Microstructural, micro-hardness and micro-residual stress analysis of welded Eurofer97 for fusion plant
This fully funded PhD is an exciting opportunity to make a contribution to the realisation of nuclear fusion.
Start date1 October 2018
The studentship covers the full cost of UK/EU tuition fees, plus a tax-free stipend of approximately £14,777 p.a., in line with standard RCUK stipend levels (2018-2019).
The Reduced Activation Ferritic Martensitic Steel Eurofer97 is the main material considered for the in-vessel components (e.g. breeding blanket structure and divertor cassette) of the demonstration fusion reactor, or DEMO. To facilitate Remote Maintenance (RM) of DEMO, the RM teams at Culham Centre for Fusion Energy (CCFE) utilise lasers to cut and weld Eurofer97 components. This rapid welding process generates significant residual stress up to c.800MPa inside the materials. The in-service elevated temperatures which these materials will experience will result in creep relaxation cracking due to the existence of the high residual stress. Such cracking often initiates at the grain level (micro-scale) in the heat affected zone (HAZ), with its altered morphology, microstructure and micromechanical properties, which can lead to high values of tensile residual stress. Understanding (i) the residual stress at the grain level, inherited from the rapid laser welding process, and (ii) how this stress evolves at elevated temperature, plays a pivotal role in avoiding catastrophic failure regarding the structural integrity of fusion power plant.
This interdisciplinary PhD project is funded by the University of Surrey’s Doctoral College Studentship Award. The project allows close collaboration between Department of Mechanical Engineering Sciences (MES) at Surrey and Culham Centre for Fusion Energy (CCFE) to create new knowledge and address challenging problems for fusion materials, using complementary world-leading facilities in both parties. The successful candidate will engage in the microstructure characterisation and micro-residual stress evaluation activities, using advanced experimental mechanical microscopy techniques available at the Department of Mechanical Engineering Sciences at the University of Surrey and multi-scale mechanical testing at CCFE. These will be combined with modelling to provide systematic means of evaluating a wide range of mechanical behaviour of the welded and aged Eurofer97. The proposed project provides a significant contribution to the ultimate objective of performing structure integrity assessment of the DEMO fusion power plant with improved accuracy and efficiency.
The main supervisor, Dr Tan Sui has the expertise involves micromechanics and micron-scale residual stress evaluation using mechanical microscopy including synchrotron X-ray, focused ion beam (FIB) and digital image correlation (DIC) techniques.The second supervisor, Dr Mark Whiting has the expertise in phase transformations in steels as well as advanced characterisations using SEM, TEM and EBSD techniques. The industrial supervisor, Dr Yiqiang Wang has consolidated knowledge of mechanical property testing of steel alloys using lab-based mechanical tests facilities.
Applicants should have (or expect to obtain by the start date) at least a 2:1 bachelors degree, and preferably a masters degree in an appropriate discipline (e.g. engineering, material sciences, physics or related subject).
If English is not the first language, IELTS 6.5 or above (or equivalent) is required, with no sub-test score less than 6
Open to European/UK students only.