Heterogeneous deformation behavior of hybrid manufactured TC11 titanium alloy via directed energy deposition

Hybrid manufacturing technique by combining of the conventional manufacturing techniques with the additive manufacturing technique has an attractive potential to fabricate the large and complex components. In this study, hybrid manufactured TC11 titanium part was produced by depositing TC11 alloy on a rolled TC11 plate via directed energy deposition (DED) process. Microstructure, microhardness and tensile properties of hybrid manufactured TC11 samples were examined. The deformation behavior of the hybrid manufactured TC11 samples was also investigated using in-situ tensile test and digital image correlation (DIC). The results demonstrate that the hybrid manufactured TC11 sample can be divided into three zones: the laser deposition zone (LDZ), the heat affected zone (HAZ) and the rolled substrate zone (SZ). The gradient microstructure is formed in the HAZ along the deposition direction due to the different thermal conditions. A special bimodal microstructure consisting of coarse primary α (αp) phase platelet and ultrafine lamellar α phase has been generated in the upper HAZ. The texture of α phase shows the highest intensity in the easily-activated orientation in the LDZ with larger Schmid factor leading to fracture when loading along the deposition direction. The small grains size with super fine αs in the HAZ results in the highest strength and microhardness.