Technical Note: Electrochemical Testing for Pitting Corrosion Above Ambient Temperatures Using the Syringe Cell

The syringe cell method has been further developed to evaluate the temperature dependence of pitting corrosion in passive alloys that pit above ambient temperature without artifacts associated with crevice corrosion. The pitting potential of commercially available duplex stainless steel type 2205 was measured at different temperatures by using a hot plate to heat the specimen. Breakdown potentials decreased by about 1 V at test temperatures above 50°C. The critical pitting temperature (CPT) of the alloy was determined to be between 54°C and 59°C by scanning the temperature of the specimen surface during constant potential holds. In all experiments, pits were observed in the area defined by the electrolyte droplet in contact with the specimen surface. Using a more conventional approach mentioned in ASTM Standard G48 Method C, the CPT of the alloy was determined to be 55°C.