Metallic powder-molded body, re-compacted body of the molded body, sintered body produced from the re-compacted body, and processes for production thereof

Abstract

In a preliminary molding step, a metallic powder mixtureobtained by blending an iron-based metal powderwith graphitesuch that the graphite is present in an amount of preferably not less than 0.1% by weight, more preferably not less than 0.3% by weight, is compacted into a preformhaving a density of not less than 7.3 g/cm. In a provisional sintering step, the preformis provisionally sintered at a predetermined temperature to form a metallic powder-molded bodyhaving a structure in which the graphite remains along a grain boundary of the metal powder. In a re-compaction step, the metallic powder-molded bodyis re-compacted into a re-compacted body. In a re-sintering step, the re-compacted bodyis re-sintered to obtain a sintered body. In a heat treatment step, the sintered bodyis heat-treated to obtain a heat-treated sintered body Accordingly, in accordance with the present invention, there are provided a re-compacted body produced from a metallic powder-molded body having an excellent deformability which is suitably applied to the production of machine parts exhibiting high mechanical properties due to the use of sintered metal, and a sintered body produced from the re-compacted body as well as a process for the production thereof.