Interpretation of electrochemically and chemically investigated corrosion behaviors of 316L SS in acid chloride environments

Abstract

The electrochemical behavior of 316L stainless steel was investigated in acid chloride environments, and pitting potentials were determined electrochemically and chemically. An increase in the anodic maximum current density was observed upon decreasing the cathodic potential from which the scan was initiated to determine the polarization curve. To determine the critical pitting potential through the chemical method, the potential was increased by increasing the concentration of ferric ions in ferric chloride while holding the chloride ion concentration constant with sodium chloride. When 316L stainless steel was immersed in 15 g/1 of FeCI36H:O containing the same chloride ion concentration as 5% NaCI with pH=2 at 57~ the corrosion potential increased to 0.47 V (SHE) within two minutes due to initial passivation. Immediately after reaching 0.47 V (SHE), which was just above the pitting potential of 0.45 V (SHE) determined electrochemically in 5% NaCI (pH=2, 57~ the corrosion potential continuously decreased, indicating the onset and propagation of pitting corrosion. A correlation between the electrochemical and chemical methods can be verified if the proper measurements are made and the observations are properly interpreted.

Comparison of corrosivity of polymeric sulfate ferric and ferric chloride as coagulants in water treatment

“…Attempt was also made to determine a correlation between the electrochemical and chemical methods [47]. Otero et al reported that, after studying the corrosion behavior of type 304L and 316L austenitic stainless steels in chloride containing solution with the concentration from 0.05 to 0.41 M, crevice corrosion was observed in the area close to pores and in some area of contact between powder particles [48].…”

Comparison of corrosivity of polymeric sulfate ferric and ferric chloride as coagulants in water treatment

“…Attempt was also made to determine a correlation between the electrochemical and chemical methods[47]. Otero et al reported that, after studying the corrosion behavior of type 304L and 316L austenitic stainless steels in chloride containing solution with the concentration from 0.05 to 0.41 M, crevice corrosion was observed in the area close to pores and in some area of contact between powder particles[48].Dawson and Ferreira also observed crevice corrosion caused by the influence of chloride ion in solution.…”