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<p>Laser Repair (LR) via Directed Energy Deposition (DED) is a key additive manufacturing technology for high-value applications. However, LR introduces microstructural heterogeneity and interfaces that complicate fatigue assessment, especially in hydrogen-rich environments which exacerbate fatigue damage. This study employs the crack tip localization method and Crack Opening Rate (COR) parameter via BSL 3D DIC to investigate hydrogen-accelerated fatigue crack propagation in laser-repaired (LR) GH4169 superalloy. The fatigue lives and crack closure levels of pure substrate (PS), pure deposited (PD), and LR specimens were compared. Hydrogen charging significantly accelerated crack growth, reducing fatigue life by 23%, 9.6%, and 29.2% in PS, LR, and PD specimens, respectively. Electron Backscatter Diffraction (EBSD) analysis shows hydrogen charging induces distinct cracking behaviors: the LR specimen exhibits crack deflection from the repair zone into the substrate via the heat-affected zone, while the PD specimen shifts from transgranular to intergranular fracture, exhibiting brittle characteristics with minimal plasticity.</p>

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Investigation of hydrogen-accelerated fatigue crack growth in laser repaired GH4169 superalloy using BSL 3D DIC

  • 期刊论文

  • 发表日期：

    2026年4月16日

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  • Wei He,
  • Quan Zhang,
  • Jiaqiang Li,
  • Xing Sun,
  • Bin Kuang,
  • Bo Liu,
  • Qihong Fang,
  • Huimin Xie,
  • Yanhuai Ding,
  • Shijie Liu,
  • Xin Li

摘要

Laser Repair (LR) via Directed Energy Deposition (DED) is a key additive manufacturing technology for high-value applications. However, LR introduces microstructural heterogeneity and interfaces that complicate fatigue assessment, especially in hydrogen-rich environments which exacerbate fatigue damage. This study employs the crack tip localization method and Crack Opening Rate (COR) parameter via BSL 3D DIC to investigate hydrogen-accelerated fatigue crack propagation in laser-repaired (LR) GH4169 superalloy. The fatigue lives and crack closure levels of pure substrate (PS), pure deposited (PD), and LR specimens were compared. Hydrogen charging significantly accelerated crack growth, reducing fatigue life by 23%, 9.6%, and 29.2% in PS, LR, and PD specimens, respectively. Electron Backscatter Diffraction (EBSD) analysis shows hydrogen charging induces distinct cracking behaviors: the LR specimen exhibits crack deflection from the repair zone into the substrate via the heat-affected zone, while the PD specimen shifts from transgranular to intergranular fracture, exhibiting brittle characteristics with minimal plasticity.