Investigation of microstructural and mechanical properties on a pure niobium fabricated by selective laser melting for defect-free process based on the energy density

This study characterized various defects, such as lack-of-fusion and balling defects, in a pure- Nb sample fabricated using selective laser melting. The process conditions were derived from thermodynamic energy-density function (power: 120-470 W, scan speed: 531-2,080 mm/s). The study proposed the optimal range of process parameters that achieved high density and prevented defects, such as lack-of-fusion, in SLM-processed pure Nb. The range of process parameters corresponding to defect-free, high-density samples was identified (power: 330-470 W, scan speed: 841-1,151 mm/s). Subsequently, the microstructural and mechanical-property variations within this range were investigated. Furthermore, hot isostatic pressing post-treatment was conducted to enhance density by reducing porosity defects, preventing the deformation induced by residual stress of the additive manufactured parts. This study highlights the potential of SLM for fabricating high-density pure-Nb components and suggests its potential applications in various fields.