An Electrochemical Test For Detecting the Intergranular Corrosion Susceptibility of a Duplex Stainless Steel

The double-loop electrochemical potentiokinetic reactivation (EPR) method was used to evaluate the intergranular corrosion (IGC) susceptibility of a duplex stainless steel (SS). The purpose of the examination was to assess the influence of simulated weld cooling rates on microstructure and the subsequent IGC susceptibility. Those specimens that were rapidly cooled through a 1200 to 815 C (2200 to 1500 F) temperature range were found to exhibit the highest degree of susceptibility to intergranular attack (IGA) relative to those cooled more slowly through this region. Specimens cooled more slowly exhibited various degrees of improvement in the resistance to susceptibility. A good correlation was obtained between a modified oxalic acid test, similar to that described by ASTM Practice A262-A, and the electrochemical double-loop technique. The use of both of these procedures for IGC susceptibility examination is well documented for the case of 300 Series SS, but heretofore has not been described for the examination of a duplex SS.