Development of EBM-fabricated titanium alloy parts for high performance leightweighting

Purpose and goal

The project focuses on electron beam melting (EBM) as AM technology for Ti alloy in both aerospace and biomedical applications. The goals of this project are i) to build confidence to use additive manufacturing (AM) for highly loaded components that would benefit significantly from the design in aerospace applications where fatigue loading is critical, and ii) to further develop AM as a main approach for bionic design demonstrated for future medical parts.

Expected results and effects

The microstructure of EBM-produced Ti6Al4V and fractography after fatigue tests were investigated and compared with LPBF-produced parts. The possible reason for the early fracture and the large spread of fatigue life was figured out. In vitro cell cultures showed good inflammatory cell attachment and viability to both implants made of virgin and recycled powders. Improved cell survival for the implants produced by recycled powder correlates with the increased oxide thickness. The knowledge obtained ensures robust EBM manufacturing and high performance of components.

Planned approach and implementation

For aerospace application, the original plan was followed in general. One change was that we used 4-point bending to evaluate the fatigue property instead of a small punch test. We also did a comparison with LPBF-produced parts which was not covered in the original proposal. For bio-application, the lack of expertise in the machining of implants made it difficult to miniaturize suitable implants for the intended small animal model. In the end, we reverted from in vivo to in vitro where larger samples could be used, to obtain preclinical data on the role of powder recycling.