On the use of accumulative roll bonding process to develop nanostructured aluminum alloy 5083 Mohammad Reza Toroghinejad a , Fakhreddin Ashrafizadeh a , Roohollah Jamaati a,b,n a Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran b Young Researchers Club, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran article info Article history: Received 5 September 2012 Received in revised form 17 October 2012 Accepted 2 November 2012 Available online 9 November 2012 Keywords: Nanostructure Accumulative roll bonding (ARB) process Mechanical properties Transmission electron microscopy (TEM) abstract In the present study, the effect of accumulative roll bonding (ARB) process at room temperature on the microstructure and mechanical properties of AA5083 strip was investigated. Microstructural observa- tions were done by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Also, mechanical properties were performed by tensile, hardness, and microhardness tests. It was observed that accumulative roll bonding is a promising process for production of nanostructured (80 nm) AA5083 strips. Nano shear bands were formed in the microstructure after the fourth cycles. When the number of cycles increased, the tensile strength and hardness of the accumulatively roll bonded strips increased. However, by increasing the number of cycles, the elongation value decreased except for the last (sixth) cycle. It was found that when the number of cycles increased, the distribution of microhardness values became more uniform. After the tensile test, debonding can be observed especially in the interface formed in the last cycle. Observations revealed that the failure mode in the accumulatively roll bonded AA5083 strip was a shear ductile rupture with elongated shallow shear dimples. & 2012 Elsevier B.V. All rights reserved. 1. Introduction During recent years, the bulk nano and ultrafine grained (UFG) materials have received considerable scientific attention. It has been reported that these materials show outstanding high strength at ambient temperatures, high speed superplastic deformation at elevated temperatures, and high corrosion resistance [1–4]. Two different approaches are being utilized to fabricate nano and UFG materials. Top-down techniques, most relevant to this work, aim to refine the grain size of microcrystalline materials. Bottom-up proce- dures consist of assembling a structure from its smallest constitu- ents, namely atoms and molecules. One of the top-down strategies includes severe plastic deformation (SPD) processing [5–8]. As is well established, SPD techniques have shown a great potential to manufacture bulk metallic materials with desired microstructure in particular nano and UFG structures [6,9,10]. Several noble techniques have been developed to create high strain in metals with minimal changes in the initial sample dimensions, such as equal channel angular pressing (ECAP) [6,9], high pressure torsion (HPT) [9,11,12], multi axial forging (MAF) [13], constrained groove pressing (CGP) [14], cyclic extru- sion compression (CEC) [15], and accumulative roll bonding (ARB) [16,17] have been proposed as effective SPD methods and were successfully applied to several materials. The accumulative roll bonding process developed by Saito et al. [16,17] has several advantages over other SPD processes that include: 1. High load capacity forming facilities and expensive dies are not needed, 2. Productivity rate is high, and 3. The amount of material to be produced is not limited. Due to its feasibility as a continuous process, accumulative roll bonding is the only appropriate process for manufacturing nanos- tructured and ultrafine grained strips and plates, which are the most widely used in commercial and industrial applications [1,16,17]. Rolling in the accumulative roll bonding process is not solely a deformation process but is a bonding process that could lead to a single body solid material. The evolution of microstruc- tures and the related mechanical properties during accumulative roll bonding process were studied for several metal strips such as commercial pure Al [2,17–19], Cu [8,20,21], Brass [22], Zr [23], Ti [24,25], Mg [5,26,27] and IF steel [16,28,29]. The ARB process is also applicable in the fabrication of multilayered composites [30–32] and metal matrix composites [1,10,33–36]. Sheets of AA5083 have been widely used in industry due to their high strength to density ratio, good formability, good weldability Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/msea Materials Science & Engineering A 0921-5093/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msea.2012.11.010 n Corresponding author. Tel.: þ98 911 2124023. E-mail address: r.jamaatikenari@ma.iut.ac.ir (R. Jamaati). Materials Science & Engineering A 561 (2013) 145–151