C-pot Calculator
Calculate carbon potential and carbon activity from CO, CO₂ and temperature. Soot risk when a_c > 1 (graphite). Pure-iron C-pot — fine-tune against your furnace controller.
Frequently Asked Questions & Practical Metallurgy
Why Carbon Potential Matters
Carbon potential (C-pot) dictates whether the steel surface absorbs, maintains, or loses carbon atoms during heat treatment. Depending on the setting, three primary interactions occur:
- Carburizing: Occurs when the atmosphere's potential is higher than the steel's current carbon content, pushing carbon into the surface (case hardening) to improve wear resistance.
- Neutral Hardening: The potential perfectly matches the steel's carbon content. This prevents carbon from being added or lost, protecting the surface finish.
- Decarburization: Occurs when the potential is too low, stripping carbon from the steel and causing it to lose surface strength.
Why is soot forming during methanol cracking?
In equilibrium theory, soot (graphite) forms when carbon activity a_c exceeds 1. Incomplete methanol cracking also causes soot: inject methanol only where the furnace is hot enough (in practice above about 800 °C). Unstable N₂/methanol flows, air leaks or high enriching-gas rates can push a_c above the limit and soot the furnace.
How do process transitions affect the atmosphere?
Constantly shifting between decarburizing, carburizing, and tempering puts immense stress on the furnace atmosphere. When jumping back and forth across hundreds of tons of parts, the CO/CO2 ratio becomes highly volatile. Using a C-pot calculator helps you instantly find the new equilibrium for each specific cycle.
Why are regular furnace burnouts critical for accurate readings?
Running heavy production for extended periods without a proper burnout leaves residual carbon inside the furnace walls. This ghost carbon skews your lambda probes and gas analyzers, forcing the atmosphere control to fight against itself.