Abstract: The present invention is a weld metal formed by gas shielded arc welding using a flux cored wire, the welded metal having a predetermined chemical composition, residual austenite particles being present in an amount of at least 2500 particles/mm2, and the volume fraction of residual austenite particles being at least 4.0%.

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 flux cored wire, which is obtained by filling the inside of a steel outer skin with a flux, is configured to have a composition that contains, in mass % relative to the total mass of the wire, 0.01-0.12% of C, 0.05% or more but less than 0.30% of Si, 1.0-3.5% of Mn, 0.1% or more but less than 1.0% of Ni, 0.10-0.30% of Mo, 0.1-0.9% of Cr, 4.5-8.5% of TiO2, 0.10-0.40% of SiO2, 0.03-0.23% of Al2O3 and 80% or more of Fe.

Abstract: Disclosed is a weld metal which is formed by gas-shielded arc welding using a flux-cored wire, and which has a specific chemical composition, in which retained austenite particles are present in a number density of 2500 per square millimeter or more and in a total volume fraction of 4.0% or more based on the total volume of entire structures of the weld metal. The weld metal has excellent hydrogen embrittlement resistance and is resistant to cracking at low temperatures even when the weld metal has a high strength.

Abstract: The weld metal of the present invention is formed by gas shield arc welding using a flux-cored wire, has a predetermined chemical component composition, and contains 20% or more of Ti. The amount of Ti-containing oxide particles having a circle-equivalent diameter of 0.15-1.0 ?m is at least 5000 per square mm, the amount of V per total mass of weld metal present as a compound within the weld metal is 0.002% or more, and the average circle equivalent diameter of V-containing carbide present in the weld metal is 15 nm or less.

Abstract: Disclosed is an iron-based soft magnetic powder for dust core use, which includes an iron-based soft magnetic matrix powder and a phosphate conversion coating on a surface of the matrix powder. The phosphate conversion coating contains nickel element and has an aluminum content of equal to or less than that in the matrix powder. The iron-based soft magnetic powder has such excellent heat resistance as to maintain electrical insulation at satisfactory level even after subjected to a high-temperature heat treatment.

Abstract: This welded metal contains 0.02-0.10% of C, 0.10-0.60% of Si, 0.90-2.5% of Mn, 0.20-2.00% of Ni, 0.05-1.0% of Cr, 0.10-1.50% of Mo, 0.040-0.15% of Ti, 0.0010-0.0050% of B, 0.030-0.100% of O and 0.015% or less (excluding 0%) of N, with the balance made up of iron and unavoidable impurities. The average circle-equivalent diameter of carbides having a circle-equivalent diameter of 0.40 ?m or more among the carbides present in the grain boundary of this welded metal is 0.75 ?m or less. Consequently, the present invention provides: a welded metal which exhibits excellent low-temperature toughness at lower temperatures, while having high strength after SR annealing, even in cases where gas sealed arc welding using a flux cored wire and having excellent work efficiency is applied; and a welded structure which is provided with this welded metal.

Abstract: The weld metal of the present invention has a given chemical composition, contains retained austenite particles in an amount of 2,500 grains/mm2 or more, and has a volume fraction of the retained austenite particles of 4.3 vol % or more and a content ratio of Cr and Mn, [Cr]/[Mn], of 0.20 or more. The weld metal has excellent resistance to hydrogen embrittlement even when the weld metal has a high tensile strength of more than 780 MPa.

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: The present invention is a weld metal formed by gas shielded arc welding using a flux cored wire, the welded metal having a predetermined chemical composition, residual austenite particles being present in an amount of at least 2500 particles/mm2, and the volume fraction of residual austenite particles being at least 4.0%.

Abstract: Disclosed is an iron-based soft magnetic powder for dust core use, which includes an iron-based soft magnetic matrix powder and a phosphate conversion coating on a surface of the matrix powder. The phosphate conversion coating contains nickel element and has an aluminum content of equal to or less than that in the matrix powder. The iron-based soft magnetic powder has such excellent heat resistance as to maintain electrical insulation at satisfactory level even after subjected to a high-temperature heat treatment.

Abstract: The weld metal of the present invention is formed by gas shield arc welding using a flux-cored wire, has a predetermined chemical component composition, and contains 20% or more of Ti. The amount of Ti-containing oxide particles having a circle-equivalent diameter of 0.15-1.0 ?m is at least 5000 per square mm, the amount of V per total mass of weld metal present as a compound within the weld metal is 0.002% or more, and the average circle equivalent diameter of V-containing carbide present in the weld metal is 15 nm or less.

Abstract: An aluminum alloy material having an excellent sea water corrosion resistance comprises an aluminum alloy substrate whose ten-points average surface roughness Rz, which is the average of five greatest peak-to-valley separations on the surface, is controlled at 0.3 ?m or over, an organic phosphonic primer film formed on a surface of the aluminum alloy substrate, and a fluorine resin paint film formed on the primer film and having a dry average thickness of 1 to 100 ?m. A plate heat exchanger having an excellent sea water corrosion resistance is also provided wherein the aluminum alloy material is used as a heat transfer unit using sea water as cooling water.

Abstract: Disclosed is a weld metal which is formed by gas-shielded arc welding using a flux-cored wire, and which has a specific chemical composition, in which retained austenite particles are present in a number density of 2500 per square millimeter or more and in a total volume fraction of 4.0% or more based on the total volume of entire structures of the weld metal. The weld metal has excellent hydrogen embrittlement resistance and is resistant to cracking at low temperatures even when the weld metal has a high strength.

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: 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: Disclosed are an aluminum alloy material and a plate heat exchanger using the aluminum alloy material, both of which have superior corrosion resistance. Specifically, the aluminum alloy material includes an aluminum alloy base material having an anodic oxide layer with an average thickness of 1 to 20 ?m as its surface layer, an organic phosphonic acid primer coating arranged on the surface of the aluminum alloy base material, and a fluorocarbon resin coating arranged on the surface of the organic phosphonic acid primer coating and having an average thickness of 1 to 100 ?m after drying.

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: A spring steel having a high strength of 1900 MPa or more and superior in the brittle fracture resistance, as well as a method for manufacturing the same, are provided. The high strength spring steel comprises, as basic components in mass %, C: 0.4-0.6%, Si: 1.4-3.0%, Mn: 0.1-1.0%, Cr: 0.2-2.5%, P: 0.025% or less, S: 0.025% or less, N: 0.006% or less, Al: 0.1% or less, and O: 0.003% or less, the amount of solute C being 0.15% or less, the amount of Cr contained as a Cr-containing precipitate being 0.10% or less, and a TS value represented by the following equation being 24.8% or more, and in point of structure, the pre-austenite grain diameter being 10 ?m or smaller, wherein TS=28.5*[C]+4.9*[Si]+0.5*[Mn]+2.5*[Cr]+1.7*[V]+3.7*[Mo] where [X] stands for mass % of element X.

Abstract: To provide a steel-aluminum welded material and a spot welding method therefor having high weld strength. The steel-aluminum welded material 3 includes a steel material 1 and an aluminum material 2 having predetermined widths. The area of a nugget 5 of a spot-welded part is determined as a function of the thickness of the aluminum material 2, and the area of a part of the nugget 5 corresponding to a part having a thickness in a range between 0.5 and 10 ?m of an interface reaction layer 6 is defined as a function of the thickness of the aluminum material 2.