Abstract: The present invention provides a coated steel product including: a steel product; a coating layer that is coated on the surface of the steel product and that includes from 8 to 50% by mass of Mg, from 2.5 to 70.0% by mass of Al, and from 0.30 to 5.00% by mass of Ca, with the balance consisting of Zn and impurities; and an intermediate layer interposed between the steel product and the coating layer, in which the intermediate layer has a sea-island structure constituted by a sea portion composed of an Al—Fe alloy phase, and island portions including a Zn—Mg—Al alloy phase having a Mg content of 8% by mass or more, and in which the sea portion composed of the Al—Fe alloy phase has an area fraction of from 55 to 90%.

Abstract: 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.

Abstract: There is provided a hot-stamped body including: a steel base metal; and a metallic layer formed on a surface of the steel base metal, wherein the metallic layer includes: an interface layer that contains, in mass %, Al: 30.0 to 36.0%, has a thickness of 100 nm to 5 ?m, and is located in an interface between the metallic layer and the steel base metal; and a principal layer that includes coexisting MgZn2 phases and insular FeAl2 phases, is located on the interface layer, and has a thickness of 3 ?m to 40 ?m.

Abstract: There is provided a hot-stamped body including: a steel base metal; and a metallic layer formed on a surface of the steel base metal, wherein the metallic layer includes: an interface layer that contains, in mass %, Al: 30.0 to 36.0%, has a thickness of 100 nm to 15 ?m, and is located in an interface between the metallic layer and the steel base metal; and a principal layer that includes coexisting Zn phases and insular FeAl2 phases, is located on the interface layer, and has a thickness of 1 ?m to 40 ?m. This hot-stamped body is excellent in fatigue properties, corrosion resistance, and chipping resistance.

Abstract: There is provided a hot-stamped body including: a steel base metal; and a metallic layer formed on a surface of the steel base metal, wherein the metallic layer includes: an interface layer that contains, in mass %, Al: 30.0 to 36.0%, has a thickness of 100 nm to 5 ?m, and is located in an interface between the metallic layer and the steel base metal; and a principal layer that includes coexisting MgZn2 phases and insular FeAl2 phases, is located on the interface layer, and has a thickness of 3 ?m to 40 ?m.

Abstract: There is provided a hot-stamped body including: a steel base metal; and a metallic layer formed on a surface of the steel base metal, wherein the metallic layer includes: an interface layer that contains, in mass %, Al: 30.0 to 36.0%, has a thickness of 100 nm to 15 ?m, and is located in an interface between the metallic layer and the steel base metal; and a principal layer that includes coexisting Zn phases and insular FeAl2 phases, is located on the interface layer, and has a thickness of 1 ?m to 40 ?m. This hot-stamped body is excellent in fatigue properties, corrosion resistance, and chipping resistance.

Abstract: Provided is a surface treated steel sheet for a fuel tank, the surface treated steel sheet including: a Zn plated layer or a Zn—Ni alloy plated layer which is formed on at least a surface of the steel sheet to be an inner surface of the fuel tank; and a chromate-free chemical conversion coating layer containing a water-and-oil repellent, the chromate-free chemical conversion coating layer being placed over the Zn plated layer or the Zn—Ni alloy plated layer on the surface to be the inner surface of the fuel tank. A water contact angle on a surface of the chromate-free chemical conversion coating layer is more than or equal to 70 degrees and an n-hexadecane contact angle on the surface of the chromate-free chemical conversion coating layer is more than or equal to 30 degrees and less than or equal to 70 degrees.

Abstract: A steel sheet for a fuel tank according to the present invention includes: a Zn—Ni alloy plated layer placed on one surface or each of both surfaces of a base metal; and a chromate-free chemical conversion coating film which is placed over the Zn—Ni alloy plated layer. The Zn—Ni alloy plated layer has a crack starting from an interface with the chromate-free chemical conversion coating film and reaching an interface with the steel sheet, the chromate-free chemical conversion coating film consists of an organosilicon compound consisting of a condensation polymer of a silane coupling agent, a phosphoric acid compound and/or a phosphonic acid compound, a vanadium compound, and a titanium compound and/or a zirconium compound, and a concentration of a total of amounts in terms of metal, per surface, of the phosphoric acid compound and/or the phosphonic acid compound+the vanadium compound+the titanium compound and/or the zirconium compound, is 5 mass % to 20 mass %.

Abstract: A steel sheet for a fuel tank includes: a Zn—Ni alloy plated layer which is placed on one surface or each of both surfaces of a base metal and formed on at least one surface; and an inorganic chromate-free chemical conversion coating film which is placed over the Zn—Ni alloy plated layer. The Zn—Ni alloy plated layer has a crack starting from an interface between the Zn—Ni alloy plated layer and the inorganic chromate-free chemical conversion coating film and reaching an interface between the Zn—Ni alloy plated layer and the steel sheet, and a water contact angle on a surface of the inorganic chromate-free chemical conversion coating film is more than or equal to 50 degrees.

Abstract: 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.

Abstract: The invention provides a coated steel including a steel, a coated metal layer coated on a surface of the steel, and an interfacial alloy layer formed at the boundary between the steel and the coated metal layer, in which the coated metal layer has a predetermined composition and structure, and in which the thickness of the coated metal layer is 0.1 ?m or more, and the thickness of the interfacial alloy layer is 500 nm or less.

Abstract: Provided is a hot stamped body which includes a base metal, and a plated layer formed on a surface of the base metal, wherein the plated layer includes an interface layer, an intermediate layer, and an oxide layer in order from a base metal side, the interface layer contains one or more kinds of Fe—Al alloy, a total area fraction of the Fe—Al alloy being 99% or more, the intermediate layer 22 contains one or more kinds of Fe—Al—Zn alloy, a total area fraction of the Fe—Al—Zn phase being 50% or more, an average composition of the intermediate layer contains, in mass %, Al: 30 to 50% and Zn: 15 to 30%, and an average film thickness of the oxide layer is 3.0 ?m or less, and Mg content in the oxide layer is 0.05 to 0.50 g/m2.

Abstract: A plated steel sheet including an alloy plating layer formed on a surface of the steel sheet consisting of, in mass %, Cr: 5 to 91%, Fe: 0.5 to 10%, and the balance: Ni and unavoidable impurities, the Ni concentration gradually decreases from an outermost surface of the alloy plating layer to a side of the steel sheet, Ni/Cr>1 in an area extending 300 nm or more from the outermost surface of the alloy plating layer, the Fe concentration in the alloy plating layer gradually decreases from the side of the steel sheet to the outermost surface, the Fe concentration in the outermost surface 0.5% or less, the total thickness of an alloy layer formed in the alloy plating layer and containing Cr and Fe is 500 to 2000 nm, and the total amount of the alloy plating layer deposited to the steel sheet is 4.5 to 55.5 g/m2.

Abstract: The present invention provides a coated steel product including: a steel product; a coating layer that is coated on the surface of the steel product and that includes from 8 to 50% by mass of Mg, from 2.5 to 70.0% by mass of Al, and from 0.30 to 5.00% by mass of Ca, with the balance consisting of Zn and impurities; and an intermediate layer interposed between the steel product and the coating layer, in which the intermediate layer has a sea-island structure constituted by a sea portion composed of an Al—Fe alloy phase, and island portions including a Zn—Mg—Al alloy phase having a Mg content of 8% by mass or more, and in which the sea portion composed of the Al—Fe alloy phase has an area fraction of from 55 to 90%.

Abstract: A Mg-containing Zn alloy coated steel including a steel and a metallic coating layer placed on a surface of the steel, in which the metallic coating layer is a layered structure of plural flat-form metal particles having a particle diameter of from 5 to 100 ?m, and a thickness of from 0.5 to 30 ?m, the composition of the metal particles include Zn from 11 to 80 mass %, Al from 3 to 80 mass %, Mg from 8 to 45 mass %, and Ca from 1 to 5 mass %, and the Zn, Al, and Mg content satisfy Zn+Al>Mg, and in which the metal particles include a quasicrystalline phase, an MgZn2 phase, and optionally a balance structure.

Abstract: A Mg-containing Zn alloy coated steel including a steel and a metallic coating layer placed on a surface of the steel, in which the metallic coating layer is a layered structure of plural flat-form metal particles having a particle diameter of from 5 to 100 ?m, and a thickness of from 0.5 to 30 ?m, the composition of the metal particles include Zn from 11 to 80 mass %, Al from 3 to 80 mass %, Mg from 8 to 45 mass %, and Ca from 1 to 5 mass %, and the Zn, Al, and Mg content satisfy Zn+Al>Mg, and in which the metal particles include a quasicrystalline phase, an MgZn2 phase, and optionally a balance structure.

Abstract: An Mg-containing Zn alloy coated steel including a steel and a metallic coating layer placed on a surface of the steel, in which the metallic coating layer is a layered structure of a flat-form metal particle having a particle diameter of from 5 to 100 ?m, and a thickness of from 0.5 to 30 ?m, the composition of the metal particles include, in terms of % by mass, Zn from 11 to 80%, Al from 3 to 80%, Mg from 8 to 45%, and Ca from 1 to 5%, while the balance is impurities, and the Zn content, the Al content, and the Mg content in terms of % by mass satisfy Zn+Al>Mg, and in which the metal particles include a quasicrystalline phase, an MgZn2 phase, and a balance structure, in which the total area fraction of the quasicrystalline phase and the MgZn2 phase is 45% or more, the area fraction of the balance structure is from 0 to 55%, the area fraction of the quasicrystalline phase is 20% or more, and the area fraction of the MgZn2 phase is 3% or more.

Abstract: The invention provides a coated steel including a steel, a coated metal layer coated on a surface of the steel, and an interfacial alloy layer formed at the boundary between the steel and the coated metal layer, in which the composition of the coated metal layer includes in terms of % by mass Zn from 20 to 83%, and Al from 2.5 to 46.5% as well as Mg and impurities as the balance, in which the Mg content is 10% or more, in which the structure of the coated metal layer includes a quasicrystalline phase, a MgZn2 phase, and a balance structure, in which the area fraction of the quasicrystalline phase is from 30 to 60%, and not less than 90 number-% of the quasicrystalline phases are a quasicrystalline phase having a particle diameter in the major axis direction of from 0.05 to 1.0 ?m, and in which the thickness of the coated metal layer is 0.1 ?m or more, and the thickness of the interfacial alloy layer is 500 nm or less.

Abstract: [Object] To provide a plated steel sheet excellent in heat resistance and productivity and a method for producing the same. [Solution] According to an aspect of the present invention, there is provided a plated steel sheet including: a steel sheet; and an alloy plating layer formed on a surface of the steel sheet, in which the alloy plating layer consists of, in mass %, Cr: 5 to 91%, Fe: 0.5 to 10%, and the balance: Ni and unavoidable impurities, the Ni concentration in the alloy plating layer gradually decreases from an outermost surface of the alloy plating layer to a side of the steel sheet, the ratio of the Ni concentration to the Cr concentration is Ni/Cr>1 in an area extending 300 nm or more from the outermost surface of the alloy plating layer, the Fe concentration in the alloy plating layer gradually decreases from the side of the steel sheet to the outermost surface of the alloy plating layer, the Fe concentration in the outermost surface of the alloy plating layer is 0.

Abstract: A steel sheet for a fuel tank according to the present invention includes: a Zn—Ni alloy plated layer placed on one surface or each of both surfaces of a base metal; and a chromate-free chemical conversion coating film which is placed over the Zn—Ni alloy plated layer. The Zn—Ni alloy plated layer has a crack starting from an interface with the chromate-free chemical conversion coating film and reaching an interface with the steel sheet, the chromate-free chemical conversion coating film consists of an organosilicon compound consisting of a condensation polymer of a silane coupling agent, a phosphoric acid compound and/or a phosphonic acid compound, a vanadium compound, and a titanium compound and/or a zirconium compound, and a concentration of a total of amounts in terms of metal, per surface, of the phosphoric acid compound and/or the phosphonic acid compound+the vanadium compound+the titanium compound and/or the zirconium compound, is 5 mass % to 20 mass %.