Microstructure development and hardening during high pressure torsion of commercially pure aluminium: strain reversal experiments and a dislocation based model
Microstructure development and hardening during high pressure torsion of commercially pure aluminium: strain reversal experiments and a dislocation based model
The effect of strain reversal on hardening due to high pressure torsion (HPT) was investigated using commercially pure aluminium. Hardening is lower for cyclic HPT (c-HPT) as compared to monotonic HPT (m-HPT). When using a cycle consisting of a rotation of 90 degree per half cycle, there is only a small increase in hardness if the total amount of turns is increased from 1 to 16. Single reversal HPT (sr-HPT) processing involves torsion in one direction followed by a (smaller) torsion in the opposite direction. It is shown that a small reversal of 0.25 turn (90 degree) reduces hardness drastically, and that decrease is most marked for the centre region. These behaviours and other effects are interpreted in terms of the average density of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs). A model is presented that describes the experimental results well. A key element of the model is the assumption that at the very high strains developed in severe plastic deformation processes such as HPT, the dislocation density reaches a saturation value. The model indicates that the strength / hardness is predominantly due to GNDs and SSDs.
severe plastic deformation (spd), aluminium alloys, high pressure torsion, dislocation, hardness
2581-2591
Zhang, Jiuwen
e7688df7-ee61-48ff-a860-f484d6ad4aa3
Gao, Nong
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Starink, Marco J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
15 March 2011
Zhang, Jiuwen
e7688df7-ee61-48ff-a860-f484d6ad4aa3
Gao, Nong
9c1370f7-f4a9-4109-8a3a-4089b3baec21
Starink, Marco J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
Zhang, Jiuwen, Gao, Nong and Starink, Marco J.
(2011)
Microstructure development and hardening during high pressure torsion of commercially pure aluminium: strain reversal experiments and a dislocation based model.
Materials Science and Engineering: A, 528 (6), .
(doi:10.1016/j.msea.2010.11.079).
Abstract
The effect of strain reversal on hardening due to high pressure torsion (HPT) was investigated using commercially pure aluminium. Hardening is lower for cyclic HPT (c-HPT) as compared to monotonic HPT (m-HPT). When using a cycle consisting of a rotation of 90 degree per half cycle, there is only a small increase in hardness if the total amount of turns is increased from 1 to 16. Single reversal HPT (sr-HPT) processing involves torsion in one direction followed by a (smaller) torsion in the opposite direction. It is shown that a small reversal of 0.25 turn (90 degree) reduces hardness drastically, and that decrease is most marked for the centre region. These behaviours and other effects are interpreted in terms of the average density of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs). A model is presented that describes the experimental results well. A key element of the model is the assumption that at the very high strains developed in severe plastic deformation processes such as HPT, the dislocation density reaches a saturation value. The model indicates that the strength / hardness is predominantly due to GNDs and SSDs.
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Zhang,_Gao_&_Starink_2011.pdf
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Published date: 15 March 2011
Keywords:
severe plastic deformation (spd), aluminium alloys, high pressure torsion, dislocation, hardness
Organisations:
Engineering Mats & Surface Engineerg Gp
Identifiers
Local EPrints ID: 168241
URI: http://eprints.soton.ac.uk/id/eprint/168241
ISSN: 0921-5093
PURE UUID: 431eda89-4bcb-4cea-aac8-4dadd28e823f
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Date deposited: 25 Nov 2010 14:29
Last modified: 14 Mar 2024 02:45
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Author:
Jiuwen Zhang
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