A method of manufacturing the same, and, and a method of manufacturing the high-strength galvanized steel plate and high-strength cold-rolled steel sheet of the maximum intensity 900MPa more excellent tensile fatigue durability

摘要

PROBLEM TO BE SOLVED: To provide a high strength cold rolled steel sheet which has excellent workability and strength, wherein surface defects are suppressed and fatigue durability is excellent, and the maximum tensile strength is ≥900 MPa, and a method for producing the same, and to provide a high strength galvanized steel sheet and a method for producing the same.;SOLUTION: The steel sheet has steel components at least comprising, by mass, 0.07 to 0.25% C, 0.9 to 2.50% Si, 0.005 to 0.09% Ti and ≤0.60% Al, and the balance iron with inevitable impurities, and has a steel sheet structure mainly composed of ferrite and martensite, wherein the average value (A) of the random intensity ratios of the X-rays in the {100}011 to {223}110 orientation groups of the sheet faces in the texture of the ferrite as the main phase in the surface layer of the steel sheet is ≤3.0.;COPYRIGHT: (C)2011,JPO&INPIT