E-Thesis 55 views
The Development of High-Performance Packaging Steels / SEAN BENNETT
Swansea University Author: SEAN BENNETT
DOI (Published version): 10.23889/SUthesis.66609
Abstract
The aim of this work is to create a new packaging grade of high strength steel for can-end applications. This new grade must have a yield strength of 650-750MPa, with a total elongation value of at-least 5% in all directions after double reduction rolling. The higher yield strength is required for d...
| Published: |
Swansea University, Wales, UK
2024
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | EngD |
| Supervisor: | Pleydell-Pearce, C. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa66609 |
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| Abstract: |
The aim of this work is to create a new packaging grade of high strength steel for can-end applications. This new grade must have a yield strength of 650-750MPa, with a total elongation value of at-least 5% in all directions after double reduction rolling. The higher yield strength is required for downgauging, as well as being capable of withstanding the pressures in the retort process, while the ductility is required to form the rivet on the end to attach the ring pull to.The methods used to achieve this involved varying typical packaging alloying elements (such as silicon, phosphorous, and nitrogen), and simulating annealing cycles using a Gleeble 3500 heating simulator where annealing parameters (such as heating rate, soak temperature, and cooling rate), were changed. The purpose of these methods was to promote strengthening via solid solution strengthening, and/or via ferrite grain refinement, and/or secondary phase strengthening.Mechanical properties were assessed using a tensile tester and hardness tester, and microstructures were analysed using optical microscopy and software to obtain statistical information regarding grain size.It was found that when subjected to the commercial annealing cycle a high nitrogen containing chemistry achieved the desired mechanical properties outlined in the project aims. This is likely due to the solid solution strengthening effect of the large amounts of solute nitrogen.Intercritical annealing at 850°C does not lead to generation of secondary phase in the steel chemistries assessed in this body of work, and sometimes decreased the strength in some chemistries.Removal of the slow cool section from simulated intercritical annealing cycles led to negligible changes in Vickers hardness value as well as no microstructural changes either.It was found that packaging steels do not undergo significant amounts of grain refinement when an ultra-rapid heating rate of 200°C/s was used, nor when a 1,000°C/s heating rate was used. |
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| Item Description: |
A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information. |
| Keywords: |
Metallurgy, packaging steel, high strength packaging steel, steel, laboratory compositions, characterisation, optical microscopy, Scanning Electron Microscopy (SEM), composition analysis, mechanical testing, tensile testing, hardness testing, yield strength, ultimate tensile strength, elongation, ferrite, carbides, grains, |
| College: |
Faculty of Science and Engineering |
| Funders: |
Tata Steel, European Social Fund |