Nippon Steel Corporation

Shota Endo

Hiroshi Shuto

Jun Ando

Akifumi Sakakibara

Koutarou Hayashi

Genki Abukawa

Kazumasa Tsutsui

Tetsu Asato

This hot-rolled steel sheet has a predetermined chemical composition, in which a microstructure contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, has a ratio L/Lof a length Lof a grain boundary having a crystal misorientation of 60° to a length Lof a grain boundary having a crystal misorientation of 7° about a <110> direction of less than 0.60, has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

Hot-rolled steel sheet

A hot-rolled steel sheet according to the present invention has a predetermined chemical composition, in which, when a height profile of a surface of the hot-rolled steel sheet is measured in each of five measurement ranges in a rolling direction and a direction perpendicular to the rolling direction, a distance in a height direction from an average height position which is an average of a height position of a point having a highest height position and a height position of a recessed part which is a point having a lowest height position to the recessed part is indicated as R(μm) in each of the height profiles, and an average of heights of two measurement points away from the recessed part in the rolling direction or the direction perpendicular to the rolling direction by 5 μm is indicated as R(μm), an average value of radii of curvature r represented by Expression (1) is 10 μm or more, and a tensile strength of the hot-rolled steel sheet is 500 MPa or more. r=(25+|R−R|)/2|R−R| . . . (1)

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Tokyo, Japan

Shota Endo