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<p>During laser cladding, the surface tension of the molten pool is altered by the addition of S element, reversing the direction of Marangoni convection and consequently modifying the flow pattern of the molten metal. Macroscopically, this results in changes in the pool morphology (depth and width). Microscopically, it affects dendrite morphology, which directly governs the mechanical properties of the cladding layer. To enhance cladding quality, it is essential that the solidification behavior under varying S element concentrations be investigated. A numerical model during laser cladding of Fe60 powder on an ASTM 1045 substrate at the macroscopic scale was established and solved in this study. Based on results such as temperature, flow velocity, temperature gradient, and cooling rate, a two - dimensional mesoscopic phase - field model was established to simulate dendrite growth under different S contents. The results show that the flow direction and velocity in the molten pool are significantly altered by S element. At low S element concentrations, the flow shows chaotic behavior, which gradually diminishes as S element content increases, leading to more stable and accelerated flow. At the mesoscale, dendrite morphology and size are modified by S element, reducing the growth rate disparity between the upstream and downstream sides of equiaxed grains with increasing S element concentration. Critical insights into the cross - scale mechanisms of S element in laser cladding are provided by this research, and guidance for process optimization is offered.</p>

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Investigation on the influence mechanism of S element concentration on the dendrite growth behavior during laser cladding solidification

  • 期刊论文

  • 发表日期：

    2025年11月5日

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  • Yichang Sun,
  • Hang Shang,
  • Xuejun Wang,
  • Lei Feng,
  • Hongchuan Li,
  • Meng Sun,
  • Jinhua Ding,
  • Ning Xu,
  • Ning Li

摘要

During laser cladding, the surface tension of the molten pool is altered by the addition of S element, reversing the direction of Marangoni convection and consequently modifying the flow pattern of the molten metal. Macroscopically, this results in changes in the pool morphology (depth and width). Microscopically, it affects dendrite morphology, which directly governs the mechanical properties of the cladding layer. To enhance cladding quality, it is essential that the solidification behavior under varying S element concentrations be investigated. A numerical model during laser cladding of Fe60 powder on an ASTM 1045 substrate at the macroscopic scale was established and solved in this study. Based on results such as temperature, flow velocity, temperature gradient, and cooling rate, a two - dimensional mesoscopic phase - field model was established to simulate dendrite growth under different S contents. The results show that the flow direction and velocity in the molten pool are significantly altered by S element. At low S element concentrations, the flow shows chaotic behavior, which gradually diminishes as S element content increases, leading to more stable and accelerated flow. At the mesoscale, dendrite morphology and size are modified by S element, reducing the growth rate disparity between the upstream and downstream sides of equiaxed grains with increasing S element concentration. Critical insights into the cross - scale mechanisms of S element in laser cladding are provided by this research, and guidance for process optimization is offered.