The following projects are open for applications. The start date in each case will be the 1st of October 2015.
Modern power systems in safety critical applications rely on the structural integrity of very strong bolts, gears, shafts and retaining components that are made of steel. The service conditions are onerous and reliability is critical to ensuring the safety and performance of the engine.
Because of the extreme requirements for strength, many of these components rely on a martensitic microstructure. But the toughness also needs to be ensured, both during the manufacturing stages and during service. The manufacturing process itself can lead to issues such a quench cracking or undesirable residual stresses.
The proposed research will involve experimental studies of both the microstructure and mechanical properties over a range of length scales. The resulting data will serve to validate theory that will be developed simultaneously for the relationship between structure and properties. The Phase Transformations and Complex Properties research group has considerable experience in the development and validation of models, which can be exploited to help in this process.
The project has the potential for significant scientific and technological outcomes. The candidate will learn and develop advanced microscopy methods, sophisticated mechanical testing and mathematical modeling. It will be carried out in close collaboration with Rolls-Royce plc and will be funded by RR and EPSRC. The stipend will be of the order of 18,500 GBP per annum.
Candidates must have an appropriate Masters qualification and the project is available to candidates who satisfy the U.K. residency requirements. The detailed application procedure is available on-line.
Dr Rosie Ward [remw2@msm.cam.ac.uk] can be consulted on the application procedure and Professor Harry Bhadeshia [hkdb@cam.ac.uk] on the scientific content.
There are demanding requirements on the next generation of nuclear reactors because the time period over which they must function without intervention is expected to be decades. This has consequences on all aspects of reactor design, including the critical pressure vessel. Such a vessel can weigh in excess of 300 tonnes and yet has to exhibit high levels of toughness through thick sections, whilst simultaneously meeting the requirements of strength and the ability to manufacture. The material must also be tolerant to inevitable chemical segregation associated with large castings.
Pressure vessels of this kind have traditionally been made of a low-alloy steel that is given a sequence of heat treatments to result in a tempered, secondary hardened mixture of bainite and martensite. There is about half a century of experience with this trusted alloy, developed using a vast number of experiments.
However, to meet modern requirements, a new nickel-rich steel is proposed, but the time period available for its assessment is years rather than decades. Therefore, this project will use advanced characterization and modelling techniques in order to develop a deep understanding of the material, both from a microstructural point of view and mechanical properties.
The project has the potential for significant scientific and technological outcomes. It will be carried out in close collaboration with Rolls-Royce plc who will fully fund the project. Sheffield Forgemasters will also be involved in helping fabricate the material. The stipend will be of the order of 18,500 GBP per annum.
Candidates must have an appropriate Masters qualification and the project is available to candidates who satisfy the U.K. residency requirements. The detailed application procedure is available on-line.
Dr Rosie Ward [remw2@msm.cam.ac.uk] can be consulted on the application procedure and Professor Harry Bhadeshia [hkdb@cam.ac.uk] on the scientific content.
Nuclear reactor pressure vessels can weigh in excess of 300 tonnes and have to be connected to a variety of components using welding. The wall thickness can be in excess of 150 mm, which means that welding using conventional techniques (such as electric arcs) can be slow because of the large number of passes needed to fill the gaps. As a consequence, productivity is also compromised.
On the other hand, electron beam welds have very large penetration and hence can easily join components thicker than 150 mm in just one pass. Furthermore, the welds are narrow and hence their heat affected zones are also narrow. This can potentially be a huge advantage in ensuring the structural integrity of welded joints. Electron beam welds do not require filler materials (they are autogenous). However, the process has not been seriously investigated in the context of nuclear pressure vessels, which are safety-critical components. The purpose of this project is to conduct fundamental studies of current arc welding and future beam welding processes in pressure vessel manufacture, to undertake predictions of the structure and properties supported by experimental assessments and to provide validated algorithms that will help the design process including the optimization of any heat treatments.
The Phase Transformations and Complex Properties Research Group has considerable experience in modelling arc and laser welds, including the prediction of microstructure and mechanical properties. This will help in developing the necessary theory for electron beam welds.
The project has the potential for significant scientific and technological outcomes. It will be carried out in close collaboration with Rolls-Royce plc who will fully fund the project. The stipend will be of the order of 18,500 GBP per annum.
Candidates must have an appropriate Masters qualification and the project is available to candidates who satisfy the U.K. residency requirements. The detailed application procedure is available on-line.
Dr Rosie Ward [remw2@msm.cam.ac.uk] can be consulted on the application procedure and Professor Harry Bhadeshia [hkdb@cam.ac.uk] on the scientific content.
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