Nippon Steel Corporation

Tsuyoshi Yamazaki

Shuhei Kasahara

This steel sheet has a predetermined chemical composition, at a depth position of ¼ of a sheet thickness from a surface, an area fraction of GAMis 50% or more and 100% or less, an area fraction of GAMis 0% or more and 20% or less, an area fraction of GAMis 0% or more and less than 50%, an area fraction of residual austenite is 0% or more and less than 4%, a total area fraction of the residual austenite, fresh martensite, cementite and pearlite is 0% or more and 10% or less, an average grain size is 15.0 μm or less, an average dislocation density is 1.0×10/mor more and 4.0×10/mless, a total of pole densities of {211}<011> and {332}<113> in a thickness middle portion is 12.0 or less, and a tensile strength is 980 MPa or more.

Steel sheet and steel sheet manufacturing method

This electric furnace includes one or more upper electrodes, one or more bottom-blowing tuyeres, a mechanical stirrer equipped with an impeller, and a charging device which injects an iron oxide-containing iron raw material.

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Tokyo, Japan

Tsuyoshi Yamazaki