Wire-based Laser Metal Deposition of Aluminium Alloys
H.H. Teng (TU Delft - Mechanical Engineering)
M.J.M. Hermans – Mentor (TU Delft - Team Marcel Hermans)
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Abstract
Wire-based laser directed energy deposition (LDED) using wire feedstock offers a promising path for fabricating medium- to large-scale structures, yet the process remains highly sensitive to both process and material conditions.
This work investigates the relationship between process parameters, microstructure, and defect formation in single-bead and multi-layer depositions of aluminium 5356 alloy, with a particular focus on understanding the evolution of bead geometry, porosity, and distortion under different processing conditions.
Single-bead experiments were conducted to explore the individual effects of key process parameters (laser power, travel speed, and wire-feeding rate) on deposition stability. The results showed that bead geometry followed predictable trends dependent on heat input and the amount of feedstock, enabling the definition of a workable processing window for further vertical builds. Although clear microstructural trends were not observed in single tracks, compositional variations at the deposition-substrate mixing area indicated local dilution effects that may influence grain morphology during the first-layer solidification.
Multi-layer depositions demonstrated the characteristic microstructural features of DED processes, including directional columnar grains and finer equiaxed dendrites, reflecting the thermal gradients and cooling conditions during the build. Defect characterisation revealed that porosity systematically increased with both layer number and travel speed. These trends are consistent with shorter melt pool lifetimes limiting gas escape. The pore morphology confirmed the predominance of gas-induced pores; combined with the absence of measurable magnesium loss, hydrogen from the feedstock remains the most likely dominant source. Thermal distortion was observed to escalate with both build height and heat input, underscoring the sensitivity of thin-wall geometries to thermal accumulation.
Overall, this study provides experimentally based insights into parameter–process interactions in wire-based LDED of aluminium alloys. The findings help clarify processing limits for thin-wall geometries, identify critical sources of defect formation, and highlight future opportunities for improving process stability through better thermal management and more precise process control.