Effects of Mo and Mn on Pitting Behavior of Duplex Stainless Steel

Effects of Mo and Mn elements on pitting corrosion resistance of lean duplex stainless steel in Cl- media solution have been studied.Gravimetric tests in 6 mass% FeCl3 at 35 ℃ and potentiodynamic analysis in 3.5 mass%NaCl were carried out.The corrosion potential (Ecoor)and the pitting potential (Epit)are shifted to a more noble po-tential because of the presence of Mo around the pits.While the presence of Mn could sharply reduce the value of pit-ting resistance equivalent number (PREn)and the pits can be formed more easily.The pits are found generating at the phase with a lower PREn.The identical tendencies between the Epit and PREn of weaker phase are the same.A corrosion mechanism has been proposed to determinate pitting corrosion behavior based on microstructural observations.