Galvanized steel sheet, member, and methods for manufacturing them

A galvanized steel sheet, comprising a steel sheet and a galvanized layer formed on the steel sheet,

• the steel sheet having a chemical composition containing,
• by mass %:
• C:
• 0.08% or more and 0.3% or less,
• Si:
• 0.5% or more and 3.0% or less,
• Mn:
• 2.0% or more and 3.5% or less,
• P:
• 0.1% or less,
• S:
• 0.01% or less,
• A1:
• 0.01% or more and 0.1% or less, and
• N:
• 0.015% or less,
• the balance being Fe and incidental impurities,
• the steel sheet having a microstructure in which an area fraction of ferrite is 20% or more and 70% or less, and
• an area fraction of martensite is 30% or more and 80% or less,
• wherein the ferrite contains:
• low-Mn ferrite having a Mn concentration of 0.80 or more times and 0.95 or less times a Mn content of the steel sheet, and
• high-Mn ferrite having a Mn concentration of 1.05 or more times and 2.5 or less times the Mn content of the steel sheet,
• a proportion of the low-Mn ferrite in the entire ferrite is 20% or more and 80% or less in terms of area fraction,
• a proportion of the high-Mn ferrite in the entire ferrite is 20% or more and 80% or less in terms of area fraction,
• the martensite has an average crystal grain size of 10 μm or less, and
• an amount of diffusible hydrogen in steel is 0.30 mass·ppm or less.