PITTING CORROSION OF SAF2205 DUPLEX STAINLESS STEEL IN ACETIC ACID CONTAINING BROMIDE AND CHLORIDE

Development of duplex stainless steels has been linked strongly with the increasing requirements of the industry for resistance of materials to highly aggressive environments. In the present work, the effects of bromide and chloride ion concentrations and temperature on the pitting corrosion of commercial grade SAF2205 duplex stainless steel were studied. Cyclic polarization and scanning electron microscopy (SEM) techniques were used to study the pitting corrosion behavior of this steel in 80%v/v acetic acid solution containing 0.01, 0.1, 0.2, and 0.5 M sodium bromide and sodium chloride, respectively. Pitting potential was found to decrease with the increase of the temperature and bromide ion concentration. In the presence of chloride ions, pitting corrosion was not observed at room temperature. Critical pitting temperature in chloride-containing solutions was estimated to be above 35°C. In the case of pitting, SEM observation revealed that pit initiation is in the austenite phase regions.