Effect of Powder Recycling on Mechanical Properties of Laser Powder Bed Stainless Steel for Nuclear Applications

Additive manufacturing is proposed as an alternative manufacturing process for nuclear plant components. This is due to the numerous advantages the technology can offer over conventional manufacturing routes especially in constructing complex near net shape geometries with short lead times. In addition, build powder can be recycled numerous times, providing minimal wastage and a significant cost benefit. Rolls-Royce has demonstrated that with a practical level of powder recycling, mechanical properties remain within specification. A clear recycling limit is not, however, well understood. It has been shown that alloy chemistry, particle size distribution and powder morphology can vary with recycling. Key variables influencing powder condition include purity of inert gas, build geometry, laser exposure duration and powder management strategy.

The objective of this project is to support the on-going efforts at the Rolls-Royce facility in Raynesway to understand the impact of powder recycling and how this influences mechanical behaviour of the material. Studies will be performed on laser powder bed fused (LPBF) stainless steel 316 and will include a thorough characterisation of the powder after different stages of exposure and recycling, an extensive metallurgical and microstructural investigation, supported by the performance of mechanical tests, data correlation and results interpretation.