A vacuum solid solution method for nickel-free high manganese and nitrogen is provided and relates to the technical field of metal material heat treatment. By vacuumizing, heat homogenizing, keeping the temperature in the final temperature range, deoxidation, and rapid cooling treatment, the present method forms a single austenitic structure from the raw materials, and promotes full and uniform dispersion of nitrogen carbide, providing a nickel-free high nitrogen stainless steel with more stable comprehensive performance and wider range of application.

A vacuum solid solution method for nickel-free high manganese and nitrogen is provided and relates to the technical field of metal material heat treatment. By vacuumizing, heat homogenizing, keeping the temperature in the final temperature range, deoxidation, and rapid cooling treatment, the present method forms a single austenitic structure from the raw materials, and promotes full and uniform dispersion of nitrogen carbide, providing a nickel-free high nitrogen stainless steel with more stable comprehensive performance and wider range of application.

A soft magnetic powder of the invention has a composition represented by Fe.sub.100-a-b-c-d-e-fCu.sub.aSi.sub.bB.sub.cM.sub.dM′.sub.eX.sub.f (at %) [wherein M is Nb, W, Ta, Zr, Hf, Ti, or Mo, M′ is V, Cr, Mn, Al, a platinum group element, Sc, Y, Au, Zn, Sn, or Re, X is C, P, Ge, Ga, Sb, In, Be, or As, and a, b, c, d, e, and f are numbers that satisfy the following formulae: 0.1≤a≤3, 0<b≤30, 0<c≤25, 5≤b+c≤30, 0.1≤d≤30, 0≤e≤10, and 0≤f≤10], wherein a crystalline structure having a particle diameter of 1 nm or more and 30 nm or less is contained in an amount of 40 vol % or more, and the difference in the coercive force of the powder after classification satisfies predetermined conditions.

A soft magnetic powder of the invention has a composition represented by Fe.sub.100-a-b-c-d-e-fCu.sub.aSi.sub.bB.sub.cM.sub.dM′.sub.eX.sub.f (at %) [wherein M is Nb, W, Ta, Zr, Hf, Ti, or Mo, M′ is V, Cr, Mn, Al, a platinum group element, Sc, Y, Au, Zn, Sn, or Re, X is C, P, Ge, Ga, Sb, In, Be, or As, and a, b, c, d, e, and f are numbers that satisfy the following formulae: 0.1≤a≤3, 0<b≤30, 0<c≤25, 5≤b+c≤30, 0.1≤d≤30, 0≤e≤10, and 0≤f≤10], wherein a crystalline structure having a particle diameter of 1 nm or more and 30 nm or less is contained in an amount of 40 vol % or more, and the difference in the coercive force of the powder after classification satisfies predetermined conditions.

Disclosed is a multi-layer rolled composite board, comprising a transition layer provided between two adjacent composite layers, wherein the transition layer is an anisotropic steel sheet. Also disclosed is a manufacturing method for the multi-layer rolled composite board, the method comprising the following steps: (1) providing a transition layer between adjacent composite layers to assemble a blank, and creating a vacuum between the layers; and (2) performing composite rolling, comprising: heating the blank to 1100-1260° C. and maintaining the temperature for 0.6 h or above, then performing hot rolling at a temperature of Ar3 or above, with the final rolling temperature being controlled to be higher than 820° C., cooling at a speed of 30-100° C./s after rolling, and then coiling, with the coiling temperature being controlled to be 20-750° C. The multi-layer rolled composite board of the present invention can be greatly transformed according to different compositions and processes so as to achieve different strength grades ranging from 150 MPa to 1700 MPa, thereby providing the basis for different specific mechanical properties for the whole steel sheet.

Provided is a method for manufacturing a high-strength galvanized steel sheet. Heating in a first half of oxidizing treatment is performed at a temperature of 400° C. to 750° C. in an atmosphere having a particular O.sub.2 concentration and a particular H.sub.2O concentration, and heating in a second half of the oxidizing treatment is performed at a temperature of 600° C. to 850° C. in an atmosphere having a particular O.sub.2 concentration and a particular H.sub.2O concentration. Subsequently, heating in a heating zone for reduction annealing is performed to a temperature of 650° C. to 900° C. at a particular heating rate in an atmosphere having a particular H.sub.2 concentration and a particular H.sub.2O concentration with the balance being N.sub.2 and inevitable impurities, and soaking in a soaking zone for the reduction annealing is performed in an atmosphere having a particular H.sub.2 concentration and a particular H.sub.2O concentration with the balance being N.sub.2 and inevitable impurities.

Provided is a method for manufacturing a high-strength galvanized steel sheet. Heating in a first half of oxidizing treatment is performed at a temperature of 400° C. to 750° C. in an atmosphere having a particular O.sub.2 concentration and a particular H.sub.2O concentration, and heating in a second half of the oxidizing treatment is performed at a temperature of 600° C. to 850° C. in an atmosphere having a particular O.sub.2 concentration and a particular H.sub.2O concentration. Subsequently, heating in a heating zone for reduction annealing is performed to a temperature of 650° C. to 900° C. at a particular heating rate in an atmosphere having a particular H.sub.2 concentration and a particular H.sub.2O concentration with the balance being N.sub.2 and inevitable impurities, and soaking in a soaking zone for the reduction annealing is performed in an atmosphere having a particular H.sub.2 concentration and a particular H.sub.2O concentration with the balance being N.sub.2 and inevitable impurities.

Provided is a steel used for chassis parts, etc. of an automobile and, more specifically, to a hot rolled steel plate for an electric resistance welded steel pipe, which shows an excellent weldability in electric resistance welding, and a manufacturing method thereof.

Provided is a steel used for chassis parts, etc. of an automobile and, more specifically, to a hot rolled steel plate for an electric resistance welded steel pipe, which shows an excellent weldability in electric resistance welding, and a manufacturing method thereof.

An aluminum-based plated steel sheet according to an aspect of the present invention includes: a base material; an aluminum-based plating layer located above the base material; and an intermetallic compound layer that is located between the base material and the aluminum-based plating layer and contains an intermetallic compound of Al and Fe, in which the base material has a chemical component within a predetermined range, the aluminum-based plating layer contains, on average, 80 mass % or more and 97 mass % or less of Al, 3 mass % or more and 15 mass % or less of Si, 0 mass % or more and 5 mass % or less of Zn, 0 mass % or more and 5 mass % or less of Fe, 0 mass % or more and 3 mass % or less in total of one or more selected from the group consisting of Mg and Ca, and impurities so that a total amount thereof is 100 mass %, an average value of a thickness of the intermetallic compound layer is 2 μm or more and 10 μm or less, a maximum value of the thickness of the intermetallic compound layer is 10 μm or more and 25 μm or less, and a standard deviation of the thickness of the intermetallic compound layer is 2 μm or more and 10 μm or less.