Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 60, Issue 6
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
  • Effect of surface roughness on specular gloss in AZ31 magnesium alloy
    Miyoshi Ohara, Yorinobu Takigawa, Kenji Higashi
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 259-263
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.259
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    In order to clarify the relationship between the surface roughness and the metallic luster and the relationship between the surface roughness and the conditions of the surface treatment, the surface roughness was examined in AZ31 magnesium alloy. The standard state of the metallic luster was the surface polished by emery paper #2000. The surface roughness and the metallic luster were quantified by the root mean square roughness, σ, with a cutt-off value of 0.002 mm and the specular gloss. It was analyzed the relationship between the metallic luster and the surface roughness. For the result, the metallic luster was available that the surface roughness was formed in the range of 0<σ/λ<0.1, and the necessary value of σ for the realization of the metallic luster was less than 53 nm. The optimal acid aqueous solution treatment was available the metallic luster, and σ was 9 nm. Finally, σ with the surface treatment conditions in the both component included the oxidant and high temperature and in the oxidant-free both components was examined, and was about 80 nm. Therefore, it was concluded that the metallic luster was unavailable.
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  • Deformation in V-bending of aluminum alloy 5083 plate
    Khamt Naranbaatar, Makoto Murata, Takashi Kuboki, Takahiro Shibata, Yi ...
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 264-268
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.264
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    Bending is a fundamental common process, which has been applied in industry for hundreds of years. There are many research works on bending process for thin sheet metal with thickness of 3 mm or less, which is used as components for various products. On the other hand, bending process for plate has also been applied according to the diversity of market needs, but only for special usage. Therefore, only a few research works have been presented and the expertise is still limited. Ogawa shows some examination results, those are able to control deformation of sheet by changing die open width and punch radius of sheet metal bending up to 6 mm thickness. In the present research, experimental examination is carried out with emphasis on the effect of the die open width on the bending behavior of thick plate with 10 mm thickness: deformation in the ridge line direction, spring-back and deduction of total length. As a result, it is quantitatively clarified that the die open width has some amount of effect on the unique phenomena in plate bending such as saddle type deformation, reduction of bending curvature from the punch radius and the deduction discrepancy from theoretical value.
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  • Microstructure and mechanical properties of Mg–Zn–Y cast alloys
    Yuichi Ienaga, Kenshi Inoue
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 269-274
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.269
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    Recently the extruded Mg–Zn–Y alloy is known as attractive for automotive components with increased strength at elevated temperature. In order to achieve these attractive properties in cast component, we focused on grain refinement of Mg96Zn2Y2 (at%) cast alloy with long-period stacking ordered (LPSO) structures and investigated the effects of zirconium addition and cooling rate on microstructures and mechanical properties. Mg96Zn2Y2 cast alloy with the addition of zirconium consisted of α-Mg phase, Mg12ZnY phase and Mg3Zn3Y2 phase as well as the alloy without zirconium. However, the coarse dendritic structure was found to transform into fine equiaxed grains by an addition of 0.2 at%Zr. Furthermore, the increased cooling rate led to the crystallization of the fine Mg3Zn3Y2 and Mg12ZnY phases forming a net-like structure. Consequently, this alloy exhibited a tensile strength of 223 MPa at 523 K, which is about twice that of A4032-T6 alloy and excellent fatigue property at high temperature of 473 K. Additionally, high elongation of 10.5% at room temperature was achieved even in the as-cast condition. This alloy also had thermal properties equivalent or higher than those of commercial magnesium alloys.
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  • Metallurgical factors affection Vickers hardness of friction stir welded joint of 7075 aluminum alloy
    Tsutomu Ito, Xiaoyong Yun, Alexandre Goloborodko, Yoshinobu Motohashi, ...
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 275-281
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.275
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    Vickers hardness of friction stir welded 7075-T6 and 7075-O aluminum alloy plates were investigated. During welding, the tool rotation and tool traverse speeds were 1500 rpm and 300 mm/min, respectively. In order to study the anisotropy in the welded joints, the joints were welded in directions parallel and right angle to the rolling direction. Defect-free joints were obtained under the above condition. A fine and equiaxed recrystallised microstructure with grain size of approximately 3 μm was formed in the stir zone of the joints. Anisotropy in welded joints along the welding directions was not detected in terms of the microstructural characteristics of the joints. After friction stir welding, the Vickers hardness of the stir zone of the T6 joints decreased, but that of the O joints increased. On the other hand, after natural aging for 5 months, the Vickers hardness of the stir zone of the T6 joints increased and closely reached the hardness level of the base metal, while the Vickers hardness of the stir zone of the O joints increased further. From the above-mentioned Vickers hardness distributions, no anisotropy was observed along the welding direction. The above-mentioned behavior in hardness of the joints was discussed briefly on the basis of the Hall-Petch relation as well as other strengthening mechanisms.
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  • Friction and wear properties on AZ91D magnesium alloy treated by anodizing from phosphate electrolytic solution
    Makoto Hino, Koji Murakami, Atsushi Saijo, Shuji Hikino, Teruto Kanada ...
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 282-287
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.282
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    The effects of various surface treatments on the friction and wear properties of AZ91D magnesium alloy substrate against the SUJ2 steel ball were evaluated by using a horizontal reciprocating friction and wear test apparatus. The friction and wear properties greatly changed due to the type of surface treatment in spite of being under equal friction and wear testing conditions. Wear loss of AZ91D magnesium alloy anodized from the phosphate solution was greatly reduced in comparison with the other surface treatments such as Dow17, conversion coatings and also no surface treatment. The above results suggest that anodizing from the phosphate solution should improve the friction and wear properties of magnesium alloy used for sliding parts.
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  • Effect of preheating temperature on ECAP formability of AC4CH aluminum casting alloy
    Yoshihiro Nakayama, Tetsuya Miyazaki
    Article type: Research Report
    2010 Volume 60 Issue 6 Pages 288-293
    Published: June 30, 2010
    Released on J-STAGE: July 30, 2010
    DOIhttps://doi.org/10.2464/jilm.60.288
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    Effects of preheating treatment on the microstructural features and the ECAP formability at room temperature were investigated for an AC4CH aluminum alloy. The preheating treatment at the temperature range from 260°C to 560°C improved the ECAP formability at room temperature, especially at around 350°C the occurrence of cracks was inhibited effectively. When the preheating treatment was carried out at 410°C or less the hardness of primary α-Al decreased with rise in preheating temperature, while the increase of the hardness was observed for the test pieces preheated at above 470°C. The observation on the eutectic Si particles showed that the mean cross-sectional area and the spherical coefficient were constant at the preheating temperatures below 410°C but increased clearly at 470°C and higher. In addition to the above, when the hardness of the primary α-Al reached to a specified value due to a strain hardening by the repetitive ECAP press, the cracks occurred in the test piece and the ECAP process became impossible. These experimental results implied that the hardness of the primary α-Al gave a useful indication for the ECAP formability at room temperature. Cracks at the rear section of the test piece initiated on the inner side of ECAP channel angle and propagated preferentially along the solidification cell regions, that is, not only at the interface between aluminum matrix and eutectic Si particles but also at the transcrystalline cracking of eutectic Si particles.
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