Fabrication of ultra-thin nanostructured bimetallic foils by Accumulative Roll Bonding and Asymmetric Rolling

Abstract

This paper reports a new technique that combines the features of Accumulative Roll Bonding (ARB) and Asymmetric Rolling (AR). This technique has been developed to enable production of ultra-thin bimetallic foils. Initially, 1.5 mm thick AA1050 and AA6061 foils were roll-bonded using ARB at 200°C, with 50% reduction. The resulting 1.5 mm bimetallic foil was subsequently thinned to 0.04 mm through four AR passes at room temperature. The speed ratio between the upper and lower AR rolls was 1:1.3. The tensile strength of the bimetallic foil was seen to increase with reduction in thickness. The ductility of the foil was seen to reduce upon decreasing the foil thickness from 1.5 mm to 0.14 mm, but increase upon further reduction in thickness from 0.14 mm to 0.04 mm. The grain size was about 140 nm for the AA6061 layer and 235 nm for the AA1050 layer, after the third AR pass.

High Strength and Ductility of Ultrathin Laminate Foils Using Accumulative Roll Bonding and Asymmetric Rolling

“…It is possible to obtain a quasi-uniform shear strain distribution through the thickness of the material under certain rolling conditions. AR-processed Al sheets [19] and bimetallic foils [18] show an excellent ductility during tensile tests. In addition, the AR technique can produce thinner foils.…”

“…[11][12][13] Variants of the SPD techniques such as asymmetric cryorolling, [14,15] Accumulative Roll Bonding (ARB) [16,17] and Asymmetric Rolling (AR) [18,19] have been developed to enable bulk fabrication of nanostructured/ultrafine-grained metal sheets/foils. The ARB and AR techniques can be used to produce continuous products and are more feasible for practical application in industries.…”

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

“…The technique can improve the mechanical properties of Al etc. [126][127][128][129][130][131] The development of SPD techniques has enabled significant improvement in the strength of UFG/NG materials. However, most UFG/NG materials still lack the necessary toughness required in engineering applications although there are many the mechanisms for enhancing ductility of UFG/NG metals.…”

“…Experimental results revealed improved bonding with no necking of the individual layers after tensile testing. Yu et al [126,128] studied the bonding strength of ultrathin UFG bimetal foils produced using ARB followed by AR.…”

“…With the rapid development of UFG/NG metals, severe plastic deformation techniques have become increasingly important in rolling. Apart from the accumulative roll bonding technique, [35][36][37][38] some other rolling methods were also considered as SPD techniques. Because there have already been some reviews of the progress in the ARB technique, [13] in this paper we have focused on the progress of other rolling techniques such as asymmetric rolling (AR), cryorolling (CR), asymmetric cryorolling (ACR), improved ARB technique, and the combination of other SPD and rolling techniques in recent years.…”