Carburization of 310 stainless steel exposed at 800–1100 °C in 2%CH4/H2 gas mixture

Carburization of 310 stainless steel has been investigated after cyclic exposures at high temperatures 800–1100 °C in a 2%CH4/H2 carburizing gas mixture for 500 h duration. A thermodynamic analysis indicates that 1000 °C is an approximate boundary 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. Below 1000 °C, 310SS suffered external carburization, oxidation, and internal carburization. In excess of 1000 °C, extensive external carburization occurred and internal Cr-carbides disappeared. Cr segregation is proposed to interpret the effect of temperature on the continuity of an external scale layer and carburization behavior.