Investigation of laser powder bed fusion for the application of additive manufacturing in the First Wall of the DTT facility

The design of plasma-facing components for fusion devices is a challenging task, due to the requirements of high geometrical precision of complex parts, as well as the need of optimizing the thermo-structural performance of the adopted materials, which are required to sustain significant heat and electro-magnetic loads. This issue has been tackled in the Divertor Tokamak Test (DTT) facility within the manufacturing activities of the First Wall (FW), where the potential application of advanced technologies to fabricate structural parts made of 316L stainless steel is being investigated. In this framework, laser powder bed fusion of metals (PBF-LB/M) has been identified as a promising additive manufacturing solution, offering unique advantages in terms of design flexibility and performance of the produced material. This study presents an examination of the preliminary results from the fabrication and test of small samples and mock-ups, with the goal of performing a first qualification of the technology for our application. The preparatory samples allowed us to evaluate the capability of PBF-LB/M to produce low-porosity parts with enhanced mechanical properties, also including a thermal treatment for stress relief. On the other hand, compatibility with the design requirements has been assessed directly on the mock-ups, which are representative of the FW layout. The results obtained confirmed the advantages of PBF-LB/M for its employment in the manufacturing route of the DTT FW, while the encountered limitations were not identified as a showstopper. Therefore, the findings of this research contribute both to the preparation activities of the DTT FW and to the advancement of additive manufacturing technologies for nuclear fusion applications.