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AssigneeSumitomo Light Metal Industries, Ltd.
InventorsShozo Tahara, Taizo Kimura, Hiroki Miyazaki, Kazuhiro Hanaki
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An aluminum alloy material for the shutter of flat recording medium cassettes. The shutter is light in weight and smoothly slidable, has good corrosion resistance and durability, and protects itself against staining with fingerprints. The aluminum alloy contains 3.0-6.0% Mg (by weight) and one or more than one optional elements of Mn.ltoreq.1.5%, Cr.ltoreq.0.3%, Cu.ltoreq.0.5%, and Ti.ltoreq.0.1%, with the balance being aluminum and inevitable impurities, and has a tensile strength of 310-410 MPa and a yield strength of 250-370 MPa. The aluminum alloy material is formed from a rolled sheet of said aluminum alloy by coating the sheet with a plastic film not thicker than 5 .mu.m. The rolled sheet undergoes intermediate annealing at higher than the recrystallization temperature, final cold rolling, and stabilizing heat treatment.
A shutter for a recording medium cassette comprising an aluminum alloy sheet having a synthetic resin coated thereon at a thickness not greater than 5.mu., the aluminum alloy comprising 3.0-6.0 wt. % Mg, aluminum and inevitable impurities and the coated alloy sheet not having the coating crack or delaminate therefrom when the alloy sheet is bent at a 90.degree. outside bend radius, said bend radius being equal to the alloy sheet thickness.
Dependencies are inferred from the claim text.