The contribution from the University of Sheffield to the "Innovative Forging and Fabrication Solutions for the Nuclear
Industry" project will be on the modelling and its validation of the welding process and development and property validation
of post weld heat treatment schedules using the heat treatment simulator produced in EP/L50466X/1. This will be
undertaken by Prof Wynne, Dr Palmiere, and Dr Jackson in collaboration with a PhD Student, supported by the grant. Thus
the aim of the project in its broadest sense is: Development of quality heat treatment schedules for thick sectioned welds.
This will be achieved by the following four work packages.
Work Package 1: Validate Finite Element Model of Thick Section Welds produced using Reduced Pressure Electron Beam
Welding (Phd Student, UoS, TWI, SFIL)
This includes determination of temperature distribution during welding, size of weld zone, size of heat affected zone,
cooling rates, and residual stress distribution. Furthermore, material type sensitivity will be investigated from current
nuclear grade steels through to next generation materials.
Work Package 2: Microstructure Evaluation of As-Welded Microstructure. (PhD Student, UoS)
A detailed investigation of the as-welded microstructure in terms of alloy segregation, weld zone sizes, grain size,
transformation product, etc will be undertaken using optical and electron microscopy. Results will be compared to the modelling results produced in WP1
Work Package 3: Development of Potential Heat Treatment Schedules for As-Welded Materials. (PhD Student, UoS, SFIL)
Review of literature on potential heat treatment schedules for welded materials, concentrating on issues relating to the
general physical metallurgy, welding methodologies and metallurgical challenges, as well as NDT evaluation techniques.
The project has already identified the steel compositions, and so this particular task should be highly focused, identifying
material and post-production issues. Thermodynamic modelling of the steel compositions will indicate the phases and
phase fractions expected. Initial risks associated with the use of the steel compositions will also be assessed.
Work Package 4: Application of Identified Heat Treatment Schedules in the Heat Treatment Simulator. (PhD Student, UoS,
SFIL)
Following on from the outcomes of WP3, the chosen heat treatment schedules will be undertaken on as welded material
using the heat treatment simulator. Mechanical property evaluation will be in the form of tensile tests, Charpy impact tests,
crack tip opening displacement tests, and hardness profiles. Microstructure characterisation will produce information on
phase fractions, segregation profiles, and microstructure type and uniformity using optical and scanning electron
microscopy. These results will then form the basis for large scale trials.
Work Package 5: Validate Linkage Between Chosen Heat Treatment and Actual Component. (PhD Student, UoS, SFIL)
This work package will compare and contrast simulated results, both mechanical and microstructure, with an actual
component. Extreme areas of the as-forged component will be investigated to ensure good variability coverage.
Microstructure at levels above optical, i.e. precipitation density, will be taken thus requiring advanced characterisation
methods such as scanning and transmission electron microscopy.
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