| 摘要 |
PROBLEM TO BE SOLVED: To provide an Al-Mg-Si-Cu based aluminum alloy sheet excellent in strength and formability, provided with improved filiform erosion resistance and particularly suitable as the one for an automotive outside sheet, and to provide its producing method. SOLUTION: This aluminum alloy sheet has a composition containing 0.25 to 0.6% Mg, 0.9 to 1.1% Si and 0.6 to 1.0% Cu and further containing one or two kinds of <=0.20% Mn and <=0.10% Cr, and the balance Al with impurities, and in which a Q phase (Cu-Mg-Si-Al phase) with a grain size of >=2μm is present by >=150 pieces/mm2 in a matrix, and, in its producing method, the ingot of an aluminum alloy having the above composition is subjected to homogenizing treatment at >=530 deg.C, is thereafter cooled to <=450 deg.C at a cooling rate of <=30 deg.C/hr, is hot-rolled and is subsequently subjected to cold rolling and solution treatment to produce the aluminum alloy sheet.
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