PROCESS FOR SINTERING FERROUS BASED POWDERS UNDER A PROTECTIVE NITROGEN BASED ATMOSPHERE

摘要

A process is disclosed for sintering ferrous based powder parts. The parts are heated to a sintering temperature at or above 1120.degree.C (2048.degree.F) for a period of at least 20 minutes in the presence of a flowing nitrogen atmosphere containing an admixture of about 5 to about 8% by volume endothermic generator gas which desirably controls decarburization of dissolved carbon promoting increased part strength. Additional control of the dissolved carbon content in the sintered part can be preferably enhanced by the addition of .4-.6% methane to the flowing nitrogen atmosphere. To avoid sooting of the parts due to the cracking of added hydrocarbons during heatup to sintering temperature with flowing atmosphere, the parts are preheated at a temperature between volatilization of the added hydrocarbon and 1250.degree.F for a period of time to volatilize the added hydrocarbons in the powder parts prior to ascending to full sintering temperature.