Effect of “475°C Embrittlement” on the Corrosion Behaviour of Grade 2205 Duplex Stainless Steel Investigated Using Local Probing Techniques

The work reported in this paper correlates microstructure development after low temperature embrittlement heat treatments with pitting corrosion susceptibility in grade 2205 duplex stainless steel. Heat-treatments at 475°C for up to 255 hours were carried out and microstructures characterised using scanning electron microscopy (SEM) and micro-hardness testing. Local electrochemical measurements using an electrochemical micro-cell were carried out and the critical pitting temperature (CPT) determined. Short-duration heat treatments for up to 10 hours showed an increase in CPT, attributed to an improved electrochemical character of the ferrite. Long-term heat treatments (>50 hours) indicated a decrease in CPT due to the precipitation of other precipitates and the formation of elemental depletion zones.