Achieving high strain rates superplasticity in SPD-processed light alloys
Key details of this case study:
Summary:
Our research has shown that advanced materials development can help the manufacturing industry achieve high-value and high-volume manufacturing, which could have huge economic and social benefits.
Status: Completed
Key staff: Dr Yi Huang , Professor Terence G. Langdon , Pedro Henrique R. Pereira
The SPD-processed AlMgSc alloy, can significantly improve the production rate in the superplastic forming process for aerospace and automotive components.
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The challenge
Severe plastic deformation (SPD) is an innovative technique for producing ultrafine-grained (UFG) metals and alloys at the submicrometer or even nanometer level. This compares with conventional techniques which can only make relatively coarse-grained microstructures.
These UFG materials offer significant strength, with the potential to achieve high strain rate superplasticity. In practice however, using SPD forming technology is limited by relative low strain rates associated with the forming process, resulting in low production rate and low-volume manufacturing.
In order to tackle the challenge of high production rates in SPD, University of Southampton researchers aimed to process UFG materials through SPD processing, and achieve superplasticity at high strain rates so that the forming time for each component may be reduced.
What we did
It is well known that the rate of flow in superplasticity varies inversely with the grain size and evidence from standard superplastic alloys shows that the superplastic regime is displaced to faster strain rates when a material’s grain size is reduced.
SPD-processed UFG materials have high-volume fraction of grain boundaries, which would make grain boundary sliding (GBS) occur at higher strain rates. This led us to assume that it would be possible to increase strain rates for superplastic forming by making substantial reductions in the grain size through SPD processing.
This project focused on developing enhanced superplasticity in a light alloy (AlMgSc alloy) by applying one of the SPD processing techniques and investigating the relationship between processing parameters, heat treatment conditions, precipitates evolutions, UFG microstructures and superplastic properties.
This research was part-funded by an ERC grant of £40,000 in 2014
Our impact
The AlMgSc alloy has been the focus for research and development for Airbus, Aleris and other companies. Due to its low density and lighter weight, it offers significant weight saving opportunities for aerospace and automotive manufacturers. However, the slow forming rate restricts its commercial applications.
By refining the grain structure of AlMgSc alloy through SPD processing, our research has shown very good thermal stability in the refined structure and the AlMgSc alloy achieved high strain rate superplasticity.
This will significantly increase production rates and enable the application of superplastic forming into the fabrication of high-volume, high-value components associated with aerospace industries.
Meanwhile, the decrease in manufacturing costs, including oil, electricity and labour, from using the AIMgSc alloy will benefit manufacturers, customers and society due to its energy efficiency and low carbon manufacturing.
The facilities we used
We used the following facilities within the University - High-pressure torsion (HPT) machine, Materials Lab; Zwick tensile testing machine.
Find out more about the Engineering and Environment Faculty's many world class facilities.
Awards received for this research
Pedro Henrique R. Pereira, a PhD researcher working on this project, won best oral presentation at NanoSPD7 (The 7th International Conference on Nanomaterials by Severe Plastic deformation) , which was held in the University of Sydney, Australia on 2–7 July 2017.
Related media
Fig 1: The microstructure of AlMgSc alloy processed to 10 turns at room temperature by a SPD technique - high-pressure torsion (HPT) followed by further annealing at 300°C, showing good thermal stability with average grain size ~0.5 um. [Pereira, Huang and Langdon, Materials Research-IBERO-American Journal of Materials, 20 (Suppl. 1) (2017) 39-45.]
Fig 2: HPT-processed AlMgSc alloy was tensile tested at 300°C, showing the superplastic elongations of 800% at fast strain rate of 1.4x10-2 s-1. [Pereira, Huang and Langdon, Letters on Materials, 5(3) (2015) 294-300.]
Related Staff Member
Dr Yi Huang PhD, MIMMM, CEng, FHEA
Dr Yi Huang is Senior Research Fellow within Engineering and Physical Sciences at the University of Southampton.
Read moreRelated Staff Member
Professor Terence G Langdon PhD, DSc, DSc hon causa, Dr hon causa, FREng
Professor Terence G Langdon is Professor of Materials Science within Engineering and Physical Sciences at the University of Southampton.
Read moreOther University of Southampton sites
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