Effect of microstructure on corrosion behavior of superduplex stainless steel at critical environment conditions

Superduplex stainless steels UNS S32750 with three different microstructures were evaluated in corrosion testing in a 70,000 ppm NaCl brine at 25, 60 and 90 °C. The corrosion behavior is strongly dependent on the microstructure, namely the presence of sigma phase precipitates. Besides the expected decrease of the pitting potential with temperature, results showed that the combined effect of very high chloride concentration and high temperature was deleterious even for the as-received samples, for which no sigma precipitation was found.