Stress corrosion cracking behaviour of the duplex Fe-10Al-29Mn-0.4C alloy in 20% NaCl solution at 100° C

Abstract

The stress corrosion cracking behaviour of the duplex Fe-10 Al-29 Mn-0.4 C alloy having two phases (α andγ) in an aqueous 20% NaCl solution (100° C) has been investigated using both the static constant load and dynamic slow strain rate tests. The constant load test shows that the duplex alloy investigated is immune to stress corrosion cracking in a 20% NaCl solution. However, the slow strain-rate test reveals that this alloy is susceptible to stress corrosion cracking at the stabilized corrosion potential, and also at potentials anodic and cathodic to this potential. Furthermore, the metallographic cross section of this duplex alloy after slow strainrate testing shows that the secondary cracks propagate transgranularly through the ferrite grains at and above the stabilized corrosion potential. However, the cracks propagate transgranularly in both the ferrite and austenite grains and also at the austenite-ferrite grain boundaries when the applied potential is cathodic to the stabilized corrosion potential.