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Abstract

A steel sheet including a chemical composition satisfying an equivalent carbon content of 0.35% or more and less than 0.60% and a steel microstructure with an area fraction of ferrite: 40% to 85%, tempered martensite and bainite: 10% to 55% in total, retained austenite: 3% to 15%, and ferrite, tempered martensite, bainite, and retained austenite: 93% or more in total. A 90-degree bending at a curvature radius/thickness ratio of 4.2 in a rolling (L) direction with respect to an axis extending in a width (C) direction causes a change of 0.50 or more in (a grain size in a thickness direction)/(a grain size in a direction perpendicular to the thickness) of the tempered martensite in an L cross section in a 0- to 50-μm region from a surface of the steel sheet on a compression side, and the steel sheet has a tensile strength of 590 MPa or more.

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First Claim