PRODUCTION OF HIGH-NITROGEN HIGH-ALLOY STEEL POWDER

摘要

PURPOSE:To permit production of high-nitrogen high-alloy steel powder without requiring specific stages by melting a raw material metal in gaseous nitrogen or mixed gaseous atmosphere composed nitrogen and ammonia of the atm. pressure or above and atomizing the metal with the gaseous nitrogen. CONSTITUTION:The raw material is charged into a melting furnace 2 provided in a tank 1 and the inside of the furnace is evacuated to remove the air and moisture from the tank 1 inside. The high-purity gaseous nitrogen or the gaseous mixture composed of the nitrogen and 0.01-5% ammonia is introduced under the pressure above the atm. pressure into the furnace through an atmosphere introducing valve 4a and the melting furnace is heated up to melt the raw material metal. The molten metal is dropped from a tundish 5 by a molten metal nozzle 6 to form the falling molten metal flow, to which the high-pressure gaseous nitrogen is injected from an injection nozzle 7 to produce the powder instantaneously. While the powder falls in an atomization chamber 8, the powder is cooled and is captured by a cyclone separator 10.