High-strength plated steel sheet and method for producing same

A high-strength plated steel sheet having a hot-dip galvanized layer or a hot-dip galvannealed layer on a surface of a base steel sheet,

• the base steel sheet comprising, in % by mass:
• C:
• 0.10 to 0.5%,
• Si:
• 1.0 to 3%,
• Mn:
• 1.5 to 8%,
• Al:
• 0.005 to 3%,
• P:
• more than 0% to 0.1% or less,
• S:
• more than 0% to 0.05% or less, and
• N:
• more than 0% to 0.01% or less,
• the plated steel sheet sequentially comprises, from an interface between the base steel sheet and the galvanized layer or galvannealed layer toward the base steel sheet:
• an internal oxidized layer comprising at least one an oxide selected from the group consisting of Si and Mn;
• a soft layer comprising the internal oxidized layer, and having a Vickers hardness of 90% or less of a Vickers hardness of a portion of t/4 of the base steel sheet where “t” is a sheet thickness of the base steel sheet;
• a hard layer consisting of a structure having metallic structure which comprises, when the metallic structure is observed through a scanning electron microscope, a low-temperature-transformation produced phase in a proportion of 20 to 85% by area of the whole of the metallic structure, and polygonal ferrite in a proportion more than 10% by area, and 70% or less by area of the whole of the metallic structure, wherein
• the metallic structure comprising retained austenite in a proportion of 5% or more by volume of the whole of the metallic structure when the metallic structure is measured by a saturation magnetization method;
• wherein the high-strength plated steel sheet satisfies:
• the average depth D of the soft layer being 20 μm or more;
• the average depth d of the internal oxidized layer being 4 μm or more and less than D;
• and
• a tensile strength being 980 MPa or more.