Primary Aerospace Structures: an AM Case Study

Conference Abstract: This case study investigated hybrid additive manufacturing (AM) for production of bluShift Aerospace's stainless steel 316L small payload rocket’s oxidizer valve body. The valve body under consideration was originally made through subtractive manufacturing of subassembly parts, which were then assembled and fastened together. Our results indicate that by leveraging AM we can reduce the mass and part count of the valve body, as well as metal waste inherent to machining practices.

The research was broken into two main thrusts including design for additive manufacturing (DfAM) and also an experimental investigation of as-printed bulk mechanical properties. DfAM included materials and processing selection, as well as generative design which was performed to reduce valve body mass. A hybrid AM approach was considered, consisting of both laser-wire direct energy deposition (LW-DED) and laser powder bed fusion (LPBF). Here, LW-DED preforms were built on top of the same made via LPBF and electric discharge machined into coupons for testing. Mechanical properties were collected through microhardness, tensile, fatigue and compact tension testing. Their microstructures were also characterized, including a determination of the microstructure at the hybrid interface. The experimentally deduced properties were used to improve the accuracy of the generatively designed part. This design for hybrid additive manufacturing approach expands the understanding of manufacturability of large-scale critical aerospace components.