The effect of chromate in the corrosion behavior of duplex stainless steel in LiBr solutions

The electrochemical behavior of duplex stainless steel (DSS) in LiBr media was investigated by anodic cyclic polarization curves and AC impedance measurements. The effect of bromide concentration and chromate presence in the solutions on the corrosion behavior of DSS was studied. It was found, by cyclic polarization curves analyses, that there was different pitting susceptibility of passive films formed on DSS depending on the chromate/bromide ratio: pitting corrosion susceptibility highly decreased from a chromate/bromide ratio lower than 0.01.The comparative investigations carried out in LiBr and LiBr + 0.032Li2CrO4 verify the assumption that the halide ions facilitate inhibitor adsorption. The addition of halides increased inhibition efficiency to a considerable extent. Passive film becomes more resistant when bromide concentration increases, although film thickness decreases.