Provided is a galvanized steel sheet having excellent plating adhesion, having a plated layer with improved friction characteristics by means of a predetermined level of Fe elution, and having excellent corrosion resistance; and a manufacturing method therefor.

The present disclosure relates to a plated steel material that can be used in an automobile, a household appliance, a building material, and the like, and more particularly, to a zinc alloy plated steel material having excellent surface quality and corrosion resistance, and a method for manufacturing the same.

The present invention relates to a method of manufacturing a directional electric steel plate having excellent surface wettability and magnetic properties. More particularly, the present invention relates to a directional electric steel plate in which a surface of a steel plate consisting of Si: 2.0 to 6.5%, acid soluble Al: 0.4 to 5%, Mn: 0.20% or less (0% exclusive), N: 0.010% or less (0% exclusive), S: 0.010% or less (0% exclusive), P: 0.005 to 0.05%, C: 0.04 to 0.12% and a balance of Fe and other unavoidable impurities is hot-dip plated with aluminum or an aluminum-silicon alloy, and heat-treated, so that aluminum on the hot-dip plated layer is diffused or infiltrated into the steel plate, and a method of manufacturing the same.

A hardened part coated with a phosphatable coating is provided. The part is made by a method that includes providing a steel sheet pre-coated with a metallic coating including from 4.0 to 20.0% by weight of zinc, from 1.0 to 3.5% by weight of silicon, optionally from 1.0 to 4.0% by weight of magnesium, and optionally additional elements chosen from Pb, Ni, Zr, or Hf, the content by weight of each additional element being less than 0.3% by weight, the balance being aluminum and unavoidable impurities and residuals elements. The steel sheet is cut to obtain a blank, the blank is thermally treated at a temperature between 840 and 950° C. to obtain a fully austenitic microstructure in the steel, the blank is transferred into a press tool and hot-formed to obtain a part. The part is cooled to obtain a martensitic or martensitic-bainitic microstructure or made of at least 75% of equiaxed ferrite, from 5 to 20% of martensite and bainite in amount less than or equal to 10%.

A method for producing a component made of a steel product coated with an Al—Si protective coating, includes: providing a substrate consisting of a steel produced coated with an Al—Si protective coating, heating the substrate to a temperature T1 such that the Al—Si protective coating is only partially pre-alloyed with Fe of the steel product, cooling the pre-alloyed substrate to room temperature, applying a corrosion protection oil to the surface of the pre-alloyed substrate, wherein the oil consists of a composition containing fatty acid ester, transporting the pre-alloyed substrate to which the oil has been applied, heating the pre-alloyed substrate to which the oil has been applied to a temperature T2 such that the Al—Si protective coating is fully alloyed with Fe of the steel product and the oil is removed without leaving residue, and shaping the re-heated substrate to form the component.

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 high-strength galvanized steel sheet comprising a cold-rolled steel sheet, an intermetallic compound formed on the cold-rolled steel sheet, and a galvanizing layer formed on the intermetallic compound, the cold-rolled steel sheet having a specific composition and a microstructure having a martensite area ratio of 7% or more and less than 25% and a ferrite area ratio of 50% or more and which includes a base metal surface portion in which the amount of internal oxides per single side is 0.05 g/m.sup.2 or less.

A method for manufacturing a press-formed article, said method comprising forming a galvanized steel sheet or an alloyed hot-dip galvanized steel sheet by hot press forming, wherein, after heating the steel sheet and holding the same, the forming is started at a temperature of 680-750° C. inclusive, while allowing liquid zinc to remain on the surface of the steel sheet, and the forming is performed while regulating the strain rate in a plastic deformation part of the steel sheet to 0.5 sec.sup.−1 or lower.

A flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.