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

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 nonuniform 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 alpha 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.

Automated summary

This study explored the ability of nitrogen to reduce the degree of anisotropy in laser-based powder bed fusion (L-PBF) fabricated Ti materials. It was found that low nitrogen content resulted in anisotropic tensile properties, while high nitrogen content significantly reduced anisotropy and improved strength and ductility.