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 3
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
  • Effect of beating pitch on in-plane bending behavior of sheet metal in incremental beat bending
    Yingjun JIN, Takashi KUBOKI, Makoto MURATA
    2006 Volume 56 Issue 3 Pages 145-149
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.145
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    Indentation of punch, beating angle and beating pitch are dominant factors for incremental in-plane bending process. In this paper, the effects of beating pitch on beating force, bending radius and strains in the three directions are clarified by finite element analysis and experiment. The results show that the beating pitch has no effect on bending radius when the actual indentation is same. On the other hand, when the setting indentation is fixed, the beating pitch has an effect on bending radius due to the elastic deformation of punch and the support part. These forming properties of in-plane bending obtained by analysis and experiment had an agreement.
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  • Micro-pore formation and mechanical properties in a hyper-eutectic Al-Si alloy fabricated by spark plasma sintering
    Nobuhito KUROISHI, Masayuki KUDOH, Kiyotaka MATSUURA
    2006 Volume 56 Issue 3 Pages 150-155
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.150
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    The samples were fabricated with various conditions in spark plasma sintering (SPS) by using a rapidly solidified powder of a hypereutectic Al-16%Si alloy. Micro-pores and Si particles were investigated metallographically, and density and Vickers hardness were estimated. As a result, micro-pores were randomly distributed in the sample preheated under a pressure before SPS but they were distributed like network along powder particles after a higher electric current application of SPS. The density decreased as electric current of SPS increased. The size and volume fraction of Si particle increased, while Vickers hardness decreased as the electric current of SPS increased. A part of the decrease in hardness is considered to be caused by particle dispersion hardening mechanism.
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  • Effect of conversion coatings on bond strength of magnesium alloy adhesive joints
    Masashi SEKIGUCHI, Chikashi OTANI, Matsufumi TAKAYA
    2006 Volume 56 Issue 3 Pages 156-161
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.156
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    Magnesium alloys are lightweight materials with high specific strength. On the other hand, magnesium alloys has excellent to casting characteristics, machineability, and electromagnetic shield characteristics etc. In recent year, magnesium products are looked for complication and precision. Adhesion is one of the essential technology for making industrial products. Adhesion technology can apply for making the electronic equipment and sporting goods. Magnesium product will be able to lightweight and recycling. Chromate is now listed as a known carcinogen and is being phased out as a conversion coating material. This paper describes bond strength of chromate conversion coating, manganese conversion coating, tin conversion coating, and Mg (OH)2 coating as a chromate-free conversion coating on AZ31B and AZ91D magnesium alloys. The results of tensile shear strength test with epoxy resin that tensile shear strength of chromate conversion coating showed 10∼12MPa. Especially Mg (OH)2 coating showed higher tensile shear strength (16MPa) with cure temperature at 363 K. The results of tensile shear strength test with modified silicone resin that tensile shear strength of manganese conversion coating and tin conversion coating are about equal to tensile shear strength of chromate conversion coating. Tensile shear strength of AZ31B magnesium alloy and tensile shear strength of AZ91D magnesium alloy showed similar tensile shear strength (3MPa). The results of tensile shear strength test with phenolformaldehyde resin that tensile shear strength of tin conversion coating showed higher than tensile shear strength of chromate conversion coating. Especially, tin conversion coating showed high tensile shear strength (6MPa) with cure temperature at 423 K. From the above results, it is obvious that these conversion coatings can be alternative to chromate-free conversion coating as surface treatment for Mg/Mg adhesion.
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  • Effect of combinations between joining and heat treatment on properties of friction stir welds in 7050 aluminum alloys
    Sunao TANAKA, Masaki KUMAGAI, Hidenori HATTA, Hideo YOSHIDA
    2006 Volume 56 Issue 3 Pages 162-165
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.162
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    In order to obtain high strength and stress corrosion cracking (SCC) resistance in friction stir welds of 7050 aluminum alloy extrusions, optimal combination of FSW, solution heat treatment (SHT) and aging has been investigated. The welds with the best combination, SHT, FSW and aging, had higher joint efficiency than the 80% of base metals and higher corrosion resistance of more than 400MPa. These stemmed from finely precipitation of η' phases. The welds prepared by the others combination showed poor SCC resistance.
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  • Effect of extrusion speed on properties of the extruded AZ31B magnesium alloy machined chip
    Tetsuo AIDA, Norio TAKATSUJI, Kenji MATSUKI, Taku OHARA, Shigeharu KAM ...
    2006 Volume 56 Issue 3 Pages 166-171
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.166
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    The effect of ram speed on surface quality and room temperature mechanical properties of AZ31B alloy machined chips extruded at elevated temperatures has been studied. Hot extrusion was applied to the machined chips as a recycling process for the chips. The extrusion tests were carried out at a ratio (R) of 100 and extrusion temperatures (TE) of 573 K and 623 K, while the ram speed (VR) was varied from 0.5 mm/s to 5 mm/s. Even at a relatively high ratio of 100, a sound extrusion surface without any cracks was obtained at ram speeds less than 3 mm/s by using a die with a round exit (R-die). However, at a ram speed of 5 mm/s, surface cracks were formed almost perpendicular to the extrusion direction on a macro- as well as micro-scale. Furthermore, the ductility of the extrusions decreased remarkably at high ram speeds. With an increase in the ram speed, the surface temperature of the extrusions measured at the die exit increased resulting in grain coarsening at the narrow surface layer of the extrusion cross section. Based on microstructural observations, the grain coarsening was found to originate at the metal layer flowing into the die exit corner along the die surface. Nitrogen gas cooling immediately after the metal layer flowed out of the die was found to be effective in suppressing the grain coarsening at the surface layer. As a result, Nitrogen gas cooling was utilized to obtain good surface quality without cracks and high ductility of the extrusions even at a high ram speed of 5 mm/s.
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  • Effect of dimensional changes induced by heat treating of aluminum alloys on bonding strength of zirconia/aluminum alloy joints
    Tomo-o TANAKA, Masaya ITO, Toshio NARITA
    2006 Volume 56 Issue 3 Pages 172-177
    Published: 2006
    Released on J-STAGE: June 16, 2006
    DOIhttps://doi.org/10.2464/jilm.56.172
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    High strength aluminum alloys, 2024 and 7075, were joined to zirconia ceramic with buffer layers, respectively, and their strengths were compared. The as-bonded state strength of 2024 aluminum alloy joint was 198MPa and higher than that of 7075 aluminum alloy joint, 112MPa. The reason of the low strength of 7075 aluminum alloy joint was that the difference in thermal co-efficiency and dimensional change of 7075 aluminum alloy was larger than these of 2024 aluminum alloy. The bonding strength of 7075 aluminum alloy joint decreased after aging, because dimensional contraction during aging increased the residual stress.
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