Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 56, Issue 1
Displaying 1-11 of 11 articles from this issue
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RESEARCH REPORT
  • Statistical fatigue properties of 2017 and 6061 aluminum alloy similar and dissimilar friction-welded joints
    Gosaku KAWAI, Yoshiaki YAMAMOTO, Takashi ICHIHARA, Hiizu OCHI, Koichi ...
    2006 Volume 56 Issue 1 Pages 2-7
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.2
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    Similar and dissimilar joints of 2017 and 6061 aluminum alloys were friction welded. Fatigue strength and fatigue life distribution of these joints were examined. The S-N curve showed that the fatigue strength of A2017/A2017 was almost the same as that of A2017 base metal, while that of A6061/A6061 was lower than that of A6061 base metal. The fatigue strength of A2017/A6061 was lower than that of A6061/A6061. The fatigue limit at 108 cycles of A2017 base metal, A2017/A2017, A6061 base metal, A6061/A6061 and A2017/A6061 were 120MPa, 120MPa, 70MPa, 60MPa and 55MPa, respectively. The shape parameter m and the location parameter γ in Weibull distribution function of the joints were lower than those of the base metals. These results suggest that the scatter in fatigue life distribution is larger and the smallest fatigue life is shorter for the present joints compared to the base metals.
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  • Hot deformation characteristics and formabilities of Mg-(2.0-4.5)%Al-(0.7-1.5)%Zn alloys
    Yu YOSHIDA, Keita ARAI, Shota ITOH, Shigeharu KAMADO, Toshiaki WADA, T ...
    2006 Volume 56 Issue 1 Pages 8-14
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.8
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    Mg-Al-Zn alloys containing 2.0-4.5%Al and 0.7-1.5% Zn were cast and subsequently hot-rolled, and then the rolled sheets having a thickness of 0.83 mm were prepared. After that, they were annealed at 498 K and 623 K for 1 h. The deformation characteristics and formabilities of as-rolled (F) and annealed sheets are investigated in terms of metallography. In tensile test at 498 K fine recrystallized grains enhance grain boundary sliding, which contributes to deformation in direction of sheet thickness, in specimens with higher Al and Zn contents, resulting in isotropic deformation behavior. Deep drawing tests at 498 K reveals that the deep drawability is improved with increasing Al and Zn contents up to Al content of 3% because more dynamic recrystallized grains are generated during forming. As a result, limiting drawing ratio (LDR) of Mg-3%Al-1%Zn reaches 3.2. Excessive Al and Zn contents generate numerous fine recrystallized grains, which give rise to significant grain boundary sliding, resulting in large reduction in thickness. Therefore, LDR of Mg-4.5%Al-1.5%Zn decrease to 2.8. However, this LDR is much higher than those of aluminum alloys and steel, indicating enough formability can be obtained even in the high strength magnesium alloy. The F-specimens containing large residual working strain exhibit higher formability than the annealed specimens as a result of dynamic recrystallization during forming. Also in the stretch forming utilizing hemispherical punch with the diameter of 40 mm, the F-specimens show excellent stretch formability. That is, limiting dome height of the alloys containing Al more than 3% reaches 15 mm.
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  • Effect of loading rate on absorbed energy and fracture surface area in wrought aluminum alloys
    Tomohiko MUKAIYAMA, Mitsuo NIINOMI, Hiroyuki TODA, Toshikazu AKAHORI, ...
    2006 Volume 56 Issue 1 Pages 15-20
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.15
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    The effect of loading rate on absorbed energy and fracture surface area of three types of wrought aluminum alloys, namely high toughness 5083-O and 6061-T651 alloys and low toughness 7075-T6 alloy are studied. A laser displacement measuring equipment and a scanning laser microscope are used in order to measure three-dimensional geometry of the fracture surface. Shear lip and plastic hinge can be observed in 5083-O and 6061-T651 aluminum alloys. According to a measuring region, the calibration factor K is notably different. Moreover, the calibrated fracture surface area of each fracture geometry changes considerably with increasing loading rate. On the other hand, in 7075-T6 aluminum alloy, macroscopic fracture geometries are not clearly defined, and almost no difference appears in the calibration factor K within the same fracture surface. Moreover, calibrated whole surface area increases linearly with increasing loading rate. In any aluminum alloys, the tends in the loading rate change of calibrated whole fracture surface area, AW, and the total absorbed energy, Et , with loading rate are similar each other. Therefore, the change of fracture surface area is one of the main factors that affect the change of absorbed energy.
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  • Tear toughness of rheocast and squeeze cast AC4CH aluminum alloys
    Shinji KUMAI, Kei KOBAYASHI
    2006 Volume 56 Issue 1 Pages 21-27
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.21
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    Cast plates of the AC4CH aluminum alloy with different thickness were fabricated by rheocasting and squeeze casting. Tear tests were performed for the as cast and heat treated products (T5 and T6) and effects of solidified structure and heat treatment on the unit crack propagation energy (UEp) were examined. Increase of the cooling rate (corresponding to the decrease in plate thickness) resulted in refined solidified structure and enlarged UEp values for as cast samples. Both spheroidized eutectic Si particles and age-hardened α-Al matrix by T6 treatment were effective to increase UEp for both rheocast and squeeze cast samples. UEp of the squeeze cast was larger than that of the rheocast. Observation of crack growth path and fracture surface revealed that the tear toughness of the present cast alloy was controlled by distribution of eutectic solidified region in the cast structure, which provided a preferential crack growth path. The discontinuous distribution for the squeeze cast is considered to be beneficial for increase in crack growth resistance rather than the continuous arrangement of the network-like eutectic region for the rheocast. Relatively small UEp was obtained for the T6 treated rheocast sample collected from the 6 mm thickness plate. This was caused by the fact that the volume fraction of the eutectic solidified region in the sample was larger than others under the present experimental condition.
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  • Development in manufacturing of carbon fiber reinforced aluminum preform wires using ultrasonic infiltration method
    Tadashi MATSUNAGA, Kenji MATSUDA, Tomei HATAYAMA, Kenji SHINOZAKI, Shi ...
    2006 Volume 56 Issue 1 Pages 28-33
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.28
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    In this study, we have developed a novel manufacturing process of “preform wires” which are semi-finished materials used for the fabrication of CF/Al composites. The preform wires were continuously fabricated using an ultrasonic infiltration method. The manufacturing apparatus fundamentally consisted of preheating furnace, ultrasonic horn and transducer and taking up reel for winding. Influence of each processing parameter on the infiltration ratio was investigated. As the optimum condition, after carbon fiber was heated at 973 K for desizing, the ultrasonic was applied at 200 W to molten Al-Mg alloy for the infiltration of the molten alloy into the bundle. The addition of magnesium into molten aluminum improved the infiltratability. CF/Al-4.7%Mg preform wires with a tensile strength of 1100 MPa was obtained at the fabricating speed of 0.22 m/s. It is clear that the ultrasonic infiltration method is effective to fabricate CF/Al preform wires.
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  • Effect of compression-torsion combined loading on grain refinement of aluminum
    Naoyuki KANETAKE, Takashi ITOH, Keitarou AONO, Yuji KUME
    2006 Volume 56 Issue 1 Pages 34-38
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.34
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    A compressive torsion process that is one of the severe plastic deformation processes was applied to a commercial pure aluminum in order to obtain fine grain. In the compressive torsion processing the material was subjected to simultaneous compressive and torsional loading without change in its shape. The possibility of grain refinement and the effects of process conditions on the refinement were investigated by changing deformation temperature, compressive pressure, torsional cycle and torsional speed. Very fine grains around several microns were obtained by the compressive torsion process. However the grain refinement was not uniform in the specimen, the fine-grained region was concentrated in peripheral parts of the operating die. Decreasing processing temperature and increasing torsional cycle are effective to decrease grain size and extend finer grain area. The compressive pressure does not influence grain size and finer grain area. Increasing torsional speed enlarges grain size because of rise in temperature due to deformation heat generated in processing.
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  • Serration, deformation band propagation and strain marking in a 5083 aluminum alloy at low temperature
    Yoshihiro NAKAYAMA, Kyohei NOMURA, Masanobu FURUTA
    2006 Volume 56 Issue 1 Pages 39-44
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.39
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    Relations among load fluctuation, geometrical shape and propagation behavior of a deformation band were examined for an inhomogeneous plastic deformation generated at relatively low temperature. The geometrical shape and propagation behavior of the deformation band were evaluated by strain gauges and surface roughness of specimen. Quantitative analysis of the load fluctuation was also carried out by fast Fourier transform method. The following results were obtained. A wavy load fluctuation was observed in two-deformation regions; i.e., one of which was a yield deformation region and the other was a serration one. The geometrical shape and the tilt of the deformation band in each deformation region were similar, while the number of cycles, the velocity of propagation and the amount of increasing strain were different each other. However, it was clearly shown that the wavy load fluctuation generated in each deformation region resulted from a continuous propagation of the deformation band.
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  • Restoration process of V-bended aluminum sheet
    Nobuo HATANAKA, Consorcio S. NAMOCO Jr., Norio TAKAKURA, Takashi IIZUK ...
    2006 Volume 56 Issue 1 Pages 45-50
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.45
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    When the surface of the press product received local damage, the value of the product falls off largely. The reconstruction processing is carried out to return the surface of the product to an original shape and dimension. However, there are many difficulties in reconstruction processing, because the mechanical properties and thickness of the sheet are not homogeneity. Such reconstruction processing is examined little. But, that is important for environmental conservation. In this paper, such processing is called ‘restoration processing’. The first, the various metal sheets were bent to the V form. Next, it was tried that this metal sheet is returned to an original flat plate. The research was carried out by the experiment and rigid plastic finite element method simulation. In the case of tension stress or compression stress which were greater than yield stress were applied the bent metal sheet, that did not return to flat plate. However, V-formed metal sheet returned to flat plate by using incremental bending method. When the work hardening exponent of the metal sheet was large, restoration processing becomes difficult.
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  • Effect of ripple mark on filiform corrosion resistance of twin-roll cast 6016 aluminum alloy strips
    Kaoru UEDA, Hiroki ESAKI, Keiichiro HATSUNO, Kazuhisa SHIBUE
    2006 Volume 56 Issue 1 Pages 51-55
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.51
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    Al-Mg-Si alloy strips were prepared by the twin roll cast (TRC) in order to investigate the effect of the ripple mark observed in the strips on filiform corrosion resistance after paint. The TRC strips have 1-2 micrometers segregation layer which included high concentration iron and silicon under the surface. In the dark portion of ripple mark, the concentration of iron and silicon in the layer were high. According to the results of the cyclic filiform corrosion test, the ripple mark decreased the corrosion resistance. In the case of the scalped strip, the corrosion resistance was improved. As a result, the ripple mark with the surface segregation layers of iron and silicon decreased the filiform corrosion resistances on TRC strips.
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