Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 48, Issue 1
Displaying 1-12 of 12 articles from this issue
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RESEARCH REPORT
  • Effect of Cu and Si content on pitting corrosion resistance of Al–Mn alloy core brazing sheet
    Shuu KURODA, Ken TOHMA
    1998 Volume 48 Issue 1 Pages 2-7
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.2
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    To investigate effect of Cu and Si content on pitting corrosion resistance of Al–Mn brazing sheet, electrochemical measurements as well as SWAAT (Sea Water Athetic Acid Testing) were carried out. Though Cu diffused from core segregated at eutectic of filler after brazing on Al–Mn–Cu alloy core brazing sheet, selective dissolution of eutectic phase occurred in the filler of Al–Mn–Cu alloy brazing sheet as that of Al–Mn alloy. Dissolution characteristics of brazing sheets were closely related to variation of pitting potential within the sheet, depending on Cu and Si content. Al–l%Mn–0.5%Cu–0.05%Si alloy core brazing sheet was the most corrosion resistant, because both eutectic and primary α phase of the filler were effective as sacrificial anode for the core, and because variation of pitting potential within the core was suitable for pitting corrosion resistance.
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  • Aging process of TiCp/Al–Mg–Si composites
    Susumu IKENO, Kenji MATSUDA, Takeshi TERAKI, Masahiro ARAKI, Seichi RE ...
    1998 Volume 48 Issue 1 Pages 8-12
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.8
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    Aging processes of TiC particle dispersed Al–l%Mg2Si composite materials were investigated by Vickers micro-hardness measurement, and transmission electron microscope (TEM) observation. At relatively lower aging temperature, the Vickers micro-hardness curves of each composite materials had a similar tendency with that of the matrix alloy. The size and distributions of the precipitates in the composite material were almost same to those of the matrix alloy. At higher aging temperature, aging time to reach a maximum hardness in the 4 vol%TiC composite materials was shortened as compared with those of the matrix alloy. At the aging temperature, age hardening was scarcely observed in 8%TiC composite materials. By the TEM observation, relatively large size of needle-or rod-like precipitates were observed in 4 vol%TiC composite material, while very coarse rod-like precipitates were sparsely distributed in 8 vol%TiC composite material. At more elevated temperature, the very coarse rod-like precipitates were observed in both the composite materials, consequently, the age hardening could not be detected on the hardness curves of the materials. The small amount of dislocations which were probably introduced by quenching after solid solution treatment were observed near the TiC particles. The precipitates near the particles were especially coarsened.
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  • Semi-solid forming of Mg–Li–Al–Ca light metal alloys
    RAMESH CHANDRAN, Tetsuya SAKAI, Shigeharu KAMADO, Yo KOJIMA, Kazuo MAT ...
    1998 Volume 48 Issue 1 Pages 13-18
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.13
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    An attempt was made to apply semi-solid forming process to Mg–Li–Al and Mg–Li–Al–Ca alloys. 5 mass% (α phase matrix), 9 mass% (α+β eutectic matrix) and 14 mass% (β phase matrix) of Li were chosen to find the optimum Li content for semi-solid forming of Mg–Li–Al alloys. Al as a hardening element and Ca for protecting the combustion of the melt were added, respectively by 1 or 3 mass% and 1 or 2 mass.%, to the Mg–Li base alloys. Microstructural changes at the solidification range were preliminarily investigated in strain-introduced specimens. The press forming was then conducted at the optimum semi-solid temperature and the tensile properties were evaluated. Dendrite arms of the α phase break up into fine spherical particles when α specimen containing calcium is heated to its semi-solid temperature. Furthermore, an increment in the amount of introduced strain decreases the diameter of solid particles in the calcium-added Mg–9 mass%Li and 14 mass%Li alloys. These strain-introduced alloys containing calcium show fine and spherical solid particles distributed uniformly throughout the formed specimen when heated to the semi-solid temperature and then press-formed. The semi-solid formed specimens indicate a superior rise in tensile strength, especially in the case of Mg–9 mass%Li–3 mass%Al alloys which have a high tensile strength of 200 MPa and an elongation of more than 20%.
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  • Recycling of thin walled AZ91D magnesium alloy die-castings with paint finishing
    Hiroki TATEISHI, Makoto INOUE, Shigeharu KAMADO, Yo KOJIMA, Tadao ITOH ...
    1998 Volume 48 Issue 1 Pages 19-24
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.19
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    A new recycling process for the thin wall AZ91D magnesium die-castings with paint-finishing was developed in order to avoid contamination by impurities and the generation of harmful gases. Slow heating up of the scrap from room temperature results in generation of a large quantity of harmful gases. However, when a virgin ingot with the same weight as the scraps is firstly melted and then scraps are directly charged into the melt, the generation of the harmful gases are extremely reduced. But some of the involatile ingredients of the paint contaminate the melt. Therefore, a sound ingot is successfully produced by increasing the killing time after the flux treatment and removing the slug from the top and bottom of the crucible before casting. Tensile properties of the recycled ingots satisfy the JIS values. The ingot recycled from scraps of the components of video for non-professional use indicates the same level of corrosion behavior with the virgin material. Whereas the ingot recycled from scraps of those for professional use shows a poor corrosion behavior. The paint film of the professional use video components is thick and, therefore, impurities such as Fe, Ni and Cr from undercoating and paint remarkably contaminate the melt. This increases the amount of crystallized Al–Mn compound containing these impurities. As a result the recycled ingot from scraps of the professional use video components exhibits the poor corrosion behavior.
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  • Speed effect on deep drawing of aluminum alloy sheet with use of volatile lubricants
    Seiji KATAOKA
    1998 Volume 48 Issue 1 Pages 25-29
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.25
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    To improve the lubricity of the volatile lubricants with low viscosity (1~4 cSt), the speed effect was investigated by using a high speed deep drawing testing machine. The punch speed ranged from 100 mm/s to 104 mm/s. Test materials are 0.6 mm thick aluminum alloy sheet (A5052P–O) and mild steel sheet (SPCC) . In case of lubrication with 6221F and 6280, the application of higher speed effect increased the limiting drawing ratio (L.D.R.) of A5052P–O from about 1.6 to 2.1 and also reduced the maximum punch load. However the speed effect in SPCC was smaller than that of A5052P–O.
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  • Prediction of bore reduction limit of aluminum beverage can by a simplified mathematical model
    Kazuharu MASADA, Akibumi FUJIWARA, Hisashi TAKEUCHI
    1998 Volume 48 Issue 1 Pages 30-35
    Published: 1998
    Released on J-STAGE: June 01, 2007
    DOIhttps://doi.org/10.2464/jilm.48.30
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    In order to get the reduction limit caused by wrinkles in the neck forming process of aluminum beverage can, a simplified mathematical model was proposed. In the model, the plastic buckling theory for flat plate based on an isotropic model by Thurlimann and Haaijer, and the Bleich's equivalent modulus are used. The effect of material properties and die angle on the reduction limit were examined by the model with the finite element analysis using LS–DYNA–3D. Main results are as follows; 1) The solutions of the model agreed well with those of the finite element analysis. 2) Low yield stress, high work hardening ratio and high die angle increases reduction limit. 3) The method to get equivalent modulus for non linear hardening material is proposed.
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  • Microstructures of friction welded joint of 6061 aluminum alloy to 304 stainless steel
    Shinji FUKUMOTO, Mikio OHASHI, Harushige TSUBAKINO, Kozo OKITA, Masato ...
    1998 Volume 48 Issue 1 Pages 36-41
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.36
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    A 6061 aluminum alloy was joined to a 304 stainless steel by friction welding. The structure of aluminum alloy was refined in the vicinity of the weld interface. However, the Vickers hardness was decreased near the interface since the precipitates were dissolved in the aluminum alloy matrix by the friction heat. The width of heat affected zone (HAZ) was decreased as the increase in the friction and upset pressure (P1 and P2) increased. The sound joints were obtained welded by P1 =30 MPa, P2 =60 MPa and t1 (friction time) ≥2.0 s. The higher P1 made the joint strength decrease owing to the excess formation of brittle intermetallic compounds at the weld interface. The inter-diffusion of each element through the weld interface were revealed using TEM–EDS analysis. Fe2Al5 was mainly formed at the weld interface. The welding temperature was estimated to be under the eutectic temperature of Al/Fe system(925 K) by the thickness of intermetallic compound. Therefore, it is assumed that this friction welding was carried out in solid state in this system.
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  • Undercooling and primary solidification behavior in mixture of hypereutectic and another Al–Si alloy melts
    Tatsuya OHMI, Kiyotaka MATSUURA, Masayuki KUDOH, Youichi ITOH
    1998 Volume 48 Issue 1 Pages 42-47
    Published: 1998
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.48.42
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    A simplified numerical model is presented to investigate the undercooling and solidification behavior of a hypereutectic Al–Si alloy during the mixing process of two kinds of molten alloys with different temperature and composition. This model involves a single slab of the second melt (Al–32 mass%Si alloy) stretching in the infinite bulk of the first melt (Al–12 mass%Si alloy). The second melt and, in some cases, a part of the first melt near the second melt are undercooled and solidified in the course of the mixing. The number of primary crystals is maximized at a certain strain rate of the stretching slab, depending on the initial thickness of the slab, while the maximum undercooling of the second melt increases as the strain rate increases. These results suggest that excessive agitation during the mixing may depress the refinement of the primary crystals.
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