Influence of second phases on the electrochemical behavior of hot dipped Al–Mg–Si coated steel

The influence of second phases on the electrochemical behavior of hot dipped Al–Mg–Si coated steel has been investigated using an open circuit potential (OCP) and anodic polarization measurements. The results of OCP monitoring data for Mg2Si particles show fast ennoblement of OCP then slowly rise until the last stage of monitoring. The localized corrosion starts from the surrounding matrix of Mg2Si particles and propagates in the coating surface. The passivation of the Al–Mg–Si coating surface during anodic polarization can be attributed to the formation of the surface oxide film, which inhibits further dissolution of the coating.