MATERIAL FOR HIGH-STRENGTH STEEL SHEET, HOT ROLLED MATERIAL FOR HIGH-STRENGTH STEEL SHEET, MATERIAL ANNEALED AFTER HOT ROLLING AND FOR HIGH-STRENGTH STEEL SHEET, HIGH-STRENGTH STEEL SHEET, HIGH-STRENGTH HOT-DIP PLATED STEEL SHEET, HIGH-STRENGTH ELECTROPLATED STEEL SHEET, AND MANUFACTURING METHOD FOR SAME

摘要

A high strength steel sheet having excellent surface quality and formability with a tensile strength of 980 MPa or more and a TS-El balance of 30000 MPa% or more is provided. A high strength steel sheet comprises: a chemical composition containing C: 0.08 % to 0.30 %, Si: 2.0 % or less, Mn: more than 3.0 % and 10.0 % or less, P: 0.05 % or less, S: 0.01 % or less, Al: 1.5 % or less, Ti: 0.010 % to 0.300 %, and N: 0.0020 % to 0.0100 % in a range satisfying 1.1 ≤ (Ti + Mn^1/2/400)/(0.01 + 5N) ≤ 6.0; and a microstructure including a retained austenite phase and a ferrite phase, wherein a ratio γMn/αMn of an average Mn concentration (γMn) of the retained austenite phase to an average Mn concentration (αMn) of the ferrite phase is 1.5 or more.