| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin-wall cold-rolled steel sheet for a drum, which is superior in formability, weldability and bake hardenability, and has a sheet thickness of less than 1.0 mm, and to provide a manufacturing method therefor. SOLUTION: A raw steel material has a composition comprising, by mass%, 0.005 to 0.10% C, 0.005 to 0.20% Si, 0.1 to 1.0% Mn, 0.005 to 0.20% P, 0.03% or less S, 0.01 to 0.1% Al, and 0.0080 to 0.0200% N. The manufacturing method comprises the steps of: heating the raw steel material to a heating temperature of 1,150°C or higher; hot-rolling it at a finish rolling temperature of 850°C or higher; starting the cooling of the steel plate to 650°C or lower at an average cooling rate of 75°C/s within 2s after the end of the rolling; winding it up at a winding temperature of 650°C or lower; pickling the steel plate and cold rolling it; and recrystallization-annealing the steel sheet at an annealing temperature of 750°C or lower; or further temper-rolling it with an elongation percentage of 0.5 to 5%. Thus manufactured thin-wall cold-rolled steel sheet for the drum contains 0.0070% or more of solid solution N, has a ratio of solid solution N to N higher than 0.60, is superior in drum manufacturability and bake hardenability, and has a sheet thickness of less than 1.0 mm. COPYRIGHT: (C)2008,JPO&INPIT
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