Neutral hardening is performed on steel alloys with sufficient hardenability to attain designated surface and core hardness, without surface treatments (carburizing or carbonitriding). When neutral hardening in an atmosphere controlled furnace, the furnace atmosphere’s carbon potential is matched to the heated part’s carbon concentration; thus the heated part surfaces are not enriched or decarburized.

After heating in a neutral atmosphere, parts are quenched into furnace-integral, temperature controlled and agitation controlled oil baths. Quenching in oil fully hardens the parts; tempering is necessary after quenching to relieve stresses in the part from the heat treat process and to reduce part hardness to the designated hardness range.

Carbon Restoration

The carbon restoration process restores partial or fully decarburized part surfaces. During the hardening process, the carbon potential of the furnace atmosphere is maintained at a level slightly in excess of the carbon content of the material being processed. After the desired surface carbon content is achieved, the parts may be quenched and tempered, or slow cooled.

IST’s metallurgical lab facility evaluates the case depth and hardness of each heat treat load, and certifies results.