| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively provide a painted Al-alloy sheet for a lid of an inner pressure can, which hardly causes a crack when a sink part is reversed, and has adequate formability in a portion to be rivet-formed. SOLUTION: An Al alloy sheet includes 3.5 to 5.0% Mg, 0.1 to 0.3% Mn, 0.2% or less Si, 0.2% or less Cu, 0.2% or less Cr and 0.25% or less Fe; and has intermetallic compounds with an circle-equivalent diameter of 0.7μm or larger distributed at a density of less than 5,000 pieces/mm<SP>2</SP>and at an area rate of less than 0.8%, in its cross-section. The painted Al-alloy sheet has a paint film formed on the surface of the above Al alloy sheet, and has a yield strength of 320 to 360 MPa after having been painted thereon. The manufacturing method comprises the steps of: homogenizing an ingot of the above Al alloy at 460°C to 530°C for 0.5 to 15 hours; rough-rolling the ingot with a reverse-system rough hot rolling mill; finish-rolling the rough-rolled plate of 380°C to 420°C at a total rolling reduction of 87% to 93%, at a rolling speed of 280 to 350 mpm and at a material temperature of 310°C to 340°C in the end of the finish rolling, with a tandem-type hot finish rolling mill; cold-rolling the plate with a reduction rate of 80% to 93% into a sheet having the final thickness; and then forming the paint film thereon. COPYRIGHT: (C)2008,JPO&INPIT
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