Relationship between extrusion temperature and corrosion resistance of magnesium alloy AZ61

The extrusion-shear (ES) process for magnesium alloys is a newly developed plastic deformation technique, which combines one step of direct extrusion and two steps of ECAP (equal channel angular pressing). Corrosion resistances of the AZ61 magnesium alloy fabricated by ES with different billet temperatures have been investigated and evaluated through immersion and electrochemical tests. Influences of Cl-concentrations, immersion times and pH values on the corrosion behaviors of samples have been evaluated by analyzing corrosion morphologies and compositions, and phase compositions of corrosive products by using SEM and X-ray diffraction. According to the experimental results, samples processed by ES at 440 degrees C billet temperature have a higher corrosion resistance than those prepared at a billet temperature of 400 degrees C, which might be attributed to the grain-size reduction and the redistribution of inter-metallic particles within microstructures.