Materials Science and Engineering A 530 (2011) 469–472 Contents lists available at SciVerse ScienceDirect Materials Science and Engineering A journal homepage: www.elsevier.com/locate/msea A novel single pass severe plastic deformation technique: Vortex extrusion M. Shahbaz, N. Pardis, R. Ebrahimi ∗ , B. Talebanpour Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran article info Article history: Received 14 June 2011 Received in revised form 12 September 2011 Accepted 29 September 2011 Available online 7 October 2011 Keywords: Severe plastic deformation Vortex extrusion Torsion extrusion Finite element analysis abstract Vortex extrusion (VE) is a new severe plastic deformation (SPD) method which is designed to intro- duce a specific amount of torsional strain to a material simultaneously being extruded using a specially designed stationary die. Plastic deformation characteristics of VE were analyzed by finite element analy- sis; processing loads, strain values as well as metal flow patterns were studied for different twist angles. Results indicated that high strain values with uniform distribution may be achieved after VE processing. Therefore, VE can be considered as a promising single pass SPD technique which can be installed on any standard extrusion equipment with no need to any additional facilities that are essential in similar method, torsion extrusion. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Ultrafine-grained (UFG) materials are well known due to their high strength and unique properties. Among different approaches in processing these materials, severe plastic deformation (SPD) methods are of more interest as they provide UFG or even bulk nanostructured materials (BNMs) with no contamination or poros- ity [1–3]. Equal channel angular pressing (ECAP) [2], high pressure torsion (HPT) [4] and accumulative roll bonding (ARB) [5] are con- sidered as efficient SPD methods for producing UFG or BNMs. Therefore, numerous studies are conducted on these methods at small scale or even with the aim of commercializing these tech- niques [6–9]. However, to simplify these processing operations or to achieve unique properties of the processed material, some efforts have been made on the modifications of these methods like multi pass equal channel angular pressing [10–12], dual equal channel lateral extrusion (DECLE) [13], torsional-equal channel angular pressing (T-ECAP) [14], incremental ECAP (I-ECAP) [15,16] and cone–cone method (CCM) [17], as well as introducing novel SPD techniques such as twist extrusion (TE) [18], simple shear extrusion (SSE) [19], tube channel pressing (TCP) [20] and cyclic expansion-extrusion (CEE) [21]. Generally, in most SPD techniques (including those mentioned here) the geometrical dimensions and the shape of the processed sample remain unchanged which makes it possible to repeat the ∗ Corresponding author. Tel.: +98 711 2307293; fax: +98 711 2307293. E-mail addresses: Mehredads1@gmail.com (M. Shahbaz), Pardis@shirazu.ac.ir (N. Pardis), ebrahimy@shirazu.ac.ir (R. Ebrahimi), Talebanpour@shirazu.ac.ir (B. Talebanpour). process as many times to impose a desired amount of strain to the sample. However, it would be more beneficial if such amount of strain could be applied during one pass of operation as it increases the process productivity and reduces the number of processing steps. Moreover, it is proved that the amount of strain per pass and the resulting structural evolution during the first pass of batch processes (like ECAP) play a key role on the final microstructure [2]. Therefore, there are some investigations on applying intense strains on a material in a single processing step such as torsion extrusion [22,23] and shear extrusion [24] which are based on con- ventional extrusion (CE). In both processes an additional amount of strain is imposed on the processing material which is carried out by rotation of extrusion die about its main axis during extrusion process which requires complicated tools and facilities. Neverthe- less, a part of this rotation dissipates due to the slippage between the die and workpiece and decreases the resulting shearing of bulk material which is not favorable [22]. This article proposes a new severe plastic deformation method, vortex extrusion (VE), to produce bulk ultra fine-grained materi- als, which overcomes such limitations and can be considered as a counterpart for torsion extrusion. To investigate the deforma- tion behavior of materials in this process, finite element software DEFORM-3D [25] was used which has the capability to model non- linear problems accurately and reliably. 2. Principles of vortex extrusion In VE the inner geometry of a stationary converging die makes the material twist about its main longitudinal axis which eliminates the problem of slippage [22] between the material and the die in 0921-5093/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2011.09.114