Microstructure homogenization and strength-ductility synergy improvement of the hybrid additive manufactured dual-phase titanium alloy by sub-critical annealing

This study employed the effect of sub-critical annealing heat treatment on the microstructure and anisotropy of the hybrid additive manufactured TC11 alloy. The results demonstrate that after sub-critical annealing, a gradient microstructure with the gradual changes in the morphology and content of primary alpha phases from the laser deposition zone to the substrate zone was formed. Moreover, the tensile anisotropy of the hybrid manufactured specimens was substantially reduced. In particular, when loading along to the deposition direction, the ultimate tensile strength of the heat-treated hybrid manufactured specimen was 1062 MPa, increased by 8.5%. And when loading perpendicular to the deposition direction, the elongation can reach 13.0%, increased by 86% compare to the as-deposited sample. These findings would also shed new insights for the modification of graded structural parts prepared by the hybrid manufacturing technique, laser additive repair and other methods.