Ultrafine grained plates of Al-Mg-Si alloy obtained by Incremental Equal Channel Angular Pressing : microstructure and mechanical properties

In this study, an Al-Mg-Si alloy was processed using via Incremental Equal Channel Angular Pressing (I-ECAP) in order to obtain homogenous, ultrafine grained plates with low anisotropy of the mechanical properties. This was the first attempt to process an Al-Mg-Si alloy using this technique. Samples in the form of 3 mm-thick square plates were subjected to I-ECAP with the 90˚ rotation around the axis normal to the surface of the plate between passes. Samples were investigated first in their initial state, then after a single pass of I-ECAP and finally after four such passes. Analyses of the microstructure and mechanical properties demonstrated that the I-ECAP method can be successfully applied in Al-Mg-Si alloys. The average grain size decreased from 15 - 19 µm in the initial state to below 1 µm after four I-ECAP passes. The fraction of high angle grain boundaries in the sample subjected to four I-ECAP passes lay within 53-57 % depending on the examined plane. The mechanism of grain refinement in Al-Mg-Si alloy was found to be distinctly different from that in pure aluminium with the grain rotation being more prominent than the grain subdivision, which was attributed to lower stacking fault energy and the reduced mobility of dislocations in the alloy. The ultimate tensile strength increased more than twice, whereas the yield strength - more than threefold. Additionally, the plates processed by I-ECAP exhibited low anisotropy of mechanical properties (in plane and across the thickness) in comparison to other SPD processing methods, which makes them attractive for further processing and applications

Recovery of metals from shredded television scrap

Godkänd; 2008; 20081113 (ysko

Properties and deformation behaviour of severe plastic deformed aluminium alloys

Two and three dimensional FEM analysis of different aluminium alloys by equal channel angular pressing using Abaqus code show lower equivalent plastic strain on outer side of both transverse and longitudinal sections of workpiece. HV hardness and microhardness tests on different ecapped alloys show that the outer sides of processed alloys also are characterized by lower values. Microstructure analysis of different areas of processed specimens after one pass indicate that the areas of lowest equivalent plastic strain exhibit an almost undeformed microstructure. Moreover the effect of strain hardening rate (SHR) has been investigated. According to FEM analysis a higher strain hardening rate leads to a larger natural corner gap, a lower equivalent plastic strain and a wider extension of outer less deformed zone

Novel deformation structures of pure titanium induced by room temperature equal channel angular pressing

Novel deformation structures of commercial pure (CP) Ti induced by equal channel angular pressing (ECAP) at room temperature have been studied by electron backscattering diffraction (EBSD). All the deformation twins occurring in CP Ti, { 10 1 ¯ 1 }, { 11 2 ¯ 1 }, { 10 1 ¯ 2 } and { 11 2 ¯ 2 } have been revealed surprisingly in one original grain as first, secondary or third generation twins. 3 variants of { 10 1 ¯ 2 } twins have been identified. The deformation mechanism of CP-Ti during ECAP at room temperature in comparison to the ECAP at elevated temperatures is discussed.Research Council of Norway Strategic University Program (Contract No.192450/I30).Scopu