Influence of chromium additions on the oxidation resistance of an austenitic Fe-30Mn-5Al alloy

Abstract

The oxidation behavior of an austenitic Fe–30Mn–5Al (wt.%) alloy with chromium contents ranging from 3 to 9 wt.% was evaluated in air between 600 and 900°C. The alloy with the highest chromium content showed the best oxidation resistance over the entire temperature range. The high mass gains of chromium-free material result from internal oxidation from the earliest stages of oxidation over the entire temperature range. Chromium additions delay the beginning of internal oxidation for longer times and/or higher temperatures. The beneficial influence of chromium additions is linked to the establishment of a rather continuous, ferrite-rich subsurface. This subsurface, together with the secondary oxygen-getter effect of chromium, favor the rapid establishment of a protective alumina layer. The different processes occurring throughout the oxidation manifest the complexity of the mechanism controlling the oxidation in chromium-free and chromium-containing alloys.