Cold Rolled Steel Sheet And Manufacturing Method Thereof

Abstract: This cold-rolled steel sheet has a predetermined chemical composition, wherein: a metallographic structure at a t/4 position, which is located at 1/4 of the sheet thickness t from the surface in a sheet thickness direction, contains, by volume ratio, 2.0% to 8.0% of residual austenite, 80.0% to 98.0% of tempered martensite, a total of 0.0% to 15.0% of ferrite and bainite, and 0.0% to 5.0% of martensite; both in a central region and in an edge region positioned 50 mm from an edge in a width direction, a 20 µm region, which is positioned 20 µm from the surface in the sheet thickness direction, has a metallographic structure containing, by volume ratio, a total of 75.0% to 100.0% of ferrite and bainite and a total of 0.0% to 25.0% of martensite and tempered martensite; and a 75 µm region, which is positioned 75 µm from the surface in the sheet thickness direction, has a metallographic structure containing, by volume ratio, a total of 0.0% to 15.0% of ferrite and bainite.

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