| 摘要 |
To provide an aluminum alloy sheet with excellent formability at high temperatures and high speeds with a reduced amount of cavities after forming and a method of production of the same. An aluminum alloy sheet consisting of 2.0-8.0 wt% of Mg, 0.06-0.2 wt% of Si, 0.1-0.5 wt% of Fe, 0. 1-0.5 wt% of Mn, and the balance of Al and unavoidable impurities, wherein a density of inter-metallic compounds having an equivalent circle diameter of 1 to 5 (m is 5000/mm2 or more and an average crystal grain size is 20 (m or less. A method of production of an aluminum alloy sheet comprising the steps of casting an alloy melt having the above described composition by a twin belt casting machine at a cooling rate of 20 to 150°C/sec at the location of 1/4 of the slab thickness during the casting to form a slab having a thickness of 5 to 15 mm, subsequently rewinding up the slab as a coil, cold rolling the slab taken out from the coil at a cold rolling reduction of 70 to 96%, and performing annealing heating the obtained cold rolled sheet at a heating rate of 50°C/sec or more to 420 to 500°C.
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