Microstructural evolution during accumulative roll-bonding of commercial purity aluminum

The microstructure in commercial purity aluminum deformed from medium to high strain (epsilon(vM) = 1.6-6.4) by accumulative roll-bonding (ARB) at 473 K was quantitatively examined by transmission electron microscopy. It was found that a sub-micrometer lamellar structure characterizes the microstructure at high strains (epsilon(vM) > 1.6), and that the lamellar boundary spacing decreases and the misorientation across the lamellar boundaries increases with increasing rolling strain. This characteristic evolution has also been observed during conventional cold-rolling of commercial purity aluminum. However, a comparison between the two processes shows a significant difference in the evolution of the microstructural parameters. These differences are discussed based on the different processing conditions characterizing ARB and conventional rolling, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.