Microstructure and mechanical properties of the AA7075 tube fabricated using shear assisted processing and extrusion (ShAPE)

Abstract

Shear-assisted processing and extrusion (ShAPE) experimental setup and tooling were adopted for extruding thin-walled AA7075 aluminum tube from as-cast non-homogenized billet material in a single run. The mechanical and microstructural characterizations were performed on the as-extruded tube through tensile, hardness, electron backscatter diffraction (EBSD), and energy dispersive spectroscopy (EDS) tests. The results showed that the ShAPE process developed a significantly refined microstructure with uniform and almost equiaxed grain structure on both hoop and axial cross-sections of the extrudate as well as through the thickness of the material. The pole figures and inverse pole figures of the EBSD data showed a strong shear texture development, and it was found out that axial shear is the dominant deformation mechanism in the regions near the inner surface of the tube, while combined axial and torsional shears are the two dominant modes of deformation near the outer surface of the extrudate. As for the mechanical properties, there was an increase of 150 and 73% in the yield and ultimate strengths of the tube produced using ShAPE process, respectively, and an 18% decrease in maximum uniform plastic elongation compared to the conventionally extruded AA7075-O tube.