Patent ID: 8425691

Claim:
A process for carburizing martinsitic stainless steel in a high temperature furnace comprising: i. reducing the pressure in the furnace by removing the air therein to create a partial vacuum at a furnace atmospheric pressure of from about 300 torr to about 500 torr; ii. contacting said steel with a hydrocarbon carburizing gas mixture consisting of acetylene and hydrogen through the intermittent pulsed injection of the gas that replaces the air removed in the pressure reduction step at a temperature of from about 1800° F. to about 2500° F.; iii. contacting said steel with the hydrocarbon carburizing gas for a period that allows the carbon to dissociate from the gas mixture and deposit on the surface of the steel to a specified depth of penetration; and, iv. quenching the steel by rapidly reducing the temperature from about 1100° C. to about 500° C. at increased pressure of about 10 barr to produce a substantially hardened martinsitic base.