Laser Wire Deposition of Thick Ti-6Al-4V Buildups: Heat Transfer Model, Microstructure, and Mechanical Properties Evaluations

This paper investigates the effect of depositing thick laser wire Ti-6Al-4V samples on the developed microstructure and subsequent mechanical properties. First, a thermal model is proposed to get a better understanding on the typical thermal cycles that the material has undergone. It is followed by a discussion on the typical structural features that developed in the as-built condition and following three post deposition heat treatments. A stress relief cycle did not substantially affect the morphology of the developed α platelets. Annealing and HIP followed by aging favored the coarsening of the post-deposited microstructure. A strengthening in terms of hardness has been observed only after the stress relief heat treatment. Developed static tensile properties were globally below the wrought levels. Stress-relieved specimens developed the higher strengths, whereas the annealed or HIPed samples followed by aging were associated with a better elongation. Charpy impact properties were higher in the annealed or HIPed condition followed by aging when compared with the stress-relieved ones. No anisotropy in the impact toughness properties was observed. The annealed and aged samples and the HIPed and aged samples produced overall very similar results showing that HIP is not required for enhance materials properties of laser wire deposition applications.