Working in collaboration with the UK Atomic Energy Authority (UKAEA), the National Physical Laboratory, and TESCAN, the researchers from Surrey University have developed and used an advanced microscopic method to map weaknesses inside welded metals during manufacturing that can compromise reactor components and reduce their lifespan.
The research, published in the Journal of Materials Research and Technology, details how they examined P91 steel, which is a candidate for future fusion plants.
The researchers applied an advanced imaging technique using a plasma focused ion beam and digital image correlation (PFIB-DIC) to map residual stress in ultra-narrow weld zones that were previously too small to study with conventional methods.
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Results showed that internal stress has a big impact on how P91 steel performs with beneficial stress making some areas harder and detrimental stress making others softer, which affects how the metal bends and breaks. At 550°C the metal became more brittle and lost more than 30 per cent of its strength.
In a statement, research lead Dr Tan Sui said: “Previous studies have looked at material performance at lower temperatures, but we’ve found a way to test how welded joints behave under real fusion reactor conditions, particularly high heat. The findings are more representative of harsh fusion environments, making them more useful for future reactor design and safety assessments.”
The data from the team is also said to provide a foundation for validating finite element simulation models and machine learning-powered predictive tools, which could accelerate the design of fusion reactors.
Dr Bin Zhu, Research Fellow at Surrey University’s Centre for Engineering Materials and a key author of the study, said: “The methodology we developed transforms how we evaluate residual stress and can be applied to many types of metallic joints. It’s a major step forward in designing safer, more resilient components for the nuclear sector.”
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