2018 | AFC ACCOMPLISHMENTS 80 2.4 ATF CLADDING AND COATINGS Production of additively manufactured components for advanced reactor development Principle Investigator: Dr. Niyanth Sridharan (ORNL) Collaborator: Dr. Kevin G. Field (ORNL) High chromium ferritic- martensitic (FM) steels are candidate materials for a range of advanced nuclear reactor concepts due to their excellent swelling resistance even to high damage doses (>50 displacements per atom – dpa). FM steels have been manufactured for nuclear applications using traditional processing routes for decades, but issues still exist including the formation of intercritically-heated zones leading to deterioration of material properties. In addition, traditional processing routes limit the geometries possible and thus complex component geometries which could improve reactor efficiency and safety are not possible. Recent advances in additive manufacturing (AM) processes, including laser-powder blown directed energy deposition (DED), could provide a new paradigm for FM steels production and use within the nuclear industry.To investigate AM as a novel processing routes for FM steel, laser- powder blown DED manufactured structures from alloy HT9 was completed and then systematically tested and characterized. Project Description: Alloy HT9 – a 12Cr-1MoVW FM steel – is under consideration for advanced nuclear reactor concepts due its low swelling rates under irradiation as demonstrated under multiple programs including those within the Fast FluxTest Facility (FFTF).The swelling resistance and radiation tolerance of HT9 is primarily attributed to the complex microstructure in the wrought condition which includes martensite laths, high dislocation density, and a mixture of different precipitate phases including M23C6 carbides and MX precipitates. Production of this microstructure is typically controlled using a series of heat treatments to both normalize the alloy and then temper the martensitic structure. Recently, the nuclear industry has shown interest in applying AM processes to produce components which replicate the wrought-like microstructure of varying FM steels including HT9.AM is a layer-wise building of a component that is completed by depositing metal powder using fusion methods.