“…Schematic illustration showing the procedure of the ARB process (Pirgazi et al, 2008a) The first scientific paper on the ARB was published in 1998 and afterwards extensive studies have been conducted regarding the microstructural evolution and mechanical properties of various materials processed in different ARB cycles. Pure aluminum (Huang et al, 2003;Saito et al, 1998;Tsuji et al, 2003a), AA5083 (Saito et al, 1999), AA6061 (Lee et al, 2002;Park et al, 2001), AA8011 (Kim et al, 2002(Kim et al, , 2005, AA3103 (Chowdhury et al, 2006a) and AA8090 (Chowdhury et al, 2006b) aluminum alloys, magnesium alloys (del Valle et al, 2005;Pérez-Prado et al, 2004), and Ti-IF steel sheets Tsuji et al, 2002a) are the most important materials which have already been successfully produced by the ARB process. The results of these investigations mainly indicate that during the first stages of ARB, ultra-fine grains with diameter less than 1 μm partially form in the sheets, and the volume fraction of these grains increases with increasing the number of cycles, so that after high levels of strain the sample is completely covered with ultra-fine lamellar grains which are not equi-axed and represent an aspect ratio bigger than one (Huang et al, 2003;Park et al, 2001;Saito et al, 1998;Tsuji et al, 2003a).…”