Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 53, Issue 1
Displaying 1-7 of 7 articles from this issue
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RESEARCH REPORT
  • Effect of Cu addition on tensile deformation and fracture behavior of Al–Mg–Si alloys
    Kenji MATSUDA, Yasuharu MYOTOKU, Kousuke KIDO, Yasuhiro UETANI, Susumu ...
    2003 Volume 53 Issue 1 Pages 2-7
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.2
    JOURNAL FREE ACCESS
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    Al–Mg–Si alloys containing Cu and excess Si were investigated by tensile test, scanning electron, scanning tunneling and transmission electron microscope observation in order to clarify the difference of their deformation behavior. Strengths and elongations of Cu-bearing alloys were higher than those of Cu-free alloys. Cu-free alloys showed the intergranular fracture, while Cu-bearing alloys showed the transgranular fracture. Frequency of the cracking on a surface of a Cu-free alloy was higher from an early stage of deformation than that of the Cu-bearing alloy. The addition of Cu suppressed the cracking in Al–Mg–Si alloys. Folds and sharp steps of grain boundaries were observed on the surface of Cu-free alloys, while Cu-bearing alloys showed transgranular deformation with wavy slip bands. The width of precipitate free zones (PFZ) in a Cu-bearing alloy was narrower than that in a Cu-free alloy. Dislocations were observed just near grain boundaries in the fractured Cu-free alloy, while there were many dislocations in grains of Cu-bearing alloys. It was considered that the improvement of elongation in Cu-bearing Al–Mg–Si alloys was caused by the suppression of preferential deformation near grain boundaries and the decrement of cracking.
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  • Precipitation in an Al–300 ppm Fe alloy
    Atsushi YAMAMOTO, Takeshi KATO, Harushige TSUBAKINO
    2003 Volume 53 Issue 1 Pages 8-14
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.8
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    Precipitation in deformed and un-deformed Al–300 ppm Fe alloy has been investigated by means of resistivity measurements and transmission electron microscopy. The un-deformed specimens were solution heat treated at 913 K for 3.6 ks, quenched into iced water and then aged at the temperatures between 393–848 K, while the deformed specimens were cold drawn or rolled at room temperature after the same solution heat treatment, and then aged. Resistivity in the un-deformed specimens decreased in two stages, while in the deformed specimens, resistivity decreased in two or three stages depending on aging temperatures. Time-Temperature-Precipitation (TTP) diagram for the un-deformed specimens consisted of one C-curve which corresponded to precipitation of stable Al3Fe. TTP diagram for the deformed specimens was separated into two C-curves: the curves in high and low temperature ranges corresponded to precipitation of Al3Fe and Al6Fe, respectively. Deformation accelerated precipitation of the metastable Al6Fe.
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  • Surface modification of aluminum alloy castings using plastic flow phenomenon
    Takeshi SHINODA, Mika KAWAI
    2003 Volume 53 Issue 1 Pages 15-19
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.15
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    Aluminum alloy castings meet a requirement of lightweight vehicles and attract a lot of attention. However they suffer from some defects such as porosity, segregation and others. Fusion processes used to modify the surface locally, lead to secondary defects like porosity and cracking in modified zone. In this paper, a new surface modification process, which uses friction phenomenon, is suggested. It is named as Friction Thermomechanical Process (hereafter referred as FTMP). In this process, a non-consumable rod is forced while rotating, against the substrate surface. The friction heat, generated at the interface between the rod and substrate, makes the substrate metal to undergo plastic deformation. The coarse cast microstructure at the substrate surface is continuously refined due to dynamic recrystallization. As a result, FTMP process is suitable for surface modification of aluminum castings. Cast defects were found to be eliminated in the surface zone of 2 mm depth where large fiat surface region. Modified zone showed refined microstructure and improved hardness.
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  • Shape restoration phenomenon and deformation behavior of aluminum alloy bars in back-torsion working
    Hiroshi ANADA, Iwao TANAKA, Mitsuaki FURUI, Shigeoki SAJI
    2003 Volume 53 Issue 1 Pages 20-26
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.20
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    When torsion is applied to an aluminum alloy bar held with chucks at a fixed distance, the material is strengthened with an appearance of spiral patterns on the surface. After that, the material is twisted in the opposite direction the same number of times. Then the shape and the surface roughness of the material are almost restored and its strength is maintained, for which this phenomenon was named ‘the Shape Restoration Phenomenon by Back-Torsion’. It is indicated that this back-torsion working makes it possible to strengthen aluminum alloy bars and aluminum alloy pipes more easily and more economically than the conventional drawing method. In this repot, deformation property of various aluminum alloy bars treated with the back-torsion working were studied.
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  • Effects of zinc and manganese contents on extrudability of Mg–Al–Zn alloys
    Tsutomu MURAI, Shin-ichi MATSUOKA, Susumu MIYAMOTO, Yoshinari OKI, Sei ...
    2003 Volume 53 Issue 1 Pages 27-31
    Published: 2003
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.53.27
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    The effects of zinc and manganese content on extrudability of Mg–Al–Zn system alloys have investigated. Zinc enhanced occurrence of surface cracks. Hence,as the zinc content increased, the extrusion speed limit became low. When the manganese and zinc content was high, the surface oxide film was thick and the surface color of the extrusion was black. On the other hand, manganese had the effect of increasing the tensile strength, 0.2% proof stress and elongation. Manganese enhanced the dynamic recrystalization in the extrusion process. As the result, the grain size of the extrusion was small.
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