GAS CARBURIZING OF STEEL WITH FURNACE ATMOSPHERES FORMED IN SITU FROM AIR AND HYDROCARBON GASES.

Carburizing trials were carried out in a Lindberg carburizing furnace, using small 1010 steel stampings as test specimens. Constant flows of air were supplied to the furnace, and the butane addition was automatically controlled to maintain a constant voltage output from a zirconia oxygen sensor located in the furnace. It is shown that butane-air blends, introduced directly into the carburizing furnace, can be used to form furnace atmospheres suitable for carburizing. Control of the atmosphere carbon potential is readily achieved by automatically regulating the inlet butane/air ratio to maintain a constant oxygen potential as measured by a zirconia oxygen sensor.