Pitting Behavior of S22053 Stainless Steel in 6% FeCl₃ Solution

Pitting behavior of S22053 stainless steel in 6% (mass fraction) FeCl₃ solution under different potential conditions was studied by potentiodynamic electrochemical impedance spectroscopy. The results show that when the potential was 0.3~0.9 V (SCE, the same below), S22053 stainless steel was in a stable passivation state; and when the potential was 1.0 V, pitting was induced on the passivation film. When the potential was 1.1~1.2 V, the etch pit continued to expand, and mainly expanded to the depth of etch pit; and when the potential was 1.3~1.4 V, new pitting was induced at the passivation site. After pitting occurred, the electrochemical impedance spectroscopy mainly characterized the characteristics of etch pit.