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High-strength hot-dip galvanized steel sheet having a maximum tensile strength of 980 MPa or more and excellent formability with little material anisotropy, high-strength galvannealed steel sheet, and method for producing the same
High-strength hot-dip galvanized steel sheet having a maximum tensile strength of 980 MPa or more and excellent formability with little material anisotropy, high-strength galvannealed steel sheet, and method for producing the same
[Abstract] Provided is a high-strength hot-dip galvanized steel sheet having small material anisotropy and excellent formability with an ultimate tensile strength of 980 MPa or more. The hot-dip galvanized steel sheet includes a hot-dip galvanized layer formed on a surface of a base steel plate. The base steel plate contains, by mass%, C: 0.1 to less than 0.40%, Si: 0.5 to 3.0%, Mn: 1.5 to 3.0%, O: limited to 0.006% or less, P: limited to 0.04% or less, S: limited to 0.01% or less, Al: limited to 2.0% or less, N: limited to 0.01% or less, and a balance including Fe and inevitable impurities. A microstructure of the base steel sheet contains ferrite of 40% or more, residual austenite of 8 to less than 60%, by volume fraction, and a balance being bainite or martensite. In a sheet thickness range of 5/8 to 3/8 from the surface of the base steel sheet, a pole density of specific crystal orientation is within a predetermined range. The hot-dip galvanized layer contains Fe: less than 7 mass% and a balance including Zn, Al, and inevitable impurities.
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