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<p>Laser–hybrid welding (LH) combines a laser heat source with a MIG (GMAW) arc. By leveraging the complementary strengths of both processes, LH enables high–productivity welding. The MIG arc supplies the filler metal (FM), thereby mitigating the lack–of–fill that can arise in laser–only joints. Owing to the higher overall heat input, the weld pool remains molten for a longer period, which promotes degassing and thus reduces porosity, as the entrained bubbles have sufficient time to escape. A further advantage of the LH configuration is the localised thermal input, which helps limit the width of the heat‑affected zone (HAZ). In this study, we evaluate how LH–welding influences the mechanical performance of joints made from the EN AW‑5454‑D Al–alloy. The investigation includes a detailed microstructural assessment of the weld metal (WM), the base material (BM), and the HAZ, with particular attention to the dissolution of Al₆(Fe, Mn) intermetallic particles induced by the welding thermal cycle. The mechanical test results for LH–welds are compared directly with those of the BM. The tensile testing revealed a slight decrease in the ultimate tensile strength and a pronounced reduction in the uniform elongation relative to the BM, while the yield strength differences were small and influenced by gauge length effects; the rolling direction anisotropy evident in the BM vanished largely in the welded condition. Instrumented Charpy testing confirmed ductile impact behaviour in all the regions; the total energy and its propagation component decreased from BM to HAZ to WM, with the dominant penalty arising from reduced crack propagation resistance. Fractography showed ductile microvoid coalescence throughout: the BM contained coarser Al₆(Fe, Mn) particles and larger equiaxed dimples, whereas the HAZ and WM exhibited refined particle populations, finer dimple carpets and locally earlier coalescence; the occasional smooth walled cavities in the WM were consistent with porosity. The surface EDX indicated that the BM and WM both retained a typical 5xxx Al–Mg–Mn chemistry, with only minor, trend level variations. Together, the results demonstrate that LH welding preserves the macroscopic integrity and alloy family chemistry, while microstructural refinement in the HAZ/WM governs the observed reductions in ductility and impact toughness.</p>

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Weld Joint Properties on the Al–Alloy EN AW–5454–D Welded by the High Productive Laser Hybrid Process

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月10日

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  • Matjaž Balant,
  • Tomaž Vuherer,
  • Peter Majerič,
  • Rebeka Rudolf

摘要

Laser–hybrid welding (LH) combines a laser heat source with a MIG (GMAW) arc. By leveraging the complementary strengths of both processes, LH enables high–productivity welding. The MIG arc supplies the filler metal (FM), thereby mitigating the lack–of–fill that can arise in laser–only joints. Owing to the higher overall heat input, the weld pool remains molten for a longer period, which promotes degassing and thus reduces porosity, as the entrained bubbles have sufficient time to escape. A further advantage of the LH configuration is the localised thermal input, which helps limit the width of the heat‑affected zone (HAZ). In this study, we evaluate how LH–welding influences the mechanical performance of joints made from the EN AW‑5454‑D Al–alloy. The investigation includes a detailed microstructural assessment of the weld metal (WM), the base material (BM), and the HAZ, with particular attention to the dissolution of Al₆(Fe, Mn) intermetallic particles induced by the welding thermal cycle. The mechanical test results for LH–welds are compared directly with those of the BM. The tensile testing revealed a slight decrease in the ultimate tensile strength and a pronounced reduction in the uniform elongation relative to the BM, while the yield strength differences were small and influenced by gauge length effects; the rolling direction anisotropy evident in the BM vanished largely in the welded condition. Instrumented Charpy testing confirmed ductile impact behaviour in all the regions; the total energy and its propagation component decreased from BM to HAZ to WM, with the dominant penalty arising from reduced crack propagation resistance. Fractography showed ductile microvoid coalescence throughout: the BM contained coarser Al₆(Fe, Mn) particles and larger equiaxed dimples, whereas the HAZ and WM exhibited refined particle populations, finer dimple carpets and locally earlier coalescence; the occasional smooth walled cavities in the WM were consistent with porosity. The surface EDX indicated that the BM and WM both retained a typical 5xxx Al–Mg–Mn chemistry, with only minor, trend level variations. Together, the results demonstrate that LH welding preserves the macroscopic integrity and alloy family chemistry, while microstructural refinement in the HAZ/WM governs the observed reductions in ductility and impact toughness.