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 10
Displaying 1-9 of 9 articles from this issue
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RESEARCH REPORT
  • Strip casting of AZ31 magnesium alloy by the melt drag process equipped with a forming belt
    Shinichi NISHIDA, Mitsugu MOTOMURA
    2006 Volume 56 Issue 10 Pages 509-513
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.509
    JOURNAL FREE ACCESS
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    The purpose of this study is to continuously produce a good AZ31 magnesium alloy strip directly from molten metal magnesium by melt drag process. The forming belt was attached on the free solidified surface side of melt drag process to cast magnesium alloy strip at higher roll speed than that of the normal melt drag process. The experiment description is that the AZ31 magnesium alloy was molten and the strip was cast by melt drag process with forming belt. In this study, the effects of several factors, such as, the roll speed, the meniscus position and the protective gas in experimental device on the continuity and the surface quality of strip, the strip thickness and the microstructure were investigated. As a result, producing rapidly solidified AZ31 magnesium alloy strip without oxidization in high roll speed up to 100 m/min by this process is possible. And the relationship between the strip thickness and the crystal grain size was investigated. The thinner the strip thickness is, the finer the crystal grain size is. Obtained minimum crystal grain size is 72 μm. The strip produced in this process can be rolled without defect. Tensile strength of the rolled strip is 303 MPa.
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  • Effect of constraint on development of rolling texture in pure aluminum single crystal having cube orientation
    Keizo KASHIHARA, Hirosuke INAGAKI
    2006 Volume 56 Issue 10 Pages 514-520
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.514
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    The effect of constraint on the development of the cold-rolling texture of pure aluminum single-crystal specimens having cube orientation was investigated. Some specimens were embedded in polycrystalline aluminum frames to apply constraint in the transverse direction. These were unidirectionally cold-rolled to obtain rolling thickness reductions between 30% and 95%. Rolling textures were compared with those of specimens rolled without constraint. The constraint provided by the frame influenced texture development in the mid-thickness region more strongly than that on the surface. In specimens rolled without constraint, both clockwise and counterclockwise crystal rotation with respect to the transverse direction occurred in the mid-thickness region, resulting in the change in the main component to {102}‹201› after 70% reduction in thickness. Upon further cold rolling, crystal rotation occurred about both the rolling and the normal directions, such that after 90% cold rolling {112}‹312› became the main orientations. In the specimens rolled with constraint, such rotation was suppressed and only crystal rotation toward {102}‹201› was observed. In both cases, the orientation density of {100}‹001› decreased dramatically with increasing rolling thickness reduction and the density became very low after 95% cold rolling.
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  • Effect of temperature and drawing speed on warm deep drawing characteristics of AZ31 magnesium alloy sheet
    Ken-ichi MANABE, Osamu SHIMOMURA
    2006 Volume 56 Issue 10 Pages 521-526
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.521
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    In this study, effect of drawing speed and flange temperature on formability of cylindrical cup warm deep drawing of AZ31 magnesium alloy sheet is clarified experimentally. For the purpose, a new locally heating and cooling deep drawing apparatus is designed and developed. Magnesium alloy used is AZ31 sheet with 0.5mm thickness. Firstly, tensile properties of the AZ31 sheet under various temperatures and strain rates were determined by tensile test. The experimental results indicate that the magnesium sheet possesses enough high strain rate sensitivity of m=0.25 at 400 degrees C. Cylindrical cup tests were conducted at various flange temperatures and drawing speeds to clarify suitable forming conditions. As a result, a cylindrical cup height map can be obtained and then it is concluded that the warm deep drawability intends to increases with increasing drawing speed and flange temperature, and there exists optimum conditions on temperature and drawing speed to enhance the drawability.
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  • Microstructures and wear property of surfaces on plasma nitrided AC4C and AC9B aluminum alloys
    Li LIU, Atsushi YAMAMOTO, Takanori HISHIDA, Hiroaki SHOYAMA, Tamio HAR ...
    2006 Volume 56 Issue 10 Pages 527-532
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.527
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    AC4C (Al–7%Si) and AC9B (Al–20%Si) aluminum alloys have been nitrided by means of the electron-beam-excited-plasma (EBEP) technique to improve surface properties. The specimens have been characterized with respect to the following properties: wear resistance, phase identification (X-ray diffraction) , surface and cross-sectional microstructures. The friction coefficient of nitrided AC4C decreased from 0.6 for an un-nitrided AC4C alloy to 0.12 and that of nitrided AC9B decreased to 0.15. Both of the two kinds of alloys nitrided by EBEP technique formed relatively uniformly AlN layer. In the AlN layer produced both on AC4C alloy and on AC9B alloy, the dendritic-shaped grains were formed perpendicular to the surface with different orientations. Si3N4 was formed not only at the Al/AlN interface but also in the AlN layer. It contributes to the adhesion properties and wear resistance of the AlN layer to the substrate.
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  • Visualization of material flow phenomenon during friction stir welding
    Motoki HIGASHIYAMA, Takeshi SHINODA, Hiroaki TAKEGAMI
    2006 Volume 56 Issue 10 Pages 533-537
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.533
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    A lot of papers have been appeared the clarification of material flow in friction stir welding. When aluminum alloy was used, metal flow during processing is imaged by metallurgical observation after friction stir welding process. It succeeded in taking a material flow phenomenon movie during friction stir with polymer plastics in this paper. This direct observation is revealed that two whirlpools occurred while friction stir resulting influence of pin and shoulder rotation was generated frictional heat. According to the changing of tool type, location of weld imperfection was transferred into behind the tool. In the use of left screw pin, location is move over revolutional movement the end of the pin during preheating time.
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  • Development of an apparatus for deposition coating with a high purity magnesium and evaluation on adhesion and corrosion resistance of the coated AZ31B magnesium alloys
    Rika TAMAI, Atsushi YAMAMOTO, Harushige TSUBAKINO
    2006 Volume 56 Issue 10 Pages 538-542
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.538
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    In order to improve corrosion resistance on magnesium alloys, coating the surfaces of magnesium alloys with high purity magnesium by applying a vapor deposition technique has been proposed by the authors. For practical application of this technique to engineering products, a new apparatus has been developed, which enables one to carry out the coating on a relatively large substrate with 250×250 mm in size. The apparatus has two vacuum chambers for evaporation and deposition, which are separated by a gate valve. For an evaporation source and a substrate, 3N–Mg and AZ31B magnesium alloy were used, respectively, which were put into the evaporation chamber and the deposition chamber, respectively. The evaporation source was heated at 823∼973 K, while the substrate was held at 323∼523 K, deposition time was 1.8 ks. The resulting substrate was coated with high purity magnesium with about 20 to 25 μm in thickness. In this study, the fundamental conditions of coating for the apparatus, microstructures of the coated layer, corrosion resistance, and adhesion between the coated layer and the matrix are described.
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  • Microstructure observations of rapidly solidified Mg97Zn1RE2 alloys
    Takaomi ITOI, Yuichiro YANO, Syuichi FUDETANI, Yoshihito KAWAMURA, Mit ...
    2006 Volume 56 Issue 10 Pages 543-549
    Published: 2006
    Released on J-STAGE: November 30, 2006
    DOIhttps://doi.org/10.2464/jilm.56.543
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    The microstructure of ternary Mg97Zn1RE2 (RE=La, Ce, Gd, Tb, Dy, Ho or Er) melt-spun alloys annealed at 573 K for 1.2 ks have been investigated in order to clarify the relationship between their microstructures and hardness. The Mg97Zn1RE2 alloys consisted of Mg grains with diameter ranging from 0.7 to 2 μm. Also, several Mg–Zn–RE ternary phases were observed inside Mg grain and at grain boundary. Long period stacking (LPS) structure characterized as 14H-type was formed inside some Mg grains in the Mg97Zn1RE2 (RE=Gd, Tb, Dy, Ho or Er) alloys, respectively. The growth of 14H-type LPS structure from another Mg–Zn–RE ternary phase at grain boundary was recognized in the Mg97Zn1RE2 (RE=Gd or Er) alloys, and also the electron diffraction pattern clearly indicated that the relationship between 14H-type LPS structure and 2H-Mg was (001)2H–Mg // (0014)14H–Mg, indicating the 14H– and 2H–Mg were coexisted in the identical grain with certain relationship. On the other hands, although the LPS structure was not observed in the Mg97Zn1RE2 (RE=La or Ce) alloys, a number of the Mg–Zn–RE (RE=La or Ce) ternary phases with less than 50 nm dispersed in the Mg matrix, respectively. The higher hardness of the Mg97Zn1RE2 (RE=La or Ce) alloys than the Mg97Zn1RE2 (RE=Gd, Tb, Dy, Ho or Er) alloys originated in the formation of the numerous nano-size Mg–Zn–RE (RE=La or Ce) phases dispersed interior Mg grains in the Mg97Zn1RE2 (RE=La or Ce) alloys.
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REVIEW—9th JILM PRIZE & AWARDS
ERRATUM
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