PURPOSE: To produce powder metal forged parts having excellent hardenability and toughness inexpensively in the stage of producing the powder metal forged parts by using the Cr-Mn low alloy steel powder of ultra low oxygen produced by an oil spraying method and decarburizing the same in a sintering stage.
CONSTITUTION: The melt of inexpensive Cr-Mn low alloy steel having excellent hardenability is pulverized in an oxidation-free state by an oil spraying method using nonpolar solvents or mineral oils, vegerable oils, etc. The powder is degreased and in that state the powder is molded under pressure without decarburization to produce green compacts. The green compacts are heated and decarburized in a high dew point atmosphere. Thereafter the atmosphere is changed to an inert gaseous atmosphere and is heated up to the sintering temp., whereby the green compacts are sintered. The treating atmosphere is changed from the inert gas to a carburizable gas contg. carbohydrate and the temp. is reduced down to the forging temp. at which the green compacts are forged. The powder metal forged parts having excellent hardenability and toughness are produced inexpensively.
SAITOU HAJIME
UNNO MASAHIDE
SATOU YASUHIRO
NISHIGUCHI MASARU
Next Patent: PRODUCTION OF POWDER METAL FORGED PARTS HAVING EXCELLENT HARDENABILITY AND TOUGHNESS