Evolution of Yield Surfaces and Texture with Finite Plastic Deformation in Aluminum Alloys

The primary objectives of this study are to determine the i) evolution of subsequent yield surfaces based on 10microstrain deviation from linearity; and ii) to report a comprehensive study of anisotropy and texture evolution with finite plastic deformation. The first study gives comprehensive experimental results on subsequent yield surfaces of a high work hardening alloy under proportional and non proportional loading paths. The size of yield surfaces under non-proportional loading decrease and no cross-effect is observed; these yield surfaces are completely different under proportional loading where the size of the yield surfaces increase and show positive cross-effect. The experimental results on subsequent yield surfaces after proportional loading paths under tension-tension stress space, for a very low and a very high work hardening Al alloy, using 10microstrain deviation from linearity as the definition of yield are presented. Subsequent yield surfaces are determined under axial, hoop, and combined hoop and axial proportional loading directions at various levels of plastic strain in each direction. Elastic moduli are also determined within each subsequent yield surface. Further, comprehensive responses of Al5754 and AZ31 are measured over wide ranges of strain rates and temperatures on same batch of two materials. These include the strain hardening, anisotropy, and texture evolution with finite plastic deformation. Tension, compression, and simple shear experiments at wide ranges of strain rates and temperatures are performed in rolling, transverse to rolling, and 45 to rolling directions. In addition, compression experiments were also performed in thickness direction. A new simple shear device is fabricated to perform simple shear experiments at elevated temperatures. Texture measurements are performed using neutron diffraction and EBSD in order to understand the deformation mechanisms of various specimens after finite deformation