LAUSR

Abstract The effect of thermal aging at 400 °C for various times on the pitting corrosion behavior of Z3CN20.09M duplex stainless steel was investigated using comprehensive study of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). It is revealed that the pitting resistance of this steel has a negative relationship with increasing the aging time. It is indicating that the property of the specimens aged and then annealed at 550 °C for 1 h can be recovered to that of the un-aged. We found by making use of TEM that through the annealing processes the Cr-rich α′ phase is dissolved in the ferrite phase, while G phase still exists in the ferrite phase at the same time, suggesting that the α′ phase is the major reason for the deterioration in pitting corrosion resistance of the thermally aged Z3CN20.09M steel.