Method for producing mixed powder for powder metallurgy, method for producing sintered compact, and sintered compact

Abstract

Provided is a mixed powder for powder metallurgy with which it is possible to obtain a sintered compact that, despite not containing Ni, has an excellent tensile strength and ductility equivalent to or better than those of a sintered compact containing Ni. This method for producing a mixed powder for powder metallurgy includes: a first mixing step, in which a starting material mixed powder is obtained by mixing a Mo-containing powder and a Cu-containing powder into an iron-based powder; a diffusion / adhering step, in which a partially-diffused alloyed steel powder is obtained by diffusing and adhering the Mo and Cu onto the surface of the iron-based powder by heat-treating the starting material mixed powder; and a second mixing step, in which the mixed powder for powder metallurgy is obtained by mixing a graphite powder into the partially-diffused alloyed steel powder. The average grain diameter of the iron-based powder is 30-120 [mu]m. A cuprous oxide powder is used as the Cu-containing powder. The component composition of the mixed powder for powder metallurgy is 0.2-1.5 mass% Mo, 0.5-4.0 mass% Cu, and 0.1-1.0 mass% C, with the remainder comprising Fe and unavoidable impurities.

Description

technical field [0001] The present invention relates to a method for producing a mixed powder for powder metallurgy, and more particularly, to a method for producing a mixed powder for powder metallurgy that has properties suitable for manufacturing high-strength sintered parts for automobiles, etc., although it does not contain Ni. Moreover, this invention relates to the manufacturing method of a sintered body, and the sintered body obtained by the said manufacturing method. Background technique [0002] Powder metallurgy technology enables the manufacture of complex-shaped components in a shape that closely approximates the product shape (so-called near-net shape) and with high dimensional accuracy. Therefore, when using powder metallurgy technology to make parts, cutting costs can be greatly reduced. Therefore, powder metallurgy products to which powder metallurgy technology is applied are used in various fields as parts for various machines. [0003] In this powder met...

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Problems solved by technology

However, during sintering, each alloy element is not sufficiently diffused in Fe to form a non-uniform structure. As a result, the strength of the finally obtained sintered body may be poor.

In addition, when Mn, Cr, V, Si, etc. are used as alloy elements, these elements are more likely to be oxidized than Fe, so there is a problem that they are oxidized during sintering and the strength of the finally obtained sintered body is reduced.

However, pre-alloyed steel powder is produced by atomizing molten steel, so oxidation in the atomizing process of molten steel and solid solution hardening of steel powder caused by complete alloying are likely to occur. As a result, there are difficulties in press forming. Problems such as increasing the density of compacted powder

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