Modelling Creep and Creep-Fatigue Damage for CSEF Power Plant Steels

The current market conditions are such that combined cycle gas turbine (CCGT) plants are now considering double two-shift operation, so potentially accruing upwards of 600 starts per year. The pressure to reduce the extent of pressure system inspections and repairs continues to increase, with the most recent capacity auction clearing prices for generation showing a significant reduction when compared to previous years. For operators of large generation facilities the key consideration is the through life revenue return, which will guide decisions on new plant builds and any capital investments on plant currently operating. On this basis the need for effective life prediction and condition monitoring tools to support the supply chain (designer, fabricator, operator and technical service provider) is evident.

Over the years, significant development has been made on the 9-12%Cr creep strength enhanced ferritic (CSEF) steels. Traditionally, in material development for power plant components, creep ductility, which can be treated as resistance to damage, has received much less attention. However, the risk of catastrophic failure due to low damage tolerance is a real challenge, in particular, in the situation where mechanical and metallurgical constraints are present. In addition, due to the increasing frequency of cyclic operations, i.e. starts up and shut downs for main steam pipelines of power plants, low cycle creep fatigue failure due to low ductility of the materials has become an important concern.

The aim of the proposed project is to investigate creep and creep fatigue behaviour which takes into account the variable ductility for CSEF power plant steels, through a comprehensive theoretical, experimental and computational programme.

Specific objectives will include:

1. Data acquisition/analysis and critical review on the currently available models and assessment procedure.
2. Experimental/physical understanding of creep and creep fatigue behaviour of CSEF power plant steels with different initial ductility.
3. Development of a novel creep and creep fatigue model which takes into account the variable ductility.
4. Application of the model for component assessment using the operational data from a modern CCGT plant.

High temperature mechanical testing and physical characterization will be carried out using well-established facility. The theoretical and modelling work will be carried out using finite element package ABAQUS through user defined subroutines.

The proposed Centre will benefit the following groups

1. Students - develop their professional skills, a broad technical and societal knowledge of the sector and a wider appreciation of the role decarbonised fuel systems will play in the UK and internationally. They will develop a strong network of peers who they can draw on in their professional careers. We will continue to offer our training to other Research Council PhD students and cross-fertilise our training with that offered under other CDT programmes, and similar initiatives where that develops mutual benefit. We will further enhance this offering by encouraging industrialists to undertake some of our training as Professional Development ensuring a broadening of the training cohort beyond academe. Students will be very employable due to their knowledge, skills and broad industrial understanding.
2. Industrial partners - Companies identify research priorities that underpin their long-term business goals and can access state of the art facilities within the HEIs involved to support that research. They do not need to pre-define the scope of their work at the outset, so that the Centre can remain responsive to their developing research needs. They may develop new products, services or models and have access to a potential employee cohort, with an advanced skill base. We have already established a track record in our predecessor CDTs, with graduates now acting as research managers and project supervisors within industry
3. Academic partners - accelerating research within the Energy research community in each HEI. We will develop the next generation of researchers and research leaders with a broader perspective than traditional PhD research and create a bedrock of research expertise within each HEI, developing supervisory skills across a broad range of topics and faculties and supporting HEIs' goals of high quality publications leading to research impacts and an informed group of educators within each HEI. .
4. Government and regulators - we will liaise with national and regional regulators and policy makers. We will conduct research directly aligned with the Government's Clean Growth Strategy, Mission Innovation and with the Industrial Strategy Challenge Fund's theme Prosper from the Energy Revolution, to help meet emission, energy security and affordability targets and we will seek to inform developing energy policy through new findings and impartial scientific advice. We will help to provide the skills base and future innovators to enable growth in the decarbonised energy sector.
5. Wider society and the publics - developing technologies to reduce carbon emissions and reduce the cost of a transition to a low carbon economy. Need to ascertain the publics' views on the proposed new technologies to ensure we are aligned with their views and that there will be general acceptance of the new technologies. Public engagement will be a two-way conversation where researchers will listen to the views of different publics, acknowledging that there are many publics and not just one uniform group. We will actively engage with public from including schools, our local communities and the 'interested' public, seeking to be honest providers of unbiased technical information in a way that is correct yet accessible.