Solute-induced near-isotropic performance of laser powder bed fusion manufactured pure titanium

Abstract

Materials produced by laser-based powder bed fusion process ( L -PBF) undergo rapid solidification and several cycles of remelting. The resulting unique microstructure imparts anisotropy to the material and leads to its non-uniform deformation under load that can cause limitations in some applications. In this study, we explored the ability of nitrogen (solute) to reduce the degree of anisotropy of L -PBF fabricated Ti materials. The correlation among microstructural changes, texture evolution, and deformation behavior was investigated. L -PBF fabricated Ti with low N content (0.01 wt%) exhibits mainly continuous epitaxial growth of α grains with a strong crystallographic texture, leading to anisotropic tensile properties. A high N content (0.31 wt%) significantly changes the structure and texture of L -PBF fabricated Ti through the introduction of refined martensite grains with random crystallographic orientations, which reduces the degree of anisotropy and enhances strength (1066 MPa) and ductility (25%). This study will facilitate the manufacture of Ti with superior near-isotropic tensile properties, which has not been realized through traditional manufacturing processes.