Control setpoint in carburizing and neutral hardening, expressed as percent carbon. It is calculated from oxygen probe millivolts, dew point or CO2 readings and furnace temperature, and checked with shim stock: thin low-carbon foil is exposed in the furnace, then weighed or burned for carbon. An atmosphere above the steel's own carbon carburizes it; one below decarburizes it.
Probe says 0.85 carbon potential but the shim came back 0.72, somebody needs to burn off that probe.
When the probe and the shim disagree, believe the shim and recalibrate the probe.
Also heard as
- CP
- carbon pot
Related terms
Endothermic gas
A carrier atmosphere of carbon monoxide, hydrogen and nitrogen made by reacting natural gas with air.
Dew point
The temperature at which water vapor in a furnace atmosphere condenses, used as a gauge of carbon potential.
Boost and diffuse
Carburizing schedule that first floods the surface with carbon, then lowers the potential so it spreads inward.
Running rich
Shop talk for a furnace atmosphere carrying more carbon than its setpoint and heading toward soot.
Decarburization
Loss of carbon from the surface of steel during heating, leaving a soft skin that will not fully harden.