HIGH-STRENGTH STEEL SHEET, HIGH-STRENGTH PLATED STEEL SHEET, HIGH-STRENGTH MOLTEN ZINC PLATED STEEL SHEET, HIGH-STRENGTH ALLOYED MOLTEN ZINC PLATED STEEL SHEET, AND METHOD OF PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an excellently processable high-strength steel sheet with tensile strength of 780 MPa or more, high Young's modulus, and good deep drawing and stretch flange properties.SOLUTION: The steel sheet has a prescribed component composition, and a microstructure which has a ferrite area ratio of 20% or more, a martensite area ratio of 5% or more, and a tempered martensite area ratio of 5% or more. In the microstructure, the average crystal grain size of the ferrite is 20.0 μm or less, and the inverse intensity ratios of γ-fibres to α-fibres in the ferrite, the martensite and the tempered martensite are each 1.00 or more.SELECTED DRAWING: None