The effect of flow velocity on the seawater corrosion behavior of AA5083 Al alloy

초록

The influence of flow velocity on the seawater corrosion behavior of AA5083 Al alloy was investigated by rotating disc test considering the change of hydrodynamics characteristics. It was considered that the change of hydrodynamic characteristics with the flow pattern transition from laminar to turbulent flow affected corrosion behavior of AA5083 Al alloy. From the analysis of hydrodynamics and the observation by SEM and OM, the surface oxide film was almost not affected in laminar condition(below 2000RPM, Re≤1.7×105) and it was removed partially in transition condition(at 3000RPM, 1.7×105≤Re≤3.5×105). The overall attack was observed by the removal of almost surface oxide film in turbulent condition(above 4000RPM, Re≥3.5×105). It is supported from the sharp decrease of the open-circuit potential (OCP) and the changes of the anodic polarization behavior at transition region.