Abstract: The present invention is a production method of a hot-dip galvanized steel sheet including annealing a belt-shaped steel sheet having a Si content of greater than or equal to 0.2% by mass, wherein the annealing is continuously carried out using an annealing furnace having an oxidation heating zone and a reduction heating zone in this order, while the steel sheet is fed using rollers. The annealing includes oxidizing a surface of the steel sheet in the oxidation heating zone at a temperature at which roll pickup does not occur and reducing an iron oxide layer, formed by the oxidizing, in the reduction heating zone before the iron oxide layer reaches an initial roller in the reduction heating zone.

Abstract: To provide a galvanized steel sheet for hot pressing which can achieve heating for suppressing the occurrence of LME cracks in a short time during a hot pressing process, and a method of manufacturing a hot press-formed product obtained by performing hot pressing using the galvanized steel sheet. Disclosed is a galvanized steel sheet for use in hot pressing, including a galvanized layer and a base steel sheet, wherein internal oxide is present on a side of the base steel sheet from an interface between the galvanized layer and the base steel sheet, the base steel sheet including defined C, Si, Mn, and Cr, with the balance being iron and inevitable impurities, wherein the base steel sheet satisfies the following formula (1): (2×[Si]/28.1+[Mn]/54.9+1.5×[Cr]/52.0)?0.05??(1) wherein, in the formula (1), [Si] represents a Si content in mass % of the base steel sheet, [Mn] represents a Mn content in mass % of the base steel sheet, and [Cr] represents a Cr content in mass % of the base steel sheet.

Abstract: A powder for a powder magnetic core, being composed of iron-base soft magnetic powder particles which each have a phosphoric acid-based chemical conversion coating on the surface. In this powder, the maximum thickness of the phosphoric acid-based chemical conversion coating is 20 to 200 nm, and recessed portions are formed on the surface of the chemical conversion coating with the total area of openings of the recessed portions being 0.5 to 50% by area relative to the total area of the observation visual fields, as determined by observing ten or more parts of the surface of the phosphoric acid-based chemical conversion coating through a scanning electron microscope with a magnification of 10000× or more.

Abstract: There are provided a flux cored wire for joining dissimilar materials with each other, capable of enhancing a bonding strength upon joining an aluminum-base material with a steel-base material, and excellent in bonding efficiency, a method for joining the dissimilar materials with each other, and a bonded joint obtained by the method. In particular, there is provided a method for joining dissimilar materials with each other, in the case of melt weld-bonding of high-strength dissimilar materials with each other, that is, the high-strength steel member with the high-strength 6000 series aluminum alloy member and in the case of the steel member being a galvanized steel member. In one mode, use is made of a flux cored wire wherein the interior of an aluminum alloy envelope is filled up with a flux, the flux has fluoride composition containing a given amount of AlF3 without containing chloride, and the aluminum alloy of the envelope contains Si in a range of 1 to 13 mass %.

Abstract: 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?1 or lower.

Abstract: A method of manufacturing a steel wire material that contains 0.05%-1.2% C (“%” means “% by mass,” same hereinafter for chemical components.), 0.01%-0.7% Si, 0.1%-1.5% Mn, 0.02% max. P (not including 0%), 0.02% max. S (not including 0%), and 0.005% max. N (not including 0%), with the remainder being iron and unavoidable impurities. The steel wire material has a scale 6.0-20 ?m thick and holes of an equivalent circle diameter of 1 ?m max. in said scale that occupy 10% by area max. Said scale does not detach in the cooling process after hot rolling or during storage or transportation but can readily detach during mechanical descaling.

Abstract: There are provided a flux cored wire for joining dissimilar materials with each other, capable of enhancing a bonding strength upon joining an aluminum-base material with a steel-base material, and excellent in bonding efficiency, a method for joining the dissimilar materials with each other, and a bonded joint obtained by the method. In particular, there is provided a method for joining dissimilar materials with each other, in the case of melt weld-bonding of high-strength dissimilar materials with each other, that is, the high-strength steel member with the high-strength 6000 series aluminum alloy member and in the case of the steel member being a galvanized steel member. In one mode, use is made of a flux cored wire wherein the interior of an aluminum alloy envelope is filled up with a flux, the flux has fluoride composition containing a given amount of AlF3 without containing chloride, and the aluminum alloy of the envelope contains Si in a range of 1 to 13 mass %.

Abstract: 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?1 or lower.

Abstract: A powder for a powder magnetic core, being composed of iron-base soft magnetic powder particles which each have a phosphoric acid-based chemical conversion coating on the surface. In this powder, the maximum thickness of the phosphoric acid-based chemical conversion coating is 20 to 200 nm, and recessed portions are formed on the surface of the chemical conversion coating with the total area of openings of the recessed portions being 0.5 to 50% by area relative to the total area of the observation visual fields, as determined by observing ten or more parts of the surface of the phosphoric acid-based chemical conversion coating through a scanning electron microscope with a magnification of 10000× or more.

Abstract: A method of manufacturing a steel wire material that contains 0.05%-1.2% C (“%” means “% by mass,” same hereinafter for chemical components.), 0.01%-0.7% Si, 0.1%-1.5% Mn, 0.02% max. P (not including 0%), 0.02% max. S (not including 0%), and 0.005% max. N (not including 0%), with the remainder being iron and unavoidable impurities. The steel wire material has a scale 6.0-20 ?m thick and holes of an equivalent circle diameter of 1 ?m max. in said scale that occupy 10% by area max. Said scale does not detach in the cooling process after hot rolling or during storage or transportation but can readily detach during mechanical descaling.

Abstract: A galvannealed steel sheet obtained by subjecting a base steel sheet to hot-dip galvanization and then alloying the galvanization layer, the base steel sheet being obtained by hot rolling a specified steel. A method for producing the galvannealed steel sheet.

Abstract: This steel wire material contains 0.05%-1.2% C (“%” means “% by mass,” same hereinafter for chemical components.), 0.01%-0.7% Si, 0.1%-1.5% Mn, 0.02% max. P (not including 0%), 0.02% max. S (not including 0%), and 0.005% max. N (not including 0%), with the remainder being iron and unavoidable impurities. The steel wire material has a scale 6.0-20 ?m thick and holes of an equivalent circle diameter of 1 ?m max. in said scale that occupy 10% by area max. Said scale does not detach in the cooling process after hot rolling or during storage or transportation but can readily detach during mechanical descaling.

Abstract: The steel wire material of the present invention contains 0.05 to 1.2% of C (mass %; same for the chemical components hereafter), 0.01 to 0.5% of Si, 0.1 to 1.5% of Mn, 0.02% or less (but not 0%) of P, 0.02% or less (but not 0%) of S, and 0.005% or less (but not 0%) of N, with the balance being iron and inevitable impurities. The wire material has a scale layer that is no thicker than 7.0 ?m or less. The scale layer has an FeO percentage of 30 to 80 vol % and an Fe2SiO4 percentage of less than 0.1 vol %. The scale layer that is formed will not peel when cooled after hot rolling or during storage and transport, but will easily peel during mechanical descaling.

Abstract: Provided is a joint product of a steel product and an aluminum material, the joint product being formed by joining the steel product having a sheet thickness t1 of 0.3 to 3.0 mm with the aluminum material having a sheet thickness t2 of 0.5 to 4.0 mm by spot welding, wherein a nugget area in a joint part is from 20×t20.5 to 100×t20.5 mm2, an area of a portion where a thickness of an interface reaction layer is from 0.5 to 3 ?m is 10×t20.5 mm2 or more, and a difference between the thickness of the interface reaction layer at a joint part center and the thickness of the interface reaction layer at a point distant from the joint part center by a distance of one-fourth of a joint diameter is 5 ?m or less, and wherein the aluminum material is pure aluminum or an aluminum alloy material.

Abstract: The present invention aims at providing a method for production of a steel product which surely retains scale during cooling, storage, and transportation and permits scale to scale off easily at the time of mechanical descaling and pickling that precede the secondary fabrication. The steel product is produced by heating and hot rolling a steel billet and spraying the hot-rolled steel product with steam and/or water mist having a particle diameter no larger than 100 ?m, for surface oxidation.

Abstract: A joined body of dissimilar metals which is produced by joining a steel material and an aluminum alloy material, wherein the steel material to be joined has a specific composition and is specified in the compositions of outer surface oxide layer and inner oxide layer and the aluminum alloy material to be joined is an Al—Mg-base or Al—Zn—Mg-base aluminum alloy having a specific composition. In the joined body of dissimilar metals, a content of Fe at a joint interface on the aluminum alloy material side is regulated, and a reaction layer of Fe and Al is formed at the joint interface of the joined body of dissimilar metals. The joined body of dissimilar metals exhibits high joint strength.

Abstract: A method produces a dust core by molding a mixture through compression molding to give a powder compact, the mixture containing an oxygen-source-releasable compound and an iron-based soft magnetic powder for powder compacts including an iron-based soft magnetic matrix powder and an insulating coating film present on the surface of the matrix powder; and heating the powder compact to oxidize at least the surface of the iron-based soft magnetic matrix powder by the action of the oxygen-source-releasable compound. The resulting dust core excels not only in mechanical strength but also in resistivity (insulation).

Abstract: A joined body of dissimilar metals which is produced by joining a steel material and an aluminum alloy material, wherein the steel material to be joined has a specific composition and is specified in the compositions of outer surface oxide layer and inner oxide layer and the aluminum alloy material to be joined is an Al—Mg—Si-base aluminum alloy having a specific composition. In the joined body of dissimilar metals, a content of Fe at a joint interface on the aluminum alloy material side is regulated, and a reaction layer of Fe and Al is formed at the joint interface of the joined body of dissimilar metals. The joined body of dissimilar metals exhibits high joint strength.

Abstract: The present invention aims at providing a method for production of a steel product which surely retains scale during cooling, storage, and transportation and permits scale to scale off easily at the time of mechanical descaling and pickling that precede the secondary fabrication. The steel product is produced by heating and hot rolling a steel billet and spraying the hot-rolled steel product with steam and/or water mist having a particle diameter no larger than 100 ?m, for surface oxidation.

Abstract: A joined body of dissimilar metals which is produced by joining a steel material and an aluminum alloy material, wherein the steel material to be joined has a specific composition and is specified in the compositions of outer surface oxide layer and inner oxide layer and the aluminum alloy material to be joined is an Al—Mg-base or Al—Zn—Mg-base aluminum alloy having a specific composition. In the joined body of dissimilar metals, a content of Fe at a joint interface on the aluminum alloy material side is regulated, and a reaction layer of Fe and Al is formed at the joint interface of the joined body of dissimilar metals. The joined body of dissimilar metals exhibits high joint strength.