巻号一覧
34 巻, 12 号
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及川 孝1984 年 34 巻 12 号 p. 673-674
発行日: 1984/12/30
公開日: 2008/07/23
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大西 忠一, 東 健司1984 年 34 巻 12 号 p. 675-681
発行日: 1984/12/30
公開日: 2008/07/23
ジャーナル フリーIn order to estimate quantitatively and theoretically, the SCC test results for Al-8%Mg alloy were analyzed with applying the fracture mechanics, based on the presumption that the principal determining parameter in SCC is the localized hydrogen embrittlement at near the crack tip. Theoretically, the high hydrogen concentration is appeared to be unable to produce through the hydrostatic stress induced diffusion only, in the case of lower yield strength materials such as one discussed here. Thus the concentration due to the increase of plastic strain was discussed by the strain field analysis, assumed that the hydrogen content at near the crack tip can increase proportionally with an increase in dislocation density associated with the plastic yielding within the plastic zone. Results of analysis for the moving crack with continuous hydrogen supply from an environment, showed that the extremely high concentration can be induced within the plastic zone, and that the theoretical prediction can be very closely consistent with the actual behavior of the alloy discussed. Nucleation and propagation of SCC crack were also considered with the fracure mechanics.抄録全体を表示PDF形式でダウンロード (982K) -
清水 保雄, 加藤 良雄, 橋本 澄人, 土屋 直巳1984 年 34 巻 12 号 p. 682-688
発行日: 1984/12/30
公開日: 2008/11/05
ジャーナル フリーAn experimental investigation was made for effects of simultaneous addition of phosphate (P-) flux and sodium halide (Na-) flux upon the cast structure and mechanical properties of hypereutectic Al-19%Si alloys. The fluxes introduced into alloy melts were P-flux (90(NaPO3)6-10Al2O3) and Na-flux (50NaF-50NaCl) which are effective, respectively, for refining the primary Si crystal and for modifying the eutectic Si crystal. The simultaneous addition of P- and Na-flux was effected by use of a composite P-Na-flux prepared by mixing both the component fluxes in weight ratio 1: 1 and 1: 2 and fusing the mixture in union. The P-Na-flux, when containing the component fluxes in some adequate weight ratios, is capable of producing such alloys as are composed in structure of fine grain primary Si crystals and modified eutectic Si crystals, of improving the tensile strength up to a level comparable with that achieved by the P-flux addition, and of improving the breaking elongation more than either the P- or Na-flux singly added.抄録全体を表示PDF形式でダウンロード (2441K) -
吉田 英雄, 宇野 照生, 馬場 義雄1984 年 34 巻 12 号 p. 689-701
発行日: 1984/12/30
公開日: 2008/11/05
ジャーナル フリーTensile properties, fracture toughness, fatigue crack propagation properties, quench sensitivity and resistance to stress-corrosion cracking were compared between 7150 and 7475 high toughness aluminum alloys. The effect of impurity level (iron and silicon) on these properties was also investigated. Further the role of minor additional elements (zirconium in 7150 and chromium in 7475) was discussed. As a result, tensile and yield strength of 7150 plates were higher than those of 7475 ones, however elongation and fracture toughness of the former were lower than those of the latter. In particular, fracture toughness of T651-tempered 7150 plates was not improved even if the content of iron and silicon were diminished. Many fine dimples (0.1 to 0.5 μm in spacing)were observed in the fracture surface of 7475 plates. On the other hand, there were few dimples in that of 7150 ones. It is considered that the difference of fracture surface was caused by minor additional elements. Zirconium in 7150 precipitates in the meta-stable phase, Al3Zr, which has a Ll2 ordered structure and has coherency with the matrix. On the other hand, chromium in 7475 precipitates in the stable phase which has no coherency with the matrix. Therefore plastic deformation around chromium-bearing compounds occurs more easily than around zirconium-bearing ones, since equilibrium phase particles (MgZn2, etc) precipitate at the misfit surface of chromium-bearing ones and precipitate-free zone occurs around them more easily compared with zirconium-bearing ones. Thus the plasticity of 7475 is superior to that of 7150.抄録全体を表示PDF形式でダウンロード (4723K) -
皆川 一泰, 中島 道則, 佐藤 栄一1984 年 34 巻 12 号 p. 702-707
発行日: 1984/12/30
公開日: 2008/07/23
ジャーナル フリーThe cause of anodic polarization behavior of high purity aluminum in deaerated acidic and neutral solutions was studied by electrochemical measurement. Anodic polarization curves showed limiting current density depending on pH in pH range 4-7. But in the pH range 1-4, anodic polarization curves showed no clear limiting current density, and the values of current density at -900 mV vs. SCE were identical. These behaviors can be explained in the following way. In neutral solution, film thicknese is large relatively, and the potential difference across the Helmholtz layer at the film-electrolyte interface is independent of the electrode potential. In this case, limiting current density depends only on pH. But in acidic solution, film thickness is very small, and the electrode potential affects the potential difference across the Helmholtz layer on which current density depends. The dissolution of film is attributed to the electrochemical reaction depending on inner potential difference at the film-electrode interface.抄録全体を表示PDF形式でダウンロード (788K) -
鈴木 寿, 伊藤 吾朗, 小山 克己1984 年 34 巻 12 号 p. 708-716
発行日: 1984/12/30
公開日: 2008/07/23
ジャーナル フリーA basic study has been made in order to obtain a brazing sheet having a high resistance to deformation during brazing. At first, the amount of deformation at brazing temperature of 610°C was measured on several brazingsheet specimens consisting of 4343 cladding alloy (both sides cladding) and Al-1.2%Mn base core alloys having no impurity or containing a small amount of Si, Fe, Cu, Mg, etc., as a function of cold reduction of specimens. Marked deformation was observed in the Si contained specimen (Si is added to the core alloy) cold-rolled by 515% and in the Fe contained specimen with a large reduction. Then, the two sorts of deformation were studied in detail in view of reaction at the interface between solid core and liquid phase of cladding alloy. It was found that the microstructure of core alloys at brazing temperature was of great importance for the stability of interface. It was concluded that in order to get an excellent brazing sheet, the core alloy was needed to show a completely recrystallized structure having coarse and elongated grains. The Al-Mn binary specimen free from impurity would satisfy the above condition.抄録全体を表示PDF形式でダウンロード (3301K) -
室町 繁雄1984 年 34 巻 12 号 p. 717-722
発行日: 1984/12/30
公開日: 2008/07/23
ジャーナル フリーPDF形式でダウンロード (1061K)
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