Effect of travel speed and sub-β transus post deposition heat treatments on thin Ti-6Al-4V laser wire deposits

Annealing or HIP below the β transus temperature was found to coarsen the as-built developed microstructure while preserving the developed macro morphology of Laser Wire Deposition (LWD) buildups. Following these thermal cycles, a general decrease in strength along with an increase in elongation have been observed. However, no trends in the tensile results could be extracted due to the scattering of the results. An additional aging cycle substantially stabilized the developed results. Samples processed at 1.4 mm/s exhibited low strength hardly meeting any of the ASTM and AMS minimum requirements and a strong anisotropy in elongation with lower values when tested along the Z direction. Samples processed at 7.2 mm/s exhibited good strength meeting the minimum wrought requirements as set by AMS4911 while elongation showed an isotropic behavior. Hardness has been found to be mostly independent of the experienced sub-β transus post deposition heat treatment. Moreover, the grain boundary strengthening mechanism with regards to the α platelets thicknesses was found to be travel speed dependent.