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

A high-strength galvanized steel sheet comprising:

• a steel sheet having a chemical composition containing a steel composition containing, in mass %,
• C:
• 0.08% or more and 0.20% or less,
• Si:
• less than 2.0%,
• Mn:
• 1.5% or more and 3.5% or less,
• P:
• 0.02% or less,
• S:
• 0.002% or less,
• Al:
• 0.10% or less, and
• N:
• 0.006% or less,
• a mass ratio of a content of Si to a content of Mn in the steel (Si/Mn) being 0.2 or more, and the balance:
• Fe and incidental impurities, and
• a steel structure in which an average grain size of inclusions containing at least one of Al, Si, Mg, and Ca and existing in an area extending from a surface to a position of ⅓ of a sheet thickness is 50 μm or less, and an average nearest distance between the inclusions is 20 μm or more;
• and
• a galvanized layer provided on a surface of the steel sheet and having a coating weight per one surface of 20 g/m2 or more and 120 g/m2 or less,
• wherein an amount of diffusible hydrogen contained in the steel sheet is less than 0.25 mass ppm,
• oxides containing at least one or more elements selected from Fe, Si, Mn, Al, P, B, Nb, Ti, Cr, Mo, V, Cu, and Ni and existing in an outer layer portion of the steel sheet within 100 μm from a surface of an underlying steel sheet immediately below the galvanized layer account for 0.010 g/m2 or more per one surface, and
• a tensile strength is 1100 MPa or more,
• and wherein the steel structure contains 30% or more and 85% or less of martensite, 60% or less (including 0%) of ferrite, 15% or less (including 0%) of bainite, and less than 5% (including 0%) of retained austenite in terms of area ratio, and
• an average grain size of ferrite is 15 μm or less.