Mechanistic Studies of Fatigue in Austenitic Stainless Steels in a Pressurised Water Reactor Primary Coolant

Introduction

This project represents an exciting opportunity to work closely with Rolls-Royce in an active international research area and the Materials Performance Centre (MPC). The MPC is the largest academic nuclear materials research group in the UK, focusing on materials degradation phenomena including environmentally sensitive behaviours of materials. The general aim of the Centre’s research is to understand the underlying mechanisms responsible for the microstructure evolution during processing and degradation modes during performance. Rolls-Royce, the industrial sponsor, is currently one of the most active researchers in this field, and has an ongoing R&D programme to investigate the effects of PWR coolant on the fatigue lives of PWR plant materials.

The project will provide the student with an opportunity to develop several valuable and marketable skills such as electron microscopy, developing environmental fatigue assessment methods, and collaborating in research projects.

Project description

Austenitic stainless steels such as 304 and 316 are extensively used in the primary circuit internals of Pressurized Water Reactor (PWR) due to their high corrosion resistance properties. However they are susceptible to environmentally assisted fracture where the aqueous high temperature coolant has a deleterious effect on the fatigue behaviour of these plant structural materials when compared to similar loading conditions in air. Therefore, understanding this phenomena and developing improved methods of assessing environmentally assisted fatigue are important for demonstrating the ongoing safety of nuclear power plants.

This project will focus on developing the mechanistic understanding of environmentally assisted fatigue in austenitic stainless steels operating in a PWR water environment. Within this subject, there are currently a number of areas of interest surrounding environmental fatigue in austenitic stainless steels including: the effects of a PWR water environment on crack nucleation, short crack growth and long crack growth; the effects of hydrogen on environmental enhancement; and the effects of material microstructure on fatigue crack nucleation and short crack growth mechanisms.

The project will aim to improve the understanding in one or more of these areas using a range of microscopy and analysis techniques, possibly including: light and/or laser confocal microscopy; Scanning Electron Microscopy (SEM), Electron Back-Scatter Diffraction (EBSD); Digital Image Correlation (DIC); and Focused Ion Beam (FIB) milling.

In addition to the insights gained from microscopy, there is also an opportunity to apply these results to the further development of current fatigue assessment methodologies, particularly with regards to short crack growth and the transition to longer crack growth, and the assessment of fatigue initiation lifetimes. The final scope of the project can also be tailored to focus on areas or investigative techniques of particular interest to the researcher.

We are looking to fill this post as soon as possible.