Heterostructure-induced anisotropy of tensile property in laser directed energy deposition TC11 titanium alloy

Grain structure is generally considered as an important factor to influence the anisotropy of mechanical properties of the additive manufactured metallic component. In this work, we revisit the mechanical anisotropy of a TC11 alloy with heterogeneous grain structure fabricated by laser directed energy deposition(L-DED) technology, and fully unravel the plastic deformation behavior with different types of heterogeneous grain morphology. It is found that the 0-BD specimens and 45-BD specimens exhibit desirable strength-ductility synergy with considerable YS, high UTS and prominent ductility. The synergistic increase in strength and plasticity is induced by the hetero-deformation of equiaxed grain and columnar grain induced. Specially, the optimum hetero-deformation induced (HDI) strengthening is obtained in 45-BD specimen due to the symmetric constraint morphology of heterostructure. The lower strength and elongation of the 90-BD specimens are associated with the fracture of alpha phases at grain boundaries perpendicular to the loading direction.