Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 59, Issue 10
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
  • Texture induced in wavy roll-formed Al–0.73%Mg–0.38%Si alloy
    Yuuko Hata, Shinji Fukumoto, Atsushi Yamamoto
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 537-541
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.537
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    Randomization of texture in Al–0.73Mg–0.38%Si alloy has been attempted by applying the wavy roll-forming method. Rolls having a wavy-shaped surface with about 8 mm in wavelength and 3 mm in amplitude were used. Specimens were solution heat treated at 813 K for 10.8 ks. The specimen was heated at 623 K for 180 s, and then immediately wavy roll-formed. The specimen was heated again and wavy roll-formed with rotating at 90° in plane. This process was repeated 8 times, then the specimen was flattened using conventional flat rolls. Wavy roll-formed specimen at room temperature was also prepared. The roll-formed specimens were annealed and then cold-rolled at room temperature and finally annealed at 773 K for 1.8 ks. For comparison, conventional flat rolled specimens were also prepared at 623 K or room temperature. Textures formed in the specimens were analyzed by electron backscattered diffraction measurements. Grain sizes formed in the warm wavy roll-formed specimen was coarser than that in the warm rolled specimen in final annealing after cold rolling. However, grain refining was accompanied with randomization of texture in the specimen wavy roll-formed at room temperature.
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  • Strength and HRTEM microstructure at bond interface of aluminum/copper clad materials
    Tomiko Yamaguchi, Wei Xie, Hidenori Era, Kazumasa Nishio
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 542-547
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.542
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    It is known that it is difficult to bond dissimilar metals such as aluminum and copper or aluminum and iron using diffusion bonding, because an intermetallic compound is easily produced at the bond interface and bonding strength becomes low. However it is possible to bond the dissimilar metals using the vacuum roll bonding which performs hot rolling in a vacuum. In this study, we investigated the effect of bonding temperature and reduction of aluminum plate thickness on bonding strength of Al/Cu clad materials when aluminum-clad copper (Al/Cu clad) materials were produced at 3 Pa in vacuum degree by the vacuum roll bondings. Bond tensile strength of Al/Cu clad materials increased as the reduction was increased. Their fracture types were classified according to the fracture pass, that is, in the base metal of the aluminum, at the bond interface of Al/Cu clad material or in the base metal and/or at the bond interface. Furthermore, the bond interfaces of Al/Cu clad materials were observed using a transmission electron microscope and an electron dispersive spectroscopy. As a result, it was clarified that Al/Cu clad materials are soundly produced using the vacuum roll bonding when thickness of diffusion layer is less than 60 nm even if intermetallic compounds were developed.
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  • Cyclic deformation behavior and fatigue properties of extruded AZ31B magnesium alloy
    Shigeki Morita, Shingo Tanaka, Masafumi Nakahara, Nobuyoshi Ohno, Yuji ...
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 548-554
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.548
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    Cyclic compressive and tensile loading-unloading tests were carried out using cylindrical smooth specimens of extruded AZ31B magnesium alloy. Load-controlled axial fatigue tests were also carried out with smooth specimens attached on strain gages at specified stress amplitudes levels. Monotonic tensile and compressive 0.2% proof stresses were 210 MPa and 105 MPa, respectively. Ratios of compressive/tensile 0.2% proof stress was approximately 0.50. Pseudoelastic behaviors were observed in compressive and tensile loading-unloading tests. The large anelastic strains were observed in compressive stress–strain hysteresis loops. The fatigue limit of load-controlled axial at 107 cycles was 90 MPa. Stress–strain hysteresis loops were linear in tensile and compressive phases at the lower stress amplitude of fatigue limit and the complicated pseudoelastic deformations were observed in tensile and compressive phases at the higher stress amplitude of fatigue limit of load-controlled axial fatigue test. Compressive mean strain generated by cyclic pseudoelastic deformations at the higher stress amplitude of fatigue limit. The deformation twins were observed in the specimen subjected to the higher stress amplitude of fatigue limit and free deformation twins were observed in the specimen subjected to the lower stress amplitude of fatigue limit. Fatigue cracks initiated at the secondary particle/matrix interface or broken secondary particle near the surface. Subsequently, small cracks tended to grow through transgranular.
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  • Through-thickness texture gradients and material properties in aluminum sheets cold rolled by different pass schedules
    Shin Tsuchida
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 555-561
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.555
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    Effect of the cold rolling pass schedule on mechanical properties and through-thickness texture gradients in 1050 aluminum sheets has been investigated with a commercial rolling mill. As the total reduction of cold rolling after the intermediate annealing was fixed at 75%, 2 passes rollings with reductions of 50%+50%, 55%+44% and 60%+38% were applied to 1.2 mm thick coil strips, and compared with 3 passes rolling of 42%+35%+33%. In the three cases of 2 passes rolling, texture gradients are similar each other and the β-fiber densities are maximum at the 50 μm inner layer as compared with the case of 3 passes rolling in which β-fiber densities are higher at every inner layer and the maximum is in the central layer of the thickness. Weak shear texture components of ‹111›||ND are recognized in the surface and 50 μm inner layer of the sheets rolled with 2 passes and in all layers that is from the surface to the central layer of the sheet rolled with 3 passes. Tensile strength changes little, however, the uniform elongation, the fracture angle in tensile specimen and the electric resistively are different with the rolling condition. The fraction of 45° ears in a drawn cup is slightly larger in the sheet by 3 passes rolling, but the differences of ears disappear after the annealing at 723 K.
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  • Influence of the factors on thermal conductivity of carbonaceous fiber reinforced aluminum composites
    Hisao Uozumi, Kota Nakanishi, Kentaro Inoue, Takayuki Tsukada, Nobuyuk ...
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 562-568
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.562
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    For improving the electrical efficiency of a hybrid car, relationship between microstructure and thermal properties of carbon nanotube, carbon fiber reinforced aluminum composites were examined as heat sink plate. In this study, influence of interfacial thermal resistance between fiber and binder, fiber diameter and binder volume fraction on thermal conductivity of the composites were examined. Firstly, in order to examine the effectivity for binding the fibers by the binder, the interfacial thermal resistance between fiber and binder was compared with that between fiber and matrix. In order to examine the influence of fiber diameter, the thermal conductivity of multi walled carbon nanotube preforms was compared with that of carbon fiber preforms. As the result, interfacial thermal resistance between fiber and binder was lower than that between fiber and matrix. Secondly, it was revealed that the larger fiber diameter leads to the higher thermal conductivity of the composite. Finally, the binder volume fraction was influenced by the microstructure so that the simply increasing and decreasing tendency was not found for thermal conductivity of the composites. By means of simulation for thermal conductivity, it was suggested that highly constricted fiber+binder part would deteriorate the thermal conductivity of the composites.
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  • Effects of up-quenching on age-hardening behaviors in Al–Mg–Si alloys
    Hiroyuki Toda, Masayuki Motoe, Kazuhiro Kadoumi, Yoshihiro Nakayama, M ...
    Article type: Research Report
    2009 Volume 59 Issue 10 Pages 569-575
    Published: October 30, 2009
    Released on J-STAGE: November 30, 2009
    DOIhttps://doi.org/10.2464/jilm.59.569
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    Inspired by a success in applying a fluidized bed furnace to high-temperature solution treatments, the present authors have attempted to modify the age-hardening characteristics of Al–Mg–Si alloys by utilizing its superior heating rate. Two-step ageing treatments have been applied to five kinds of alloys with different Mg2Si and excess Si contents. Heating rates for the first and the second ageing treatments have been varied as well as ageing temperature for the first ageing treatment. It has been clarified that the rapid heating to the first ageing temperature enhances strength compared to the standard T6-temper for all the alloys tested, especially for a balanced alloy with a low Mg2Si content. It has been confirmed that small precipitates are formed in high density in such cases. In most cases, the improvements in hardness have been observed by adding the ageing treatment at 353 or 373 K for only 0.8 ks before the ordinary ageing at 450 K. We attribute this to the suppression of unfavorable clusters which ordinarily form below those temperatures during heating.
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