The nucleation of cube grains during primary recrystallization of aluminum

M M Miszczyk,H Paul

doi:10.1088/1757-899x/375/1/012031

Abstract

The formation of cube grains during recrystallization has been analyzed in commercial AA1050 alloy and pure Al single crystal of S{234}<524> orientation. Samples of AA1050 alloy were deformed along two deformation modes to form different as-deformed texture components and then lightly annealed. One group of the samples was plane strain compressed (PSC) in a channel-die. The second group was deformed by equal channel angular extrusion (ECAE). The results obtained on polycrystalline AA1050 alloy were compared with recrystallization behavior of PSC single crystal of S{234}<524> orientation. The textures were measured by SEM/EBSD and X-ray diffraction. It was found that a very weak residual cube{100}<011> component was observed in the samples of AA1050 alloy after both deformation modes. After annealing cube-oriented grains were extensively formed only in PSC samples. These grains were situated preferentially inside or in between the S-oriented areas with local disorientations about <111> axes. Cube-oriented grains were not formed during annealing of the ECAE samples, where main as-deformed texture components close to two complementary orientations of {124}<651>-type were transformed towards two components of ∼{100}<011> and ∼{221}<114>, essentially by <110> rotations. In single crystalline samples cube grains were extensively formed during annealing despite (near)cube-oriented areas haven’t been observed in the as-deformed microstructure.

Highlights

Control of earing properties of thin sheets relies on a careful control of the texture
Most of the authors argue that {100}-oriented grains evolve from ‘cube bands’, which are present in the deformed microstructure, often as thincube zones between high orientation gradients created by diverging rotations of unstable orientations [13] or fragmented leftovers of the original cube grains [8]
The present results provide detailed information about the development of cube texture in a commercial AA1050 alloy and a model Al single crystal of S{234} orientation

Summary

Introduction

Control of earing properties of thin sheets relies on a careful control of the texture. [8] that despite large volumes of cube crystallite are unstable (and rotates towards different variants of S orientation) but small fragments could be metastable because they are subject to a different stress state These less deformed areas conserve orientations near the original cube orientation and they are the source of cube grains nucleation during recrystallization. The experiments on deformed single crystals of fcc metals of stable orientations, deformed up to moderate strains clearly show that orientations of the as-deformed state are not retained in the new grains orientations during primary recrystallization [9, 10, 14, 15] In these simple cases the orientation and the underlying microstructure of the asdeformed matrix are clearly defined due to the strong stability of such crystals. The textures were measured on the ED/TD plane (where: TD denote transverse direction) with the use of the Philips X Pert PW-1830 X-ray diffractometer

Microstructure and texture of the as-deformed state

Texture changes during annealing

Conclusions