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<p>Gray cast iron components in nuclear power plants are prone to damage under harsh operational conditions, necessitating high-precision repair techniques. This study investigates the remanufacturing of such components using multi-pass laser cladding, with a focus on the influence of laser power on microstructure and mechanical properties. Increasing laser power from 1400 W to 2400 W elevated heat input, reduced the cooling rate of the molten pool and promoted coarsening of austenite and γ-phase grains. Carbon diffusion from the substrate led to the formation of coarse Fe<sub>3</sub>C brittle phases. The heat-affected zone exhibited increased ferrite, decreased pearlite and significant microstructural softening. As laser power increased, tensile strength dropped from 179.6&#xa0;MPa to 144.6&#xa0;MPa, elongation decreased from 6.6 to 1.9%, and impact energy declined from 2.7&#xa0;to 1.5&#xa0;J. Fracture analysis revealed cleavage characteristics in the heat-affected zone, attributed to ledeburite brittleness and weakened graphite interfaces. Kernel average misorientation mapping indicated high dislocation density in the cladding zone and low values in the heat-affected zone, clarifying residual stress distribution. This work provides theoretical support for high-reliability laser cladding repair of nuclear power components.</p>

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Microstructure and Mechanical Properties of Damaged Gray Cast Iron Components Remanufactured by Multi-Pass Laser Cladding for Nuclear Power Plants

  • 期刊论文

  • 发表日期：

    2026年1月28日

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  • Minglei Hu,
  • Shujun Chen,
  • Ke Xu,
  • Jie Wen,
  • Tao Yuan,
  • He Shan,
  • Shun Wang,
  • Shuwen Wang

摘要

Gray cast iron components in nuclear power plants are prone to damage under harsh operational conditions, necessitating high-precision repair techniques. This study investigates the remanufacturing of such components using multi-pass laser cladding, with a focus on the influence of laser power on microstructure and mechanical properties. Increasing laser power from 1400 W to 2400 W elevated heat input, reduced the cooling rate of the molten pool and promoted coarsening of austenite and γ-phase grains. Carbon diffusion from the substrate led to the formation of coarse Fe3C brittle phases. The heat-affected zone exhibited increased ferrite, decreased pearlite and significant microstructural softening. As laser power increased, tensile strength dropped from 179.6 MPa to 144.6 MPa, elongation decreased from 6.6 to 1.9%, and impact energy declined from 2.7 to 1.5 J. Fracture analysis revealed cleavage characteristics in the heat-affected zone, attributed to ledeburite brittleness and weakened graphite interfaces. Kernel average misorientation mapping indicated high dislocation density in the cladding zone and low values in the heat-affected zone, clarifying residual stress distribution. This work provides theoretical support for high-reliability laser cladding repair of nuclear power components.