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Effect of creep parameters on the steady-state flow stress of pure metals processed by high-pressure torsion

Effect of creep parameters on the steady-state flow stress of pure metals processed by high-pressure torsion
Effect of creep parameters on the steady-state flow stress of pure metals processed by high-pressure torsion
The correlation between the flow stress and grain size for severely deformed metals remains undefined because the conventional Hall-Petch relationship ignores the expected contributions from thermally-activated phenomena in nanomaterials and also it fails to explain the reported strain softening of metals having low melting temperatures. In this study, the contribution of thermally-activated creep mechanisms to the room temperature flow stress is evaluated for 31 pure metals processed by high-pressure torsion. The steady-state grain size and the hardness of these metals are first compared to theoretical predictions from high temperature creep mechanisms. It is shown that these mechanisms are not able to predict the flow stress, although the data from metals with low melting temperatures fall close to the theoretical prediction for high-temperature grain boundary sliding suggesting a possible explanation for the unusual softening of these metals. Nevertheless, a detailed analysis demonstrates that a modified model for grain boundary sliding at low temperature provides the capability of correctly predicting the flow stresses for metals having both high and low melting temperatures. The results confirm the significance of thermally-activated phenomena in determining the flow stress of nanomaterials processed by severe plastic deformation.
Severe plastic deformation (SPD), creep, grain boundary sliding, high pressure torsion, ultrafine-grained materials
0921-5093
Figueiredo, Roberto B.
64fe521f-9463-435f-a4a4-503c308ec82c
Edalati, Kaveh
ca70a7e0-bcb8-4a62-bddb-f7a6cbcad803
Langdon, Terence G
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Figueiredo, Roberto B.
64fe521f-9463-435f-a4a4-503c308ec82c
Edalati, Kaveh
ca70a7e0-bcb8-4a62-bddb-f7a6cbcad803
Langdon, Terence G
86e69b4f-e16d-4830-bf8a-5a9c11f0de86

Figueiredo, Roberto B., Edalati, Kaveh and Langdon, Terence G (2022) Effect of creep parameters on the steady-state flow stress of pure metals processed by high-pressure torsion. Materials Science and Engineering: A, 835, [142666]. (doi:10.1016/j.msea.2022.142666).

Record type: Article

Abstract

The correlation between the flow stress and grain size for severely deformed metals remains undefined because the conventional Hall-Petch relationship ignores the expected contributions from thermally-activated phenomena in nanomaterials and also it fails to explain the reported strain softening of metals having low melting temperatures. In this study, the contribution of thermally-activated creep mechanisms to the room temperature flow stress is evaluated for 31 pure metals processed by high-pressure torsion. The steady-state grain size and the hardness of these metals are first compared to theoretical predictions from high temperature creep mechanisms. It is shown that these mechanisms are not able to predict the flow stress, although the data from metals with low melting temperatures fall close to the theoretical prediction for high-temperature grain boundary sliding suggesting a possible explanation for the unusual softening of these metals. Nevertheless, a detailed analysis demonstrates that a modified model for grain boundary sliding at low temperature provides the capability of correctly predicting the flow stresses for metals having both high and low melting temperatures. The results confirm the significance of thermally-activated phenomena in determining the flow stress of nanomaterials processed by severe plastic deformation.

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Figueiredo_MSEA-2021 - Accepted Manuscript
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More information

Accepted/In Press date: 10 January 2022
e-pub ahead of print date: 14 January 2022
Published date: 19 January 2022
Keywords: Severe plastic deformation (SPD), creep, grain boundary sliding, high pressure torsion, ultrafine-grained materials

Identifiers

Local EPrints ID: 454317
URI: http://eprints.soton.ac.uk/id/eprint/454317
ISSN: 0921-5093
PURE UUID: 41e3b546-5b72-4adc-842b-112027e54d99
ORCID for Terence G Langdon: ORCID iD orcid.org/0000-0003-3541-9250

Catalogue record

Date deposited: 07 Feb 2022 17:40
Last modified: 10 Jan 2023 05:01

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Contributors

Author: Roberto B. Figueiredo
Author: Kaveh Edalati

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