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Nagoya-shi, Japan

Minoda T.,Sumitomo Light Metal Ind. LTD.
Keikinzoku/Journal of Japan Institute of Light Metals | Year: 2011

The influence of the room temperature pre-aging (RTPA) conditions on the strength of 7N01 aluminum alloy in T6 temper was changed by the zinc and magnesium contents. When both the zinc and magnesium contents were the lowest and the RTPA was omitted, the strength became the lowest because the aging rate during artificial aging decreased and a non-homogeneous precipitation of the n′ phase occurred. On the other hand, the n′ phase became finer and the strength in T6 temper became higher as the RTPA was longer and higher. Also, the two-step artificial aging resulted in a higher strength. It was considered that the GP(I)zones, which formed during RTPA, dissolved and the GP(II)zones formed during heating process of the artificial aging. Because the GP(II)zones were the precursor to the n′ phase, the strength became higher by the RTPA and the two-step aging. Furthermore, the influence of RTPA on the strength in T6 temper decreased with the increasing zinc and magnesium contents, and it almost disappeared when both the zinc and magnesium contents were maximum values. It was considered that the aging rate increased, and the GP(I)and GP(II)zones adequately formed during the heating stage of the artificial aging process because the solute atoms of the zinc and magnesium were sufficiently present.


Fujimura R.,Sumitomo Light Metal Ind. LTD. | Koyama T.,Sumitomo Light Metal Ind. LTD. | Uchida H.,Sumitomo Light Metal Industries Ltd.
Keikinzoku/Journal of Japan Institute of Light Metals | Year: 2013

In this work, the influence of cation species on the corrosion behavior of Al-Mg-Si alloy in Cl-containing solution was studied by immersion test and electrochemical measurement. The results of immersion test showed that severe pitting corrosion occurred at the Al-masking boundary of the sample and more weight loss of samples after immersion test gained in MgCl2 solution than those in NaCl and CaCl2solutions. Anodic polarization curves showed little difference in pitting potential of Al-Mg-Si alloy in Cl-containing solutions regardless of the cation species. On the other hand, cathodic polarization curves showed the increase of cathodic current density in MgCl 2 solution than those in NaCl and CaCl2 solutions. This electrochemical behavior suggested the remarkable corrosion of Al-Mg-Si alloy in MgCl2 solution was caused by the increase of cathodic reaction. The reason why the cathodic reaction increased in MgCl2 solution was considered that the pH at cathode surface was kept by buffering action of Mg2+ because of the less solubility of Mg (OH)2. © 2013 The Japan Institute of Light Metals.


Tanaka H.,Sumitomo Light Metal Ind. LTD. | Ikawa S.,Sumitomo Light Metal Ind. LTD.
Materials Transactions | Year: 2012

It is known in aluminum alloy sheets that two ears on a cup formed by deep drawing in 0 and 180° to the rolling direction may grow up by cold rolling. In the previous reports, Goss and RD rotated cube textures were fingered as the cause of the 0°/180° earing. But the growth process of the 0°/180° earing is not clear. In the present work, texture analysis has been carried out in cold rolling process with AA 6016 aluminum alloy sheets that have a strong cube texture through the thickness and weak Goss texture at the center layer. RD rotated cube texture is formed at the surface layer by cold rolling whereas cube texture at the center layer decreases rapidly. It is indicated that RD rotated cube texture at the surface layer and persisting Goss texture at the center layer cause high 0°/180° earing. These texture factors are discussed by a crystal plasticity finite element analysis. The calculated earing profiles derived by the finite element analysis show much the same patterns of experimental earing profiles. © 2012 The Japan Institute of Metals.


Tanaka H.,Sumitomo Light Metal Ind. LTD. | Minoda T.,Sumitomo Light Metal Ind. LTD.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

The effect of transition elements on grain refinement of 7475 aluminum alloy sheets produced by warm rolling was investigated. The alloy which contains zirconium instead of chromium showed ultra fine structures with stable subgrains after warm rolling at 350 °C, followed by solution heat treatment at 480 °C. The average subgrain diameter was approximately 3 μm. It became clear that zirconium in solution has the effect of stabilizing subgrains due to precipitation of fine Al3Zr compounds during warm rolling. On the other hand, chromium-bearing compounds precipitate before warm rolling and they grow up to relatively large size during warm rolling. The warm rolled sheets with fine subgrains have unique properties compared with conventional 7475 aluminum alloy sheets produced by cold rolling. The warm rolled sheets solution heat treated had subgrain structures through the thickness with a high proportion of low-angle boundary less than 15°. The strength of the warm rolled sheets in T6 condition was about 10% higher than that of conventional 7475 aluminum alloy sheets. As the most remarkable point in the warm rolled sheets, the high Lankford (r) value of 3.5 was measured in the orientation of 45° to rolling direction, with the average r-value of 2.2. The high r-value would be derived from well developed β-fiber textures, especially with the strong {011}〈211〉 brass component. The warm rolled sheets also had high resistance to SCC. From Kikuchi lines analysis and TEM images, it was found that PFZs were hardly formed along the low-angle boundaries of the warm rolled sheets in T6 condition. This would be a factor to lead to the improvement of resistance to SCC because of reducing the difference in electrochemical property between the grain boundary area and the grain interior. © 2014 The Nonferrous Metals Society of China.


Minoda T.,Sumitomo Light Metal Ind. LTD. | Yoshida H.,Sumitomo Light Metal Ind. LTD.
Keikinzoku/Journal of Japan Institute of Light Metals | Year: 2010

Influences of cooling rates after homogenization heat treatment and heating temperatures of ingots before extrusion on thermal stability of fibrous structure of 2024 aluminum alloy extrusion after T4 temper was investigated. The thermal stability of the fibrous structure was influenced by both the main elements (copper and magnesium) and the transition element (manganese). The fibrous structure was stabilized when the solute atoms of copper, magnesium and manganese were increased by rapid cooling after the homogenization heat treatment and the extrusion temperature was close to the nose temperature of the manganese precipitation. Therefore, the thermal stability of the fibrous structure decreased when the copper and magnesium were not present or the manganese amount was reduced by half. Furthermore, the cooling rate and the heating temperature influenced the crystallographic texture of the extrusion. When the fibrous structure was stable, cube and brass texture tended to increase, while the copper texture tended to decrease in the F temper. The formation of the crystallographic texture was affected by recovery with precipitation of copper and magnesium during the extrusion process.

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