Effect of Chromium Content on Corrosion Behaviors of Fe-9Al-30Mn-(3,5,6.5,8)Cr-1C Alloys

Abstract

The corrosion behaviors of the as-quenched austenitic Fe-9%Al-30%Mn-(3,5,6.5,8)%Cr-1%C (in mass%) alloys in 3.5% NaCl solution have been examined. Passivation could be observed for all of the four alloys. The corrosion potential (E_corr) and pitting potential (E_pp) increased pronouncedly as Cr content increased from 3 to 5%, and decreased as Cr content up to 6.5 and 8%. The decrease of E_corr and E_pp of alloys containing 6.5 and 8% Cr was due to the formation of (Fe,Mn,Cr)₇C₃ carbides within the austenite matrix and on the grain boundaries. The present result indicates that the Fe-9%Al-30%Mn-5%Cr-1%C alloy exhibited the highest corrosion resistance in 3.5% NaCl solution. It is worthy to note that the corrosion behaviors of the austenitic FeAlMnCrC alloys with higher Cr (≥3%) content have never been reported in previous literature.