It was recalled that the crystallographic rotation field for deformation in torsion was such that it was possible for orientations close to stable orientations to rotate away from the stable orientation. A Taylor-type model was used to demonstrate that this phenomenon had the potential to transform randomly generated low-angle boundaries into high-angle boundaries. After imposing an equivalent strain of 1.2, up to 40% of the simulated boundaries exhibited a misorientation in excess of 15°. These high-angle boundaries were characterized by a misorientation axis which was almost parallel to the sample radial direction. A series of hot torsion tests was carried out on AA1050 alloy in order to find signs of boundaries formed via this mechanism. A number of deformation-induced high-angle boundaries were identified; many of which had misorientation axes and rotation senses which were similar to those seen in simulations. Between 10 and 25% of all of the high-angle boundary present, in samples which had been twisted to equivalent strains of between 2 and 7, could be attributed to the present mechanism.

The Generation of New High-Angle Boundaries in Aluminium during Hot Torsion. M.R.Barnett, F.Montheillet: Acta Materialia, 2002, 50[9], 2285-96