Stress and Creep Damage Evolution in Materials for Ultra-Supercritical Power Plant

Lead Research Organisation: Open University
Department Name: Engineering & Innovation


Future fossil power generation plant will have to operate at higher temperatures to increase its thermal efficiency and reduce its carbon footprint. High-chromium martensitic steels (such as P91, P92) have been developed for elevated temperature applications and are being used increasingly in supercritical power stations, but there are early signs of cracking around weldments in service. The underlying physics and micro-mechanisms contributing these failures needs to be understood and quantified so that new design and life assessment methods can be developed. The aim of this training research proposal is to exploit the potential of neutron and synchrotron radiation measurement techniques at Central Facilities. The techniques will be applied to measure fabrication residual stresses at multiple length-scales in high Cr weldments and quantify how they relax during service high temperature exposure, to measure and spatially resolve plastic and creep deformation across weldments, and to quantify volumetrically the evolution of creep cavitation leading to cracking. The project will use ENGIN-X, LOQ and SANS_2D instruments at ISIS and JEEP at Diamond and involve the student spending four training placements these instruments. The project fits closely with a programme of high temperature materials for energy research at the Open University where the student will have access to complementary test facilities. Welded test specimens will provided by European Technology Development Ltd whose involvement will facilitate dissemination of the results and capabilities of advanced measurement techniques to the power generation industry worldwide.


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Description Creep strength enhanced 9-12% Cr steels have been identified as the most promising class of materials for key components operating at high temperatures in advanced power plants. The research examined the effectiveness of post weld heat treatments and discovered how (Type IV) cracking is influenced by both the heat treatment process, locked in stresses that remain after the treatment, and the weld geometry. A digital image correlation (DIC) technique was applied to resolve tensile and time- dependent creep deformation properties along the length of P91 cross-weld samples for the first time.
Exploitation Route A confirmatory programme of creep testing is desirable so that the benefits of the new understanding relating to the significance of weld residual stress, post-weld heat treatment and creep damage can be incorporated in new life predictive models. The full field DIC technique can be applied to study welded components in far more spatial detail than previously possible.
Sectors Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Transport

Description The findings have attracted the interest of power sector SME and UK based fossil power generation industry partners. Follow-on work at the Open University examining ferritic-martensitic steel welds has been sponsored by UK industrial partners using the DIC technology demonstrated in the research project.
First Year Of Impact 2013
Sector Energy,Manufacturing, including Industrial Biotechology
Impact Types Economic

Description Maintenance grant
Amount £3,000 (GBP)
Organisation Australian Nuclear Science and Technology Organisation 
Sector Public
Country Australia
Start 06/2012 
End 08/2012
Description Travel grant
Amount £800 (GBP)
Organisation Armourers & Brasiers 
Sector Private
Country United Kingdom
Start 05/2012 
End 07/2012
Description ETD 
Organisation European Technology Development (ETD Consulting)
Country United Kingdom 
Sector Private 
PI Contribution Sharing the progress and outcomes of this research project with a SME
Collaborator Contribution Provision of specialist advice from an industrial perspective throughout the project. Helping to secure the supply of P91 material at the outset of the project.
Impact The PhD student worked for several weeks on a project assisting the consultancy business of the SME (direct economic benefit to the SME).
Start Year 2010
Description Secondment at ANSTO 
Organisation Australian Nuclear Science and Technology Organisation
Department Bragg Institute
Country Australia 
Sector Public 
PI Contribution The OU has strong links with ANSTO (Australian Nuclear Science and Technology Organization) which has a longstanding interest and active research programme studying the performance and management materials in the power generation industry. Two successful applications for neutron beamtime were made at the Bragg Institute. The PhD student sponsored by this grant spent 3 months at ANSTO. conducting creep and neutron diffraction experiments.
Collaborator Contribution Access to neutron beamtime on the KOWARI instrument, with training, allowing the researcher to carry out neutron diffraction experiments. Use of creep rigs for creep rupture tests
Impact 1 journal paper and contributions to the PhD thesis of the Open University student
Start Year 2012
Description Training at ISIS 
Organisation Science and Technologies Facilities Council (STFC)
Department ISIS Neutron and Muon Source
Country United Kingdom 
Sector Academic/University 
PI Contribution The PhD student funded by the grant spent 3 months as a placement with instrument scientist (a co-supervisor of the student). The main objectives met were: 1)Assisting instrument scientist and other Open University researchers in their experiments 2) Enriching collaboration between the OU and with instrument scientists at ISIS
Collaborator Contribution 1) Providing training and learning opportunity for the student 2) Strengthening the synergy between STFC facilities and The Open University
Impact Thesis of PhD student. The PhD student assisted several visiting research teams undertake neutron diffraction experiments on the ENIN-X instrument.
Start Year 2011