Prediction of deformation-induced anisotropy in profile extrusion of aluminum alloys

Abstract

Considering the entire material, when the metal is deformed during a specific process, active slip planes tend to rotate and make the slip direction more nearly parallel to the principal axis of tension. This condition of nonrandom distribution of crystal orientation is known as preferred orientation, and it is also called as deformation texture. Texture affects the overall macroscopic properties of materials such as the anisotropy in the rolled sheet. In bulk metal forming processes, extrusion is the most effective process for production of uniform cross section. Because of the extreme deformations taking place during extrusion, the aluminum profiles have highly anisotropic properties. The experimental and analytical investigations on three point bending and stretch bending have shown the importance of mechanical anisotropy. Therefore, these characteristics of deformation should be reflected on the conventional finite element scheme as a deformation-induced anisotropy. The anisotropic characteristics can then be studied in the industrial extrusion process as an important measure to evaluate the product quality. In the present work, the deformation-induced anisotropic evolution of material properties is introduced by applying the phenomenological yield potential. Deformation-induced anisotropic properties may represent the microscopic deformation characteristics macroscopically. The Barlat``s six-component yield criterion is introduced to analyze the anisotropic characteristics implying the macroscopic deformation. Moreover, the comparison with crystallographic texture analysis based on the crystal plasticity helps to validate the proposed algorithm. Predicted material anisotropy of the simple deformation modes, such as uniaxial stress state and pure shear stress state, is compared with the result from the crystallographic texture analysis based on the crystal plasticity, and, application to the combined stress state as the simulated stress state of the rolling...