| 摘要 |
PURPOSE:To manufacture the titled Al alloy sheet having superior corrosion resistance and weatherability, by applying homogenizing heat treatment to an Al alloy ingot having a specific composition consisting of Si, Fe, Ti, and Al and by subjecting the above ingot to hot rolling, cold rolling, and heat treatment under specific conditions. CONSTITUTION:The Al alloy ingot consisting of 0.7-2.5% Si, 0.10-0.70% Fe, 0.01-0.05% Ti, and the balance Al with impurities is subjected to homogenizing heat treatment at and below the melting temp. The ingot then is hot- rolled at 350-450 deg.C, cold-rolled, and process-annealed at 350-450 deg.C for <=60sec. Successively, the above sheet is subjected to final cold rolling at >=15% draft to be above sheet is subjected to final cold rolling at >=15% draft to be formed to the prescribed thickness and further to final heat treatment at 150-250 deg.C for 1-30hr. In this way, an Al alloy sheet is which precipitated grains of 1-0.1mum average grain size principally composed of Si are uniformly dispersed in a density of >=3,000pieces/mm<2> can be obtained. On sulfuric acid bath electrolytic coloring treatment, the above Al alloy sheet forms a gray surface film excellent in corrosion resistance and weatherability.
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