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<p>The fatigue behavior of a second-generation single-crystal nickel-based superalloy was examined under thermomechanical fatigue (TMF) at temperatures ranging from 450 to 850&#xa0;°C, using strain-controlled conditions. The study aimed to analyze cyclic deformation behavior, investigate dominant damage mechanisms, and assess cracking behavior in both in-phase (IP) and out-of-phase (OP) tests. Under IP TMF conditions, the primary damage manifestation was primarily attributed to creep-fatigue interactions, collectively leading to a reduced lifetime. Conversely, in the OP tests, the damage predominantly stemmed from the oxidation-fatigue mechanisms occurring at high mechanical strains. Creep-induced damage emerges as an additional factor at lower mechanical strains, rendering the material more susceptible to crack propagation. Consequently, the fatigue life exhibited considerable reduction and tended to reverse compared to the IP case. Further tests were conducted across various maximum temperature cycling ranges of 950 and 1038&#xa0;°C to explore the effect of temperature on IP TMF lifespans. Increased mobility of dislocations and oxidation penetration were found to further reduce the fatigue life of ruptured specimens, with this effect believed to be proportional to the temperature variation in the IP TMF test. The microstructures and damage evolution were examined to provide insights into the changes in fatigue life.</p> Graphic Abstract <p></p>

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Temperature Dependence on Cracking Behavior in Thermomechanical Fatigue of Nickel-Based Single-Crystal Superalloy

  • 期刊论文

  • 发表日期：

    2025年2月15日

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  • Van Hung Dao,
  • Hee Soo Yun,
  • Sang Koo Jeon,
  • Jaeyeong Park,
  • Seung Hoon Nahm

摘要

The fatigue behavior of a second-generation single-crystal nickel-based superalloy was examined under thermomechanical fatigue (TMF) at temperatures ranging from 450 to 850 °C, using strain-controlled conditions. The study aimed to analyze cyclic deformation behavior, investigate dominant damage mechanisms, and assess cracking behavior in both in-phase (IP) and out-of-phase (OP) tests. Under IP TMF conditions, the primary damage manifestation was primarily attributed to creep-fatigue interactions, collectively leading to a reduced lifetime. Conversely, in the OP tests, the damage predominantly stemmed from the oxidation-fatigue mechanisms occurring at high mechanical strains. Creep-induced damage emerges as an additional factor at lower mechanical strains, rendering the material more susceptible to crack propagation. Consequently, the fatigue life exhibited considerable reduction and tended to reverse compared to the IP case. Further tests were conducted across various maximum temperature cycling ranges of 950 and 1038 °C to explore the effect of temperature on IP TMF lifespans. Increased mobility of dislocations and oxidation penetration were found to further reduce the fatigue life of ruptured specimens, with this effect believed to be proportional to the temperature variation in the IP TMF test. The microstructures and damage evolution were examined to provide insights into the changes in fatigue life.

Graphic Abstract