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<p>Laser Directed Energy Deposition(L-DED) is an important method for repairing single crystal coatings. However, defects in the deposition such as premature columnar to equiaxal transition(CET) can affect the quality. An assisted external energy field can effectively reduce the defects. This paper investigated the steady-state magnetic field-assisted L-DED of GH3536 coatings onto single-crystal DD6 substrates, focusing on the effects of different magnetic field strengths on the directional growth, microstructure, and microhardness. The results showed that the assistance of magnetic field facilitates the growth of single crystals along the direction of the substrate. When the intensity was 200&#xa0;mT, the electromagnetic braking effect suppressed the flow velocity of the molten pool, resulting in the height of columnar crystal grain region of 448.259&#xa0;μm, which was 1.20&#xa0;times observed in the absence of magnetic field, and the area of stray grains in the upper part of the coating has decreased by homogenizing the solute distribution. The thermoelectric magnetic convection effect promoted solute diffusion causing the dendrites and PDAS to appear coarsened. The microhardness has increased to an average microhardness of 340&#xa0;HV<sub>0.2</sub> at 200&#xa0;mT, which is 7. 9% higher than at no magnetic field.</p>

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Effects of Steady-State Magnetic Field on GH3536/DD6 Single-Crystal Superalloy by Laser Directed Energy Deposition

  • 期刊论文

  • 发表日期：

    2025年11月11日

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  • Haihan Li,
  • Xinlin Wang,
  • Mengru You,
  • Yang Gao,
  • Tianmin Guan

摘要

Laser Directed Energy Deposition(L-DED) is an important method for repairing single crystal coatings. However, defects in the deposition such as premature columnar to equiaxal transition(CET) can affect the quality. An assisted external energy field can effectively reduce the defects. This paper investigated the steady-state magnetic field-assisted L-DED of GH3536 coatings onto single-crystal DD6 substrates, focusing on the effects of different magnetic field strengths on the directional growth, microstructure, and microhardness. The results showed that the assistance of magnetic field facilitates the growth of single crystals along the direction of the substrate. When the intensity was 200 mT, the electromagnetic braking effect suppressed the flow velocity of the molten pool, resulting in the height of columnar crystal grain region of 448.259 μm, which was 1.20 times observed in the absence of magnetic field, and the area of stray grains in the upper part of the coating has decreased by homogenizing the solute distribution. The thermoelectric magnetic convection effect promoted solute diffusion causing the dendrites and PDAS to appear coarsened. The microhardness has increased to an average microhardness of 340 HV0.2 at 200 mT, which is 7. 9% higher than at no magnetic field.