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

A method for producing a high-strength hot-dip galvanized steel sheet comprising a steel sheet having a chemical composition containing, in % by mass, C:

• not less than 0.08% and not more than 0.25%, Si:
• not less than 0.1% and less than 2.0%, Mn:
• not less than 1.5% and not more than 3.5%, P:
• 0.02% or less, S:
• 0.01% or less, Al:
• 0.10% or less, and N:
• 0.006% or less, the mass ratio of Si to Mn (Si/Mn) being 0.25 or more, and the balance being Fe and incidental impurities, and a zinc coating layer formed on the surface of the steel sheet with a coating weight of not less than 20 g/m2 and not more than 120 g/m2 per one surface of the steel sheet, the method comprising subjecting the steel sheet to annealing and hot-dip galvanization in a continuous hot-dip galvanizing facility, wherein the maximum temperature T of the steel sheet in an annealing furnace is 900° C. or less, wherein the dew point X (° C.) of an atmosphere in the furnace in the steel sheet temperature range of 700° C. to T° C. is controlled to be not less than a temperature calculated by the following inequality (1), and wherein the atmosphere in the furnace contains hydrogen in an amount of not less than 3.0 vol % and not more than 20.0 vol %, and at least one of SO2 in an amount of not less than 0.1 vol ppm and not more than 3.0 vol ppm and HCl in an amount of not less than 0.5 vol ppm and not more than 10.0 vol ppm, with the balance of the atmosphere being nitrogen and impurities:
• Dew
• ⁢
• point
• ⁢
• X
• ≥
• (
• -
• 5
• ⁢
• 0
• +
• [
• Si
• ⁢
• %
• ⁢
• by
• ⁢
• mass
• ]
• ×
• (
• T
• -
• 600
• )
• /
• 30
• +
• [
• Mn
• ⁢
• %
• ⁢
• by
• ⁢
• mass
• ]
• ×
• (
• T
• -
• 600
• )
• /
• 25
• )
• (
• 1
• )
• where Si % by mass refers to the mass % of Si in the chemical composition of the steel sheet, and Mn % by mass refers to the mass % of Mn in the chemical composition of the steel sheet.