Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Volume 22, Issue 10
Displaying 1-7 of 7 articles from this issue
  • Hisashi SUZUKI, Motohiro KANNO, Kazuyoshi FUKUNAGA
    1972 Volume 22 Issue 10 Pages 599-604
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    The vacancy-trapping model to explain aging retardation in Al-Cu-Sn alloys had been examined by the present authors and the conclusion obtained was that the model had been inadequate and not acceptable. The present study, therefore, was attempted to further examine the same subject in the Al-Cu-Cd system.
    Two sorts of alloy systems with 3 and 4wt.% Cu were used. In each alloy system, the Cd content was care-fully varied from 0wt.% to 0.37wt.%.
    The results obtained were as follows:
    (1) When specimens were of one-phase at the solution temperature, the retardation of aging was not observed at low temperatures. However, the retardation was clearly seen in two-phase specimens as the Cd content increased.
    (2) It was found that the retardation in this alloy system was also caused by the decrease of solid solubility of Cu in the α phase at solution temperatures, as in the Al-Cu-Sn alloys.
    (3) The theory based on the vacancy-trapping model to explain the aging retardation was again proved to be erroneous in the present study.
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  • Hisahi SUZUKI, Motohiro KANNO, Shigenori ASAMI
    1972 Volume 22 Issue 10 Pages 605-612
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Double aging in (α+T) type two-phase Al-Zn-Mg alloys was investigated by hardness measurement and transmission electron microscopy. Specimens were solution-treated at 470°C, subsequently quenched into iced water and finally subjected to various heat treatments. The results obtained were as follows:
    Under the condition of T1<TGP<T2 (where T1 and T2 were the first-step and the second-step aging temperatures respectively, and TGP was the G. P. zone solvus temperature determined for each specimen), the maximum hardness attained in each specimen by double aging was naturally superior to that by normal aging at T2 but was inferior to that by normal againg at T1. Double aging under the conditions of T1<T2<TGP and TGP<T<1<T2 showed almost no effects on the maximum hardness. The hardness obtained under the former aging condition was undoubtedly larger than that obtained under the latter condition.
    Normal aging at a temperature just below TGP was considered to be the most effective aging to get the highest hardness in the present alloy system, because the hardness obtained by the above normal aging was higher than that obtained by the usual double aging.
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  • Toshiro KOBAYASHI
    1972 Volume 22 Issue 10 Pages 613-627
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Standard V notch Charpy specimens with various widths were machined from T-4 treated Al-Zn-Mg and annealed Al-Mg alloy plates and effect of specimen size on impact fracture behavior at low temperatures was studied. Fracture toughness of TIG welds in these alloys and these and of Al-Mg-Si alloy plates was evaluated from load deflection curves during fracture by using fatigue pre-cracked type Charpy specimens.
    Although impact values of 5 and 10mm wide specimens were reduced at low temperatures, no change of impact value of 2mm wide specimens was introduced by lowering testing temperatures. The latter fact was considered as an apparent phenomenon since similar effect as in 5 and 10mm wide specimens was also observed by recording the load-deflection curves. The real fracture energy of the specimens was apt to be masked by other energies such as specimen toss energy and energy absorbed in the testing machine. This fact should be taken into account when toughness of aluminum alloys is evaluated.
    GIC value in Al-Zn-Mg and Al-Mg-Si alloys at -196°C was estimated to be about 1kg mm/mm2, which agreed well with the value obtained in the previous study for press boundary notch specimens. This shows that press boundary notch specimens can be used to evaluate fracture toughness instead of fatigue pre-cracked type specimens which require troublesome specimen preparation.
    Al-Zn-Mg and Al-Mg alloy welds became singificantly brittle at -196°C and showed an unstable rapid fracture mode. GIC value in this case was evaluated to be 0.55-0.80 kg•mm/mm2. Further to evaluate GIC from facture load in high stress fracture mode was considered to be questionable since large plastic deformation was introduced near the crack tip. In this case, however, crack opening displacement (COD) obtained from deflection to fracture load in Charpy impact test was considered to be more effective to know the real fracture toughness. With this method, GIC of Al-Mg alloy plate at -196°C was estimated to be about 5.4kg mm/mm2.
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  • Yoshinori NISHIDA, Shizuo SUZUKI
    1972 Volume 22 Issue 10 Pages 628-633
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    In order to study the effect of the pressure during solidification on hydrogen in aluminum ingots, aluminum melted in the hydrogen atmosphere was solidified under various pressures.
    The results obtained are as follows:
    (1) Macroscopic defects of aluminum ingots containing hydrogen decreased as pressure increased and almost disappeared at the pressure of 500 kg/cm2.
    (2) Densities of aluminum ingots containing hydrogen increased with an increase of the pressure. However, when the pressure was larger than 500 kg/cm2, the increase of the densities was not observed. The higher the pressure, the more uniform density was attained through the whole ingot.
    (3) It was found that there was a correlation between blister formation and pressure. From this, it was inferred that the experimental equation of Eichenauer and Pebler was useful to evaluate the hydrogen solubility in solid aluminum under high pressure.
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  • Study on Al-Mg alloy sheets for forming use (2nd report)
    Ken-ichiro AOKI, Mototsugu KATSUTA, Makoto SUGAMATA
    1972 Volume 22 Issue 10 Pages 634-641
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Deep drawing tests were conducted on Al-Mg alloy sheets after solution treatment at 400°C for one hour had been performed to eliminate a yield point. Some problems developed after deep drawing were also studied. The results obtained are as follows:
    (1) As Mg content increases, larger limiting drawing ratio and higher formability were obtained when Al-Mg alloy sheets were solution treated. The addition of Cu in Al-Mg alloys resulted in the further improvement in the formability.
    (2) From the X-ray study, excellent formability of these alloys was considered to be due to the increase of (200) planes parallel to the sheet plane.
    (3) A visual check showed that water quenched samples developed better surfaces than air cooled samples. However, the addition of Cu decreased the difference of the surface finish between the water quenched and the air cooled samples.
    (4) Formation of cracks was not observed after the 1.5 year immersion test had been conducted on circular cylindrical shells made by deep drawing.
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  • Takakado NAKAYAMA
    1972 Volume 22 Issue 10 Pages 642-650
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
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  • Harero IWAMURA
    1972 Volume 22 Issue 10 Pages i-ii
    Published: October 30, 1972
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
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