Patent ID: 8906516

Claim:
A galvannealed steel sheet having high corrosion resistance after painting, the steel sheet comprising, on a mass percent basis, C: 0.05% to 0.15%, Si: 0.1% to 1.0%, Mn: 0.5% to 2.7%, Al: 1.00% or less, P: 0.025% or less, S: 0.025% or less, and Cr: 0% to 0.8% as chemical components, the remainder being Fe and incidental impurities, wherein the galvannealed steel sheet includes a galvannealed layer on at least one surface of a steel sheet in an amount of 20 to 120 g/m 2 per side, a percentage of exposed zinc metal relative to a total amount of exposed zinc oxide and zinc metal on the galvannealed layer surface being 20% or more and less than 80%, and an amount of internal oxidation in a region disposed not more than 5 μm from the surface of the steel sheet is 0.02 g/m 2 or more and 0.1 g/m 2 or less, and wherein the steel sheet satisfies the following formulae: Si≦0.68%, Cr≦−1.25Si+0.85, and Si>0.68%, Cr=0, wherein Si and Cr denote respective contents (mass %) of Si and Cr.