Microstructure influencing physical and mechanical properties of electrolytic tough pitch copper produced by equal channel angular pressing Oscar F. Higuera a,b,⇑ , José M. Cabrera a,c a Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Universidad Politécnica de Cataluña, Barcelona Tech, Av. Diagonal 647, 08028 Barcelona, Spain b Facultad de Ingeniería Mecánica, Universidad Tecnológica de Pereira, Vereda La Julita, Pereira, Colombia c Fundació CTM Centre Tecnológic, Av. Bases de Manresa 1, 08242 Manresa, Spain article info Article history: Received 23 July 2012 Received in revised form 27 May 2013 Available online 11 August 2013 Keywords: ECAP ETP copper SPD EBSD Electrical conductivity Mechanical properties abstract Samples of electrolytic tough pitch (ETP) copper were subjected to equal-channel angular pressing (ECAP) for up to 16 passes at room temperature following route Bc. The microstructural evolution was followed by Oriented Image Microscopy (OIM) and Differential Scanning Calorimetry (DSC) was used to estimate the activation energy and the recrystallization temperature after each ECAP pass. Also, mechanical properties after each pass were evaluated by tensile tests. Finally, electrical properties were analyzed. Results show that the stored energy increases on increasing ECAP deformation, while the recrystallization temperature decreases significantly. From a mechanical point of view a stable state is attained after 4 passes. Similarly, electrical conductivity slightly decreases down to a saturation state. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The control of material structures by severe plastic deformation (SPD) presents significant scientific and prac- tical interest, because of the structure refinement to the sub-micron scale that can be attained, which provides a reasonable compromise between high strength and satis- factory ductility that is especially attractive for structural applications (Segal, 2008). The presence of an area with a large amount of grain boundaries results in unusual and extraordinary changes in physical properties. Equal chan- nel angular pressing (ECAP) is an effective method of applying SPD to develop ultrafine grained microstructure in various metallic alloys (Iwahashi et al., 1997). The ECAP process operates in simple shear and it is characterized by several processing parameters, namely: die design, strain, temperature, strain rate, pressure, friction and so on, which influence the micro mechanics of deformation (operating slip systems, shearing patterns, etc.) and lead to the forma- tion of specific microstructures (Valiev and Langdon, 2006), which in turn are needed for specific industrial applications, such as high mechanical strength, and good both ductility and electrical conductivity. According to Meyers et al. (2006) this can be achieved by generating bi- modal structures. For this purpose the implementation of low temperature heat treatments between passes or after the ECAP process have been proposed, but the results showed improvements in ductility at the expense of the mechanical resistance. The influence of bimodal structures generated in situ by ECAP on the thermal, mechanical and electrical behavior of an ETP copper is analyzed in this investigation. 0167-6636/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mechmat.2013.07.011 ⇑ Corresponding author at: Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Universidad Politécnica de Cataluña, Barcelona Tech, Av. Diagonal 647, 08028 – Barcelona, Spain. Tel.: +34 934011097; fax: +34 934016706. E-mail addresses: osfahico@gmail.com, osfahico@utp.edu.co (O.F. Higuera), jose.maria.cabrera@upc.es (J.M. Cabrera). Mechanics of Materials 67 (2013) 9–14 Contents lists available at ScienceDirect Mechanics of Materials journal homepage: www.elsevier.com/locate/mechmat