Iron-based mixed powder for powder metallurgy and iron-based sintered body

Abstract

Provided is an iron-based mixed powder for powder metallurgy that has excellent compressibility and, even in a typical production process with a compacting pressure of less than 600 MPa, enables production of a sintered body having a tensile strength of 1200 MPa or more and excellent impact resistance. An iron-based mixed powder for powder metallurgy consists of: a partially diffusion-alloyed steel powder comprising an iron-based powder and Mo diffusionally adhered to a surface of the iron-based powder; and an alloying metal powder. The iron-based powder has a certain chemical composition, the partially diffusion-alloyed steel powder has a Mo content of 0.20 mass % or more and 1.5 mass % or less, and an apparent density of 2.8 g/cm 3 or more and 3.6 g/cm 3 or less, and the alloying metal powder contains at least one of a Cu powder and a Ni powder with a certain apparent density in a certain amount.

1 . An iron-based mixed powder for powder metallurgy, consisting of:
 a partially diffusion-alloyed steel powder comprising an iron-based powder and Mo diffusionally adhered to a surface of the iron-based powder; and   an alloying metal powder,   wherein the iron-based powder has a chemical composition containing Mn: 0.04 mass % or more and 0.15 mass % or less and Si: 0.01 mass % or more and 0.10 mass % or less with a balance consisting of Fe and inevitable impurities,   the partially diffusion-alloyed steel powder has a Mo content of 0.20 mass % or more and 1.5 mass % or less, and an apparent density of 2.8 g/cm 3  or more and 3.6 g/cm 3  or less,   the alloying metal powder contains one or both of a Cu powder with an apparent density of 0.5 g/cm 3  to 2.0 g/cm 3  and a Ni powder with an apparent density of 0.5 g/cm 3  to 2.0 g/cm 3 , and   an addition amount of the Cu powder is 0 mass % to 3.0 mass %, an addition amount of the Ni powder is 0 mass % to 3.0 mass %, and a total addition amount of the Cu powder and the Ni powder is 0.5 mass % or more, with respect to a total mass of the partially diffusion-alloyed steel powder and the alloying metal powder.   
     
     
         2 . The iron-based mixed powder for powder metallurgy according to  claim 1 , wherein a mass ratio of the Ni powder to a total mass of the Cu powder and the Ni powder is 0.8 or less. 
     
     
         3 . An iron-based sintered body obtainable by carburizing, quenching, and tempering a sintered body produced using the iron-based mixed powder for powder metallurgy according to  claim 1 . 
     
     
         4 . An iron-based sintered body obtainable by carburizing, quenching, and tempering a sintered body produced using the iron-based mixed powder for powder metallurgy according to  claim 2 .