RMIT research reveals powder-bed layer density as key factor for Ti-6Al-4V part quality
April 1, 2025
Researchers from RMIT University in Australia have published an article titled ‘Effect of Powder Characteristics on Layer Density, Defects, and Tensile Properties of Ti‑6Al‑4V via Laser Powder Bed Fusion: Establishing Benchmark Parameters for Quality.’ The work investigates the pivotal role of powder-bed layer density in determining the mechanical properties and defect profile of Ti-6Al-4V samples produced via Laser Beam Powder Bed Fusion (PBF-LB).
To quantify powder-bed layer density, the RMIT team innovatively combined the powder-bed capsule technique with micro-computed tomography (micro-CT). This approach enabled them to effectively measure powder-bed layer density in any PBF-LB machine, with the SLM Solutions PBF-LB machine used in this particular study.
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In a side-by-side comparison of four Ti-6Al-4V powders from two suppliers (A and B), they uncovered a paradox: despite being less spherical and containing more agglomerates, the powder from Supplier A produced significantly better results in the final builds.
The key factor was the powder-bed layer density: powder from Supplier A achieved 67.11% of the theoretical density of Ti-6Al-4V, significantly higher than the 60.14% achieved by Supplier B. This discrepancy in powder-bed layer density led to noticeable differences in build quality.
Specifically, samples manufactured with Supplier B’s powder displayed more and larger pores, particularly elongated ones near the part surface. In contrast, the higher powder-bed layer density of Supplier A’s powder contributed to enhanced build quality and mechanical performance, including a 40% increase in tensile ductility.
Based on their findings, the RMIT team recommended prioritising powder-bed layer density as a key criterion in powder selection, rather than treating it as an afterthought. For PBF-LB of Ti-6Al-4V, they proposed a benchmark powder-bed layer density of at least 65% of the theoretical density of Ti-6Al-4V to ensure high-quality builds in SLM Solutions PBF-LB systems.
The full paper is available to read here.
