Selective laser melting of weak-textured commercially pure titanium with high strength and ductility: A study from laser power perspective

In this study, fully dense commercially pure titanium (CP Ti) parts were successfully fabricated by selective laser melting (SLM) using the same optimal laser energy density Ep but with two different laser powers: high laser power EH ~250 W and low laser power EL ~50 W. It was found that at the same Ep different laser powers led to different phase formation, microstructure, texture and mechanical properties of the selective laser melting fabricated (SLMed) CP Ti. A weak-textured CP Ti with isotropic mechanical properties was achieved using EH while a strong-textured CP Ti with anisotropic mechanical properties was obtained using EL. The underlying mechanism was attributed to the formation of α' phase in the CP Ti as a result of the higher cooling rates at EH. The formation of α' phase also contributed to the observed high ultimate compressive strength ~1.1 GPa and high compressive strain ≥50% in the SLMed weak-textured CP Ti at EH. This study provides important insights into the role of laser energy in the SLM fabrication of CP Ti with tailorable crystallographic texture and thus mechanical properties.status: publishe