| 摘要 |
PURPOSE:To obtain a sintered forged parts excellent in strength, accuracy and surface roughness, by applying sintering, cooling, forging and re-sintering to a preform being the compression molded green compact of a ferrous metal powder under specific conditions before applying cold coining to the surface thereof. CONSTITUTION:A ferrous metal powder is subjected to compression molding to form a preform which is, in turn, sintered at 1,100 deg.C or more. Subsequently, the sintered preform is cooled so that the surface temp. thereof reaches 600-700 deg.C and the central temp. is held to 900 deg.C or more to perform forging. Further, the treated preform is re-sintered at 1,100 deg.C or more and, thereafter, cold coining is applied to the surface of the resulting forged parts. By this method, not only the strength of the sintered forged parts is enhanced but also the accuracy and surface roughness thereof are made excellent.
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