Microstructure and corrosion behavior of AZ31 alloys prepared by dual directional extrusion

Microstructure evolution and corrosion behavior of Mg alloys AZ31 processed by a severe plastic deformation technique, dual directional extrusion (DDE) are reported. The forward extrusion (FE) technique is also taken into account on the AZ31 alloys for comparison. Mean grains for the samples extruded by the DDE are refined significantly with increased extrusion ratio and lowered extrusion temperature, which as a result enhance resistance against salt corrosion. The alloys extruded by the DDE exhibit better corrosion resistance than those by the FE, which is explained by the finer grains, more homogeneous microstructure, and lower density of dislocation in the DDE-ed samples owing to the dynamic recrystallization.

► Grains in the AZ31 alloys are refined significantly by the DDE technique.
► The grain refinement enhances the resistance of Mg alloys against corrosion.
► High extrusion ratio and low extrusion temperature improve properties of Mg alloys.
► DDE is effective to tailor performances of AZ31 for many engineering applications.