Electrochemical studies of 254SMO stainless steel in comparison with 316L stainless steel and Hastelloy C276 in phosphoric acid media in absence and presence of chloride ions

Abstract

The electrochemical behaviour of 254SMO stainless steel in phosphoric acid media, both with and without chloride ions, has been investigated and compared with that of 316L stainless steel and Hastelloy alloy C276. Open circuit potential measurements, potentiodyn amic polarisation curves, and SEM analyses were used in the study. The 254SMO alloy displayed better corrosion resistance that 316L, being passive in 3M H₃ PO₄ solutions for [Cl^-] ≤ 1M and in 6M H₃ PO₄ solutions for [Cl^-] ≤ 0·1M. Its performance was comparable with that of Hastelloy C276, except in 6M H₃ PO₄solutions containing 1M NaCl, where 254SMO exhibited an active region over the entire range of temperatures studied (26–70°C) while Hastelloy C276 remained passive under these circumstances.