Influence of atmosphere on high‐temperature oxidation of Fe‐Cr‐Si model alloy

The aim of this work is to show the influence of the gaseous environment on the ferritic Fe-Cr-Si model alloy oxidation during 70 h, at 900 °C and 950 °C. Two different atmospheres have been used: air or nitrogen containing 5 Vol.% hydrogen (N 2-5%H 2). After air oxidation, a non-adherent chromia scale formed. In the N 2-5%H 2 gaseous environment, it clearly appears that silicon segregation near the internal scale-metal interface is favoured. In this low oxygen containing gas, adherent chromia and silica scales have been formed. Silica subscale associated to an adherent chromia scale obtained in low oxygen conditions are a good protection barrier against carburisation.