A hot-dip galvanized steel sheet wherein the hot-dip galvanized steel sheet comprises a base steel sheet and a hot-dip galvanized layer, a ferrite phase is, by volume fraction, 40% or more and 97% or less in a range of ⅛ thickness to ⅜ thickness centered at a position of ¼ thickness from the surface of the base steel sheet, a hard structure is 3% or more in total, wherein the hot-dip galvanized steel sheet has the hot-dip galvanized layer in which Fe is 5.0% or less and Al is 1.0% or less, and columnar grains formed of a ζ phase is 20% or more in an entire interface between the plated layer and the base steel sheet on the surface of the base steel sheet in which a ratio of a volume fraction of the hard structure in a surface layer range of 20 μm depth in a steel sheet direction from an interface between the hot-dip galvanized layer and the base steel sheet is 0.10 times or more to 0.90 times or less of a volume fraction of the hard structure in the range of ⅛ thickness to ⅜ thickness, and wherein the hot-dip galvanized steel sheet has a refined layer at the side of the interface in the base steel sheet, and wherein an average thickness of the refined layer, an average grain size of ferrite in the refined layer and a maximum size of the oxide included in the refined layer are defined respectively.

A ferritic stainless steel sheet comprises a chemical composition containing, in mass %, C: 0.030% or less, Si: 3.0% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.010% or less, Cr: 11.0% to 30.0%, Al: 8.0% to 20.0%, Ni: 0.05% to 0.50%, N: 0.020% or less, and at least one selected from the group consisting of Zr: 0.01% to 0.20% and Hf: 0.01% to 0.20%, with a balance consisting of Fe and inevitable impurities.

A hot-dip galvanized steel sheet includes a base steel sheet and a hot-dip galvanized layer formed on at least one surface of the base steel sheet, in which the hot-dip galvanized layer includes Fe in a content of more than 0% to 5% or less, Al in a content of more than 0% to 1.0% or less, and columnar grains formed by a ζ phase on the surface of the steel sheet, further, 20% or more of the entire interface between the hot-dip galvanized layer and the base steel sheet is coated with the ζ phase, and a ratio of an interface formed between grains in which coarse oxides are present among grains and the base steel sheet with respect to the entire interface between the ζ phase and the base steel sheet in the hot-dip galvanized layer is 50% or less, the base steel sheet has predetermined chemical components and a refined layer in direct contact with the interface between the base steel sheet and the hot-dip galvanized layer, an average thickness of the refined layer is 0.1 to 5.0 μm, an average grain size of ferrite in the refined layer is 0.1 to 3.0 μm, one or two or more of oxides of Si and Mn are contained in the refined layer, and a maximum size of the oxide is 0.01 to 0.4 μm, and a volume fraction of residual austenite in a range of ⅛ thickness to ⅜ thickness centered at a position of ¼ thickness from the surface of the base steel sheet is 1% or more.

A method for making a vehicle body component includes forming a generally flat plate of unhardened, hot-formable sheet steel with a marginal shape which corresponds essentially to the developed configuration of the finished vehicle body component. The formed plate is hot-formed and hardened in a single press tool to define a sheet profile which corresponds to the configuration of the finished vehicle body component, and a surface coating is applied to the sheet profile.

The present invention has as its object the provision of a coated steel member and coated steel sheet excellent in hydrogen embrittlement resistance in a corrosive environment and methods for manufacturing the same. The coated steel member of the present invention is provided on its surface with an Al—Fe-based coating containing Cu and one or more of Mo, Ni, Mn, and Cr in a total by mass % of 0.12% or more by heating, cooling, and manufacturing a coated steel sheet having a layer containing Cu on its surface under predetermined conditions.

A method for producing a nitrided packaging steel from a hot-rolled steel product with a carbon content of 400 to 1200 ppm, utilizing a cold-rolling of the steel product to a flat steel product, subsequent recrystallization annealing of the cold-rolled flat steel product in an annealing furnace, in particular a continuous annealing furnace. A nitrogen-containing gas is supplied into the annealing furnace and is directed at the flat steel product to introduce unbonded nitrogen into the flat steel product in an amount corresponding to a concentration of more than 100 ppm, or to increase the amount of unbonded nitrogen in the flat steel product to a concentration of more than 100 ppm, and subsequent cooling of the recrystallized annealed flat steel product at a cooling rate of at least 100 K/s directly after the recrystallization annealing. Using this method, cold-rolled flat steel products may be produced for packaging purposes with a tensile strength of more than 650 MPa and in particular between 700 and 850 MPa.

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 cold-rolled sheet is provided. The cold-rolled sheet includes a steel substrate with a carbon content C.sub.0 between 0.07% and 0.5%, expressed by weight, and a metal pre-coating on at least the two principal faces of the steel substrate. The substrate has a decarburized area on the surface of each of the two principal faces. The depth p.sub.50% of the decarburized area is between 6 and 30 micrometers, and p.sub.50% is the depth at which the carbon content is equal to 50% of the content C.sub.0. The sheet does not contain a layer of iron oxide between the substrate and the metal pre-coating.

A nitrided packaging steel in the form of a flat steel product and method for producing a nitrided packaging steel with a carbon content of 10-1000 ppm and uncombined nitrogen, dissolved in the steel, of more than 100 ppm. The nitriding is performed in two stages: a first stage, in which a molten steel is nitrided to a nitrogen content of at most 160 ppm by introducing a nitrogen-containing gas and/or a nitrogen-containing solid into the molten steel, and a second stage, in which a flat steel product produced from the nitrided molten steel by cold rolling is treated with a nitrogen-containing gas in order to increase further the amount of uncombined nitrogen in the flat steel product. The second stage is performed in an annealing furnace, in which the flat steel product is at the same time annealed in a recrystallizing manner. The packaging steels produced are distinguished by great strength, in excess of 600 MPa, and good elongation to fracture, regularly in excess of 5%, as well as by good forming properties.

Provided is a galvanized steel sheet having excellent spot weldability; and a method for producing same. The galvanized steel sheet includes a base steel sheet and a zinc-based plating layer formed on the base steel sheet, wherein the surface layer of the base steel sheet may have a decarburization rate of at least 30% as represented by equation 1. [Equation 1]: Decarburization rate (%) of surface layer=(1−average carbon concentration in surface layer/bulk carbon concentration)*100, where the surface layer refers to a region extending to a depth of 35 μm from the surface of the base steel sheet.