Innovative Forging and Fabrication Solutions for the Nuclear Industry

936c5873-8d95-4114-b23e-b33e496ae99b

Closed

EPSRC
EPSRC
EPSRC
EPSRC
EPSRC

£690,050

May 31, 2015

Dec. 31, 2017

The Sheffield Hallam team will conduct novel experiments to characterise mechanical properties of formed and thick
section components from large forgings. Initial work will focus on developing the specimen design and test strategy using
3D Digital Image Correlation (3DDIC) to obtain Crack Tip Opening Angle (CTOA) resistance curves for the material; post
weld heat treated conditions will be of primary concern. Using CTOA measurements and crack extension data is an
established method of determining both KIc and JIc, using data from 3DDIC has been applied to thin section specimens
and will need adapting for thick sections particularly for uneven crack front phenomena.
Once specimen geometries and test techniques have been established the results will be compared to data for the same
material obtained using standard test methods according to BS EN to the UK Civil Nuclear code. This will serve as
validation of the suitability of DIC to determine fracture properties of the material.
Having validated the technique a series of tests comparing different heat treatment procedures and different regions of
interest in the forging (determined by SFIL) will be evaluated. The results of these tests will be compared to the
microstructural properties of the different specimens and optimal treatments identified.
Running concurrently with DIC based fracture toughness measurements will be a benchmarking fatigue program at
elevated temperature (c.700C) using the current treatment parameters for the material. This will provide baseline high
temperature fatigue properties. Once optimal microstructures are determined based on fracture toughness results a
second set of fatigue tests will be conducted using the ideal structure at elevated temperature to confirm any increase in
performance.
Once initial fracture characterisation is complete development work will start on acquiring high temperature values of KIc
and JIc, the equipment to adapt the currently available DIC hardware at SHU has been factored in and the potential results
are deemed to be of high value both to the academic community and the lead partner. A systematic approach drawing on experience within SHU and LaVision (hardware supplier) and a working relationship with Instron UK will enable trials to
take place with relative ease. Development work is likely to focus on the finer points of obtaining robust correlation from
the high temperature surface, namely speckle pattern retention and reducing interference from the emitted photons from
the specimen.

Potential Impact:
The Pathways to Impact statement details the strategy to maximise the impact of this work. The key impact will be realised
through the achievement of the principle aim, namely bringing novel experimental mechanical characterisation techniques
into the development of structural civil nuclear components, particularly in the optimisation of mechanical properties. In
addition, further developing advanced techniques for mechanical characterisation will benefit the study of fracture
mechanics and the failure of materials; this in turn will improve our fundamental understanding of mechanical failure.
The approach to maximise the dissemination and therefore impact of the findings will be to use both traditional publication
strategies and also through more diverse communication methods. Committing to public science talks and academic
workshops will help further the impact of this work.