Plastic anisotropy and texture evolution during tensile testing of extruded aluminium profiles

Abstract

This paper reports an investigation on the evolution of texture and plastic anisotropy during uniaxial tensile testing of extruded profiles produced from two variants of an AlZnMg alloy: one contains Zr and shows a non-recrystallized structure; the other is Zr-free and shows a recrystallized structure. Tensile tests were carried out at 0°, 45° and 90° from the extrusion direction and from which, experimental r-values were derived from quadratic polynomial functions fitting to the width and thickness strains in the tensile tested samples. The r-values and Taylor factors for the initial and tensile tested samples were simulated from the measured textures using the full constraints and relaxed constraints Taylor models. The results show remarkable differences in textures and anisotropy in the two profiles. Although the initial textures of the profiles are much sharper, the texture development in the tensile tests follows similar tendencies commonly observed in sheet metals. In general, the r-values predicted from the textures depict the same tendencies of variation with tensile strain as those for the experimental r-values, suggesting that the variation of plastic anisotropy is mainly caused by the texture evolution. The Taylor factors were used to simulate the in-plane anisotropy in yield strength and subsequent work hardening. For the latter, a better agreement with the experimental data was obtained when the texture changes due to tensile deformation was taken into consideration.