Microstructure, Chemical- and Phase Composition of Sanicro 25 Austenitic Steel After Oxidation in Steam at 700 °C

Microstructural investigation of Sanicro 25 austenitic steel after steam oxidation at 700 °C for up to 5000 h was conducted using advanced analytical- and high-resolution electron microscopy methods. The study revealed the presence of Cr 2 O 3 plates at the scale surface. Underneath the scale was a chromium-depletion zone that evolved with the oxidation process. In the area that was not affected by oxidation, numerous M 23 C 6 , ε-Cu precipitates and some W-rich Laves phase were formed.