| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly productive aluminum alloy sheet for PP (pilfer proof) caps which has a low earing ratio, a reduced variation in an earing ratio in a sheet-width direction and excellent cap openability. SOLUTION: The aluminum alloy sheet for caps has a composition consisting of 0.3 to 0.8% Mn, 0.3 to 0.8% Mg, 0.1 to 0.7% Fe, 0.1 to 0.5% Si and the balance essentially Al. In the aluminum alloy sheet, an earing ratio of 45°earing is≤2%, a variation in an earing ratio in a sheet-width direction is≤1% and tensile strength is 145 to 190 MPa. Its manufacturing method is as follows: after homogenizing treatment at 540 to 610°C, hot roughing is carried out using a reversing rolling mill while performing the last pass and the last but one pass each at≥30% rolling rate and regulating hot roughing finishing temperature to≥440°C; hot finish rolling is done at 330 to 360°C finishing temperature to obtain a hot rolled plate in a recrystallized state; primary cold rolling is applied to the hot rolled plate at≥60% rolling rate; and, after process annealing, the resultant cold rolled sheet is subjected to finish cold rolling and stabilizing treatment. COPYRIGHT: (C)2008,JPO&INPIT
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