Stress Corrosion Cracking of Heat Treated 2205 DSS in Caustic Solutions

Stress corrosion cracking (SCC) of duplex stainless steel equipments employing caustic solution has been reported recently. This increase in SCC susceptibility of the steel may be due to the changes in the microstructure of the steel brought about by various metal fabrication processes. During metal fabrication, localized areas of DSSs may become exposed to different cooling rates or aging temperatures, which may lead to a change in the microstructure or produce precipitates in these regions. This change 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. Hence 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 was annealed at 1000 ºC and 1150 ºC and then aged at 475 ºC, 600 ºC and 800 ºC. The heat treated specimens were then tested for stress corrosion cracking susceptibility in caustic environment. It was found that changes in microstructure of the steel due to various heat treatments had a significant effect on its stress corrosion cracking susceptibility in caustic environment.