INFLUENCE OF A PREFABRICATED-CROWN ROLLING PROCESS ON THE CORROSION BEHAVIOUR OF AZ31 MAGNESIUM ALLOY

The present study aims to investigate the effect of a prefabricated-crown rolling process on the corrosion characteristic of the AZ31 magnesium alloy. Specimens made of the AZ31 alloy were rolled under various crown conditions, and their microstructure evolution and corrosion behavior were analyzed. The corrosion behavior was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion-current density of the AZ31 alloy with a side pressure of 37.5 % of the plate thickness of the precast convexity decreased from 3.79 x 10(-6) A/cm(2) to 1.80 x 10(-6) A/cm(2), and the difference between the edge and the middle of the AZ31 alloy was shortened from 2.05 x 10(-6) A/cm(2) to 1.14 x 10(-6) A/cm(2). The charge-transfer resistance also increased from 507.1 Omega.cm(2) to 581.2 Omega.cm(2). The improvement in the corrosion resistance is a result of the more stable corrosion products and microstructure refinement formed after the prefabricated-crown rolling process.