Severe Plastic Deformation (SPD) techniques have been used by researchers for last three decades in order to obtain Ultra-Fine Grained (UFG) materials. Equal Channel Angular Pressing (ECAP) is preferred more than other SPD techniques thanks to its high performance and practicability. Hexa Equal Channel Angular Pressing (Hexa-ECAP) – modified ECAP technique which enables to apply ECAP routes for cylindrical samples properly – was preferred in this study. Within the objective of this study, the effects of coefficient and ram velocity on the mean effective strain and strain inhomogeneity of Hexa-ECAP processed Al7075 aluminium alloy were investigated. Also, the effects of ram velocity and friction coefficient on hardness homogeneity were investigated benefitting from the similarity between the hardness distribution and the strain distribution.

A Cu-1Cr-0.1Zr alloy has been subjected to ECAP processing via route Bc and aging at 250-800°C. Electron BackScatter diffraction (EBSD), Transmission Electron Microscopy (TEM) and X-Ray Diffraction Line Profile Analysis (XRDLPA) techniques have been used to unveil some peculiarities of the grain and subgrain structure with a special emphasis on the comparison of the grain size estimated by the three techniques. For the alloy ECAP processed and aged up to 16 passes, the grain size (from EBSD, 0.2 < d < 5 μm), subgrain size (from TEM, d ~ 0.75 μm) and “apparent” average crystallite size (from XRDLPA, d < 0.25 μm) are manifestly different. The results were compared to the published data and analyzed based on the fundamental aspects of these techniques.

This work investigates the compaction behaviour of commercial pure aluminium chips (CP Al) produced during a machining operation and subsequently consolidated by Equal Channel Angular Pressing (ECAP). Empirical models were developed to describe the relative density and hardness of the compacted product of ECAP as functions of the initial machining input parameters including cutting edge angle (CA), depth of cut (DOC) and then the number of consolidation pass during ECAP. The models were developed utilizing response surface methodology (RSM) based on data from a central composite face centred factorial design of experiments approach. The models were then validated by using Analysis of Variance (ANOVA). The effect of input parameters on the relative density and hardness of the ECAP consolidated samples are presented and discussed including details as regards to the mechanical and microstructural properties. An optimum set of input parameters are identified and presented where the best relative density and hardness are demonstrated.

The FEM simulations of the ECAP including real conditions of the process – the friction between the metal extruded and the die walls, as well as, the channels rounding, were done here in two scales – macro- and micro-. The macroscopic analyses were done for isotopic material with a non-linear hardening using the UMAT user material procedure. The pure Lagrangian approach was applied here. The stress, strains and their increments, as well as, the deformation gradient tensor were recorded for selected finite elements in each calculation step. The displacements obtained in the macroscopic FEM analysis are then used as the kinematic input for the polycrystalline structure. The dislocation slip was included as the source of the plastic deformation here for the face-centered cubic structure. The results obtained with the use of the crystal plasticity show the heterogeneous distribution of stress and strain within the material associated with the grains anisotropy. The results in both micro- and macro- scales are coincident. The FEM analyses show the potential of the application of the crystal plasticity approach for solving elastic-plastic problems including the material forming processes.

The paper gives an introduction to nanostructuring techniques used for industrial fabrication of bulk nanocrystalline metals – basic

materials utilized in shaping nanoscale structures. Nanostructured metals, called nanometals, can be produced by severe plastic deformation (SPD). We give an expert coverage of current achievements in all important SPD methods and present future industry developments and research directions including both batch and continuous processes. In the laboratories of both WUT and UOS we have developed industry standard equipment and machinery for nanometals processing. Utilizing the latest examples from our research, we provide a concise introduction to the field of mass production of nanometals for nanotechnology.

Equal-channel angular pressing (ECAP) was used as a technique for severe plastic deformation (SPD) on Al alloy AA3004. This technique produced fully dense materials of refined grain structure to sub-micrometer dimensions and advanced mechanical properties. The ECAP processing of samples was conducted as 1 to 4 passes through the die at room temperature. We present the results of the studied homogeneity evolution with the ECAP treatment. Furthermore, a Scanning Electron Microscope (SEM) was used for examination of the microstructure changes in samples undergone from 1 to 4 passes. The microhardness-HV increased upon each ECAP pass. The resulting micro-hardness evolution was attributed to crystalline microstructure modifications, such as the d-spacing (studied by X-ray Diffraction-XRD) depending on the number of ECAP pressings. The microcrystalline changes (grain refining evaluated from the Scanning Electron Microscopy – SEM images) were found to be related to the HV, following the Hall-Petch equation.