| 摘要 |
PROBLEM TO BE SOLVED: To provide an Al-Mg-Si alloy sheet for forming superior in hem bendability, for a body sheet in automobiles or the like. SOLUTION: The aluminum alloy sheet includes 0.3-1.0% Mg, 0.3-1.2% Si, one or more elements of Mn, Cr, Zr, V, Fe, Ti, and Zn, in a small amount, 1.0% or less Cu, and the balance Al, and has notch elongation of 10% or more. The Al alloy sheet further has 60μm or less of an average grain size, 5μm or less of the maximum length of intergranular precipitates, 1,000 pieces/mm<SP>2</SP>or less of dispersion density of second phase particles with diameters of 2μm or larger in circle terms, and 5% or less of an area rate of the second phase particles with 0.5μm or larger. The manufacturing method comprises homogenizing a slab of the above aluminum alloy at 480°C or higher, hot-rolling it at a starting temperature of 480°C or higher, with a temperature descending time during 480-350°C of 20 minutes or shorter, recrystallizing it one or more times at a recrystallization rate of 10% or higher during the temperature descending time, cold-rolling it with a reduction of 20% or higher, subsequently solution-treating it at 480°C or higher for 5 minutes or shorter, then cooling it to 45-150°C at 100°C/min or higher, and successively subjecting it to stabilization treatment of holding at the same temperature range for 2 hours or longer, or further subjecting it to final heat treatment at 170-280°C for 5 minutes or shorter. COPYRIGHT: (C)2003,JPO
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