Microstructural Features and Mechanical Properties after Industrial Scale ECAP of an Al 6060 Alloy

Abstract

Future applications of ultrafine-grained, high performance materials produced by equalchannel angular pressing (ECAP) will most likely require processing on an industrial scale. There is a need for detailed microstructural and mechanical characterisation of large-scale, ECAP-processed billets. In the present study, we examine the microstructure and mechanical properties as a function of location and orientation within large (50 x 50 x 300 mm³) billets of an Al-6060 alloy produced by ECAP (90° channel angle) with different magnitudes of backpressure. The internal deformation is analysed using a grid-line method on split billets. Hardness is recorded in longitudinal and crosssectional planes. In order to further characterise the local, post-ECAP mechanical properties, tensile tests in different layers are performed. Moreover, low-voltage scanning transmission electron microscopy observations highlight relevant microstructural features. We find that the homogeneity and anisotropy of mechanical properties within the billets depend significantly on the geometry of the shear zone. We demonstrate that deformation gradients can be reduced considerably by increasing the backpressure: The opening-angle of the fan-shaped shear zone is reduced from ψ ≈ 20 ° to ψ ≈ 7 ° when the backpressure is increased from 0 to 150 MPa. Backpressures of 150 MPa result in excellent homogeneity, with a relative variation of tensile mechanical properties of less than 7 %. Our investigation demonstrates that ECAP is suitable for processing homogenous, high performance materials on a large scale, paving the way for advanced industrial applications.

Effect of Strain Localization on Pitting Corrosion of an AlMgSi0.5 Alloy

“…The ingot was extruded at room temperature (RT) reducing the initial diameter of 110 mm to a cross-section of 50 × 50 mm² (samples referred to as RT-extruded). Severe plastic deformation was achieved using the combination of RT-extrusion with a subsequent large-scale ECAP single pass at RT [22,23] (samples referred to as ECAP). The internal angle of the die was 90°, the pressing speed 20 mm min −1 and the backpressure 200 MPa.…”

“…Additional impacts by further processing are excluded. A commercial alloy AlMgSi0.5 with a well-known microstructure [21][22][23] was selected. The results of the micro-scale electrochemical studies are compared to standard macro-scale experiments including the material conditions of the foregoing processing steps casting and extrusion.…”

Microstructure and Texture Inhomogeneity after Large Non-Monotonic Simple Shear Strains: Achievements of Tensile Properties

“…However, the effect of this strain's non-homogeneity and the corresponding microstructural differences on the tensile properties has not been studied yet. On the other hand, it was well proved that the higher strains in the processes such as ECAP, which was achieved after processing by several passes, results in the more homogeneous microstructure and the uniform distribution of mechanical properties [2,11,12]. monotonic, it is non-monotonic in a pass of TE and SSE.…”

Influence of Extrusion Temperature on the Aging Behavior and Mechanical Properties of an AA6060 Aluminum Alloy

“…The high densities of dislocations and vacancies produced by large plastic strains ensure effective strain hardening; they also increase the diffusion rates of solute atoms, and can therefore significantly accelerate precipitation kinetics [2,3]. In case of severe plastic deformation (SPD), e.g., by equal-channel angular pressing (see e.g., [4][5][6] or high-pressure torsion, a rearrangement of dislocations into cell walls and subsequently into small and large angle grain boundaries results in the formation of fairly homogeneous ultrafine-grained (UFG) microstructures [7]. At elevated temperatures, partial or complete dynamic precipitation may also occur during SPD [8][9][10][11].…”