Abstract: A method for producing a water-atomized metal powder, comprising applying water to a molten metal stream, dividing the molten metal stream into a metal powder, and cooling the metal powder, wherein the metal powder is further subjected to secondary cooling with cooling capacity having a minimum heat flux point (MHF point) higher than the surface temperature of the metal powder in addition to the cooling and the secondary cooling is performed from a temperature range where the temperature of the metal powder after the cooling is not lower than the cooling start temperature necessary for amorphization nor higher than the minimum heat flux point (MHF point).

Abstract: A water-atomized metal powder is produced by dividing a molten metal stream into a metal powder by making injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more impinge on the molten metal stream and cooling the metal powder. Cooling with injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more enables can be performed not in the film boiling region but in the transition boiling region from the beginning of cooling. A gas-atomized metal powder may also be produced by dividing a molten metal stream into a metal powder by making an inert gas impinge on the molten metal stream and cooling the metal powder with injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more.

Abstract: A method for producing a water-atomized metal powder, comprising applying water to a molten metal stream, dividing the molten metal stream into a metal powder, and cooling the metal powder, wherein the metal powder is further subjected to secondary cooling with cooling capacity having a minimum heat flux point (MHF point) higher than the surface temperature of the metal powder in addition to the cooling and the secondary cooling is performed from a temperature range where the temperature of the metal powder after the cooling is not lower than the cooling start temperature necessary for amorphization nor higher than the minimum heat flux point (MHF point).

Abstract: A water-atomized metal powder is produced by dividing a molten metal stream into a metal powder by making injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more impinge on the molten metal stream and cooling the metal powder. Cooling with injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more enables can be performed not in the film boiling region but in the transition boiling region from the beginning of cooling. A gas-atomized metal powder may also be produced by dividing a molten metal stream into a metal powder by making an inert gas impinge on the molten metal stream and cooling the metal powder with injection water having a liquid temperature of 10° C. or less and an injection pressure of 5 MPa or more.

Abstract: Provided is an alloy steel powder for powder metallurgy that is capable of achieving both high strength and high toughness in a sintered body using the same. An alloy steel powder for powder metallurgy of this disclosure comprises a composite alloy steel powder and graphite powder. The composite alloy steel powder has a specific surface area of 0.100 m2/g or more and Mo content in a range of 0.2 mass % to 1.5 mass %, and the graphite powder content with respect to 100 mass % of the alloy steel powder for powder metallurgy is in a range of 0.1 mass % to 1.0 mass %.

Abstract: A mixed powder for powder metallurgy includes a machinability improvement powder that is crystalline layered alkaline silicate heat-treated at 400° C. to 1100° C. and whose mix proportion is in an amount of 0.01% to 1.0% by mass in terms of total content of an iron-based powder, an alloying powder, and the machinability improvement powder. Such a mixed powder not only enables a compact to be sintered without adversely affecting the environment in a sintering furnace, but also enables a sintered body having excellent lathe machinability and excellent drill machinability to be obtained.

Abstract: An iron-based powder for powder metallurgy effectively prevents agglomeration of a lubricant, has excellent flowability, can evenly fill thin-walled cavities, keeps the ejection force after formation low, and does not lower sintered body strength by adhering either or both of an alloy component and a cutting ability improving agent to the surface of iron powder with a binder that has a melting point of 150° C. or lower, adhering carbon black to the surface of the binder, and setting the amount of free binder to 0.02 mass % or less.

Abstract: An iron-based powder for powder metallurgy effectively prevents agglomeration of a lubricant, has excellent flowability, can evenly fill thin-walled cavities, keeps the ejection force after formation low, and does not lower sintered body strength by adhering either or both of an alloy component and a cutting ability improving agent to the surface of iron powder with a binder that has a melting point of 150° C. or lower, adhering carbon black to the surface of the binder, and setting the amount of free binder to 0.02 mass % or less.

Abstract: The present invention provides a method for mixing a raw material powder for powder metallurgy that allows efficient mixing at a low cost with a simple measure and easy adjustment of the apparent density by performing first agitation mixing in which a powder mixture obtained by adding, to an iron powder, one or two or more members selected from lubricant powders, free-machining agent powders, and lubricant powders for sliding surface, an alloying powder, and a binding agent is agitated while increasing the temperature to a temperature TK equal to or higher than the melting point TM of the binding agent, the resultant is agitated while maintaining the temperature TK, and the resultant is further agitated while reducing the temperature from the temperature TK, and performing second agitation mixing in which the obtained powder mixture is agitated while cooling.

Abstract: Flowability-improving particles are adhered to surfaces of iron powder through a binder to provide an iron-based powder for powder metallurgy which has excellent flowability and which is capable of uniformly filling a thin-walled cavity and compaction with high performance of ejection force.

Abstract: In an iron-based powder, 0.01% to 5.0% by mass of a flaky powder having an average particle size of longitudinal size of 100 or less, a thickness of 10 ?m or less, and an aspect ratio (longitudinal size-to-thickness ratio) of 5 or more with respect to the iron-based mixed powder is contained, whereby the flowability of an iron-based mixed powder is increased, the density of a green compact is increased, and ejection force is greatly reduced after compaction, thereby accomplishing an increase in product quality and a reduction in production cost.

Abstract: In an iron-based powder, 0.01% to 5.0% by mass of a flaky powder having an average particle size of longitudinal size of 100 or less, a thickness of 10 ?m or less, and an aspect ratio (longitudinal size-to-thickness ratio) of 5 or more with respect to the iron-based mixed powder is contained, whereby the flowability of an iron-based mixed powder is increased, the density of a green compact is increased, and ejection force is greatly reduced after compaction, thereby accomplishing an increase in product quality and a reduction in production cost.

Abstract: In an iron-based powder, 0.01% to 5.0% by mass of oxide particles having an average size of 0.5 ?m or more are contained, whereby the flowability of an iron-based mixed powder is increased and thereby the density of a green compact is increased, and ejection force is greatly reduced after compaction, thereby accomplishing an increase in product quality and a reduction in production cost.

Abstract: A high-strength sintered compact is produced at low cost using an alloy steel powder for powder metallurgy containing no nickel or copper by compacting the alloy steel powder for powder metallurgy or a mixed powder containing the alloy steel powder at a pressure of 700 MPa or more and sintering the compact at a temperature of 1,150° C. to 1,300° C. The alloy steel powder used contains 0.3% to 0.7% by mass of chromium, 0.1% to 0.5% by mass of manganese, 0.1% to 0.5% by mass of molybdenum, and 0.25% to 0.5% by mass of oxygen, the balance being iron and incidental impurities.

Abstract: Flowability-improving particles containing 50 to 100% by mass of carbon black are adhered to surfaces of iron powder through a binder to provide an iron-based powder for powder metallurgy which has excellent flowability and which is capable of uniformly filling a thin-walled cavity, compaction with high ejection force, and maintaining sufficient strength of a sintered body in subsequent sintering.

Abstract: The present invention provides a method for mixing a raw material powder for powder metallurgy that allows efficient mixing at a low cost with a simple measure and easy adjustment of the apparent density by performing first agitation mixing in which a powder mixture obtained by adding, to an iron powder, one or two or more members selected from lubricant powders, free-machining agent powders, and lubricant powders for sliding surface, an alloying powder, and a binding agent is agitated while increasing the temperature to a temperature TK equal to or higher than the melting point TM of the binding agent, the resultant is agitated while maintaining the temperature TK, and the resultant is further agitated while reducing the temperature from the temperature TK, and performing second agitation mixing in which the obtained powder mixture is agitated while cooling.

Abstract: Flowability-improving particles are adhered to surfaces of iron powder through a binder to provide an iron-based powder for powder metallurgy which has excellent flowability and which is capable of uniformly filling a thin-walled cavity and compaction with high performance of ejection force.

Abstract: Flowability-improving particles containing 50 to 100% by mass of carbon black are adhered to surfaces of iron powder through a binder to provide an iron-based powder for powder metallurgy which has excellent flowability and which is capable of uniformly filling a thin-walled cavity, compaction with high ejection force, and maintaining sufficient strength of a sintered body in subsequent sintering.

Abstract: An iron-based powder mixture for powder metallurgy is provided, in which iron-based powder is blended with at least one selected from talc and steatite, and preferably further blended with metallic soap, thereby when a compacted body is sintered, furnace environment is not adversely affected, and excellent compaction performance is achieved even in a low temperature range of less than 100° C., and more preferably, an obtained sintered body has excellent machining performance.

Abstract: A highly compressible iron powder for powder metallurgy has an optimized particle size distribution. The Vickers microhardness of the particles that do not pass through the sieve having the nominal opening of 150 ?m is controlled to be at most about 110. The iron powder is suitable for production of magnetic parts having high magnetism and mechanical parts having high mechanical strength.