Sheffield Forgemasters has announced a breakthrough in the industrialisation of Electron Beam Welding (EBW) for thick-section materials. Using EBW, the company weld-joined two 200mm thick, 3m diameter vessel sections in UK-SMR nuclear grade steel. The weld, equivalent to approximately 10m of length, was completed in a single pass and in a dramatically short timeframe.
The operation was completed in just 140min, with no reportable defects shown in preliminary non-destructive testing (NDT), demonstrating a radical breakthrough in welding technology. A weld of this kind would traditionally take months and include numerous stages of NDT as well as heat-treatment.
Professor Jesus Talamantes-Silva, research, design and technology director at Sheffield Forgemasters, said: “This is the most critical milestone in our project to industrialise EBW and to eliminate the requirement for large vacuum chambers typically used in this technology, we have pioneered the use of local vacuum EBW alongside our project partners, Cambridge Vacuum Engineering (CVE).”
“It follows a body of work started in 2015 with support from Innovate UK to establish the basic science for local vacuum EBW, which was successful, producing welds with very favourable mechanical properties.”
The company initiated a subsequent 2019 project: ‘Industrialisation of large-scale electron beam welding for nuclear industry applications’ to further prove the technology, supported by the Department for Business, Energy and Industrial Strategy (BEIS) as part of its £505 million Energy Innovation Portfolio.
Sheffield Forgemasters’ aim is to incorporate advanced fabrication techniques, offering significant savings on both processing time and cost through the potential of EBW over the more traditional method of TIG welding for thick-section pressure vessels.
The EBW process uses local vacuum and a high-power electron gun which penetrates the vessel material with an electron beam, to melt and fuse the two components together in one pass, rather than building up of multiple layers of weld filler wire.
Dr Michael Blackmore, senior development engineer and project lead, added: “We completed the weld and carried out the factory acceptance testing of the machine tool, a process that verifies that the equipment is built and operating in accordance with design specifications at CVE's site in Cambridge.”
The project, led by Sheffield Forgemasters, underpins the company’s ambitious commitment to the UK’s civil nuclear ambitions as demonstrated through its supply of complex, nuclear-grade demonstrator forgings to the Rolls-Royce SMR programme.
To ensure successful dissemination and awareness of the EBW technology, an industry steering committee including the Ministry of Defence, Rolls-Royce submarines and SMR divisions, the UK Atomic Energy Authority and Cavendish Nuclear, was formed. Engagement with the Office for Nuclear Regulation and Environment Agency was also instigated by BEIS as the project progressed.
Dr Blackmore continued: “We are due to start building an X-Ray enclosure to house the EBW equipment, and it will be ready during Q2 2022. We are also planning to fully demonstrate the welding capabilities by fabricating a full-scale nuclear pressure vessel which will consist of five main components, four shells and a nuclear head, to ensure a reliable and repetitive process.”
The project benefits from partner contributions and support from CVE, Arc Energy Resources, The Welding Institute, the Nuclear Advanced Manufacturing Research Centre at the University of Sheffield, and the Universities of Cambridge and Manchester.
Bob Nicolson, managing director of CVE, said: “We have been proud to host the ONR, EA and BEIS representatives during visits to our Cambridge factory to officially present progress and hardware capabilities to be utilised at Sheffield Forgemasters.”
Sheffield Forgemasters actively supports the development of materials and processes for the nuclear sector. Safety-critical components, namely castings and forgings, have been produced using conventional methods. More advanced manufacturing techniques such as Hot-Isostatic Pressing and advanced metal-forming have also been successfully implemented at its Brightside Lane facility.
Although the main core activity of the EBW project is welding, other work packages within the project will also advance Sheffield Forgemasters’ technical expertise in areas such as fracture mechanics and cladding.
The project was part funded under the £26 million Advanced Manufacturing and Materials Programme within the BEIS Energy Innovation Programme.