| 摘要 |
PURPOSE:To manufacture a rolled Al alloy sheet excelling in strength and formability, causing no deterioration in strength after baking finish, and suitable for use in automobile body seats by subjecting an Al alloy ingot having a specific composition to homogenizing treatment, to rolling to prescribed thickness, and to heat treatment under specific conditions. CONSTITUTION:The Al alloy ingot containing, by weight, 1.2-1.5% Si, 0.25-0.85% Mg, 0.05-0.4% Fe, 0.3-1.5% Cu, and further 1 or >=2 kinds among 0.05-0.6% Mn, 0.05-0.3% Cr, and 0.05-0.15% Zr is cast. The ingot is heated at 450-580 deg.C for 1-48hr to be homogenized and is then subjected to hot rolling or further to cold rolling to be rolled into a sheet with prescribed thickness. The sheet is maintained in a temp. range of 500-580 deg.C for >=20sec, cooled rapidly at >=1,000 deg.C/min cooling rate and then subjected to ageing by an ordinary method.
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