In part 1, we discussed what happens when refractory is contaminated by the carbon-rich furnace atmosphere.

Furnace atmosphere burnout is a controversial subject among both captive and commercial heat treaters.

Atmosphere control is critical to the success of heat-treat practices, especially with the carburizing process.

The carbon potential in the process furnace atmosphere to ensure a good carburized case should be determined by the type of steel to be treated and the carburizing process temperature.

If it has been ascertained that the endothermic generator is functioning correctly, then the next step is to observe the process furnace atmosphere conditions.

Protective atmospheres for heat-treatment shops (captive or commercial) can fall into five categories: endothermic, blended gases, exothermic, elemental gases, vacuum and air.

We resume our discussion of furnace gases (see part 1).

The question “What is an atmosphere?” is often asked.

If the steel part has been surface treated by carburizing, carbonitriding, austenitic nitrocarburizing, ferritic nitrocarburizing, nitriding or boronizing, one cannot always grind into the finished surface.

The result of hardness testing is what will determine the success of the heat-treatment procedure and the material’s response to that heat treatment.