The metastable pitting potential and its relation to the pitting potential for four materials in chloride solutions

摘要

The metastable pitting potential for four materials, Q235 steel, X70 steel, pure iron and 316L stainless steel in chloride solutions were measured by slow scan potentiodynamic polarization. For the four materials, good linear relationship exists between the metastable pitting potential E_m and pitting potential E_b. The close relationship between the two parameters is attributed to the passivity of the metals in environments, which plays the key role in both the nucleation processes of metastable pitting and stable pitting. Higher passivity results in higher average pitting potential and larger difference between average £b and E_m values.