A method for producing a steel strip containing, in addition to iron as the main component and unavoidable impurities, one or more of the following oxygen-affine elements in wt. %: Al: more than 0.02, Cr: more than 0.1, Mn: more than 1.3 or Si: more than 0.1, where the surface of the steel strip is cleaned, oxidation-treated and annealed. The treated and annealed steel strip is subsequently coated with a hot-dip coat. In order to be less cost-intensive and to achieve uniform, reproducible adhesion conditions for the coat, the steel strip is oxidation-treated prior to the annealing at temperatures below 200° C., where on the surface of the steel strip, with the formation of oxides with iron from the steel strip, an oxide layer is formed, which contains iron oxide and is reduction-treated during the course of the annealing under a reducing atmosphere to achieve a surface consisting substantially of metallic iron.

The invention relates to a method and a device for rapidly cooling a metal strip and removing residues present on the strip after this cooling, wherein the residues are formed during a cooling of said metal strip by a non-oxidizing liquid solution for the metal strip and a stripping liquid solution for the oxides present on the surface of the strip, or by a mixture of this liquid solution and a gas.

The present invention relates to a zinc plated steel sheet having excellent surface quality and spot weldability, and a manufacturing method therefore. A zinc plated steel sheet according to one aspect of the present invention comprises a base steel sheet and a zinc-based plating layer formed on the surface of the base steel sheet, wherein the GDOES profile of oxygen, which is measured in the depth direction from the surface of the base steel sheet, has a form in which a local minimum point and a local maximum point alternately appear in the depth direction from the surface, and the difference (a local maximum value—a local minimum value) between the oxygen concentration (a local minimum value) at the local minimum point and the oxygen concentration (a local maximum value) at the local maximum point can be 0.1 wt % or more.

A cold-rolled sheet according to an example of the present invention comprises at most 0.004 wt % (exclusive of 0 wt %) of C, at most 0.02 wt % (exclusive of 0 wt %) of Si, 0.1 to 0.3 wt % of Mn, at most 0.05 wt % (exclusive of 0 wt %) of Al, at most 0.02 wt % (exclusive of 0 wt %) of P, at most 0.001 wt % (exclusive of 0 wt %) of S, at most 0.004 wt % (exclusive of 0 wt %) of N, 0.015 to 0.035 wt % of Ti, and 0.001 to 0.003 wt % of B, with the balance being Fe and other inevitable impurities, and has a microstructure in which the crystal grain aspect ratio defined by the following equation 1 is 1.4 to 4.0.

Crystal grain aspect ratio=average crystal grain diameter in the rolling direction/average crystal grain diameter in the thickness direction   [Equation 1]

The present disclosure relates to a system for manufacturing a hybrid component including a first thermal supplier configured to heat a steel plate, a rolling roll for undercut configured to pressurize the steel plate heated by the first thermal supplier, and to form an undercut on one surface of the steel plate, a first molding roll configured to pressurize the steel plate formed with the undercut to mold the steel plate in a shape of a component to be manufactured, a composite material feeder configured to supply a composite material tape to be seated on one surface of the steel plate formed with the undercut through the first molding roll, and a composite material pressurization roll configured to pressurize the steel plate on which the composite material tape is seated.

Provided is a metallic coated steel product which is less likely to experience LME and blowhole formation and is likely to exhibit an improved corrosion resistance at welding heat affected zones. The metallic coated steel product is a hot-dip metallic coated steel product including a steel product and a plating layer that is provided on a surface of the steel product and includes a Zn—Al—Mg alloy layer. In a cross-section of the Zn—Al—Mg alloy layer an area fraction of MgZn.sub.2 phase is from 45 to 75%, a total area fraction of MgZn.sub.2 and Al phases is not less than 70%, and an area fraction of Zn—Al—MgZn.sub.2 ternary eutectic structure is from 0 to 5%; and the plating layer has a predetermined chemical composition.

A steel sheet including a chemical composition satisfying an equivalent carbon content of 0.60% or more and less than 0.85%, and a steel microstructure with an area fraction of ferrite: less than 40%, tempered martensite and bainite: 40% or more in total, retained austenite: 3% to 15%, and ferrite, tempered martensite, bainite, and retained austenite: 93% or more in total. A 90-degree bending at a curvature radius/thickness ratio of 4.2 in a rolling (L) direction with respect to an axis extending in a width (C) direction causes a change of 0.40 or more in (a grain size in a thickness direction)/(a grain size in a direction perpendicular to the thickness) of the tempered martensite in an L cross section in a 0- to 50-μm region from a surface of the steel sheet on a compression side. The steel sheet has a tensile strength of 980 MPa or more.

A plated steel includes: a steel; and a plating layer that is provided on a surface of the steel, in which the plating layer includes, by mass %, Al: 5.00% to 35.00%, Mg: 2.50% to 13.00%, Fe: 5.00% to 40.00%, Si: 0% to 2.00%, Ca: 0% to 2.00%, and a remainder of Zn and impurities, and in a cross section of the plating layer, the area fraction of a Zn solid-solution Fe.sub.2Al.sub.5 phase in which 5% or more of Zn is solid-soluted is 10% to 60% and the area fraction of a MgZn.sub.2 phase is 10% to 90%.

A plated steel includes: a steel; and a plating layer that is provided on a surface of the steel, in which the plating layer includes, by mass %, Al: 5.00% to 35.00%, Mg: 2.50% to 13.00%, Fe: 5.00% to 40.00%, Si: 0% to 2.00%, Ca: 0% to 2.00%, and a remainder of Zn and impurities, and in a cross section of the plating layer, the area fraction of a Zn solid-solution Fe.sub.2Al.sub.5 phase in which 5% or more of Zn is solid-soluted is 10% to 60% and the area fraction of a MgZn.sub.2 phase is 10% to 90%.

The invention relates to a system and a method for the hot-dip galvanization of components, preferably for mass-production hot-dip galvanization of a plurality of identical or similar components, in particular in batches, preferably for batch galvanization.