A flat steel product which, following a 5% biaxial deformation, exhibits, on one surface, a Wsa(1-5) value of <0.35 μm, a planar anisotropy Δr of −0.5 to +0.5 and, from the surface to a depth of <200 μm, and a nanohardness of >0.1 to <3.0 GPa. Also, a method of making the product where a slab including (in wt. %) 0.0003-0.050% C, 0.0001-0.20% Si, 0.01-1.5% Mn, 0.001-0.10% P, 0.0005-0.030% S, 0.001-0.12% AI, and 0.0001-0.01% N, the remainder Fe and impurities is heated to 1200-1270° C., rough-rolled with a reduction of 80-90%, and finish-hot-rolled at 850-950° C. with a reduction of 85-95%, for a total deformation of 95-99.5%. The reduction in the last hot roll pass is 1-25%, and the product is cooled at 4-30 K/s to a coiling temperature of 620-780° C. Following pickling, the product is cold-rolled with a total degree of deformation of 70-90% and recrystallization annealed at 650-900° C.

A coated steel sheet including a steel sheet and a coating layer provided on at least part of the surface of the steel sheet, in which the coating layer has a predetermined chemical composition in terms of % by mass, and the coating layer has a granular Mg.sub.2Sn phase-containing structure in an area fraction of from 5 to 65%, and a structure containing a solid solution of Zn and Al, and the granular Mg.sub.2Sn phase-containing structure is a structure constituted with a Zn phase and a granular Mg.sub.2Sn phase having a crystal grain size of less than 1 μm dispersed in the Zn phase.

A coated steel sheet including a steel sheet and a coating layer provided on at least part of the surface of the steel sheet, in which the coating layer has a predetermined chemical composition in terms of % by mass, and the coating layer has a granular Mg.sub.2Sn phase-containing structure in an area fraction of from 5 to 65%, and a structure containing a solid solution of Zn and Al, and the granular Mg.sub.2Sn phase-containing structure is a structure constituted with a Zn phase and a granular Mg.sub.2Sn phase having a crystal grain size of less than 1 μm dispersed in the Zn phase.

A high strength steel sheet is formed of steel having the composition containing by mass % over 0.015% and less than 0.100% C, less than 0.50% Si, over 1.0% and less than 2.0% Mn, 0.05% or less P, 0.03% or less S, 0.01% or more and 0.3% or less sol. Al, 0.005% or less N, less than 0.35% Cr, 0.0010% or more and 0.0050% or less B, less than 0.15% Mo, less than 0.030% Ti, and iron and unavoidable impurities as a balance, wherein the steel satisfies 2.1≤[Mneq]≤3.1, the microstructure of the steel includes a ferrite and a second phase, a volume fraction of the second phase is set to 2.0 to 12.0%, a total ratio of a volume fraction of martensite and a volume fraction of retained γ to the volume fraction of second phase is 60% or more, and the number of carbides which are present within ferrite particles, have an aspect ratio of 3.0 or less and have a diameter of 0.25 to 0.90 μm is set to 10000 pieces/mm.sup.2 or less.

A high strength steel sheet is formed of steel having the composition containing by mass % over 0.015% and less than 0.100% C, less than 0.50% Si, over 1.0% and less than 2.0% Mn, 0.05% or less P, 0.03% or less S, 0.01% or more and 0.3% or less sol. Al, 0.005% or less N, less than 0.35% Cr, 0.0010% or more and 0.0050% or less B, less than 0.15% Mo, less than 0.030% Ti, and iron and unavoidable impurities as a balance, wherein the steel satisfies 2.1≤[Mneq]≤3.1, the microstructure of the steel includes a ferrite and a second phase, a volume fraction of the second phase is set to 2.0 to 12.0%, a total ratio of a volume fraction of martensite and a volume fraction of retained γ to the volume fraction of second phase is 60% or more, and the number of carbides which are present within ferrite particles, have an aspect ratio of 3.0 or less and have a diameter of 0.25 to 0.90 μm is set to 10000 pieces/mm.sup.2 or less.

Zn alloy plated steel material having excellent weldability and processed-part corrosion resistance and a method for production of Zn alloy plated steel material are provided. In the Zn alloy plated steel material comprising base steel material and a Zn alloy plating layer, the Zn alloy plating layer includes, by wt %, Al: 0.1-5.0%, Mg: 0.1-5.0%, as well as a remainder of Zn and inevitable impurities. The Zn alloy plated steel material includes a lower interface layer and an upper interface layer between the base steel material and the Zn alloy plating layer, wherein the lower interface layer is formed on the base steel material and has a dense structure, and the upper interface layer is formed on the lower interface layer and has a network-type or island-type structure.

Zn alloy plated steel material having excellent weldability and processed-part corrosion resistance and a method for production of Zn alloy plated steel material are provided. In the Zn alloy plated steel material comprising base steel material and a Zn alloy plating layer, the Zn alloy plating layer includes, by wt %, Al: 0.1-5.0%, Mg: 0.1-5.0%, as well as a remainder of Zn and inevitable impurities. The Zn alloy plated steel material includes a lower interface layer and an upper interface layer between the base steel material and the Zn alloy plating layer, wherein the lower interface layer is formed on the base steel material and has a dense structure, and the upper interface layer is formed on the lower interface layer and has a network-type or island-type structure.

The present invention provides a method for producing a sheet. The method includes providing a substrate, depositing a metal coating over at least one surface by dipping the substrate in a bath in order to obtain the sheet, wiping the metal coating by means of at least one nozzle projecting through at least one outlet a wiping gas onto the metal coating, the sheet being run in front of the nozzle, the wiping gas being ejected from the nozzle along a primary direction of ejection (E), a confinement box delimiting a confined zone at least downstream of the zone of impact (I) of the wiping gas on the sheet and solidifying the metal coating. The method satisfying: $\frac{Z}{d}\le 12\mathrm{and}{f}_{O_2}\le \frac{{10}^{-4}}{W^2}\left(0.63+\sqrt{0.4+{94900}^{*}{W}^2}\right)\mathrm{with}W=\frac{\sqrt{\mathrm{PdZ}}}{V}.$

The present invention provides a method for producing a sheet. The method includes providing a substrate, depositing a metal coating over at least one surface by dipping the substrate in a bath in order to obtain the sheet, wiping the metal coating by means of at least one nozzle projecting through at least one outlet a wiping gas onto the metal coating, the sheet being run in front of the nozzle, the wiping gas being ejected from the nozzle along a primary direction of ejection (E), a confinement box delimiting a confined zone at least downstream of the zone of impact (I) of the wiping gas on the sheet and solidifying the metal coating. The method satisfying: $\frac{Z}{d}\le 12\mathrm{and}{f}_{O_2}\le \frac{{10}^{-4}}{W^2}\left(0.63+\sqrt{0.4+{94900}^{*}{W}^2}\right)\mathrm{with}W=\frac{\sqrt{\mathrm{PdZ}}}{V}.$

A method of producing a hot-dip Zn alloy-plated steel sheet includes: dipping a base steel sheet in a hot-dip Zn alloy plating bath to form a hot-dip Zn alloy plating layer on a surface of the base steel sheet; and contacting an aqueous solution containing a water-soluble corrosion inhibitor with a surface of the hot-dip Zn alloy plating layer to cool the base steel sheet and the hot-dip Zn alloy plating layer having a raised temperature through formation of the hot-dip Zn alloy plating layer. A temperature of the surface of the hot-dip Zn alloy plating layer when the aqueous solution is to be contacted with the surface of the hot-dip Zn alloy plating layer is equal to or more than 100° C. and equal to or less than a solidifying point of the plating layer. The aqueous solution containing the water-soluble corrosion inhibitor satisfies the Equation [{(Z.sub.0−Z.sub.1)/Z.sub.0}100≧201.