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

A high-strength galvanized steel sheet having a chemical composition containing, by mass %,

• C:
• 0.030% to 0.250%,
• Si:
• 0.01% to 3.00%,
• Mn:
• 3.10% to 8.00%,
• P:
• 0.001% to 0.100%,
• S:
• 0.0001% to 0.0200%,
• N:
• 0.0005% to 0.0100%,
• Al:
• 0.001% to 2.000%, and a balance of Fe and incidental impurities,
• a steel microstructure including, in terms of area fraction, 35% or more and 80% or less of ferrite, 0.1% or more and less than 5.0% of as-quenched martensite, 3.0% or more and 35% or less of tempered martensite, and 8% or more of retained austenite, in which an average grain diameter of the ferrite is 6 μm or less, in which an average grain diameter of the retained austenite is 3 μm or less,
• in which a value calculated by dividing an average Mn content (mass %) in the retained austenite by an average Mn content (mass %) in the ferrite is 1.5 or more,
• in which a value calculated by dividing a sum of an area fraction of tempered martensite having a circle-equivalent grain diameter of 3 μm or less and an area fraction of retained austenite having a circle-equivalent grain diameter of 3 μm or less by a sum of an area fraction of all the tempered martensite and an area fraction of all the retained austenite is 0.4 or more, and
• in which a value calculated by dividing an area fraction of retained austenite grains adjacent to three or more ferrite grains having different crystal orientations by the area fraction of all the retained austenite is less than 0.6, a galvanizing layer on a surface of the steel sheet, and a diffusible hydrogen content in steel of 0.3 mass ppm or less.