Importance

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Abstract

This cold-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure of a t/4 portion, which is at a ¼ position of a sheet thickness t from a surface of the cold-rolled steel sheet in a sheet thickness direction, includes, by volume percentage, retained austenite: 2.5% or more and 10.0% or less, tempered martensite: 80.0% or more and 97.5% or less, ferrite and bainite: 0.0% or more and 15.0% or less in total, and martensite: 0.0% or more and 3.0% or less, and in a surface layer area at a position 25 μm away from the surface in the sheet thickness direction, an amount of solute Si is 0.30% or more and 1.50% or less by mass %, a volume percentage of ferrite in the metallographic structure is 0.0% or more and 20.0% or less, and a density of ferrite grains having a grain size of 15 μm or more is 0 grains/mm² or more and 3,000 grains/mm² or less.

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First Claim