To obtain an aluminum alloy sheet excellent in chemical convertibility, corrosion resistance, adhesive strength of coating film or the like by adopting an alloy design in which the concentration of Mg in the surface layer part is controlled to ≤20%.
This aluminum alloy has a composition containing, by weight 2.5 to 5.5% Mg, 0.05 to 0.4% Cu, 0.005 to 0.2% Mn, 0.005 to 0.1% Cr, 0.01 to 0.05% Ti, ≤0.08% Si, ≤0.1% Fe and 0.0001 to 0.01% Be and further containing, at need, one or more kinds selected from 0.001 to 0.1% Zr, 0.001 to 0.1% V and 0.0001 to 0.01% B, and the residue is substantially Al. A substrate high in affinity with a coating film can be formed by a chemical treatment using zinc phosphate, and the coated sheet is applied to such as an automotive outside sheet excellent in corrosion resistance and adhesion for a coating film.
SHIMADA KAORU
MORIYAMA TAKESHI
SUZUKI TOSHIAKI
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