Steel Sheet And Steel Sheet Manufacturing Method

Abstract: This steel sheet contains, in mass%, 0.15-0.50% of C, 0.01-1.00% of Si, 1.00-3.00% of Mn, 0-0.0200% of P, 0.0001-0.0200% of S, 0.001-0.100% of Al, 0-0.020% of N, and the remainder comprises Fe and impurities. The area ratio of the metal structure is 0% or more and 10% or less for retained austenite, and 0% or more and 5% or less in total for pearlite, ferrite, and bainite. The structure of the remainder is constituted by martensite and temper martensite. The maximum diameter of MnS according to extreme value statistics is 30 µm or less, the surface roughness Ra is 5 µm or less, and the Vickers hardness of the surface layer is less than the tensile strength Ts (MPa) of the steel sheet × 0.25.

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