Application of PDM (point defect model) on 2205 duplex stainless steel

The corrosion behavior of 2205 duplex stainless steel in 0.1%, 1.0% and 3.5% (mass%) NaCl solution by electrochemical measurements was investigated, respectively. The experimental analysis based on PDM (point defect model) shows that the pitting corrosion resistance of the material tends to be worse with the increasing of concentration of NaCl solution. When the passive film forms, oxygen ion vacancy is produced on metal/film interface and consumed on film/solution interface, however metal ion vacancy exists on film/solution interface and being consumed on metal/ film interface. Migration of oxygen ion vacancy causes the growth of the passive film but it also destroys the film simultaneously. In addition, on the basis of PDM theory, a dissolution model of passive film has been established. The model explains that the passive film of 2205DSS on austenite γ phase probably dissolves faster than on ferrite α phase in the simulated marine environment.