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

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. To accomplish this, two deposition strategies were examined: Group I with intermittent air cooling between successive layers and Group II with a short inter-pass dwell time of 15 seconds. Mechanical characterization indicated that Group II demonstrated superior tensile properties, higher yield strength, and ultimate tensile strength in both build and scan directions compared to Group I. Hardness measurements along the build height revealed a systematic increase from the substrate to the top of the wall, correlating with reduced thermal cycling and diminished over-aging in upper regions. Analysis via X-ray computed tomography showed a pronounced reduction in porosity for Group II, which also exhibited finer pore morphology compared to Group I. This reduction indicated that minimizing inter-pass cooling time enhances mechanical performance despite higher cumulative heat input by promoting finer porosity. These findings underline the significance of thermal control in reducing porosity and enhancing properties in 6xxx-series aluminium alloys fabricated via DED-Arc.