| 摘要 |
PURPOSE:To easily obtain a sintered steel having superior machinability, by adding a graphite powder, to the surface of which a part or all of respectively prescribed percentages of fluorides of alkaline earths is allowed to adhere, to an iron powder as raw material, by mixing the above, and by sintering the resulting mixture so as to minimize dimensional change and deterioration in mechanical strength. CONSTITUTION:A part or all of the fluorides of alkaline earths having >=1,200 deg.C melting point (four kinds of MgF2, CaF2, SrF2, and BaF2) is previously added to the graphite powder to undergo mixing. Then, the graphite powder after the above treatment is added to the iron powder as raw material to undergo mixing and the resulting mixture is sintered, so that desired sintered steel excellent in machinability can be obtained. It is necessary to regulate the additive quantity of the above fluorides of alkaline earths to the graphite powder to 0.1-1.2wt% based on the iron powder as raw material. Moreover, it is desirable that grain size of the above fluoride is regulated to <=44mum, preferably <=10mum, for the purpose of adhesion to the graphite powder.
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