Characterization of Additive Manufacturing for Process Tubing

Additive manufacturing (AM) is being considered as a primary manufacturing process for heat pipes. The Savannah River National Laboratory is researching AM to fabricate a hydrogen isotope separation unit for a thermal cycling absorption process that cycles from cryogenic to moderate temperatures and is a pressure boundary. AM is being explored as a replacement technology to improve heat transfer. Simple test samples with three internal geometries were designed and built from type 316L stainless steel using the powder bed fusion laser process. Nine test article geometries were prepared and subjected to tensile and burst testing and were interrogated using x-ray computed tomography and metallography. The parameters selected for processing the tubes produced a consistent product with acceptable tensile properties and microstructures; however, the process parameters used did not produce full density and minor modifications are needed to achieve full density.