Porosity and elevated-temperature tensile response of PBF-LB/M Ti-6Al-4V across laser beam profiles mapped using a spot-size-aware energy metric

Laser beam shaping in PBF-LB/M modifies the spatial laser energy distribution, affecting melt-pool evolution, defect formation, and mechanical response. Ti-6Al-4V was processed using Gaussian, core–ring, and ring-dominated beam profiles. Measured beam maps were used to determine the effective beam diameter in a modified energy metric (VEDM, J mm⁻² s⁻¹/²) for cross-mode comparison. Densification and pore characteristics were assessed in cubes and tensile specimens. Core–ring and ring-dominated profiles transitioned from lack-of-fusion defects at low input to near-full density at higher input, whereas Gaussian shifted toward keyhole-type porosity at the highest input. At VEDM = 332 J mm⁻² s⁻¹ /², the µCT-scanned tensile gauge regions showed lower relative density for Gaussian (∼98.6%) than for core–ring and ring-dominated conditions (∼99.8%). Tensile specimens produced with Gaussian and ring-dominated beams were tested at RT, 200 °C, and 400 °C. All conditions showed temperature-dependent softening. However, at high VEDM and 400 °C, the ring-dominated condition retained higher ductility (∼10%) than the Gaussian condition (∼7%), while maintaining a comparable peak stress. Fractography showed pore-assisted initiation in the Gaussian condition and ductile tearing with pronounced necking in the ring-dominated condition. Overall, elevated-temperature tensile performance was primarily associated with pore type and severity, while VED<inf>M</inf> provides a practical framework for cross-mode comparison.

Content

Subjects

Additive manufacturing

High-temperature tensile properties

Laser beam shaping

PBF-LB/M

Relative density

Ti-6Al-4V

DDC Class

620.1: Engineering Mechanics and Materials Science

Funding References

Funding(s)

RMIT European Doctoral Innovators Programme

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https://creativecommons.org/licenses/by/4.0/

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publishedVersion

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1-s2.0-S2352492826010901-main.pdf

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