The corrosion behaviors of five Fe-Mn-Al (Femnal) alloys with ferrite contents varying from 0.5% to 98% were studied in 3.5% sodium chloride (NaCl) at room temperature. Potentiodynamic polarization tests and immersion tests were performed. In deaerated solution, the corrosion potentials (Ecorr) of these alloys were very close. The passive current (ip) increased and the width of the passive region decreased as the ferrite content increased. However, the nearly ferritic alloy showed much better passivation behavior, presumably because of the addition of 6.23% Cr. In aerated solution, either no passive region or a very small passive region was observed. From the immersion test, general corrosion was found to be minor. Pitting was the primary corrosion form, except for the ferritic alloy. The pits were found more frequently in the ferrite phase or at the interface between the ferrite and austenite phases.

Subject
Pits, Corrosion resistant alloys, Ferrite content, Sodium chloride solution, Pitting, Passivation, Immersion, Corrosion resistance, Ferrite, Alloys, Potentiodynamic polarization, Austenite, Types of corrosion
Keywords:
austenite, Femnal alloys, ferrite, general corrosion, immersion testing, phases, pitting, potentiodynamic polarization, sodium chloride solution, two-phase alloys
NACE International
1995
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