Substructure evolution during different hot deformation processes of commercial non-heat treatable aluminium alloys

The objective of the present work was to examine to what extent different laboratory testing equipment, such as plane strain compression (PSC), torsion, rolling and extrusion reveal the same substructure evolution during hot deformation of aluminium. The investigation included three non-heat treatable aluminium alloys; commercial purity aluminium (cp Al), cp Al + 1wt.%Mn and cp Al + 1wt.%Mg. The substructure was characterized by the subgrain size and the misorientation between nearest neighbour subgrains using a scanning electron microscope equipped with the SINTEF EBSP-system. The results showed that the subgrain size of the PSC-materials was significantly smaller as compared with the other deformation modes. The larger subgrain sizes in the hot rolled and extruded specimens were attributed to recovery effects owing to a delay in quenching time. In the case of the hot torsion specimens, the larger subgrain size as compared with the PSC-results was ascribed to texture effects by means of differences in the Taylor factor when deforming in shear and plane strain deformation conditions. The misorientation results for the different deformation conditions were inside the same scatter band.