Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 57, Issue 5
Displaying 1-6 of 6 articles from this issue
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RESEARCH REPORT
  • Tensile and cold-rolling properties of high-purity Mg–3mass%Al–1mass%Zn alloy
    Tadashi HAITANI, Yosuke TAMURA, Hiroshi TAMEHIRO, Norio KONO, Hiroshi ...
    2007 Volume 57 Issue 5 Pages 185-190
    Published: 2007
    Released on J-STAGE: June 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.185
    JOURNAL FREE ACCESS
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    A high-purity AZ31 magnesium alloy containing no manganese was prepared using distilled magnesium (>99.99%). The tensile and cold-rolling properties were then examined and compared with a commercial-purity AZ31 magnesium alloy. The high-purity alloy exhibited excellent tensile ductility and cold-rolling workability. It achieved a cumulative reduction of 20% with a high surface finish before cracks formed. It was found that the high-purity alloy deformed more uniformly, showing twin deformations distributed evenly across the specimen, while the commercial alloy contained highly deformed regions resulting in early crack formations. Due to the high amount of cold reduction and uniform deformation characteristics of the high-purity alloy, the annealed specimen exhibited a recrystallized structure with a fine, uniform grain size of 2 μm.
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  • Effect of Si content on turning machinability of Al–Si binary alloy castings
    Masatsugu KAMIYA, Takao YAKOU, Tomohiro SASAKI, Yoshiki NAGATSUMA
    2007 Volume 57 Issue 5 Pages 191-196
    Published: 2007
    Released on J-STAGE: June 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.191
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    In this study, Al–Si alloy was employed as a specimen which added Si to improve the chip breakability, and the effect of eutectic Si and primary Si on the machinability of the Al–Si alloy was investigated. For chip breakability, eutectic Si made chip thin, and primary Si was cracked during machining and acted as a nucleus of chip breaking. For surface roughness, the effect of eutectic Si was higher than that of primary Si, and eutectic Si reduced the adhesion on cutting edge. The decrease of surface roughness resulted in a corresponding decrease in adhesion on cutting edge. Additionally, the cracking of primary Si was responsible for the increase of surface roughness in hypereutectic alloys. Tool wear was increased with an increase of the number of eutectic Si. In hypereutectic alloys, tool wear was accelerated by the contact between tool and crashed primary Si.
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  • Improvement of tribological and fatigue properties of casting magnesium alloy AZ91 modified laminate DLC coating
    Hiroyuki AKEBONO, Hideto SUZUKI
    2007 Volume 57 Issue 5 Pages 197-202
    Published: 2007
    Released on J-STAGE: June 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.197
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    In recent years, magnesium alloys have been widely used because of their lightweight and easy recycling. However, magnesium alloys are inferior in wear resistance. Therefore, it is necessary to improve this property to use magnesium alloys for more machine parts. In this study, DLC (Diamond Like Carbon) coating, which is well known for its high hardness, low friction and excellent wear resistance, was performed on a cast magnesium alloy AZ91. However, it is difficult to perform hard coating like DLC on the soft materials like magnesium alloys in terms of adhesion strength between the substrate and the coating. So, in this study, in order to acquire the high adhesion strength, DLC coated process was performed by using UBMS (Unbalanced Magnetron Sputtering) method, and inter-layer which was doped Tungsten was formed on the substrate, and on the inter-layer two kinds of DLC coatings were laminated for nano order. Wear tests and fatigue tests were carried out. Magnesium alloy coated DLC indicated excellent wear friction. Furthermore, the fatigue reliability was elevated by DLC coatings compared with substrate only.
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  • Hydrogen absorption behavior in Al–Mg alloys exposed to an SO2 atmosphere during subsequent annealing
    Hidetoshi UMEDA, Goroh ITOH, Yoshinori KATO
    2007 Volume 57 Issue 5 Pages 203-209
    Published: 2007
    Released on J-STAGE: June 30, 2007
    DOIhttps://doi.org/10.2464/jilm.57.203
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    Hydrogen in aluminum and its alloys has a great influence on the occurrence of blisters. It is known that hydrogen may be absorbed during heat treatment process. In this study, the effect of exposure to SO2-bearing atmosphere on the hydrogen absorption into Al–Mg alloys during annealing was investigated. The exposure treatment was confirmed to cause absorption of sulfur on the specimen surface, and was found to increase the hydrogen content during annealing in a wet atmosphere due to promotion of hydrogen absorption. In contrast, without the exposure treatment, the hydrogen content decreased during the annealing due to release of hydrogen. The amount of absorbed hydrogen increased with increasing annealing temperature, time and humidity in the atmosphere. The morphology of oxide film formed during annealing was affected by the sulfur adsorption on the surface and was presumed to influence the hydrogen absorption/release behavior in Al–Mg alloys. In pure aluminum, however, there was no significant influence of the exposure on the inner hydrogen content after annealing, while the number of blisters that occurred on the surface after annealing increased by the sulfur adsorption on the surface prior to annealing.
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