E-Thesis 424 views
Advanced characterisation of microstructural evolution and liquation mechanisms in RR1000 employing a novel semi-solid testing facility / SEAN JOHN
Swansea University Author: SEAN JOHN
DOI (Published version): 10.23889/SUthesis.59111
Abstract
Inertia friction welding is a joining technique that is used in many industries as it can create high quality welds with narrow heat affected zones. The nickel superalloy RR1000 is routinely joined via inertia friction welding, during the manufacture of compressor components for gas turbine engines,...
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Swansea
2022
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Davies, Helen |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa59111 |
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| Abstract: |
Inertia friction welding is a joining technique that is used in many industries as it can create high quality welds with narrow heat affected zones. The nickel superalloy RR1000 is routinely joined via inertia friction welding, during the manufacture of compressor components for gas turbine engines, at Rolls-Royce Plc. The conditions experienced at the weld interface of an inertia friction weld are extreme, with a combination of rapid heating rates to high temperatures and severe strain rates. These conditions are such that liquation of RR1000 is to be expected. The liquation mechanisms of two variants of RR1000 have been investigated, building on previous research, to further understand the dynamic evolution of microstructure and mechanical properties during inertia friction welding of RR1000. This investigation was accomplished by the design and commissioning of a novel semi-solid testing facility. The facility underwent numerous modifications to allow representative replication of the conditions experienced during inertia friction welding. To investigate the liquation mechanisms occurring in RR1000, fine grain and coarse grain compression specimens were heated to temperatures between 900°C and 1200°C at heating rates between 1°Cs-1 and 25°Cs-1. The fine grain and coarse grain variants were found to liquate via two mechanisms. The fine grain primarily experienced constitutional liquation of the primary γ’ precipitates, while incipient melting of the γ phase was experienced by the coarse grain variant. The liquid propagation rate in both variants was characterised. The knowledge and understanding gained via the use of this facility was then applied to analyse the microstructures from a series of interrupted RR1000 inertia friction welds. Inspection of these interrupted welds revealed evidence of liquation like that observed in the specimens tested in the semi-solid testing facility. This research has given an insight into the role of liquation during inertia friction welding of RR1000. |
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| Item Description: |
A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions. |
| Keywords: |
Materials Engineering, Nickel Superalloys, Microstructure, Evolution, Liquation, Mechanical testing |
| College: |
Faculty of Science and Engineering |