Oxidation of a Fe-18Cr-8Ni austenitic stainless steel at 850 °C in O2: Microstructure evolution during breakaway oxidation

Oxidation tests of AISI 304L in breakaway conditions (850 °C in O2) were performed up to 312 h. The evolution of the oxidation affected zone microstructure was investigated using a combination of composional/elemental (TEM, Raman spectroscopy) and structural (EBSD) mapping techniques as well as thermodynamic calculations. The formation of a dense and continuous Cr2O3 healing layer at the border of the internal oxidation zone happens along the grain boundaries and is linked to their more efficient Cr supply. The propagation of the oxidation front is related to a local conversion of Cr2O3 in less protective FeCr2O4.