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<p>The application of laser directed energy deposition (LDED) for the <i>in-situ</i> repair of key GH4169 superalloy components confronts two technical barriers: fatigue performance degradation in the repaired region and extreme service conditions. To overcome these limitations, systematic characterization of high-temperature fatigue behavior is essential for assessing repair quality and informing process optimization. Among the controllable LDED parameters, laser power (LP) directly affects fabrication quality and plays a significant role in influencing the fatigue crack growth (FCG) behavior. In this study, the high-temperature bi-prism-based single-lens three-dimensional digital image correlation (BSL 3D DIC) system was employed to investigate the FCG behavior of compact tension specimen types under varying LPs (500/650/800 W) and temperatures (23 °C/650 °C), including pure substrate, pure deposited, and laser repaired (LR) specimens. The fatigue test for the LR specimens was set up to allow the crack to propagate along the repair interface. The results show that an LP of 650 W restored the fatigue life of the LR specimen to a level comparable to that of the pure deposited material, whereas powers outside this range significantly reduced the performance. A novel parameter, crack opening ratio, is introduced to characterize the crack closure effect. The evolution characteristics of the crack closure effect throughout the entire high-temperature fatigue process for repaired specimens under different LPs are presented and comparatively analyzed, clarifying the influence of LPs on FCG behavior. The Paris’ law incorporating the crack closure effect is thus modified, offering a robust framework for process optimization and high-temperature fatigue life prediction in LR complex structures.</p>

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Effects of laser power on high-temperature fatigue crack growth of laser-repaired Ni-based superalloy GH4169

  • 期刊论文

  • 发表日期：

    2026年5月27日

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  • Xing Sun,
  • Yingcong Li,
  • Fakang He,
  • Hao Zheng,
  • Jiaqiang Li,
  • Bo Liu,
  • Qihong Fang,
  • Wei He,
  • Jian Li,
  • Huimin Xie

摘要

The application of laser directed energy deposition (LDED) for the in-situ repair of key GH4169 superalloy components confronts two technical barriers: fatigue performance degradation in the repaired region and extreme service conditions. To overcome these limitations, systematic characterization of high-temperature fatigue behavior is essential for assessing repair quality and informing process optimization. Among the controllable LDED parameters, laser power (LP) directly affects fabrication quality and plays a significant role in influencing the fatigue crack growth (FCG) behavior. In this study, the high-temperature bi-prism-based single-lens three-dimensional digital image correlation (BSL 3D DIC) system was employed to investigate the FCG behavior of compact tension specimen types under varying LPs (500/650/800 W) and temperatures (23 °C/650 °C), including pure substrate, pure deposited, and laser repaired (LR) specimens. The fatigue test for the LR specimens was set up to allow the crack to propagate along the repair interface. The results show that an LP of 650 W restored the fatigue life of the LR specimen to a level comparable to that of the pure deposited material, whereas powers outside this range significantly reduced the performance. A novel parameter, crack opening ratio, is introduced to characterize the crack closure effect. The evolution characteristics of the crack closure effect throughout the entire high-temperature fatigue process for repaired specimens under different LPs are presented and comparatively analyzed, clarifying the influence of LPs on FCG behavior. The Paris’ law incorporating the crack closure effect is thus modified, offering a robust framework for process optimization and high-temperature fatigue life prediction in LR complex structures.