Oxidation of an austenitic stainless steel with or without alloyed aluminum in O2 + 10% H2O environment at 800 °C

Oxidation behavior in O2 + 10% H2O at 800 °C of an austenitic stainless steel with or without aluminum is investigated. The Al-free steel enters into breakaway oxidation stage after only 15 h exposure, while the one with 2.7 wt% aluminum shows high oxidation resistance. This minor amount of aluminum is lower than the critical content to form an intact alumina scale, but it promotes the formation of a thin Al-rich inner layer which is favor in prohibiting holes formation due to volatilization of CrO2(OH)2 and Kirkendall effect. A compact scale develops and protects the Al-containing steel very well.