Evaluation of aged duplex stainless steel UNS S32750 susceptibility to intergranular corrosion by optimized double loop electrochemical potentiokinetic reactivation method

Optimized double loop electrochemical potentiokinetic reactivation (DL-EPR) in combination with microstructure observation were successfully applied to study the sensitization of super duplex stainless steel UNS S32750 aged at 900 °C for different duration to intergranular corrosion (IGC). The results indicated that the degree of sensitization increased gradually with the aging time increased from 10 min to 4 h due to the sigma phase precipitation, and Ir:Ia value reached the maximum value of 17.1%. However, further increasing aging time slightly decreased the sensitization due to the healing effect incurred by the diffusion of chromium from adjacent grains to chromium-depleted zone.

► Optimization DL-EPR test condition for DSS UNS S32750. ► Quantitatively and rapidly evaluate intergranular corrosion. ► Characterization of the relationship between precipitation and kinetics. ► Announce the relationship between precipitation and intergranular corrosion.