Tests were performed in a carburizing environment with an inlet gas mixture (volume %) of 5.0% H2, 5.0% CO, 5.0% CH4 and the balance argon. The calculated oxygen potential and carbon activity at 1800°F (980°C) were 9 x 10-22 atm. and 1.0, respectively.
The results are presented in terms of the mass of carbon pickup per unit area, which was obtained from the equation M = C (W/A) where M = the mass of carbon pickup per unit area (mg/cm2), C = difference in carbon (weight fraction) before and after exposure, W = weight of the unexposed specimen (mg) and A = surface area of the specimen exposed to the test environment (cm2).