The invention relates to the technical field of galvanization of iron-based or iron-containing components, especially steel-based or steel-containing components (steel components), preferably for the automotive or motor vehicle industry, but also for other industrial fields of application (for example for the construction industry, the field of general mechanical engineering, the electrical engineering industry etc.), by means of hot galvanization (hot clip galvanization). More particularly, the invention relates to a method of hot galvanization (hot dip galvanization) and to a plant for this purpose, and additionally to a flux and flux bath usable in this connection and to the respective uses thereof, and additionally also to the products obtainable by the method and/or in the plant (i.e. hot galvanized iron or steel components).

Provided is a technique that can produce a hot dip Zn—Al—Mg-based alloy coated steel product with a good plating appearance, without the need for heating of a steel product prior to immersion in a hot dip plating bath. Flux (11) for hot dip Zn—Al—Mg-based alloy plating contains: ZnCl.sub.2; and a low-reactive chloride which has low reactivity with respect to Mg in a plating bath and contains at least two chlorides selected from the compound group consisting of alkali metal chlorides and alkaline-earth metal chlorides, and a composition of the ZnCl.sub.2 and the low-reactive chloride is adjusted so that a liquidus temperature of the flux is 450° C. or lower.

Provided is a technique that can produce a hot dip Zn—Al—Mg-based alloy coated steel product with a good plating appearance, without the need for heating of a steel product prior to immersion in a hot dip plating bath. Flux (11) for hot dip Zn—Al—Mg-based alloy plating contains: ZnCl.sub.2; and a low-reactive chloride which has low reactivity with respect to Mg in a plating bath and contains at least two chlorides selected from the compound group consisting of alkali metal chlorides and alkaline-earth metal chlorides, and a composition of the ZnCl.sub.2 and the low-reactive chloride is adjusted so that a liquidus temperature of the flux is 450° C. or lower.

A method is for producing a high strength coated steel sheet having a yield stress YS>800 MPa, a tensile strength TS>1180 MPa, and improved formability and ductility. The steel contains: 15%≤C≤0.25%, 1.2%≤Si≤1.8%, 2%≤Mn≤2.4%, 0.1%≤Cr≤0.25%, Al≤0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature higher than Ac3 and lower than 1000° C. for a time of more than 30 s, then quenched by cooling it to a quenching temperature QT between 250° C. and 350° C., to obtain a structure consisting of at least 60% of martensite and a sufficient austenite content such that the final structure contains 3% to 15% of residual austenite and 85% to 97% of martensite and bainite without ferrite, then heated to a partitioning temperature PT between 430° C. and 480° C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated and cooled to the room temperature.

A method is for producing a high strength coated steel sheet having a yield stress YS>800 MPa, a tensile strength TS>1180 MPa, and improved formability and ductility. The steel contains: 15%≤C≤0.25%, 1.2%≤Si≤1.8%, 2%≤Mn≤2.4%, 0.1%≤Cr≤0.25%, Al≤0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature higher than Ac3 and lower than 1000° C. for a time of more than 30 s, then quenched by cooling it to a quenching temperature QT between 250° C. and 350° C., to obtain a structure consisting of at least 60% of martensite and a sufficient austenite content such that the final structure contains 3% to 15% of residual austenite and 85% to 97% of martensite and bainite without ferrite, then heated to a partitioning temperature PT between 430° C. and 480° C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated and cooled to the room temperature.

The present invention provides an iron-aluminum-based plated steel sheet, and a manufacturing method therefor, the iron-aluminum-based plated steel sheet comprising a base steel sheet and a plated layer formed on the surface of the base steel sheet, wherein the alloy plated layer comprises: a diffusion layer comprising an Fe—Al-based intermetallic compound having a cubic structure; and an alloyed layer formed on the diffusion layer and composed of an alloy phase differing from that of the cubic structure, the thickness of the diffusion layer is 3-20 μm, and the thickness of the diffusion layer is greater than 50% of the total thickness of the plated layer.

A steel sheet has a predetermined chemical composition and a metal structure represented by, in area fraction, polygonal ferrite: 40% or less, martensite: 20% or less, bainitic ferrite: 50% to 95%, and retained austenite: 5% to 50%. In area fraction, 80% or more of the bainitic ferrite is composed of bainitic ferrite grains that have an aspect ratio of 0.1 to 1.0 and have a dislocation density of 8×10.sup.2 (cm/cm.sup.3) or less in a region surrounded by a grain boundary with a misorientation angle of 15° or more. In area fraction, 80% or more of the retained austenite is composed of retained austenite grains that have an aspect ratio of 0.1 to 1.0, have a major axis length of 1.0 μm to 28.0 μm, and have a minor axis length of 0.1 μm to 2.8 μm.

A high-strength steel sheet has a specific composition and a microstructure. In the microstructure, the area fraction of elongated ferrite phase grains having an aspect ratio of 3 or more is 1% or less, the average crystal grain size of martensite included in a region extending 50 μm from a surface of the steel sheet is 20 μm or less, the content of oxide particles having a minor axis length of 0.8 μm or less in the region extending 50 μm from the surface of the steel sheet is 1.0×10.sup.10 particles/m.sup.2 or more, and the content of coarse oxide particles having a minor axis length of more than 1 μm in the region extending 50 μm from the surface of the steel sheet is 1.0×10.sup.8 particles/m.sup.2 or less. The content of hydrogen trapped in the steel sheet is 0.05 ppm by mass or more.

A method of pretinning a core wire for a guidewire having an elongate axis, comprising placing a ball of solder within a pocket in a soldering block; melting the ball of solder; holding a core wire over the ball of solder, with the elongate axis in a horizontal orientation; lowering a portion of the core wire into the ball of solder while maintaining the elongate axis in a horizontal orientation; removing the core wire from the ball of solder.

A method of pretinning a core wire for a guidewire having an elongate axis, comprising placing a ball of solder within a pocket in a soldering block; melting the ball of solder; holding a core wire over the ball of solder, with the elongate axis in a horizontal orientation; lowering a portion of the core wire into the ball of solder while maintaining the elongate axis in a horizontal orientation; removing the core wire from the ball of solder.