Comparison of microstructures and mechanical properties of composite extruded AZ31 sheets

Abstract

The microstructures and mechanical properties of the composite extruded AZ31/AZ31 and AZ31/4047 Al sheets were investigated and made a comparison to the conventional extruded AZ31 sheet. Owing to the introduced intense shear deformation at the interface during the composite extrusion, grain refinement and tilted texture were detected in AZ31 layers of the AZ31/AZ31 and AZ31/4047 Al sheets, while the conventional extruded AZ31 sheet exhibited a relative coarse, inhomogeneous microstructure and strong basal texture. The compression-tension yield ratio was increased gradually from the AZ31 to the AZ31/AZ31 and AZ31/4047 Al sheets. Besides, the AZ31/4047 Al sheet could successfully accomplish the whole bending forming process at room temperature, while the AZ31 and AZ31/AZ31 sheets were both bend-formed to failure with significant cracks in the outer tensile region under the identical bending parameters. Moreover, under the same bending strain, both the outward offset degree of strain neutral layer and the sheet thickening were more serious in the AZ31/4047 Al composite sheet than those of the AZ31 and AZ31/AZ31 sheets. The foremost reason was the quite wide gap of material properties between Mg alloy AZ31 layer (tensile loading in the outer region) and Al 4047 layer (compressive loading in the inner region). Keywords: Mg alloy sheet, Composite extrusion, Tension–compression yield asymmetry, Bendability