Patent ID: 9044920
Filing Date: 2015-06-02
Classification: B32B,C21D,C22C,C23C,Y10T

Abstract:
1. A high strength galvanized steel sheet exhibiting excellent fatigue property, the steel sheet having a composition containing by mass % 0.03 to 0.15% C, 2.00% or less Si, 1.0 to 2.5% Mn, 0.050% or less P, 0.0100% or less S, 0.050% or less Al, 0.0050% or less N, 0.010 to 0.100% Ti, 0.010 to 0.100% Nb, 0.0010 to 0.0100% Sb, and Fe and unavoidable impurities as a balance, wherein the microstructure includes a ferrite phase having an average grain diameter of 15 μm or less and an area fraction of 60% or more and a martensite phase having an area fraction of 5 to 40%, and an amount of one or more kinds of oxide selected from a group consisting of Fe, Si, Mn, Al, P, Nb and Ti generated in a surface layer portion of the steel sheet within a range from a surface of a base steel sheet directly below a galvanized layer to 100 μm away from the surface in a direction of steel-sheet-side depth, an amount of all of the one or more oxides being less than 0.060 g/m