Grain orientation dependence of microstructure in aluminium deformed in tension

Abstract

The evolution of deformation microstructure in medium to high stacking fault energy fcc metals has been described in terms of a general framework of grain subdivision involving the formation of rotates volume elements for all deformation modes. The rotated volume elements are ordinary dislocation cells and cell blocks, where a cell block contains a group of cells. The cell blocks are bounded by dislocation boundaries accommodating the lattice misorientations between neighboring cell blocks that deform with different slip system combinations and/or by different strains or strain amplitudes. An important aspect of the deformation structure development is the pronounced dependence on the crystal orientation. This has been shown by the formation of different types of deformation microstructures, for which the dislocation boundaries formed during deformation are characterized by their different morphology, spacing, crystallographic orientation and misorientation angle, in single crystals of different orientations deformed in tension and in rolling. Studies of polycrystal behavior are much less extensive but an orientation effect has been observed on a macroscopic scale in specimen deformed in rolling and on a microscopic scale in specimens deformed in tension and in rolling. The previous studies have shown a need for a more precise characterization of the effectmore » of grain orientation on the microstructural evolution of polycrystalline metals. Such a characterization, if successful, could lead to prediction of the evolution of the deformation microstructure in order to establish quantitative correlation between microstructure, crystallographic texture and properties of polycrystals. The present study only concerns the microstructure, which has been characterized in pure polycrystalline aluminium deformed in tension at room temperature.« less