Influence of sensitization on pitting corrosion in surfacing layer of 2209 duplex stainless steel

The sensitization of 2209 duplex stainless steel surfacing layer was processed in different time (15 min, 30 min, 1 h, 2 h) under 850 ℃, and the influence of sensitization time on the pitting resistance of 2209 duplex stainless steel surfacing layer was studied by immersion experiment and EIS. These results showed that pitting corrosion originated from the ferrite phase in different time sensitized sample. Moreover, the pitting corrosion rate was correlated with the sensitization time, if sensitizing processing time was less than 30 min, pitting corrosion weightlessness of surfacing layer was not obvious, while it longer than 30 min, pitting corrosion weightlessness would increase obviously. The EIS supported, with the increasing of sensitization time, capacitive reactance curvature radius would decrease continuously. Which indicated that both the stability of the passive film and pitting resistance were decreased, being similar with the result of immersion experiment.