Optimization of Additive Manufacturing Parameters for CoCrMo Alloy Using PBF-LB/M Manufacturing. Effects on Density, Porosity, and Mechanical Properties

Effects on Density, Porosity, and Mechanical Properties

Abstract

Laser powder bed fusion of Cobalt-Chromium-Molybdenum for biomedical applications is well established and requires parameter windows that reliably meet ASTM F75 while remaining transferable across builds. Yet, machine specific process windows and the confirmatory validation are often under-reported. A two-level factorial design with 24 runs on a TruPrint1000 quantified the effects of laser power (115-175 W), scan speed (400-1300 mm/s), and hatch spacing (50-200 µm) on relative density, hardness, and tensile properties. The model was validated via replicate runs and a Monte Carlo robustness analysis (10,000 iterations at 1% failure probability). Hatch spacing dominated densification and mechanical response. The optimized and validated parameter set (laser power of 165.5 W, scan speed of 714 mm/s, hatch spacing of 63 µm, laser spot size of 55 µm, and layer thickness of 20 µm) corresponds to a volumetric energy density of 187 J/mm³. This configuration achieved ρ higher than 99.75% and mechanical properties exceeding ASTM F75 requirements for tensile and yield strength, elongation, and hardness. These results confirm the suitability of the established parameters for producing high-performance Cobalt-Chromium-Molybdenum components. Future work may expand the validation to complex, implant-like geometries and include advanced three-dimensional pore characterization and support structure analyses to further link process robustness and functional implant performance.