A hot stamped steel includes a base material, a plated layer that is formed on a surface of the base material, and an oxide film that is formed on a surface of the plated layer; chemical composition of the plated layer contains 20.00 to 45.00 mass % of Al, 10.00 to 45.00 mass % of Fe, 4.50 to 15.00 mass % of Mg, 0.10 to 3.00 mass % of Si, 0.05 to 3.00 mass % of Ca, 0 to 0.50 mass % of Sb, 0 to 0.50 mass % of Pb, 0 to 1.00 mass % of Cu, 0 to 1.00 mass % of Sn, 0 to 1.00 mass % of Ti, 0 to 0.50 mass % of Sr, 0 to 1.00 mass % of Cr, 0 to 1.00 mass % of Ni, and 0 to 1.00 mass % of Mn with a remainder of Zn and impurities; and chemical composition of the oxide film contains 20.0 to 55.0 at % of Mg, 0.5 to 15.0 at % of Ca, 0 to 15.0 at % of Zn, and 0 at % or more and less than 10.0 at % of Al with a remainder of O and a total of 5.0 at % or less of impurities, and the adhesion amount of the oxide film per one surface is in a range of 0.01 to 10 g/m.sup.2.

A manufacturing method of a steel sheet includes: a step of performing continuous casting of molten steel having a Si content of 0.4 mass % to 3.0 mass % to obtain a slab; a step of performing hot rolling of the slab to obtain a hot-rolled steel sheet; a step of performing cold rolling of the hot-rolled steel sheet to obtain a cold-rolled steel sheet; a step of performing cold-rolled sheet annealing of the cold-rolled steel sheet; a step of performing pickling after the cold-rolled sheet annealing; a step of performing water washing after the pickling; and a step of performing drying after the water washing. A dew point is set to −35° C. or lower in the cold-rolled sheet annealing, an electrical conductivity of a rinse water to be used in the water washing is set to 5.0 mS/m or less, a water-washing time is set to 15 seconds or less in the water washing, and the drying is started within 60 seconds from an end of the water washing.

A high-strength hot-dip galvanized steel sheet has a hot-dip galvanized layer on a surface of the steel sheet, a specific component composition, and a steel microstructure containing, on an area percentage basis, 0% to 15% of ferrite and upper bainite in total, 80% to 100% of lower bainite and martensite in total, and 0% to 10% of retained austenite, and containing precipitates having a particle size of 100 to 2,000 nm in an amount of 10.sup.9 to 10.sup.12 particles/m.sup.2 in a region extending to a position 100 to 300 μm from the surface layer of the steel sheet, in which the ratio of the average amount of C at a position 5 μm from the surface layer of the steel sheet to the average amount of C at a position 70 μm from the surface layer of the steel sheet in the thickness direction is 0.20 to 0.80.

A high-strength hot-dip galvanized steel sheet includes a hot-dip galvanized layer on a surface of the steel sheet and has a specific component composition and a steel microstructure containing, on an area percentage basis, 90% to 100% of martensite and carbide-containing bainite in total and 0% to 10% of retained austenite, and containing prior austenite grains having an aspect ratio of 2.0 or less, in a region extending from 300 μm to 400 μm from the surface layer, in which the ratio of the average amount of C at 5 μm from the surface layer to the average amount of C at 70 μm from the surface layer is 0.2 to 0.8, and the ratio of the standard deviation of the amount of C to the average amount of C in a region extending from 300 μm to 400 μm from the surface layer is 0.40 or less.

The high-strength hot-dip galvanized steel sheet has a specific chemical composition and the following steel microstructure. In a region extending from 300 to 400 μm from a surface layer of the steel sheet in a thickness direction of the steel sheet, the total area fraction of martensite and bainite containing carbides is 60 to 100%, and the average grain size of prior austenite is 15 μm or less. In the region extending from 300 to 400 μm from the surface layer of the steel sheet in the thickness direction of the steel sheet, the ratio of the height of a peak of P in an Auger electron spectrum at a position 5 nm or more from a prior-austenite grain boundary to the height of a peak of P in an Auger electron spectrum at the prior-austenite grain boundary is 0.20 or more.

A high-strength hot-dip galvanized steel sheet has a hot-dip galvanized layer on a surface of the steel sheet, a specific component composition, and a steel microstructure containing, on an area percentage basis, 0% to 15% of ferrite and upper bainite in total, 80% to 100% of lower bainite and martensite in total, and 0% to 10% of retained austenite, and containing precipitates having a particle size of 100 to 2,000 nm in an amount of 10.sup.9 to 10.sup.12 particles/m.sup.2 in a region extending to a position 100 to 300 μm from the surface layer of the steel sheet, in which the ratio of the average amount of C at a position 5 μm from the surface layer of the steel sheet to the average amount of C at a position 70 μm from the surface layer of the steel sheet in the thickness direction is 0.20 to 0.80.

High strength steel sheet improved in formability, bending load, and bendability is provided. The high strength steel sheet has a center part of sheet thickness and a surface soft part formed at one side or two sides of the center part of sheet thickness, has metal structures of the center part of sheet thickness comprised of, by area ratio, tempered martensite: 85% or more, one or more of ferrite, bainite, pearlite, and retained austenite: total of less than 15%, and as-quenched martensite: less than 5%, has metal structures of the surface soft part comprised of, by area ratio, ferrite: 65% or more, pearlite: 5% or more and less than 20%, one or more of tempered martensite, bainite, and retained austenite: total of less than 10%, and as-quenched martensite: less than 5%, has average distances of pearlite at the surface soft part of 3 μm or more, and has Vickers hardness (Hc) of the center part of sheet thickness and Vickers hardness (Hs) of the surface soft part satisfying 0.50≤Hs/Hc≤0.75.

A steel sheet includes a hot-dip galvanized layer or a galvannealed layer on a surface of the steel sheet, the steel sheet including: in mass %, C: 0.06% or more and 0.22% or less; Si: 0.50% or more and 2.00% or less; Mn: 1.50% or more and 2.80% or less; Al: 0.02% or more and 1.00% or less; P: 0.001% or more and 0.100% or less; S: 0.0005% or more and 0.0100% or less; N: 0.0005% or more and 0.0100% or less; and a balance: Fe and impurities.

A high-strength hot-dip coated hot-rolled steel sheet excellent in terms of surface appearance quality and coating adhesiveness and a method for manufacturing. The method includes performing hot rolling followed by pickling on steel to form a pickled steel sheet, the steel having a chemical composition containing, by mass %, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 1.0% or less, Mn: 0.3% or more and 2.5% or less, P: 0.08% or less, S: 0.02% or less, Al: 0.001% or more and 0.20% or less, and Fe and inevitable impurities. The method further includes performing rolling with a rolling reduction ratio of 1% or more and 10% or less, and a hot-dip coating treatment. The obtained steel sheet has an arithmetic average roughness Ra of 2.0 μm or less on the surface of the steel sheet, and a tensile strength of 590 MPa or more.

The high-strength hot-rolled coated steel sheet includes a steel sheet having a chemical composition containing, by mass %, C: 0.03% to 0.09%, Si: 0.01% to 1.60%, Mn: 2.20% to 3.60%, P: 0.100% or less, S: 0.0100% or less, Ti: 0.05% to 0.18%, B: 0.0005% to 0.0050%, Al: 0.005% to 0.40%, N: 0.010% or less, and a balance of Fe and inevitable impurities, in which a CSM value expressed by the equation 33.8[% C][% Mn]+12.4[% Si]/[% Mn] is 3.3 to 12.0, and a steel microstructure containing bainite in an amount of 85% or more in terms of area fraction and martensite in an amount of 2.0% or more and 15.0% or less in terms of area fraction and includes a coating layer or an alloyed coating layer on a surface of the steel sheet.