| 摘要 |
PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet having excellent high temperature high speed forming property and having reduced cavities after forming, and to provide its production method. SOLUTION: The aluminum alloy sheet has a composition comprising, by mass, 2.0 to 8.0% Mg, 0.06 to 0.2% Si, 0.1 to 0.5% Fe, and 0.1 to 0.5% Mn, and the balance Al with inevitable impurities, and in which the density of intermetallic compounds with a diameter of the equivalent circle of 1 to 5μm is≥5,000 pieces/mm<SP>2</SP>, and the average crystal grain size is≤20μm. In the method for producing an aluminum alloy sheet, alloy molten metal having the above composition is cast at a cooling rate of 20 to 150°C/sec on the casting by a twin belt casting machine so as to be a slab with a thickness of 5 to 15 mm. Successively, the slab is coiled, the slab uncoiled from the coil is cold-rolled at a cold rolling ratio of 70 to 96%, and the obtained cold-rolled sheet is annealed so as to be heated at 420 to 500°C at a temperature rising rate of≥5°C/sec. COPYRIGHT: (C)2006,JPO&NCIPI
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