Transcending the boundaries of large-scale component fabrication by additive manufacturing of powder metallurgical hot isostatic pressing canisters

Powder metallurgical hot isostatic pressing (PM-HIP) enables the fabrication of complex near-net shape parts with excellent mechanical properties for critical applications across aerospace, energy, and medical sectors. However fabricating PM-HIP canisters via traditional sheet metal forming, machining, and welding is not only time-intensive, but also limited in design flexibility. Moreover the propensity for defects and dimensional inaccuracies, particularly for large-scale complex geometries is high. This work demonstrates the feasibility of a combined additive manufacturing (AM) and PM-HIP approach which benefits from the intrinsic advantages of both AM and PM-HIP. A range of AM modalities including Laser Powder Bed Fusion (LPBF), Directed Energy Deposition (DED), and Wire Arc Additive Manufacturing (WAAM) were employed to fabricate HIP canisters across length scales. Parts as small as 3 inch diameter simple cylinderical shells of SS316L were printed using LPBF and DED before being filled with SS316L powder and HIPed to understand the influence of AM canisters on post-HIP microstructure and properties. Further, a hybrid combination of AM and 5-axis CNC technology was used to fabricate a T-valve shell, which was later filled with SS316L powder and HIPed. Post-HIP specimen was inspected for porosity, shrinkage, microstructure, and mechanical properties in the AM-shell, PM-core as well as the AM-PM interface. Finally to demonstrate the scalability of this technology, a 60 inch diameter SS410 impeller shell were printed using WAAM, filled with A508 powder and HIPed. In summary, this talk will touch upon component design, in-situ process monitoring, data visualization, non-destructive evaluation, metallography, microscopy, and mechanical testing. The results from this study are expected to lay the foundation for a transformative shift in PM-HIP of large-scale components, by enabling greater design freedom, reduced lead times, and expanded applications using a convergent AM+PM-HIP approach.