Calculate gas compositions, dew point, and carbon potential for industrial furnace atmospheres — endogas, nitrogen-methanol, hydrogen blends, and more.
Controlling furnace atmosphere composition is fundamental to producing consistent, defect-free heat-treated parts. Whether you are carburising low-alloy steel, bright annealing stainless, or sintering PM components, the relationship between gas composition, dew point, and carbon potential determines surface chemistry and final mechanical properties.
For endothermic and nitrogen-methanol systems, even small deviations in CO/CO₂ ratio or methanol drip rate can shift carbon potential by 0.1–0.2 %C — enough to push a carburised gear outside case depth and surface carbon specification. Our calculator uses established equilibrium thermodynamics (Harris equation, iron-carbon activity) to translate measured gas analysis directly into carbon potential at any temperature from 850 °C to 1050 °C.
Dew point is a common alternative measurement: the calculator converts between dew point and carbon potential in both directions, and also outputs the expected CO/CO₂ and H₂/H₂O ratios that an infrared analyser should read for a target atmosphere setpoint.
Carbon potential (Cp) is the carbon content at which the furnace atmosphere is in equilibrium with steel at a given temperature — expressed as weight percent carbon. An atmosphere with Cp = 0.80 %C will neither add nor remove carbon from a steel surface that already contains 0.80 %C. For carburising, a higher Cp drives carbon into the steel surface; for neutral hardening, Cp is matched to the steel's bulk carbon content to prevent decarburisation.
In a CO-H₂-N₂ atmosphere, dew point measures the moisture content of the gas. A lower (more negative) dew point corresponds to a more reducing atmosphere and a higher carbon potential. At 930 °C in a typical endogas atmosphere, a dew point of −10 °C corresponds to approximately Cp 0.80 %C, while −25 °C gives around Cp 1.0 %C. The precise relationship depends on CO content and temperature, which the calculator handles automatically.
Nitrogen-methanol systems typically operate at a total gas flow of 3–6 furnace volumes per hour. Methanol cracks to CO + 2H₂ in the hot zone (above approximately 700 °C), so a 60/40 N₂/MeOH split by volume delivers roughly 20% CO and 40% H₂ — similar to endogas. The calculator outputs recommended N₂ flow (Nm³/hr) and methanol drip rate (ml/min or litres/hr) for your furnace volume and target atmosphere.
Yes. Bright annealing of stainless steels (austenitic grades such as 304, 316) requires a highly reducing, hydrogen-rich atmosphere — typically 75–100% H₂ with a very low dew point (below −40 °C). The calculator supports H₂/N₂ blend selection and outputs the required dew point to maintain oxide-free surfaces, referencing the Ellingham diagram stability boundaries for Cr₂O₃ and FeO at your annealing temperature.
Join engineers from Howmet, Safran, Hoganas, and 50+ other companies already using the Bloor Engineering platform.
Create Free Account →Also available: Carbon Potential Calculator · Diffusion Calculator · Furnace Load Calculator