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

Pawel H Dluzewski

doi:10.1155/tsm.19.81

Abstract

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

Highlights

Many constitutive models based on the concept of orientation distributions of crystals and slips are developed to describe the plastic anisotropy of polycrystals
At the same time a modelling of the anisotropic behaviour of polycrystal was developed on the base of the balance equations for slips, see e.g. Lin and Ito (1966), Tokuda, Kratochvil and Ohno (1985). Using such models it was shown that yield surfaces corresponded approximately to envelopes of elementary yield conditions for microslips, see e.g. Kiryk and Dluzewski (1989)
In our computer simulations the injection of the yield surface started in the direction of preloading and was continued subsequently in reversed directions until the orthogonal direction to the preloading has been reached

Summary

Introduction

Many constitutive models based on the concept of orientation distributions of crystals and slips are developed to describe the plastic anisotropy of polycrystals. The idea of describing the plastic flow of metals as an effect of thermally activated dislocation glides was proposed by Seeger (1954). This concept has been developed in many more complicated models, e.g. At the same time a modelling of the anisotropic behaviour of polycrystal was developed on the base of the balance equations for slips, see e.g. Lin and Ito (1966), Tokuda, Kratochvil and Ohno (1985) Using such models it was shown that yield surfaces corresponded approximately to envelopes of elementary yield conditions for microslips, see e.g. Using such models it was shown that yield surfaces corresponded approximately to envelopes of elementary yield conditions for microslips, see e.g. Kiryk and Dluzewski (1989)

Methods

Results

Conclusion