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

A high-strength coated steel sheet comprising:

• a base steel sheet;
• and
• a coating layer formed on a surface of the base steel sheet;
• the base steel sheet including
• a chemical composition containing, by mass %,
• C:
• 0.05% to 0.15%,
• Si:
• 0.01% to 1.80%,
• Mn:
• 1.8% to 3.2%,
• P:
• 0.05% or less,
• S:
• 0.02% or less,
• Al:
• 0.01% to 2.0%,
• one or more of B:
• 0.0001% to 0.005%, Ti:
• 0.005% to 0.04%, and Mo:
• 0.03% to 0.50%, and the balance being Fe and inevitable impurities, and
• a microstructure, as observed a cross section in a thickness direction perpendicular to a rolling direction, including a martensite phase and a ferrite phase, in which a volume fraction of the martensite phase is 50% to 80%, in which a volume fraction of tempered martensite with respect to the whole martensite phase is 50% or more and 85% or less, in which an average grain diameter of the ferrite phase is 3 μm or more and 13 μm or less, and in which a volume fraction of ferrite grains having an aspect ratio of length in a width direction of the steel sheet to length in the thickness direction of the steel sheet of 2.0 or less with respect to the whole ferrite phase is 70% or more, wherein
• yield strength (YP) of the high-strength coated steel sheet is 550 MPa or more.