Mechanical and corrosion behavior of titanium alloys additively manufactured by selective laser melting – A comparison between nearly β titanium, α titanium and α + β titanium

Abstract

Mechanical and corrosion behaviors of SLM-processed Ti-13Nb-13Zr alloy with primarily β phase and acicular martensitic α′ microstructure, CP Ti in martensitic α′ structure and Ti-6Al-4V with martensitic α′ and a small amount of β phase microstructural conditions were studied in this work. A factor f (tensile strength/elastic modulus) was used to define the mechanical performance and the Ti-13Nb-13Zr alloy exhibits the highest f (15.22 ± 0.19) comparing with CP Ti (9.90 ± 0.10) and Ti-6Al-4V (12.47 ± 0.14). Among the three materials, Ti-13Nb-13Zr alloy demonstrates lower stress-controlled fatigue resistance but higher strain-controlled fatigue performance than CP Ti and Ti-6Al-4V. Fatigue crack initiation occurred in the surface/subsurface pores and the river pattern was observed in the crack initiation zone and crack propagation zone. The results of the potentiodynamic polarization indicate that the Ti-13Nb-13Zr alloy has the highest corrosion potential comparing with that of CP Ti and Ti-6Al-4V alloy because that Nb2O5 is more chemically stable than V2O5 and solid layers of Nb2O and ZrO2 are existed in passive TiO2 layers during the corrosion process which could reduce the Cl− ingress into the oxide layer and increase the structural integrity of the oxide film.