Experimental and Crystal Plasticity Finite Element Model Characterization of the Formability and Anisotropy of ShAPE Extruded AA7075 Tubes

In a previous work the authors characterized the mechanical properties of Shear-Assisted Processing and Extrusion (ShAPE) extruded AA7075 tubes using uniaxial tension tests. In the current study, the goal was to characterize and compare the anisotropic properties and formability of ShAPE extruded and conventionally extruded AA7075 tubes and to correlate them with their microstructure. To that end, a crystal plasticity finite element model (CPFEM) was developed with 3D representative volume elements (RVE) based on the microstructure of O-tempered, conventionally extruded, and as-fabricated ShAPE extruded AA7075 tubes. The Marciniak–Kuczynski (M–K) technique and the Yld2004 yield function were used to predict formability. The 18 anisotropy coefficients of Yld2004 were calibrated using data measured from biaxial expansion of tubes and separately from data generated virtually from CPFEM. The ShAPE extruded tube with equiaxed grain structure showed isotropic behavior under both tension–tension (T–T) and tension–compression (T–C) conditions. However, the conventionally extruded tube with pancake-shaped grain structure showed some level of anisotropy under tension–tension. It was found that for the ShAPE extruded tube, the non-quadratic Yld2004 yield function can be fully isotropic. Also, the as-fabricated ShAPE extruded AA7075 tube showed lower forming limit under all biaxial strain paths compared to the O-tempered conventionally extruded tube.