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Volume 36, Issue 5
Displaying 1-10 of 10 articles from this issue
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Takakazu TANAKA1986 Volume 36 Issue 5 Pages 253-254
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
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Hideyuki KANEMATSU, Masazumi OKIDO, Takeo OKI1986 Volume 36 Issue 5 Pages 255-261
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe effect of heat treatments on the SCC susceptibility of Al-Zn-Mg alloy in 0.6N NaCl solution was investigated by the potentiostatic SSRT (Slow Strain Rate Technique) in connection with its polarization behavior. Solutiontreated, peak-aged and over-aged specimens were tested, and the potential of these specimens was regulated in the region of pitting corrosion, unstable passivity and stable passivity respectively, which were found from their polarization curves in 0.6N NaCl solution at 298K. And the fracture surface of specimen was observed by a scanning electron microscope (SEM).
At the pitting potential, all these specimens fracture transgranularly at first, being followed by intergranular cracking inside of the specimen. Transgranular cracking is considered as the crack induced by pitting corrosion, and intergranular cracking as the rupture-growth of the oxide film on grain boundaries. The fracture ratio of intergranular cracking to dimple pattern for over-aged specimen is smaller than that of solution-treated specimen. It is explained from the viewpoint of the growth of oxide film.View full abstractDownload PDF (2920K) -
Shigeyuki KIKUCHI, Tadakazu OHNISHI, Kenji HIGASHI1986 Volume 36 Issue 5 Pages 262-271
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSEffect of (Fe+Si) content on the fracture toughness of extruded 7050 alloys was investigated. A reducing of (Fe+Si) content increased the macroscopic fracture toughness of the alloy. An over-aging treatment also did it. These effects may be appreciated by a good interrelation between (Fe+Si) content and inclusions acting as crack sites. However, reducing (Fe+Si) content tended to lead to formation of localized brittle fracture under a lower stress, especially for T651 materials. Facility in forming localized brittle fracture was related to development of a double fiber texture with <111> and <100>, and the higher development, the more facility. Accordingly, in extrusions such as of 7050 alloy, it may be worthwhile to examine microscopically the details of fracture features as well as the macroscopic fracture toughness. A fractographical examination and an AE monitoring suited for this purpose.View full abstractDownload PDF (3017K) -
Tadakazu OHNISHI, Nobuya SEKO, Kenji HIGASHI, Shigeyuki KIKUCHI1986 Volume 36 Issue 5 Pages 272-278
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSStress corrosion resistance of 7050 extrusions with four levels of purity was investigated in the extruding direction. In the case of T651, the most superior resistance was found in the alloy with 0.24% (Fe+Si), in this experiment, and increasing or decreasing purity resulted in a lowering of resistance. Marked improvement of resistance was obtained by the over-aging treatment (T751) for each alloys, although a similar purity effect was also detected. A lowering of resistance with decreasing purity seems to be due to the increase of amounts of inclusions acting as crack sites. On the other hand, a reducing of resistance with increasing purity appears to be owing to development of the double fiber texture with <111> and <100> which can cause localized brittle fracture at a lower load. To select the optimum purity and/or to avoid severe development of the double fiber texture are preferable to improve resistance of extrusions in the extruding direction.View full abstractDownload PDF (1731K) -
Yasuhiro UETANI, Yoshio ASAI, Susumu IKENO, Shizuo TADA1986 Volume 36 Issue 5 Pages 279-285
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSTensile tests have been carried out at room and low temperatures in order to examine the applicabilities of Hollomon equation σ=KHεnH and Ludwik equation σ=σ0+KLεnL to the stress-strain curves of Al-Mg, Al-Cu and Al-Zn alloys. Hollomon equation does not hold in each alloy, and the higher the solute concentration, the larger the deviation from the linearity on log-log plots. On the other hand, Ludwik equation agrees well with the observed stress-strain relationship in low strain ranges where values of nL are approximately equal to those calculated from the slopes of log-log plots of dσ/dε and strain. The amount of strain to maximum load which is predicted from Ludwik equation in higher strain ranges is fairly close to the observed one.View full abstractDownload PDF (940K) -
Hideyuki SAITOH, Yoshiaki IIJIMA, Ken-ichi HIRANO1986 Volume 36 Issue 5 Pages 286-291
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSBehavior of tritium in a quasi-binary Al-1 mass% Mg2Si alloy has been studied by the electronmicroautoradiography. It is found that the G. P. zone in this alloy does not act as a trapping site but a repeller for hydrogen. Dislocation is found to be capable of trapping hydrogen as well as being a short-circuiting diffusion path for hydrogen, while trapping of hydrogen by the grain boundary is not found. Interfaces between the intermediate β' precipitate and the matrix and between the equilibrium β precipitate and the matrix are proved to have strong trapping effect for hydrogen.View full abstractDownload PDF (2110K) -
Junichi ENDO, Tadao MUROTA1986 Volume 36 Issue 5 Pages 292-296
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDeformation of aluminum-fin tubes in uniform bending has been experimentally studied and compared with that of tubes without fin. When the plane of the fin is perpendicular to the bending plane, both the bending moment and the flattening of cross-section are identical with those in tubes without fin. But when the plane of the fin coincides with the bending plane, the bending moment and the flattening of cross-section become larger than those in ordinary tubes and wrinkles can be seen on the inner side fin. These effects of slittless fin on the deformation in bending are quantitatively clarified.View full abstractDownload PDF (533K) -
Yoichi TAMAZAKI1986 Volume 36 Issue 5 Pages 297-304
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
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Morphological instability of planar solid-liquid interfaceGoro OHIRA1986 Volume 36 Issue 5 Pages 305-313
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
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Osamu WADA, Shigeo MANABE, Shinsuke ISHIKAWA, Jin Hu FUNG1986 Volume 36 Issue 5 Pages 314-324
Published: May 31, 1986
Released on J-STAGE: July 23, 2008
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