METHOD OF HEAT TREATING METALLIC PARTS BY CARBURIZATION

摘要

The method of carburizing steel workpieces comprises loading workpieces to be carburized in a furnace and maintaining them in a carbon enriching atmosphere comprising carbon monoxide, hydrogen and nitrogen. The treatment comprises a first phase carried out at a temperature from 850 DEG C. to 1050 DEG C. followed by a second phase carried out at a temperature from 700 DEG C. to 950 DEG C. During the first phase an atmosphere is used having a carbon potential from about 1.1% to about 1.6% by weight and during the second phase the amount of nitrogen in the atmosphere is increased from two to thirty times so that the carbon potential for the second phase is at least about 0.5% by weight less than the carbon potential for the first phase.