Multiscale residual stress evaluation for laser-welded Eurofer97 steel of nuclear fusion power plants

Assoc. Prof. Tan SUI,  University of Surrey, UK

15:00-16:00,  July 18, 2023

Room 308, Xu Zuyao Building

Biography

Dr Tan SUI is Reader/Associate Professor and Deputy Head of the Centre for Engineering Materials, the School of Mechanical Engineering Sciences (MES) at the University of Surrey. She holds a prestigious Royal Academy of Engineering Industrial Fellowship and visiting role at the National Physical Laboratory (NPL), to accelerate the innovative assessment for the lifespan extension of nuclear materials with the UK Atomic Energy Authority (UKAEA). She is also a Chartered Scientist (CSci) and a Fellow (FIMMM) of the Institute of Materials, Minerals and Mining (IoM3). Prior to the University of Surrey in 2018, she was a Senior Researcher at the University of Oxford after she obtained DPhil degree in 2014. Her expertise involves advanced materials characterisation and nano/micromechanics, using synchrotron/neutron, in situ FIB/SEM techniques and micromechanical modelling, with a strong track record that spans several areas of research, including advanced residual stress characterisation in structural and engineering alloys for nuclear fusion application and bioinspired composites materials for next generation of dental crown application. Her outstanding research track is also reflected in her over 60 peer-reviewed journal publications, including 15 publications with IF>10. 

Abstract

Assembly and maintenance of nuclear fusion power plants require multiple joining techniques. The critical in-vessel joints, such as laser-welded Eurofer97 steel, present significant residual stress issues, necessitating a comprehensive understanding of residual stress and its impacts on structural integrity, reliability, and sustainability. This talk will explore the current state of residual stress measurement techniques, highlighting their advantages and limitations in capturing the complex stress distribution in fusion plant components. Building upon this knowledge, we have developed in-house multiscale residual stress evaluation techniques using plasma focused ion beam and digital image correlation (PFIB-DIC) and nanoindentation, and validated the techniques by leveraging neutron diffraction and high-resolution 2D neutron imaging strain measurements. We will also demonstrate the state-of-the-art 3D strain tomographic reconstruction via a limited number of neutron Bragg edge imaging projections. Our novel approach enables a detailed examination of residual stress at multiple length scales, shedding light on its interaction with microstructures and material performance by incorporating in situ neutron diffraction and DIC techniques and micro-hardness evaluation. By establishing correlations between residual stress, microstructural characteristics, and material performance, we gain insights into the underlying mechanisms governing the behaviour of fusion plant materials. This integrated analysis lays the foundation for addressing critical material challenges, unlocking the potential for improved structural integrity and long-term sustainability in nuclear fusion power plants.