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AssigneeKawasaki Steel Corporation
InventorsKuniaki Ogura, Hiroyuki Ishikawa, Takeo Omura, Yoshiaki Maeda, Minoru Nitta, Hiroshi Ohtsubo, Yutyaka Yoshii
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This invention is to control the diffusion of C (carbon) from added graphite to particles of iron powder in the sintering to thereby improve the accuracy of dimensional change in the sintered body by using iron powder for powder metallurgy and a mixed powder thereof as a starting material in the production of sintered mechanical parts by adding the iron powder with Cu powder and graphite powder and companying and sintering them, in which 0.008-0.5 wt % in total of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/l mol of O.sub.2 is included in the iron powder and not less than 20% of the element is rendered into an oxide, or 0.01-0.20 wt % in total of an oxide powder of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/l mol of O.sub.2 is added to the mixed powder.
A powder for powder metallurgy comprising 0.01-0.20 wt % in total of oxide powder of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/l mol of O.sub.2 and a mixed powder, said mixed powder including 0.5-1.0 wt % graphite powder or a mixture of 0.5-1.0 wt % graphite powder and 1.5-2.0 wt % Cu powder, and the remainder being iron powder.
Dependencies are inferred from the claim text.