巻号一覧
46 巻, 2 号
選択された号の論文の8件中1～8を表示しています
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研究論文
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水野 兼雄, 古谷 重雄, 横田 成昭, 福迫 達一1996 年 46 巻 2 号 p. 55-60
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーThe average cooling rate, dendrite arm spacing (DAS), tensile strength and hardness of AC4B aluminum alloy castings were investigated. The average cooling rate decreases with increasing thickness of the casting and increasing casting mass. The DAS increases and tensile strength and hardness decrease with increasing thickness of the casting. The solidification time, tf of the casting was represented by tf=K(M)n, using casting modulus, M=V/S (V: volume of a casting, S: surface area of a casting) as proposed by Chvorinov. In the present work, n=1.8 and K=138 were experimentally determined. The relationship between the n-th power of the casting modulus (M), and the average cooling rate (VS), DAS (DS), tensile strength (σB) and hardness (HV) were linear on a logarithmic scale. The following equations were obtained in the present experiment for the casting modulus, the average cooling rate, dendrite arm spacing, tensile strength and hardness; VS=360(M)-0.1, DS=1.4(M)-0.6, &simga;B=200(M)-0.24, HV=40(M)-0.24, &simga;B=4800 VS-2.0, HV=3000 VS-2.0, DS=20 VS-0.6抄録全体を表示PDF形式でダウンロード (589K) -
柳川 政洋, 松本 克史, 安倍 睦, 大家 正二郎1996 年 46 巻 2 号 p. 61-64
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーGrain growth behavior in Al–6%Mg alloy was investigated and the results were as follows. (1) The grain growth kinetics for the early stages of annealing obeyed parabolic kinetics (D/2)2 − (D0/2)2=Kt, where D is a grain size after annealing for time, t, K is a temperature-dependent rate parameter and D0 is the grain size at time equal to zero. The apparent activation energy of the grain growth for the early stages of annealing was 1.05 eV and it was supposed that the process was diffusion controlled by Mg atoms. Equilibrium grain size was present for the later stages of annealing and the temperature dependence was observed. (2) It is supposed that the equilibrium grain size is caused by the loss of mobility due to the segregation of solute atom (Mg) on the grain boundary, and that its temperature dependence is due to the temperature dependence of the magnitude of segregation of solute atom on the grain boundary.抄録全体を表示PDF形式でダウンロード (472K) -
北澤 君義, 若林 昭彦, 村田 和也, 八重嶋 公郎1996 年 46 巻 2 号 p. 65-70
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーAn incremental forming process in which a blank is formed to fit on a tool-envelope surface made by relative motion of a tool around the blank, has been developed. The incremental forming process seems to be suited to small-lot production from viewpoint of a die-less forming operation, and are also thought to be important in metal-flow control operation. So, the possibility of metal-flow control in CNC incremental stretch-expanding of aluminum sheets was examined. Effect of tool path schedule on strain distribution and forming limit in shell components is examined using hard aluminum sheet. It is found that the tool path schedule has influence on strain distribution in shell components, and the associated metal-flow has influence on the forming limit. Thus, it was concluded that the incremental stretch-expanding seems to be a promising working process for flexible manufacture from viewpoint of metal-flow control.抄録全体を表示PDF形式でダウンロード (1106K) -
鎌士 重晴, 新川 貴啓, 和田 貴樹, 小島 陽1996 年 46 巻 2 号 p. 71-76
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーMagnesium matrix alloy composites was fabricated employing Mg–4 mass%Zn–0.2 mass%Ca alloys as a matrix alloy and aluminum borate whisker as a reinforcement fiber by squeeze casting. Relationships between the fabrication conditions and the soundness of composites, and the aging characteristics and high temperature tensile properties of the obtained sound composites were investigated. As the preform sintering temperature raises, the preform compressive strength increases without the crystal structural changes up to 1400°C. As the preform sintering and pouring temperatures increase, the area of the preform cracking and non-infiltrating region decrease, resulting in the reduction of tensile strength scatter at room temperature. MgO polycrystalline layer with a thickness of the order of 0.1 μm is created at whisker-matrix interface and enhances the bonding strength at the interface. Precipitates finely distribute and amount of age hardening slightly increases by pre-aging at 50~70°C for 24 h before aging at 180°C for 1 h, but the strength of the composites is unchanged. As-cast and T7-treated composites reinforced with 26 vol% aluminum borate whisker has the tensile strength of 350∼360 MPa at room temperature, whereas exhibits that of 130~140 MPa at 250°C. SEM fractographs suggest that the considerable softening of matrix alloy at 250°C makes easy to debond at the edge of whisker at 250°C and that crack propagation in the matrix is easy due to the fine distribution of the whisker.抄録全体を表示PDF形式でダウンロード (1235K) -
鎌士 重晴, 関原 一敏, 大西 智, 小島 陽1996 年 46 巻 2 号 p. 77-82
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーMg–Al and Mg–Zn alloys containing Si or Ca, which forms intermetallic compounds having high melting temperatures with magnesium, were initially strained compressively and then press-formed at the semi-solid state. Microstructures, heat treatment characteristics and mechanical properties of the formed specimens were evaluated. Microstructures with uniformly distributed fine and spherical particles are obtained by applying the semi-solid forming to the strain-induced bulk. The Mg–Al specimens with Si or Ca have microstructures with the fine eutectic phase produced by the rapid cooling and exhibit precipitation structures in the whole grains, resulting in the marked age hardening. As the forming temperature rises, the amount of liquid phase increases and the fluidity of a semi-solid material is improved, resulting in the decreased generation of defects during forming. But the mechanical properties become degraded due to the increased amount of the eutectic phase. To increase the forming temperature also causes the localized liquid phase to the edge side of the disc-like specimens and results in the formation of the non-uniform macrostructures. Tensile properties of all formed specimens at the ambient temperature are far superior to those of the as-cast specimens, but lower than those of the formed AZ91D magnesium alloy. The tensile properties, however, become superior to those of the AZ91D magnesium alloy at temperatures above 150°C. In particular, the Mg–Al–Ca alloy shows high strength at elevated temperatures because of the fine Al2Ca phase crystallized at grain boundaries.抄録全体を表示PDF形式でダウンロード (1230K) -
板垣 武志, 当摩 建1996 年 46 巻 2 号 p. 83-88
発行日: 1996年
公開日: 2007/03/30
ジャーナル フリーPitting growth mechanism in dilute chloride solution on clad aluminum alloys having potential slope was investigated by an electrochemical technique. The ability of pitting growth in the direction of thickness was determined by the relation between effects of positive potential slope by additional elements and of negative potential slope by concentration of Cl− at the pit bottom. In dilute chloride solution, pitting grew in the direction of thickness in spite of potential slope if it was gentle. Not only positive potential slope, but also potential defference of more than 90 mV between core alloy and sacrificial anode is required to protect core alloys for 7 days in tap water containing 1 ppm Cu2+.抄録全体を表示PDF形式でダウンロード (805K)
解説：小山田記念賞
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吉田 英雄, 毛利 英一, 箕田 正, 日比野 壮美, 岡島 賢三, 伊藤 日出国, 塚本 鎮正1996 年 46 巻 2 号 p. 89-96
発行日: 1996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 (1593K)
連載講座
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加藤 雅治1996 年 46 巻 2 号 p. 97-108
発行日: 1996年
公開日: 2022/02/15
ジャーナル フリーPDF形式でダウンロード (10169K)
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