Start date and planned duration: February 2019, 36 months
- Develop an additive manufacturing (AM) process for the deposition of high temperature materials, including repair of failed components.
- Progress inspection techniques for AM deposited high temperature materials particularly in repaired locations.
- Characterise high temperature properties, microstructure and macrostructure of AM parts made from high temperature materials.
- Understand the stresses present in the AM repairs in order to estimate and optimise the service life of repaired components.
The project will develop an AM process suitable for depositing high-temperature materials such as Alloy 800HT or 310 stainless steel, extending TWI’s current AM capabilities to new materials. The processes developed will include repairing existing complex thermally aged components. The deposited material will then be inspected using NDT techniques to develop understanding of possible inspection regimes for the deposited ‘virgin’ AM material and the parent-AM interface in repaired components. Inspection will include definition and detection strategies for the unique new defect types produced by AM deposition of these materials. The microstructures and high temperature properties of the deposited materials will be characterised in detail, including high temperature thermomechanical testing such as creep and high temperature tensile tests. This will advance TWI knowledge of AM deposits and the influence of AM deposition processes on complex parent materials during repair/manufacturing processes. This material property and microstructural characterisation will be complemented by finite element analysis (FEA) and computational fluid dynamics (CFD). The latter will be used to understand the heat fluxes experienced by the repaired part and the former will consider the combined thermo-mechanical stresses acting on the component. Together, this will allow for the thermal stresses developed in the repaired components during high temperature service to be analysed. The FEA will particularly focus on the thermal stresses which may develop at the interface of ‘virgin’ AM material and repaired components. The wire plus arc AM (WAAM) process is considered to be most appropriate for repair of large components.
Benefits to Industry
The outcomes of the project will allow industry to evaluate AM technologies as a means of repairing complex, high value components. The process parameters developed will enable the repair of high-temperature components, reducing non-operating time or costs associated with maintaining stock of spares. NDT investigations combined with associated characterisation and testing will enable industry to more clearly define NDT assessment strategies for AM deposits/repairs.
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