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<p>Directed Energy Deposition-Arc (DED-Arc) was employed to fabricate walls from a heat-treatable Al-Mg-Si alloy (EN-AW 6063) in order to investigate the influence of inter-pass thermal management on porosity evolution, microstructural development, and mechanical performance. Two deposition strategies were examined: Group I, which incorporated intermittent air cooling between successive layers, and Group II, which used a short inter-pass dwell time of 15 s without active temperature control, resulting in higher cumulative heat input. Mechanical characterization revealed superior tensile properties in Group II, with higher yield strength (Rp0.2) and ultimate tensile strength (Rm) in both build and scan directions compared to Group I. Hardness measurements along the build height showed systematic increase from the substrate toward the top of the wall, reflecting reduced thermal cycling and diminished over-aging in the upper regions. This trend is consistent with the thermal history inherent to layer-wise deposition in heat-treatable Al-Mg-Si alloys. X-ray computed tomography demonstrated a pronounced reduction in porosity for Group II, which exhibited a lower porosity fraction and significantly finer pore morphology, with a mean equivalent pore diameter of ~0.3 mm compared to ~0.8 mm in Group I. The predominantly spherical pore shape indicates hydrogen-induced porosity as the governing mechanism. In Group I, longer inter-pass dwell times promoted slower solidification and repeated reheating, facilitating hydrogen supersaturation and pore coalescence into larger voids that acted as critical stress concentrators. Fractographic analysis confirmed ductile failure in both groups, while highlighting enhanced pore interconnectivity in Group I, leading to severely reduced elongation up to an order of magnitude lower than in Group II. Overall, the results demonstrate that minimizing inter-pass cooling time, despite higher cumulative heat input, promotes finer porosity and improved mechanical performance in DED-Arc fabricated EN-AW 6063. The results highlight thermal control to reduce porosity and enhance properties in 6xxx-series aluminum wire-arc additive manufacturing.</p>

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Process–Porosity–Property Relationships in Directed Energy Deposition (DED-Arc) of Al-Mg-Si Alloy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月4日

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  • Sharath P. Subadra,
  • Eduard Mayer,
  • Robin N. Wilke,
  • Suresh Alaparthi,
  • Axel Marquardt,
  • Luisa Marzoli,
  • Guney Guven Yapici,
  • Shahram Sheikhi

摘要

Directed Energy Deposition-Arc (DED-Arc) was employed to fabricate walls from a heat-treatable Al-Mg-Si alloy (EN-AW 6063) in order to investigate the influence of inter-pass thermal management on porosity evolution, microstructural development, and mechanical performance. Two deposition strategies were examined: Group I, which incorporated intermittent air cooling between successive layers, and Group II, which used a short inter-pass dwell time of 15 s without active temperature control, resulting in higher cumulative heat input. Mechanical characterization revealed superior tensile properties in Group II, with higher yield strength (Rp0.2) and ultimate tensile strength (Rm) in both build and scan directions compared to Group I. Hardness measurements along the build height showed systematic increase from the substrate toward the top of the wall, reflecting reduced thermal cycling and diminished over-aging in the upper regions. This trend is consistent with the thermal history inherent to layer-wise deposition in heat-treatable Al-Mg-Si alloys. X-ray computed tomography demonstrated a pronounced reduction in porosity for Group II, which exhibited a lower porosity fraction and significantly finer pore morphology, with a mean equivalent pore diameter of ~0.3 mm compared to ~0.8 mm in Group I. The predominantly spherical pore shape indicates hydrogen-induced porosity as the governing mechanism. In Group I, longer inter-pass dwell times promoted slower solidification and repeated reheating, facilitating hydrogen supersaturation and pore coalescence into larger voids that acted as critical stress concentrators. Fractographic analysis confirmed ductile failure in both groups, while highlighting enhanced pore interconnectivity in Group I, leading to severely reduced elongation up to an order of magnitude lower than in Group II. Overall, the results demonstrate that minimizing inter-pass cooling time, despite higher cumulative heat input, promotes finer porosity and improved mechanical performance in DED-Arc fabricated EN-AW 6063. The results highlight thermal control to reduce porosity and enhance properties in 6xxx-series aluminum wire-arc additive manufacturing.