Corrosion behavior and electrochemical property of Q235A steel in treated water containing halide ions (F-, Cl-) from nonferrous industry

The corrosion behaviors and electrochemical properties of Q235A steel in the treated water containing corrosive halide anions (F-, Cl-) have been investigated with corrosion tests of static coupon and dynamic coupon testing, electrochemical measurement of open-circuit potential and linear sweep voltammetry. The results reveal that the existence of F- and Cl- ions in the simulated treated water accelerate the corrosion rate of Q235A steel. The corrosion rate reaches maximum with F- concentration of 50 mg/L, Cl- concentration of 200 mg/L, respectively. However, Q235A steel would passivate when an applied potential is added to the system. Meanwhile, the initiating passive potential becomes positive with F-, Cl- concentration increasing. There is a little influence of F-, Cl- concentration on the initiating passivation current density. Therefore, it is necessary to control F-, Cl- concentration in the treated water when it is recycled by the pipelines made of Q235A steel.