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Volume 50, Issue 10
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
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Takayoshi FUJINO, Masaki MIYAMOTO, Hayao NOGUCHI2000 Volume 50 Issue 10 Pages 486-490
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSIt is known that the coatings produced by MBV method and Alojin method are inferior with point of anticorrosion, because those coatings have characteristic of thin amorphous coatings and much cracks on the surface of coating. Manufacture of the thick coating which was superior in corrosion-resistance is needed, and this study has attempted to obtain chemical conversion coatings in 0.01 mol/l Sr(OH)2 bath with boehmite process. The major component of first coating was Al(OH)3, because Al(OH)3 was remade in supersaturated sodium aluminate solution and the first coatings were examined by secondary treatment. The chemical structure, and its composition of each chemical coatings were investigated by X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermal analysis and secondary ion mass spectrometry. It is found that the first coating formed by dipped at 70°C for 60 min. was thickness of about 10 μm. The structure of first coating has two layers: one crystal layer was growing from uniform amorphous layer and another amorphous layer was thickness of about 3 μm. Crystallinity of the crystal layer (Gibsite) was enhanced by secondary treatment, the amorphous layer was double thickness compared with first coating, which was confirmed by measure of XRD and SEM. This secondary treatment coatings showed excellent corrosion-resistance (10 times or more). The mechanism of corrosion protection by secondary coating had been attributed to reason that the dissolution of aluminum decreased with coating of thick and uniform amorphous layer.View full abstractDownload PDF (430K) -
Tadashi MINODA, Hideya HAYAKAWA, Hideo YOSHIDA2000 Volume 50 Issue 10 Pages 491-494
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe effect of iron content on the surface quality of 6063 aluminum alloy extrusions was investigated. From the view point of surface defects, pick-up decreased with iron content. In our previous paper, it was found out that pick-up defects were caused by peritectic reaction of Al, β-AlFeSi and Mg2Si in cell boundaries during extrusion and the transformation of AlFeSi particles from β to α during homogenization was effective to reduce pick-up. As the result of estimation of α ratio, α ratio increased with iron content in the as-cast ingots. Furthermore, it was confirmed that the transformation of AlFeSi particles from β to α during homogenization was encouraged with higher iron content. Then, there was a good correlation between pick-up and α ratio. From the view point of surface roughness, Rz decreased with iron content because heavy pick-up defects decreased with increasing iron content. On the other hand, Ra increased with iron content because die line became severely.View full abstractDownload PDF (484K) -
Osami SERI, Takeo ASAHI2000 Volume 50 Issue 10 Pages 495-498
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSAn attempt has been made to clarify influence of environmental solution contaminated by combustion gas of polyvinyl-chloride disposal on corrosion behavior of aluminum wire. Electrochemical measurement and metallurgical observation by SEM show that the environment above is detrimental to corrosion of aluminum and causes the pitting attacks severely.View full abstractDownload PDF (333K) -
Tomoshi TAKAHASHI, Kazuko HIRAYAMA, Yoritoshi MINAMINO, Toshimi YAMANE ...2000 Volume 50 Issue 10 Pages 499-504
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSQuaternary and ternary interdiffusion experiments of 7000 aluminum alloys have been performed at 725 K and 755 K. The concentration profiles indicate that the diffusion distance of Cu is shorter than those of Zn and Mg in the solid solutions. The direct interdiffusion coefficients DAlZnZn, DAlMgMg, are positive, and indirect coefficients DAlZnMg, DAlMgZn are negative in the ternary Al–Zn–Mg alloys. The effective interdiffusion coefficients in 7000 aluminum alloys are in the order DeffZn,C>DeffMg,C>DeffCu,C. When the concentration distribution of Zn and Mg are almost constant and the concentration of Cu approaches zero in the Al–Zn–Mg/Al–Zn–Mg–Cu couple, it is obvious that DeffCu,C=D4Cu,Cu=D*Cu(Al–Zn–Mg). The ratio values of indirect to direct diffusion coefficients suggest that attractive interactions of Zn–Mg and Cu–Mg exist in the Al–Zn–Mg–Cu alloys.View full abstractDownload PDF (480K) -
Takeshi SAWAI, Koichi OGAWA, Hiroshi YAMAGUCHI, Hiizu OCHI, Yoshiaki Y ...2000 Volume 50 Issue 10 Pages 505-511
Published: 2000
Released on J-STAGE: June 01, 2007
JOURNAL FREE ACCESSFriction welding of 6061 aluminum alloy similar material was carried out in order to examine a relationship between heat input and joint performance. The joint performance is evaluated by tensile test. The heat input is a heat source for welding solid materials and is classified into six inputs, that is, friction heat input and deformation heat input during friction stage, upset stage and total stage respectively. The most important heat input for evaluating the joint performance among these heat inputs was experimentally investigated through the tensile strength of joints welded with many welding conditions because the friction welding mechanism is so complexed. As the results, the deformation heat input during upset stage was much related with the joint performance, and sound welded joints were obtained with 200 J/s or more deformation heat input. Moreover, it was recognized that the deformation heat input during upset stage was in proportion to the upset loss, therefore, sound welded joints were obtained with 3 mm or over upset loss also.View full abstractDownload PDF (938K) -
Toshikatsu ASAHINA, Hiroshi TOKISUE2000 Volume 50 Issue 10 Pages 512-517
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSPure magnesium and AZ31 alloy plates with 4 mm thickness were butt welded without addition of filler wire using a high voltage electron beam welding machine. Effect of welding speed on the electron beam weldability was investigated by the microstructural observation and mechanical properties. Regardless of the base metal, the welded joints were almost free from welding defects and showed good bead appearance at appropriate welding condition. The arcing phenomena did not occur at every welding speeds. Microstructure of the fusion zone of pure magnesium welded joint was coarse, and typical epitaxial growth of columnar grains was observed at fusion boundary. The very fine crystal grains were observed in the fusion zone of AZ31 alloy welded joint. Hardnesses of both fusion zone and heat affected zone of the welded joint are nearly equal to that of each base metal. Regardless of the welding speed, both tensile strength and impact value of the welded joint show same value to those of the base metal, but the elongation of the welded joint is inferior to that of the base metal. From both of the tensile test and impact test, welded joint of pure magnesium were fractured at the center of the fusion zone, but in case of AZ31 alloy welded joint, crack occurred at fusion boundary and it propagated through the fusion zone.View full abstractDownload PDF (842K)
REVIEW
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Shin-ya KOMATSU, Toshiki MURAMATSU2000 Volume 50 Issue 10 Pages 518-526
Published: 2000
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (865K)
Errata
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2000 Volume 50 Issue 10 Pages E1
Published: 2000
Released on J-STAGE: February 17, 2009
JOURNAL FREE ACCESSDownload PDF (35K)
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