Critical pitting temperature dependence of 2205 duplex stainless steel on dichromate ion concentration in chloride medium

In this study, the influence of various concentrations of dichromate (Cr2O72-) and chloride ions on critical pitting temperature (CPT) of duplex stainless steel 2205 (DSS 2205) is investigated by employing potentiodynamic and potentiostatic CPT measurement methods. Potentiostatic results indicate that by adding 0.01 M Cr2O72- to 0.1 M NaCl solution the CPT raised by 12 °C. Based on potentiodynamic CPT measurements in the solutions with (Cr2O72-)/(Cl-) ratio equal to one for solutions containing 0.1 M NaCl + 0.1 M Cr2O72- and 0.01 M NaCl + 0.01 M Cr2O72-, no CPT was detected up to 75 °C.

Research highlights
► A 12 °C increase in the CPT was found by the addition of 0.01 M Cr2O72- to 0.1 M NaCl solution.
► No pitting corrosion was observed in a solution that contains 0.1 M Cr2O72- up to 86 °C.
► At (Cr2O72-)/(Cl-) ratio equal to one no pitting was detected upto 75 °C.