Special Rolling Techniques for Improvement of Mechanical Properties of Ultrafine-Grained Metal Sheets: a Review

Interest in ultrafine-grained (UFG) materials has grown rapidly in past 20 years. This review focuses on the application of special rolling techniques for improvement of the mechanical properties of UFG metal sheets. These techniques include asymmetric rolling, cryorolling, asymmetric cryorolling, cross-accumulative roll bonding, and skin-pass rolling. The techniques also include a combination of processes such as equal channel angular press and subsequent rolling, combined high-pressure torsion and subsequent rolling, as well as combined accumulative roll bonding and subsequent asymmetric rolling. We also discuss the main mechanisms leading to improvement in the ductility of UFG materials related to the special rolling techniques.