| 摘要 |
PROBLEM TO BE SOLVED: To provide an aluminum alloy hard sheet as a can-top material for a stay-on-tab type negative pressure can, reduced in earing rate so as to prevent inferior seaming and also reduced in strength anisotropy so as to prevent a score part from cracking by drop shock. SOLUTION: An ingot of an Al alloy, which has a composition containing, by weight, 0.8-3.0% Mg, 0.01-1.2% Mn, 0.10-0.50% Fe, and 0.05-40% Si and satisfying (Fe+Mn)/Si<=20, is hot rolled. This hot rolling is performed under the conditions of 400-580 deg.C hot rolling starting temperature, >=50 m/min rolling speed in the last pass but two, >=100 m/min rolling speed in the last pass but one, >=150 m/min rolling speed in the last pass, 20-70% draft in the last pass, and 220-370 deg.C hot rolling finishing temperature. Further, process annealing is applied by means of continuous annealing where heating is performed up to 320-550 deg.C with or without holding for <=10 min or batch annealing where heating is performed at 220-500 deg.C for 0.5-24 h, followed by final cold rolling of >=40%. After the final cold rolling, final annealing is applied at 100-240 deg.C for <=10 h.
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