The effects of some anions on metastable pitting of 316L stainless steel

The effects of PO43-, CrO42-, SO42- and NO3- anions on metastable pitting of 316L stainless steel in NaCl Solutions were investigated using potentiostatic and potentiodynamic polarization tests. The four anions all retard nucleation of metastable pitting. The inhibition effect decreases in the order: PO43- > CrO42- > SO42- > NO3-. The propagation rates of metastable pits are also decreased by the anions tested. Both Metastable pitting potential E-m and stable pitting potential E-p increase almost linearly with the increase of each anion concentration, and have very close increasing slopes. (C) 2001 Elsevier Science Ltd. All rights reserved.