| 摘要 |
PROBLEM TO BE SOLVED: To obtain a uniform rough surface as that of an Al alloy plate for a lithographic printing plate, and also, to maintain the uniformity of the rough surface over the whole length of a coil. SOLUTION: The Al alloy plate is composed of an Al alloy comprising 0.1 to 0.5% Fe, 0.05 to 0.20% Si, 0.005 to 0.07% Cu and 0.005 to 0.08% Ti. The average area of the crystal grains is≤0.1 mm<SP>2</SP>, the average length in the rolling direction of the crystal grains is≤1,300μm, the average length in a direction orthogonal to the rolling direction is≤100μm, the ratio between the average length A in a direction orthogonal to the rolling direction in the inwardly coiled part and the average length B in a direction orthogonal to the rolling direction in the outwardly coiled part in a product plate coil, A/B satisfies 0.8≤A/B≤1.2, and the ratio between the average area C of the crystal grains in the inwardly coiled part and the average area D of the crystal grains in the outwardly coiled part, C/D satisfies 0.8≤C/D≤1.2. In its production method, upon hot rolling, the draft in the finish rolling is regulated in such a manner that the ratio between the finish plate thickness in the rough rolling and the finish plate thickness in the finish rolling reaches≥9, the finish plate thickness in the rolling is controlled to 1.2 to 4.0 mm, the finish temperature in the rolling is controlled to 280 to 360°C, the difference between the maximum temperature part and the minimum temperature part in the finished plate is controlled to≤30°C by the regulation in the injection amount of a coolant in the finish rolling, and thereafter, cold rolling is performed without intermediate annealing. COPYRIGHT: (C)2007,JPO&INPIT
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