METHOD OF HEAT TREATING A METAL WITH NITROGEN RICH GAS PREHEATED AND THEN HAVING OXYGEN-REACTIVE GAS ADDED

摘要

A method for forming a heat treating atmosphere in which a nitrogen rich gas containing small amounts of oxygen is preheated. An oxygen-reactive gas, such as a hydrocarbon gas, is combined with the nitrogen rich gas and the mixture is reacted outside of the furnace at temperatures above which substantial sooting does not occur. The resulting heat treating atmosphere is then forwarded to the furnace for conducting the heat treating process. IMAGE