Trans. Nonferrous Met. Soc. China 25(2015) 1367−1375 Microstructure and texture evolution of Al-7075 alloy processed by equal channel angular pressing M. H. SHAERI 1 , M. SHAERI 2 , M. T. SALEHI 3 , S. H. SEYYEDEIN 3 , F. DJAVANROODI 4,5 1. Department of Metallurgy and Materials Engineering, Engineering Faculty, Imam Khomeini International University, Qazvin 34149−16818, Iran; 2. Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran; 3. Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran; 4. Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran; 5. Department of Mechanical Engineering, Prince Mohammad Bin Fahd University, Al Khobar 31952, Saudi Arabia Received 4 July 2014; accepted 25 October 2014 Abstract: Equal channel angular pressing is an effective technique to control the texture and microstructure of metals and alloys. Texture and microstructure of an Al-7075 alloy subjected to repetitive equal channel angular pressing through a 90° die were evaluated by X-ray diffractometer and orientation imaging microscopy. It is observed that processing through different routes leads to different types of textures, in both qualitative and quantitative senses. The texture calculation by Labotex software reveals that texture strengthens after the first pass and weakens by progressing ECAP process up to 4 passes. Microstructure investigations show that after 4 passes of equal channel angular pressing via routes B C and A, very fine grains with average grain size of about 700 nm and 1 μm appear, respectively, and most of the grains evolve into arrays of high angle boundaries. The effects of covering the Al-7075 billets with copper tube on texture and microstructure were also studied. Key words: equal channel angular pressing; crystallographic texture; aluminum alloy; ultra-fine grain 1 Introduction Equal channel angular pressing (ECAP) or extrusion (ECAE) is known as the most promising technology among the potential severe plastic deformation (SPD) processing techniques, which can be applied to producing ultra-fine grained materials in bulk metallic alloys [1]. In equal channel angular pressing process, a billet is extruded repetitively through a die with two channels of equal cross section intersecting at an abrupt angle, Φ, and with a corner curvature angle, Ψ, [2,3]. Since the cross sectional shape of the billet remains nearly the same during the process, it is now well recognized as a promising method to enhance the strength of various metallic alloys through the occurrence of grain refinement in severe plastic deformation. In multi-pass ECAP, the evolution of crystallographic texture is quite complex due to the various strain path changes instigated by the prescribed processing route. The most common routes are termed A, C, B A and B C according to the rotation of the billet around the specimen’s longitudinal axis between successive passes: A, no bar axis rotation; C, 180° rotation after each pass; B A , clockwise 90° rotation after even numbered passes and counter clockwise 90° after odd numbered passes; and B C , 90° rotation after each pass [3−8]. Investigation of texture evolution is essential to understand the mechanisms of plastic deformation and grain refinement during ECAP [9]. The large plastic deformation and strain-path changes involved in the process result in significant and complex changes of crystallographic texture [10]. In the literature, many studies have been conducted to evaluate the effects of material properties and processing variables on ECAP texture evolution [7−26]. For a given material, the texture development mainly depends on the die angle (Φ), processing route, number of passes (N) and initial texture [7,9,22−26]. On the characteristics of ECAP textures, most of the studies have shown that textures developed during ECAP deformation are often compared Corresponding author: M. H. SHAERI; Tel: +98-2833901190; Fax: +98-2833780073; E-mail: shaeri@ENG.ikiu.ac.ir DOI: 10.1016/S1003-6326(15)63735-9