The Effect of Slips on the Anisotropic Behaviour of Polycrystalline Aluminium at Elevated Temperature

A transition from the field of micro-heterogeneous strains through the crystal strain orientationdistribution function to the averaging scheme used in slip theory is presented. The conjugate measuresof stress and strain have been derived for slip theory. The theory is utilized here to the modelling of the strongly anisotropic, thermally activated, flowprocess observed for untextured aluminium in the plastic strain range from 1 * 10 − 6to 0.5 % . Thesubsequent yield surfaces are obtained by numerical simulation in time, the whole processcorresponding to the definition of yielding used by Phillips and Tang (1972). It is shown that theobserved athermal stress is closely related to residual stresses and depends strongly on the plasticstrain offset applied. In the present considerations a role of orientation distribution of mobiledislocation densities in the anisotropic flow of polycrystalline metals is discussed.