Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Volume 45, Issue 11
Displaying 1-14 of 14 articles from this issue
  • Masakazu OKAZAKI
    1995 Volume 45 Issue 11 Pages 587-596
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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  • Hideto SUZUKI
    1995 Volume 45 Issue 11 Pages 597-609
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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  • Hiroyuki TODA, Toshiro KOBAYASHI
    1995 Volume 45 Issue 11 Pages 610-621
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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  • Keiichiro TOHGO
    1995 Volume 45 Issue 11 Pages 622-632
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
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  • Nobuyasu SUGIURA, Toshiro KOBAYASHI, Isamu YAMAMOTO, Seishi NISHIDO, K ...
    1995 Volume 45 Issue 11 Pages 633-637
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    In order to design an optimum balance between high safety and light weight, the materials used in the automobile industry must be evaluated on their mechanical characteristics especially under the dynamic loading conditions. However, such evaluation is rather difficult and no standard procedure is readily available. In this study, the strain rate dependency of tensile properties during the impact tensile test of an AC4CH-T6 high quality aluminum casting alloy has been examined. The strain rated dependency of the yield strength, percentage elongation and reduction of area of the alloy have been clarified and discussed.
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  • Nobuyasu SUGIURA, Toshiro KOBAYASHI, Isamu YAMAMOTO, Seishi NISHIDO, K ...
    1995 Volume 45 Issue 11 Pages 638-642
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    The 3-point bend test is conducted under static and dynamic loading conditions for an AC4CH-T6 high quality aluminum casting alloy and the results are compared with the ones previously obtained by the tensile test in order to establish relationships between the characteristic values for both tests. Good correlations have been confirmed between values of the yield strength, ultimate strength and true fracture strain for the two types of test. The dependency of the absorbed energy on the strain rate is found to be almost similar in the 3-point bend test and tensile test.
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  • Keijiro NAKASA, Toshihiro SHIMIZU
    1995 Volume 45 Issue 11 Pages 643-648
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Fatigue tests were carried out on notched specimens of Ti-15V-3Cr-3Al-3Sn alloy at frequency of 0.5 or 0.1Hz and stress ratio of 0.1 under electrolytic hydrogen-charging in sulfuric-acid aqueous-solution at charging current densities of 1000 and 2000A/m2, and the results were compared with those tested in air. The crack initiation life is decreased by hydrogen charging especially when the range of apparent stress intensity factor is low. The crack propagation rate is decreased by hydrogen charging when the range of stress intensity factor ΔK is moderate, while when ΔK is small the crack propagation rate under hydrogen charging is almost the same as that in air. The fracture surface of charged specimen reveals larger amount of quasi-cleavage fracture. The measurement of crack closure reveals that the crack opening ratio under charging is almost the same as that in air.
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  • Teruto KANADANI, Akira SAKAKIBARA, Keiyu NAKAGAWA
    1995 Volume 45 Issue 11 Pages 649-653
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Fatigue strength of an age hardened and reversion annealed Al-2mass%Cu alloy was examined by a repeated tension fatigue test. The fatigue strength of the specimen fully aged around room temperature after quenching from 823 K did not depend on whether the soft surface layer was present or not, but the specimen aged after quenching from 723 K, which had a thicker soft surface layer, showed higher strength than the specimen without soft surface layer. Fatigue strength of the specimen of which the soft surface was removed, however, was independent of quenching temperature. Reversion annealing for 600 s at 323 K after aging, which made the soft surface layer thicker, increased the fatigue strength. It is concluded from these results that the formation of the soft surface layer in the present alloy can increase fatigue strength in repeated tensile test, as in the case of the Al-Zn alloy.
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  • Toshiro KOBAYASHI, Mitsuo NIINOMI, Toru IRISA, Takayuki SAKAI, Takuzo ...
    1995 Volume 45 Issue 11 Pages 654-659
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    The toughness of Al-Li system alloy increases in general with lowering temperature. The mechanism of the toughness increase at low temperature has not been, however, clearly defined yet. In this study, the relationship between formation of laminated cracks and stress triaxiality are investigated on 2091 Al-Li system alloys. The number of laminated cracks increases with rising stress triaxiality. The dynamic fracture toughness value Jd increases at 77 K and exhibits greater value at a thickness, B, of 1mm. The increasing ratio at 77 K in fracture toughness of specimens with laminated cracks is much greater than that of specimens without laminated cracks. The laminated cracks will lead to the stress relaxation at the main crack tip increase the fracture toughness.
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  • Shuhei OHSAKI, Makio IINO, Masaki UTSUE, Kazunori KOBAYASHI, Toshimasa ...
    1995 Volume 45 Issue 11 Pages 660-665
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Effect of double-aging on the short-transverse fracture toughness of Al-Li alloys 2090 and 2091 was investigated by using a CNSB (chevron notched short bar) specimen. The fracture toughness KQVM is reduced with a progress of the firststep aging, but is fairly improved by a double-aging treatment. The double-aged alloy 2091 exhibits a superior strength-toughness balance to that of the single-aging. The increase in KQVM by the double-aging is attributed to a relaxation of intense slip due to dissolution of shearable δ' phase and growth of δ'-PFZ width. For alloy 2090, coasening of grain boundary precipitates concurs with the δ' phase dissolution, which assumedly accelerates microvoid growth at grain boundaries, leading to a lower improved toughness.
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  • Atsushi YAMAMOTO, Morihiko MAEDA, Harushige TSUBAKINO, Takuichi IMANAK ...
    1995 Volume 45 Issue 11 Pages 666-670
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Ultrasonic fatigue tests have been performed on commercial 1050 aluminum. Internal friction (Q-1) has been measured during fatigue tests and as a function of strain amplitude (ε). It is shown that more than 109 cycles test is necessary in order to determine the fatigue limit. Q-1 versus ε curves have the inflection points at particular strain amplitude which corresponds to the strain at fatigue limit. Below this strain amplitude, Q-1 does not change and any slip bands are not observed on the specimen surface fatigued for 1010 cycles.
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  • Hajime IKUNO, Shogo IWANAGA, Yoji AWANO
    1995 Volume 45 Issue 11 Pages 671-676
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Automobile engine materials require higher thermal fatigue resistance with increasing combustion temperature. Porosity in aluminum alloy castings is a serious defect which decreases the strength of the castings. In this study, the effect of porosity on thermal fatigue lives was investigated using JIS AC2B-T6 alloy castings. The thermal fatigue lives were evaluated by a newly-developed test method using restraining holders composed of low-thermal-expansion material. In a high total strain range, the maximum pore area on a fracture surface correlated to the thermal fatigue life. In a low total strain range, on the other hand, the total porosity area on a fracture surface correlated to the thermal fatigue life. It has been clarified that the fracture mechanism was changed by the total strain range, affecting the correlation between the porosity and the thermal fatigue lives.
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  • Manabu NAKAI, Takehiko ETOH
    1995 Volume 45 Issue 11 Pages 677-681
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Fracture toughness and fatigue crack propagation rate in 2024 alloys have been investigated through changing the morphologies of constituens and dispersoids. Fracture toughness is proportional to the square root of the spacing of constituents, mainly Cu2FeAl7 in 2024 alloys. Broadening the spacing from 58μm to 140μm, the fracture toughness increases by 18%. The fact that the dimple diameter becomes larger with increasing constituent spacing leads to the increase in fracture toughness. In a low ΔK region, the fatigue crack propagation rate becomes slower mainly by broadening the spacing of dispersoids, Cu2Mn3Al20. Broadening the spacing from 0.45μm to 0.64μm, the propagation rate decreases by 50%. In a high ΔK region, on the other hand, the propagation rate becomes slower mainly by broadening the spacing of constituents.
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  • Harushige TSUBAKINO
    1995 Volume 45 Issue 11 Pages 682-683
    Published: November 30, 1995
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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