Creep Behaviour of Pure Aluminium Processed by Equal- Channel Angular Pressing Vaclav Sklenicka, Jiri Dvorak, Milan Svoboda Institute of Physics of Materials, Academy of Sciences of the Czech Republic, CZ-616 62 Brno, Czech Republic 1 Introduction It is well known that physical and mechanical properties of metallic materials are very sensitive to their grain sizes. Equal-channel angular pressing (ECAP) is a processing procedure in which a material is subjected to a very severe plastic strain without any concomitant change in the cross-sectional dimensions of the work-piece [1-4]. Numerous reports over the last decade have firmly established ECAP processing as a technique for achieving very significant grain refinement in bulk polycrystalline materials with the grain sizes typically reduced to the submicrometer and/or nanometer level and thus to levels that are generally not attainable in conventional thermomechanical processing. There are many reports demonstrating that these remarkable grain refinements lead to unusual properties in the as- processed materials [5,6]. It is surprising to note that there have been no published results to date describing the creep properties of materials processed by ECAP. Accordingly, the present investigation was undertaken to address this deficiency. Specifically, the creep behaviour and microstructural characteristics of pure aluminium after ECAP were examined. 2 Experimental Material and Procedures High purity (99.99%) aluminium with an initial grain size of ∼ 5 mm in the as-received state, was subjected to ECAP. The ECAP pressing was conducted at room temperature with a die that had a 90 angle between the die channels and one or repetitive pressing followed either route A, B or C [7] - Fig.1. In routes B ≡ B c and C, the rotation was always 90and 180, respectively, in the same sense. Constant stress tensile creep tests were conducted at 473K and at applied stress of 15 MPa on the ECAP billets. For comparison purposes, some creep tests were also conducted on unpressed coarse-grained aluminium. Following ECAP passes and creep testing, samples were prepared for examination by means of light microscopy, and both scanning (Philips SEM 505) and transmission (Philips CM 12) electron microscopy. Figure 1: The three processing routes for ECAP [7]