A protective role of Cl− ion in corrosion of stainless steel

Corrosion behaviour of stainless steel was comparatively explored in 0.6 M KCl, KBr and their mixed solution. If Cl− and Br− ions simultaneously exist, Cl− ions were found to be less susceptible to metastable pitting corrosion and they can inhibit pit corrosion, which attributes Cl− ions have low adsorption coefficient or adsorption site to reduce pit growth from metastable to stable state. Pits will initiate at the locations where surface inclusions exist, which express morphological diversity during corrosion. This study expects to provide a new insight into the role of Cl− ion in corrosion of steel.