Influence of nitridation on the oxidation of a 304 steel at 800 °C

This paper presents a study on the oxide growth on a AISI 304 chromia-forming alloy, in air at 800 °C. After the nitridation treatment was performed on the steel surface, a γN solid solution is detected. In this case, no nitride formation in the alloy surface could be observed. In situ X-ray diffraction has been used to follow the oxides evolution at testing temperature. At the beginning of the oxidation test, CrN is formed together with Fe2O3. Nevertheless, Cr2O3 quickly appears and leads to a protective oxide scale formation growing according to a parabolic rate law. During oxidation in situ X-ray diffraction also shows that Fe2O3 is transformed into FeCr2O4. Our results show that nitridation increases the high temperature oxidation resistance of 304 steels at 800 °C.