Effect of recycled powder content on the structure and mechanical properties of Ti-6Al-4V alloy produced by direct energy deposition

Direct energy deposition (DED) is a promising additive manufacturing technique in the area of aerospace, automotive, shipbuilding and medical industries. DED allows producing large-scale parts that imply the use of a significant amount of powders. Powder reuse is an important task that leads to a reduction in the cost of the final products. In this work, Ti-6Al-4V samples were fabricated by DED technique with a mixture of unused and recycled powders in the recycled powder content of 0%, 10%, 25%, and 50%. The results show that the morphology of the powder does not change significantly due to a low number of powder uses. Chemical analysis reveals a slight decrease of V in the recycled powder. The evolution of macrostructure with increasing recycled powder content was not revealed. In the as-built samples, the columnar prior beta grains grow toward the build direction with a typical Widmanstatten structure consisting of the thin alpha' laths. The mix of Widmanstatten microstructure and basket weave microstructure appears after the annealing at 800 celcius. Furthermore, the horizontal and vertical annealed samples exhibit ductile fracture and inconspicuous anisotropy of tensile and impact mechanical properties. (c) 2021 Elsevier B.V. All rights reserved.