Effects of Extrusion Temperature on Electrochemical Performance and Corroded Surface Morphology of AZ31 Magnesium Alloy

AZ31 magnesium sacrificial anode containing a steel core was fabricated by hot extrusion using plane porthole dies, and the effects of extrusion temperature on the surface quality, microstructure, electrochemical property and corroded surface morphology of the magnesium anode in saturated calcium sulfate-magnesium hydroxide solution were investigated. The results show that the magnesium anodes with high appearance quality was obtained when the extrusion ratio reached 12 and temperature varied between 320 to 380 ℃; the grain size of the magnesium alloy first decreased then increased with the increase of extrusion temperature, and the minimum grain size reached 12.2 μm; with the extrusion temperature increase, the current efficiency and open circuit potential of the magnesium alloy first increased then decreased, while the corrosion degree first reduced then accelerated. At 380 ℃, the current efficiency and open circuit potential reached the largest value of 63.93% and -1.586 V, meanwhile the surface pits quantity was the least as the corrosion degree was the lightest.