High-strength hot-dip galvanized steel sheet and method for manufacturing the same

A hot-dip galvanized steel sheet having a chemical composition comprising, in mass %,

• C:
• 0.08 to 0.35%,
• Si:
• 0.01 to 3.0%,
• Mn:
• 2.0 to 4.0%,
• P:
• 0.010% or less (excluding 0),
• S:
• 0.002% or less (excluding 0),
• Al:
• 0.01 to 1.50%, and
• B:
• 0.0005 to 0.010% and
• further comprising one or more selected from
• Mo:
• 0.03 to 2.0% and
• Ti:
• 0.010 to 0.10%, with the balance being Fe and unavoidable impurities,
• wherein the steel sheet has a steel microstructure in which, in a region extending from 300 to 400 μm from a surface layer of the steel sheet in a thickness direction of the steel sheet, the total area fraction of martensite and bainite containing carbides is 60 to 100%, and the average grain size of prior austenite is 15 μm or less, and in which, in the region extending from 300 to 400 μm from the surface layer of the steel sheet in the thickness direction of the steel sheet, the ratio of the height of a peak of P in an Auger electron spectrum at a position 5 nm or more from a prior-austenite grain boundary to the height of a peak of P in the Auger electron spectrum at the prior-austenite grain boundary is 0.20 or more, the peak of P in the Auger electron spectrum being measured using an Auger electron spectrometer during Ar ion sputtering, and
• wherein the steel sheet has a hot-dip galvanized layer on a surface thereof.