| 摘要 |
PROBLEM TO BE SOLVED: To provide an aluminum alloy plastic product capable of suppressing the progress of partial corrosion linearly extending to the deep part on the inside of the material and excellent in partial corrosion resistance and fatigue strength. SOLUTION: This product contains, by weight, 0.2 to 1.2% Si, 0.35 to 1.5% Mg and <=0.20% Ti and/or 0.3% V, and the balance substantial Al. In the cross- section parallel to the plastic working direction, Ti and/or V high concentration parts and Ti and/or V low concentration parts extending to the plastic working direction in the cross-section parallel to the plastic working direction are superimposed in layers. The Ti and/or V high concentration parts are preferably the ones having an area ratio of 45 to 95% in the cross-section parallel to the plastic working direction. It is produced by casting the molten metal of an alloy at a molten metal cooling rate of >=5 deg.C/sec, subjecting the obtd. ingot to homogenizing treatment at 520 to 580 deg.C for 1 to 8 hr, executing plastic working after cooling, transforming the cast crystal grains into layers and moreover executing heat treatment for improving its mechanical strength.
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