HOT-ROLLED STEEL SHEET FOR ULTRA-THIN STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a hot-rolled steel sheet which is suitable for use in manufacturing a high-quality ultra-thin steel sheet having uniform material quality and sheet thickness in the sheet width direction regardless of its extreme ultra-thinness and large width; and a method for manufacturing the hot-rolled steel sheet.;SOLUTION: The hot-rolled steel sheet for an ultra-thin steel sheet preferably comprises, by mass%, 0.1% or less C, 0.03% or less Si, 0.05-0.60% Mn, 0.02% or less P, 0.02% or less S, 0.02-0.20% Al, 0.015% or less N, 0.01% or less O, and a balance comprising Fe and unavoidable impurities. The hot-rolled steel sheet has a sheet thickness of 2 mm or less, a sheet width of 950 mm or more, and a crown within ±40 μm. In the area excepting the width end of both sides of the steel sheet in an as-cold-rolled state (herein, the sum of ratio of the sheet width at both side ends to the area is 5% or less), the variation quantity of sheet thickness is within ±4%, the variation quantity of hardness (HR30T) is within ±3, and the sheet thickness is 0.2 mm or less.;COPYRIGHT: (C)2010,JPO&INPIT