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Enhanced grain refinement and microhardness by hybrid processing using hydrostatic extrusion and high-pressure torsion

Enhanced grain refinement and microhardness by hybrid processing using hydrostatic extrusion and high-pressure torsion
Enhanced grain refinement and microhardness by hybrid processing using hydrostatic extrusion and high-pressure torsion
An investigation was conducted to examine the microstructure and mechanical properties of an Al-5483 aluminium alloy subjected to a hybrid severe plastic deformation (SPD) process consisting of hydrostatic extrusion (HE) followed by high-pressure torsion (HPT) for up to 10 revolutions. The results are compared with those for samples processed separately by HE or by HPT. Microhardness measurements were taken on cross-sectional planes of the HE billets and on the HPT disks and in addition the microstructures were examined using transmission electron microscopy. The results demonstrate that the hybrid process of HE+HPT induces additional grain refinement when compared with HPT with average grain sizes of ~60 and 90 nm, respectively. Also, a significantly higher fraction of high-angle grain boundaries (HAGBs) was present after HE+HPT and the beneficial role of HE pre-processing was also apparent in the microhardness measurements. After the hybrid process, the microhardness saturated at Hv ≈ 255 which is higher than after either HPT (Hv ≈ 235) or HE (Hv ≈ 160). A linear Hall-Petch relationship was maintained for coarse-grained and SPD-processed samples with high fractions of HAGBs (above 70%) while samples with higher fractions of low-angle grain boundaries showed a significant deviation from linearity.
0921-5093
513-520
Bazarnik, Piotr
7612d50d-0cfc-43b1-a48f-f5062caacc1e
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Lewandowska, Malgorzata
c574d02d-d34d-4164-8ed1-90c3d77584d2
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Bazarnik, Piotr
7612d50d-0cfc-43b1-a48f-f5062caacc1e
Huang, Yi
9f4df815-51c1-4ee8-ad63-a92bf997103e
Lewandowska, Malgorzata
c574d02d-d34d-4164-8ed1-90c3d77584d2
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86

Bazarnik, Piotr, Huang, Yi, Lewandowska, Malgorzata and Langdon, Terence G. (2018) Enhanced grain refinement and microhardness by hybrid processing using hydrostatic extrusion and high-pressure torsion Materials Science and Engineering: A, 712, pp. 513-520. (doi:10.1016/j.msea.2017.12.007).

Record type: Article

Abstract

An investigation was conducted to examine the microstructure and mechanical properties of an Al-5483 aluminium alloy subjected to a hybrid severe plastic deformation (SPD) process consisting of hydrostatic extrusion (HE) followed by high-pressure torsion (HPT) for up to 10 revolutions. The results are compared with those for samples processed separately by HE or by HPT. Microhardness measurements were taken on cross-sectional planes of the HE billets and on the HPT disks and in addition the microstructures were examined using transmission electron microscopy. The results demonstrate that the hybrid process of HE+HPT induces additional grain refinement when compared with HPT with average grain sizes of ~60 and 90 nm, respectively. Also, a significantly higher fraction of high-angle grain boundaries (HAGBs) was present after HE+HPT and the beneficial role of HE pre-processing was also apparent in the microhardness measurements. After the hybrid process, the microhardness saturated at Hv ≈ 255 which is higher than after either HPT (Hv ≈ 235) or HE (Hv ≈ 160). A linear Hall-Petch relationship was maintained for coarse-grained and SPD-processed samples with high fractions of HAGBs (above 70%) while samples with higher fractions of low-angle grain boundaries showed a significant deviation from linearity.

Text 1-s2.0-S0921509317316040-main - Accepted Manuscript
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Accepted/In Press date: 4 December 2017
e-pub ahead of print date: 6 December 2017
Published date: 17 January 2018

Identifiers

Local EPrints ID: 416221
URI: http://eprints.soton.ac.uk/id/eprint/416221
ISSN: 0921-5093
PURE UUID: baa33e7b-406a-4d07-b8a2-074b2a2ae668
ORCID for Yi Huang: ORCID iD orcid.org/0000-0001-9259-8123
ORCID for Terence G. Langdon: ORCID iD orcid.org/0000-0003-3541-9250

Catalogue record

Date deposited: 08 Dec 2017 17:30
Last modified: 17 Jan 2018 17:30

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Contributors

Author: Piotr Bazarnik
Author: Yi Huang ORCID iD
Author: Malgorzata Lewandowska

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