Steam oxidation of 316Nb Stainless-Steel from 850°C to 1350°C: kinetics and thermodynamic analysis

This paper presents a comprehensive study on the steam oxidation behaviour of 316Nb stainless steel at temperatures ranging from 850°C to 1350°C. The oxidation process formed complex, multilayered scales on the 316Nb samples. The outermost layer, primarily composed of iron oxides (magnetite and wüstite), was non-adherent and brittle. At temperatures above 1150°C, an intermediate layer containing oxygen, iron, and chromium was observed. The innermost layer exhibited a porous, fine-grained structure of oxidic particles embedded in a metallic Fe-Ni matrix. The oxidation kinetics can be approximated by a parabolic law after an initial incubation period, with 316Nb demonstrating superior resistance to steam oxidation compared to 304L stainless steel below 1200°C. Above this temperature, both alloys exhibited similar oxidation behaviour. A key insight from this study is the absence of catastrophic oxidation in 316Nb, despite its significant molybdenum content