Modelling of high temperature viscoplastic flow of aluminium alloys by hot torsion testing

Abstract

Hot torsion testing of aluminium alloy 5252 was performed to model viscoplasticflow of aluminium alloys in high temperature deformation processes such as hot extrusion. Constitutive equations relating temperature, strain rate, strain, and flow stress have been established and validated from the data obtained, which are compensated for temperature change caused by heat generation during deformation. An optimisation procedure for the identification of material constants is presented. It is shown that the temperature rise during deformation may lead to a significant difference in the flow behaviour, which may not be ignored in the formulation of constitutive equations. The two methods used to identify the material constants, one based on equilibrium of torque and the other on the equivalent stress and strain rate, essentially produce the same results, indicating an alternative in application.