A number of stress corrosion cracking (SCC) failures of duplex stainless steel (DSS) equipments
exposed to the sulfide containing caustic solutions has been reported in recent years. SCC susceptibility
of the DSS may be due to changes in the microstructure of the steel brought about by various metal
fabrication processes. During metal fabrication, localized areas of DSSs may be exposed to different
cooling rates or aging temperatures, which may lead to changes in the microstructure. These changes in
microstructure may in-turn affect the general and localized corrosion or SCC susceptibility of the
affected area as compared to the rest of the metal. In this study the effect of different annealing and
aging temperatures on the microstructure and SCC behavior of 2205 DSS in sulfide-containing caustic
solution was evaluated. 2205 DSS samples were annealed at 1000ºC or 1150ºC and then aged at 475ºC,
600ºC or 800ºC. The heat-treated specimens were then tested for SCC susceptibility in white liquor. It
was found that the changes in the microstructure of the steel due to various heat treatments had a
significant effect on its SCC susceptibility in caustic environments.
Keywords: duplex stainless steel, stress corrosion cracking, caustic, heat treatment, white liquor