Disclosed is a method of manufacturing a blank for hot stamping, which includes forming a plated layer on a steel plate by immersing the steel plate in a plating bath including aluminum and silicon; and heating the steel plate on which the plated layer is formed at a first temperature for a first time period.

A double-annealed steel sheet is provided. The composition of which includes, expressed in percent by weight, 0.20%≤C≤0.40%, 0.8%≤Mn≤1.4%, 1.60%≤Si≤3.00%, 0.015≤Nb≤0.150%, Al≤0.1%, Cr≤1.0%, S≤0.006%, P≤0.030%, Ti≤0.05%, V≤0.05%, B≤0.003%, N≤0.01%. A remainder of the composition includes iron and unavoidable impurities resulting from processing. The microstructure of the steel sheet includes, in area percentages, 10 to 30% residual austenite, 30 to 60% annealed martensite, 5 to 30% bainite, 10 to 30% fresh martensite and less than 10% ferrite A fabrication method and vehicle parts are also provided.

Provided is a high-strength hot rolled steel sheet that has excellent stretch flange formability, bendability, and low-temperature toughness while maintaining high strength of a tensile strength TS of 1180 MPa or more, and a method for manufacturing the high-strength hot rolled steel sheet.

The high-strength hot rolled steel sheet includes a specific chemical composition, and a steel structure in which a lower bainite phase and/or a tempered martensite phase at 90% or more in terms of a total area fraction is contained as a dominant phase, an average grain size of the dominant phase is 10.0 μm or less, and an amount of Fe in Fe-based precipitates is 0.70% or less in mass %, in which an arithmetic average roughness (Ra) of a surface is 2.50 μm or less, and a tensile strength TS is 1180 MPa or more.

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.

Provided are a high-strength galvanized hot-rolled steel sheet and a method for manufacturing the steel sheet. A steel sheet has a chemical composition, and a galvanized layer is disposed on the steel sheet. The chemical composition includes, in mass %, C: 0.02% or greater and 0.30% or less, Si: 0.01% or greater and 2.5% or less, Mn: 0.3% or greater and 3.0% or less, P: 0.08% or less, S: 0.02% or less, and Al: 0.001% or greater and 0.20% or less. The galvanized layer has a coating weight per side of 20 to 120 g/m.sup.2. A surface of the steel sheet has a specific surface area ratio, r, of 2.5 or less, and an amount of Si present in the galvanized layer and an amount of Mn present in the galvanized layer respectively satisfy: amount of Sir0.06, and amount of Mnr0.10.

A method for hot forming a steel component is provided. The steel component is heated into a range of complete or partial austenitization in a heat treatment step. The heated steel component is both hot-formed and quench-hardened in a forming step. A first pretreatment step precedes the heat treatment step in terms of process, in which first pretreatment step the steel component is provided with a corrosion-resistant protective layer in order to protect against scaling in the heat treatment step. Before the heat treatment step is performed, a surface oxidation process occurs in a second pre-treatment step, in which a weakly reactive, corrosion-resistant oxidation layer is formed on the scale protection layer by means of which oxidation layer abrasive tool wear is reduced in the forming step.

The invention relates to a hot-forming composite material (1) composed of an at least three-layer material composite comprising a core layer (1.1) of a hardenable steel and two outer layers (1.2), cohesively bonded to the core layer (1.1), of a ferritic, transformation-free FeAlCr steel.

A process for producing a steel component with a metallic, corrosion protection coating and very good mechanical properties may involve directly applying an iron-based alloy to a steel substrate. The iron-based alloy may contain 50-80% by weight of Fe, 0-30% by weight of Mg, 0-5% by weight of Al, 0-5% by weight of Ti, 0-10% by weight of Si, 0-10% by weight of Li, 0-10% by weight of Ca, 0-30% by weight of Mn, and a balance of Zn and unavoidable impurities. The steel substrate that has been coated with the iron-based alloy may then be subjected to hot forming in order to obtain the steel component. A metallic coating that protects against corrosion for steel components to be produced by the process of hot forming can be obtained.

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.

The present invention provides a method for manufacturing more beautiful black coated steel sheets by uniformly blackening the coating layer. Specifically, the present invention provides a method for manufacturing black coated steel sheets, which brings ZnAlMg alloy coated steel sheets (1) into contact with steam in a closed container (10), wherein said closed container (10) can maintain a predefined internal pressure through variable control of the amount of steam flowing into said closed container (10) and/or the amount of steam flowing out of said closed container (10), and in said closed container (10) that can maintain said predefined pressure, said ZnAlMg alloy coated steel sheets (1) have contact with the steam introduced into said closed container (10).