Patent ID: 7468107

Claim:
A method of carburizing a steel component, comprising: heating said component to a carburizing temperature of about 1900 degrees F. and greater; contacting said component at said carburizing temperature with a methane-containing endothermic carburizing atmosphere that comprises methane, carbon monoxide, hydrogen, and nitrogen for a carburization time; monitoring concentration of methane in said carburizing atmosphere; controlling a level of methane enrichment of said carburizing atmosphere in a substantially continuous manner by feedback control of said monitored concentration of methane according to said carburization time and said carburizing temperature, said methane enrichment controlling said carburizing atmosphere to further control carburizing of a carbon-enriched surface case on an underlying non-carburized core of said component; and cooling said component at a relatively slow rate effective to provide said surface case free of martensite on said component.