Abstract: A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream is higher than the melting point by 100° C. or more, spraying primary cooling water from a plurality of directions at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream of the primary cooling water from one direction and an impact direction on the molten metal stream of the primary cooling water from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+50° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

Abstract: A production method for water-atomized metal powder includes: in a region in which the average temperature of a molten metal stream having an Fe concentration of 76.0 at % or more and less than 82.9 at % is 100° C. or more higher than the melting point, spraying primary cooling water at a convergence angle of 10° to 25°, where the convergence angle is an angle between an impact direction on the molten metal stream from one direction and an impact direction on the molten metal stream from any other direction; and in a region in which 0.0004 seconds or more have passed after an impact of the primary cooling water and the average temperature of metal powder is the melting point or higher and (the melting point+100° C.) or lower, spraying secondary cooling water on the metal powder under conditions of an impact pressure of 10 MPa or more.

Abstract: Provided is a soft magnetic powder that can produce a dust core having excellent magnetic properties. The soft magnetic powder has a chemical composition, excluding inevitable impurities, represented by a composition formula of FeaSibBcPdCueMf, where the M is at least one element selected from the group consisting of Nb, Mo, Zr, Ta, W, Hf, Ti, V, Cr, Mn, C, Al, S, O, and N, 79 at %?a?84.5 at %, 0 at %?b<6 at %, 0 at %<c?10 at %, 4 at %<d?11 at %, 0.2 at %?e?0.53 at %, 0 at %?f?4 at %, a+b+c+d+e+f=100 at %, a particle size is 1 mm or less, and a median of circularity of particles constituting the soft magnetic powder is 0.4 or more and 1.0 or less.

Abstract: Provided is alloyed steel powder having excellent fluidity, formability, and compressibility without containing Ni, Cr, or Si. The alloyed steel powder includes iron-based alloy containing Mo, in which Mo content is 0.4 mass % to 1.8 mass %, a weight-based median size D50 is 40 ?m or more, and among particles contained in the alloyed steel powder, those particles having an equivalent circular diameter of 50 ?m to 200 ?m have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area).

Abstract: Disclosed is a partially diffusion-alloyed steel powder having excellent fluidity, formability, and compressibility without containing Ni, Cr, and Si. A partially diffusion-alloyed steel powder having excellent fluidity, formability, and compressibility that includes an iron-based powder and Mo diffusionally adhered to a surface of the iron-based powder, in which Mo content is 0.2 mass % to 2.0 mass %, a weight-based median diameter D50 is 40 ?m or more, and among particles contained in the partially diffusion-alloyed steel powder, those particles having an equivalent circular diameter of 50 ?m to 200 ?m have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area).

Abstract: Disclosed is an alloyed steel powder for powder metallurgy from which sintered parts that do not contain expensive Ni, or Cr or Mn susceptible to oxidation, that have excellent compressibility, and that have high strength in an as-sintered state can be obtained. The alloyed steel powder for powder metallurgy has: a chemical composition containing Cu: 1.0 mass % to 8.0 mass %, with the balance being Fe and inevitable impurities; and constituent particles in which Cu is present in an precipitated state with an average particle size of 10 nm or more.

Abstract: Provided is a method of manufacturing a soft magnetic dust core. The method includes: preparing coated powder including amorphous powder made of an Fe-B-Si-P-C-Cu-based alloy, an Fe-B-P-C-Cu-based alloy, an Fe-B-Si-P-Cu-based alloy, or an Fe-B-P-Cu-based alloy, with a first initial crystallization temperature Tx1 and a second initial crystallization temperature Tx2; and a coating formed on a surface of particles of the amorphous powder; applying a compacting pressure to the coated powder or a mixture of the coated powder and the amorphous powder at a temperature equal to or lower than Tx1?100 K; and heating to a maximum end-point temperature equal to or higher than Tx1?50 K and lower than Tx2 with the compacting pressure being applied.

Abstract: Disclosed is an alloyed steel powder for powder metallurgy from which sintered parts that do not contain expensive Ni, or Cr or Mn susceptible to oxidation, that have excellent compressibility, and that have high strength in an as-sintered state can be obtained. The alloyed steel powder for powder metallurgy has: a chemical composition containing Mo: 0.5 mass % to 2.0 mass % and Cu: 1.0 mass % to 8.0 mass %, with the balance being Fe and inevitable impurities; and a microstructure in which an FCC phase is present at a volume fraction of 0.5% to 10.0%.

Abstract: [Object] Provided is a method for manufacturing atomized metal powder having a high amorphous material fraction by using a water atomizing method. [Solution] A method for manufacturing atomized metal powder in which atomized metal powder having an amorphous material fraction of 90% or more is obtained, the method including ejecting high-pressure water so as to collide with a molten metal stream flowing vertically downward, separating the molten metal stream into metal powder, and cooling the metal powder, in which the high-pressure water collides with the molten metal with a collision pressure of 20 MPa or higher, and in which a temperature of the molten metal and/or a temperature of the high-pressure water are controlled so that the high-pressure water is in a subcritical state or a supercritical state on a collision surface with the molten metal.

Abstract: Provided is a mixed powder for powder metallurgy having a chemical system not using Ni which causes non-uniform metallic microstructure in a sintered body. A mixed powder for powder metallurgy comprises: a partially diffusion alloyed steel powder in which Mo diffusionally adheres to a particle surface of an iron-based powder; a Cu powder; and a graphite powder, wherein the mixed powder for powder metallurgy has a chemical composition containing Mo: 0.2 mass % to 1.5 mass %, Cu: 0.5 mass % to 4.0 mass %, and C: 0.1 mass % to 1.0 mass %, with the balance consisting of Fe and inevitable impurities, and the partially diffusion alloyed steel powder has: a mean particle diameter of 30 ?m to 120 ?m; a specific surface area of less than 0.10 m2/g; and a circularity of particles with a diameter in a range from 50 ?m to 100 ?m of 0.65 or less.

Abstract: Provided is a method for manufacturing soft magnetic iron powder. A method for manufacturing soft magnetic iron powder, the method including ejecting high-pressure water to collide with a molten metal stream falling vertically downward, breaking up the molten metal stream into metal powder, and cooling the metal powder, in which, when a falling rate of the molten metal stream per unit time is defined as Qm (kg/min) and an ejection rate of high-pressure water per unit time is defined as Qaq (kg/min), a mass ratio (Qaq/Qm) is 50 or more, and a total content of ferrous constituents (Fe, Ni, and Co) is 76 at % or more.

Abstract: This soft magnetic powder is represented by composition formula FeaSibBcPdCue with the exception of unavoidable impurities. In the composition formula, a, b, c, d and e satisfy 79?a?84.5 at %, 0?b<6 at %, 4?c?10 at %, 4<d?11 at %, 0.2?e<0.4 at %, and a+b+c+d+e=100 at %.

Abstract: An iron powder for dust cores has an apparent density is 3.8 g/cm3 or more, a mean particle size (D50) is 80 ?m or more, 60% or more of powder with a powder particle size of 100 ?m or more has a mean grain size of 80 ?m or more inside the powder particle, an area ratio of inclusions to a matrix phase of the powder is 0.4% or less, and a micro Vickers hardness (testing force: 0.245 N) of a powder cross-section is 90 Hv or less. It is thus possible to obtain iron powder for dust cores in order to manufacture a dust core that has low hysteresis loss even after the iron powder is formed and subjected to strain relief annealing.

Abstract: An Fe—Mo—Cu—C-based alloy steel powder for powder metallurgy has a chemical composition containing Mo: 0.2 mass % to 1.5 mass %, Cu: 0.5 mass % to 4.0 mass %, and C: 0.1 mass % to 1.0 mass %, with a balance being Fe and incidental impurities, wherein an iron-based powder has a mean particle size of 30 ?m to 120 ?m, and a Cu powder has a mean particle size of 25 ?m or less. Despite the alloy steel powder for powder metallurgy having a chemical composition not containing Ni, a part produced by sintering a press formed part of the powder and further carburizing-quenching-tempering the sintered part has mechanical properties of at least as high tensile strength, toughness, and sintered density as a Ni-added part.

Abstract: Provided is a soft magnetic dust core having high density and favorable properties. A method of manufacturing a soft magnetic dust core includes: preparing coated powder including amorphous powder made of an Fe—B—Si—P—C—Cu-based alloy, an Fe—B—P—C—Cu-based alloy, an Fe—B—Si—P—Cu-based alloy, or an Fe—B—P—Cu-based alloy, with a first initial crystallization temperature Tx1 and a second initial crystallization temperature Tx2; and a coating formed on a surface of particles of the amorphous powder; applying a compacting pressure to the coated powder or a mixture of the coated powder and the amorphous powder at a temperature equal to or lower than Tx1?100 K; and heating to a maximum end-point temperature equal to or higher than Tx1?50 K and lower than Tx2 with the compacting pressure being applied.

Abstract: Iron powder for dust cores that is appropriate for manufacturing a dust core with low iron loss is obtained by setting the oxygen content in the powder to be 0.05 mass % or more to 0.20 mass % or less, and in a cross-section of the powder, setting the area ratio of inclusions to the matrix phase to be 0.4% or less.

Abstract: Soft magnetic powder for dust cores that yields dust cores having low eddy current loss is provided. Raw material powder for soft magnetic powder comprises Fe: 60 mass % or more, a ?-phase stabilizing element, and an electric resistance-increasing element: 1.0 mass % or more.

Abstract: Provided is a mixed powder for powder metallurgy having a chemical system not using Ni which causes non-uniform metallic microstructure in a sintered body. A mixed powder for powder metallurgy comprises: a partially diffusion alloyed steel powder in which Mo diffusionally adheres to a particle surface of an iron-based powder; a Cu powder; and a graphite powder, wherein the mixed powder for powder metallurgy has a chemical composition containing Mo: 0.2 mass % to 1.5 mass %, Cu: 0.5 mass % to 4.0 mass %, and C: 0.1 mass % to 1.0 mass %, with the balance consisting of Fe and inevitable impurities, and the partially diffusion alloyed steel powder has: a mean particle diameter of 30 ?m to 120 ?m; a specific surface area of less than 0.10 m2/g; and a circularity of particles with a diameter in a range from 50 ?m to 100 ?m of 0.65 or less.

Abstract: The present invention provides iron powder for dust cores that has excellent compressibility and low iron loss after formation. In the iron powder for dust cores, Si content is 0.01 mass % or less, apparent density is 3.8 g/cm3 or more, the ratio of iron powder particles with a particle size of 45 ?m or less is 10 mass % or less, the ratio of iron powder particles with a particle size of over 180 ?m and 250 ?m or less is less than 30 mass %, the ratio of iron powder particles with a particle size of over 250 ?m is 10 mass % or less, and the Vickers hardness (test force: 0.245 N) of a powder cross-section is 80 Hv or less.

Abstract: Provided is an iron-based sintered body having excellent mechanical properties. In the sintered body, the area fraction of pores is 15% or less and the area-based median size D50 of the pores is 20 82 m or less.