Abstract: An alloy steel powder having a basic alloy composition, which is composed of at least one of manganese, chromium, molybdenum and vanadium, and the remainder being iron, and having low carbon, nitrogen and oxygen contents is excellent in the compressibility and moldability at the press molding and further excellent in the carburizing property and hardenability in its sintered steel or powder forged steel.

Abstract: A process and an apparatus for producing low-oxygen iron-base metallic powder are disclosed. The low-oxygen iron-base metallic powder is produced by alloying and/or admixing iron-base metallic raw powder to be subjected to a final reduction, which has an apparent density in filled state corresponding to 16-57% of theoretical true density, an oxygen content of not more than 6% by weight and a particle size of not more than 1 mm, with carbon or carbonaceous granule in an amount corresponding to not more than an target alloying carbon content of a final product (% by weight) + an oxygen content of the powder just before the final reduction (% by weight) .times. 1.35 to form a starting powder, preheating the starting powder at a temperature of 780.degree.-1,130.degree. C. in a non-oxidizing atmosphere having a theoretical oxygen partial pressure of not more than 2.1.times.10.sup.-1 mmHg and a dew point of not more than +5.degree. C.

Abstract: A shaft furnace for producing low-oxygen iron-base metallic powder for metallurgy is disclosed. The shaft furnace comprises a zone of storing and feeding a metallic raw powder, a preheating zone, an induction heating zone and a zone of cutting and cooling a product cake in a vertical array from top to bottom. The preheating zone and induction heating zone have a special structure for ensuring a smooth descent of the raw powder and the cake.

Abstract: A process for producing low-oxygen iron-base metallic powder are disclosed. The low-oxygen iron-base metallic powder is produced in a shaft-type apparatus comprising a preheating zone and an induction heating zone by alloying and/or admixing iron-base metallic raw powder to be subjected to a final reduction, which has an apparent density corresponding to 16 to 57% of theoretical true density, an oxygen content of not more than 6% by weight and a particle size of not more than 1 mm, with carbon or carbonaceous granule in an amount corresponding to not more than a target alloying carbon content of a final product (% by weight)+ an oxygen content of the powder just before the final reduction (% by weight).times. 1.35 to form a starting powder, preheating the starting powder at a temperature of 780.degree. to 1,200.degree. C. in a non-oxidizing atmosphere having a thermodynamically calculated oxygen partial pressure of not more than 2.1.times.10.sup.-1 mmHg and a dew point of not more than +5.degree. C.

Abstract: A metal block having a high density can be easily obtained directly from metal powder by charging the metal powder in a metallic container, disposing carbonaceous powder through a partition plate on the metal powder so as to interrupt the metal powder from the air, uniformly heating the metal powder in the air together with the container and subjecting the metal powder in the air together with the container to a primary hot working and to a secondary hot working with or without effecting a uniform heating step.

Abstract: Iron or iron alloy powders having a low oxygen content to be used for powder metallurgy are produced by subjecting iron or iron alloy powder materials having an oxygen content of not more than 8% by weight and a total carbon amount including carbon alloyed in said powders being not more than 6% by weight corresponding to the oxygen content to an induction heating under a relative density of 5-65% based on a density of the molding steel of said powders by means of an alternating current of 50 cycles-1 megacycle to heat said powders at a temperature of 750.degree.-1,400.degree.C to effect reduction rapidly.