Carburization Behavior of 310 Stainless Steel in CH4/H2 Gas Mixture with Trace Amount of Oxygen

The carburization behavior of 310 stainless steel has been studied after cyclic exposures to carburizing gas mixtures at elevated temperatures for 500 hr exposures. A thermodynamic analysis indicated that 1000 °C was an approximate critical temperature, below which the environment should result in mixed oxidizing/carburizing behavior while above this temperature, reducing-carburizing behavior should occur. The experimental results agree well with the thermodynamic analysis, at 800 °C in 2% CH4/H2 for 310SS which suffers both external oxidation, carburization, and internal carburization. At 1100 °C in 10% CH4/H2 external carburization occurs and internal carburization becomes less pronounced. Schematics are illustrated to show corrosion mechanisms in various exposure environments.