Steel Sheet And Welded Joint

Abstract: This steel sheet has a predetermined chemical composition, and has, at a t/4-position which is a position at a distance of t/4 from the surface in a sheet thickness direction cross section when the sheet thickness is defined as t, a metal structure including 20% or more of ferrite and a total of 40% or more of bainite and martensite in volume fraction, the remaining portion being at least one selected from retained austenite and perlite. In a square-shaped area in which the length of one side is t/4 and which is centered at the t/4-position in the sheet thickness direction cross section, when the Mn concentration is measured at multiple measurement points located apart at a 1 µm-interval, the proportion of measurement points in which the Mn concentration is at least 1.1 times of the average value of the Mn concentration at all the measurement points is less than 10.0%. The steel sheet has a tensile strength of 980 MPa or more. The product between the tensile strength and the total elongation of the steel sheet is 10500 MPa·% or more.

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