4 号 p. 168-173
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーThe aim of this study is to determine optimum forging conditions for Mg–Gd–Nd–Zr and Mg–Gd–Y–Zr alloys. Firstly, homogenization temperature of these alloys was altered at the solvus temperature, above and below that temperature to evaluate the effect of grain size and remained compound on high temperature deformation characteristics by conducting high temperature tensile and compression tests. Consequently, an increase in elongation is obtained in specimens with both a small amount of compound and a small grain size. However, the prevention of grain coarsening is found to be a more important factor for the increase in elongation of these specimens than the amount of compound. As a next step, these specimens controlled the grain size more than 65 μm were used for die forging into a piston shape under the conditions of a die speed of 0.36 to 0.41 m/s, a specimen temperature of 500°C and a mold temperature of 300°C. Applying these optimum forging conditions leads to the production of die-forged pistons with an excellent surface finish and without internal cracks.抄録全体を表示PDF形式でダウンロード (2236K) -
井上 誠, 岩井 正雄, 松澤 和夫, 鎌士 重晴, 小島 陽1998 年 48 巻 4 号 p. 174-178
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーRelation between the amount of refined pure magnesium, impurities in the refined magnesium and purification time has been investigated for vacuum distilled magnesium alloys AM100A and AM60B. Corrosion characteristics of pure magnesium which was refined and then remelted in a vacuum high frequency induction furnace were investigated by means of a salt spray test and an electrochemical method. The extent of purification, defined by the quantity ratio of refined magnesium to alloy used increases linearly with increasing purification time, though purification rate is higher in alloy AM100A than in alloy AM60B. Zinc content in the refined magnesium decreases with purification time. The corrosion loss of the remelted pure magnesium in salt spray test, is as low as that of high purity commercial magnesium alloys. Both the amount of impurities and the current density of cathodic part of polarization curve are greater in the commercially pure magnesium than in the refined pure magnesium.抄録全体を表示PDF形式でダウンロード (800K) -
池野 進, 片山 暢, 松田 健二, 蓮覚寺 聖一, 品川 不二雄, 上谷 保裕1998 年 48 巻 4 号 p. 179-184
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーAl–1.0 mass%Mg2Si–0.34 mass%Si alloy specimens which had been aged at 423 K for various times were tensile tested at room temperature. Changes in local deformation near grain boundaries with aging time were investigated by scanning tunneling microscopy. When a little loss in elongation occurred at early stage of aging, the folds generated at the grain triple junction. But they were very ambiguous and did not develop with increasing amount of deformation. The fold formations were difficult to be explained by the maximum resolved shear stress on a grain boundary plane (Fmax). If the elongation appreciably decreased and intergranular fracture began to occur with the progress of aging, the folds developed and became more clear. The fold formations at this stage could be explained by the Fmax in many cases. Frequencies of fold formations increased with the aging time over a range of under-aged to peak-aged condition, and this correlated approximately to the decrease in elongation. Even if the elongation considerably recovered in the specimen which had been aged at 473 K up to over-aged condition, the frequency of fold formation was similar to that of the peak-aged condition. In this case, however, two types of folds which had developed largely or had developed scarcely with the progress of deformation were observed and the frequency of the former ones decreased to about a half of the all folds.抄録全体を表示PDF形式でダウンロード (1310K) -
田村 洋介, 河野 紀雄, 茂木 徹一, 佐藤 英一郎1998 年 48 巻 4 号 p. 185-189
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーThe investigation was performed to examine the influence of undissolved Zr particles in molten magnesium on the grain refinement of Mg–Zr alloy. A Mg–30%Zr master alloy was added to the molten pure magnesium at 993 K. All samples revealed that 0.4%Zr was dissolved in the pure magnesium. Sedimentation of Zr particles occured for holding the molten magnesium up to 7.2 ks at the temperature of 993 K and the grain size of the solidified structure became larger with prolonging holding time. However, when the molten metal was agitated just before pouring, grain refinement always occured. It is suggested that the undissolved Zr particles in the melt are nucleation sites of the solidifying magnesium or primary zirconium crystals. Zr content was the lowest around the undissolved Zr particles observed in Zr–enriched cored structure, because the undercooling occured for growth of the predendritic region.抄録全体を表示PDF形式でダウンロード (1121K) -
山下 友一, 渡辺 亨, 松田 健二, 穴田 博, 池野 進1998 年 48 巻 4 号 p. 190-194
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーThe effects of homogenizing treatment and iron content on the tensile properties of 6061 aluminum alloy billet were investigated mainly by tensile test and transmission electron microscopic observation. With the specimens produced by the vertical semi-continuous casting process, the iron content is 0.18, 0.7 and 1.4 mass%, the DAS is 9 and 25 μm, and the grain size is constant at about 80 μm. In the 0.18 mass% Fe alloy, elongation in as-cast is larger in DAS–9 μm than in DAS–25 μm. If they were air cooled after the homogenizing treatment, the difference in elongation between them is decreased with the increase of homogenizing time. On the other hand, if these samples were water quenched after the homogenizing treatment, even when DAS is different, no difference in elongation was found. The cause for this was presumed to be that the cooling condition after the homogenizing treatment accelerated the fracture of specimens by precipitating a coarse β' phase in the air cooling, and its elongation was reduced. It was revealed that the second phase formed between dendrite arms increased with the increase of iron content, the smaller the DAS is, the larger the elongation, and the difference of DAS did not disappear even in a long time homogenizing treatment.抄録全体を表示PDF形式でダウンロード (1832K) -
櫻井 惠三, 足立 勝重, 花﨑 伸作1998 年 48 巻 4 号 p. 195-198
発行日: 1998年
公開日: 2007/03/30
ジャーナル フリーThis study involves a basic research to determine the optimum cutting condition with the main objective of revealing the breaking mechanism of the continuous cone-shaped helical chips produced during intermittently decelerated feed drilling. The friction torque due to chips flowing through the drill flute and the breaking torque of chips are determined experimentally and the breaking mechanism of chips in intermittently decelerated feed drilling is investigated. The following facts are ascertained from the obtained results. (1) Chips formed in intermittently decelerated feed drilling break at points where chip thickness changes. (2) Chip breakage occurs when the resulting friction torque between the hole wall and chip exceeds the breaking torque of chips. (3) Chip breakage depends solely on the length of the fast feed section or the total length of the fast and slow feed sections, and varies according to the breaking strength of chips.抄録全体を表示PDF形式でダウンロード (674K)
技術報告
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福本 信次, 波々伯部 朋子, 椿野 晴繁1998 年 48 巻 4 号 p. 199-203
発行日: 1998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 (1057K)
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