Corrosion Performance of Friction Stir-Welded Magnesium Alloy Under Potentiodynamic Polarization Test in Sodium Chloride Solutions

Extruded AZ61A Mg alloy plates of 6 mm thickness were friction stir-welded. Corrosion performances of the specimens were evaluated by conducting potentiodynamic polarization tests in sodium chloride (NaCl) solution at different pH values, chloride ion concentrations, and exposure time. In addition, an empirical relationship was established to predict the corrosion rate of friction stir welds of AZ61A magnesium alloy. A central composite rotatable design includes three factors, and five levels were used to minimize the number of experimental conditions. Response surface methodology (RSM) was used to develop the relationship. The corrosion rate increased with the increase of chloride ion concentration and decreased with the increases of pH values and exposure time.