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<p>Blade crack failure is a common failure mode in steam turbines. The cracks found at the blade root of the forward fifth-stage blade on the low-pressure rotor of the steam turbine. To investigate the cause of failure, an optical microscope (OLM) was used to observe the fracture morphology, a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) were employed to analyze the microscopic characteristics of the fracture surface, room-temperature tensile tests and Brinell hardness tests were conducted to analyze the mechanical properties of the failed blade, and finally, the finite element method was applied to perform stress analysis on the blade. The results show that the step caused by machining lead to loose assembly between the blade and the wheel groove, inducing fretting wear and causing surface damage in the contact area; the loosely assembled state also exacerbates the stress concentration at the first tooth of the blade root; under the combined action of multi-stress superposition and vibration, fatigue cracks initiate from the surface damage, stably propagate under the drive of alternating stress, and eventually form high-cycle fatigue cracks. Based on the analysis results, some suggestions for preventing crack failure of steam turbine blades are proposed.</p>

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Crack Failure Analysis of Low-Pressure Rotor Steam Turbine Blades in Thermal Power Plant

  • 期刊论文

  • 发表日期：

    2026年2月10日

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  • Wenfu Yuan,
  • Song Xue,
  • Fengtao Hu,
  • Yuchi Zhong,
  • Lin Huang,
  • Honglin Jiang,
  • Buyun Xiang,
  • Xingyu He

摘要

Blade crack failure is a common failure mode in steam turbines. The cracks found at the blade root of the forward fifth-stage blade on the low-pressure rotor of the steam turbine. To investigate the cause of failure, an optical microscope (OLM) was used to observe the fracture morphology, a scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) were employed to analyze the microscopic characteristics of the fracture surface, room-temperature tensile tests and Brinell hardness tests were conducted to analyze the mechanical properties of the failed blade, and finally, the finite element method was applied to perform stress analysis on the blade. The results show that the step caused by machining lead to loose assembly between the blade and the wheel groove, inducing fretting wear and causing surface damage in the contact area; the loosely assembled state also exacerbates the stress concentration at the first tooth of the blade root; under the combined action of multi-stress superposition and vibration, fatigue cracks initiate from the surface damage, stably propagate under the drive of alternating stress, and eventually form high-cycle fatigue cracks. Based on the analysis results, some suggestions for preventing crack failure of steam turbine blades are proposed.