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 10min to 4h 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. © 2012 Elsevier Ltd.