Effect of Scanning Strategy on Mechanical Properties of Ti-6Al-4V Alloy Manufactured by Laser Direct Energy Deposition

Direct energy deposition (DED) is an additive manufacturing method that allows repairing the broken parts and building the meter-scale samples. However, the printing of large parts is associated with huge residual stresses and martensite phase formation, which can change the geometry of final samples or initiate the crack. The last factor is especially important for titanium alloys. In this work, we investigated the effect of DED thermal history on the obtained structural and mechanical properties of Ti-6Al-4V using a thermocouple. It was demonstrated that printing with long pauses leads to alpha ' phase formation, which embrittles the material. Continuous printing with small pauses between tracks leads to the formation of the dual alpha+beta structure. The effect of the texture on the material properties is also discussed. As a result of the study, the specific DED process parameters allow the same mechanical characteristics for as-built titanium alloy and the alloy after heat treatment.