Joining techniques between P91 steel and 316 L stainless steel for nuclear fusion applications (materials strand project)

Supervisors: Aneeqa Khan (University of Manchester), John Francis (University of Manchester), Ed Pickering (University of Manchester) and Yiqiang Wang (CCFE)

Typically, components in a fusion reactor need to be made of a variety of different materials to cope with the diverse range of demands placed on the component by fusion reactor conditions, including 14 MeV neutron irradiation, high temperatures, plasma exposure and pulsed operations. The use of various dissimilar materials means that the joining between them is often of concern, and we must ensure the structural integrity of the components during operations. There are several candidate materials that are being considered for the UK Atomic Atomic Energy Authority ‘STEP’ (Spherical Tokamak for Energy Production) programme, including P91 Steel and 316 L Stainless Steel. Joining such dissimilar materials is a challenging process and there are a variety of techniques that can be used, including brazing, electron beam welding and laser welding. It is also important to understand the response to the welds to fusion relevant damage. In order to determine the best techniques for joining P91 and 316 L SS, this project will characterize the welds using in-situ testing and X-Ray/neutron diffraction techniques. There will also be the possible addition of computed tomography (CT), using in-situ mechanical testing experiments to investigate the mechanical behaviours of the welds. The project will be based at the University of Manchester and also make use of the National Lab Facilities at Diamond Light Source (DLS) and ISIS, supervised by Dr. Aneeqa Khan at the University of Manchester at Harwell and Dr. Ed Pickering and Dr. John Francis at the University of Manchester. The project will also work closely with the Materials Technology group at UKAEA.

The objectives of the project will be to:

  • Characterize the as-welded behaviour of a variety of welds under different conditions between 316 L SS and P91
  • Measure the levels of residual stress present in the as-welded materials
  • Investigate how the mechanical behaviour changes following irradiation and/or thermal exposure.
  • Measure how the residual stresses present change following irradiation and/or thermal exposure.

This project will mainly be based at Manchester, but will involve travel to either the synchrotron facilities at Harwell or other international synchrotron facilities, depending on award of beam time. There may also be opportunity to travel to carry out irradiation/thermal treatments of the welds.

The student will develop skills in metallographic preparation and microstructural examination and interpretation. The PhD will also offer specific training in proposal writing (for national facilities), and the collection and analysis of complex X-ray synchrotron/neutron data.  The data analysis involved will almost certainly require the use of a programming language and script writing.

This project is offered by the University of Manchester. For further information please contact:

Aneeqa Khan

Ed Pickering

John Francis