Additively Manufactured β-Ti5553 with Laser Powder Bed Fusion—Microstructures and Mechanical Properties of Bulk and Lattice Parts

Ti5553 (Ti-5Al-5Mo-5V-3Cr wt.%) is a titanium alloy with promising applications in safety-critical structures due to its high strength-to-weight ratio and near-β microstructure which opens pathways for tailoring mechanical performance based on annealing conditions. In order to utilize its advantageous properties, efficient manufacturing must be possible. Laser powder bed fusion (L-PBF) involves the layer-by-layer fabrication of complex geometries such as lattices which help reduce component weight. Moreover, L-PBF expedites part deployment since components can be built on-demand without multi-step assembly. Thus, the successful realization of L-PBF Ti5553 relies on a fundamental understanding of the alloy’s additively manufactured microstructure and mechanical behavior. In support of production efforts at Lawrence Livermore National Lab and Kansas City National Security Campus, the present work investigates the hierarchical microstructures and mechanical properties of L-PBF Ti5553 bulk and lattice parts. The characterization techniques include room-temperature tensile tests, nanoindentation, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The presence of second-phase (ω) nanoprecipitates in the lattice material distinguishes its microstructure from that of the bulk and moreover, indicates the challenges in predicting bulk mechanical response based on lattice properties. The present results provide a starting framework for the successful printing of Ti5553 bulk and lattice parts by comprehensively examining the processing-structure-property-paradigm of the deposited material system.