| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet having excellent high-speed superplastic formability, which is produced by a sheet continuous casting process without increasing bare metal cost, also without increasing the number of production steps and without the need of additional elements for fining crystal grains, and to provide a method for producing the same. <P>SOLUTION: The aluminum alloy sheet has a chemical composition including, by mass, 2.5-5.0% Mg, 0.1-0.3% Fe, 0.06-0.12% Si, and the balance aluminum with inevitable impurities in which the content of Mn is limited to ≤0.1% and that of Cr is limited to ≤0.05%, and has a microstructure in which the number of second phase grains with the diameter of the equivalent circle of ≥0.2 μm is ≤20,000 pieces/mm<SP POS="POST">2</SP>, and which is a fibrous unrecrystallized structure or a recrystallized structure with the average grain size of ≤20 μm. In its production, an alloy molten metal having the above composition is cast into a slab with a thickness of 5 to 15 mm by a sheet continuous casting machine, is wound, and is cold-rolled at a cold rolling ratio of 70 to 96% as it is without being subjected to homogenizing treatment, or is further subjected to final annealing. <P>COPYRIGHT: (C)2012,JPO&INPIT |
