| 摘要 |
A method for producing a galvanized steel sheet including (a) melting a steel having a steel composition comprising 0.005 to 0.04 mass % C, 1.5 mass % or lower Si, 1.0 to 2.0 mass % Mn, 0.10 mass % or lower P, 0.03 mass % or lower S, 0.01 to 0.1 mass % Al, less than 0.008 mass % N and 0.2 to 1.0 mass % Cr, wherein Mn (mass %)+1.29 Cr (mass %) is 2.1 to 2.8, and the balance being iron and unavoidable impurities, (b) hot rolling and cold rolling the steel from step (a) to provide a steel sheet, and (c) annealing the steel sheet from step (c) at an annealing temperature of at least the Ac1 point and not more than the Ac3 point, wherein the galvanized steel sheet has a structure which includes a ferrite phase and a martensite phase with a volume fraction being at least 3.0% and less than 10%, the average particle diameter of the ferrite is larger than 6 μm and not more than 15 μm, and 90% or more of the martensite phase exists in a ferrite grain boundary.
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