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Acta Aeronautica et Astronautica Sinica ›› 2024, Vol. 45 ›› Issue (19): 429737.doi: 10.7527/S1000-6893.2024.29737

• Material Engineering and Mechanical Manufacturing • Previous Articles    

Effect of film cooling holes on creep properties of nickel-based single crystal superalloy

Shicheng ZHAO1,2, Rong JIANG1,2(), Haoxiang GONG1,2, Lu ZHANG1,2, Xuping LU3, Haiyong ZHA3, Yingdong SONG1,2   

  1. 1.Key Laboratory of Aero-engine Thermal Environment and Structure,Ministry of Industry and Information Technology,College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China
    2.Jiangsu Province Key Laboratory of Aerospace Power System,College of Energy and Power Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China
    3.Strength Research Department,AECC Sichuan Gas Turbine Research Establishment,Chengdu 610500,China
  • Received:2023-10-18 Revised:2023-11-26 Accepted:2024-01-06 Online:2024-01-15 Published:2024-01-15
  • Contact: Rong JIANG E-mail:rjiang@nuaa.edu.cn
  • Supported by:
    Science Center for Gas Turbine Project(P2022-A-III-003-001);The Natural Science Foundation of Jiangsu Province(BK20220136);Postgraduate Research & Practice Innovation Program of NUAA(xcxjh20220205)

Abstract:

In order to meet the increase of the turbine inlet temperature of advanced aeroengines, film cooling is used to reduce the blade temperature. However, the geometrical integrity of the blade structure is destroyed by the film cooling holes, which makes the turbine blade more susceptible to creep damage around the film cooling holes under the influence of centrifugal and thermal stresses. Therefore, it is important to understand the creep performance of nickel-based single crystal superalloys with film cooling holes. The creep damage mechanism of DD6 single crystal superalloy with the cylindrical, dustpan and dovetail film cooling holes were studied through the creep experiment and finite element simulation at 1 000 ℃/300 MPa, and the detailed microscopic characterizations were conducted. The results show that the average creep lives of cylindrical and dustpan holes are similar to each other, and are increased by 17.4% and 15.9% respectively compared with the dovetail hole. Based on the fracture analysis, stress concentration and oxidation around the hole edge led to cracking first. Combined with Scanning Electron Microscope(SEM),Electron Back-Scattered Diffraction (EBSD) and finite element simulation, the plastic deformation zone obtained by EBSD corresponds to the high stress region obtained by finite element analysis, and the γ' phase rafting morphology and the oxidation is related to the stress distribution. Energy Dispersive Spectrometer (EDS) analysis indicates that oxides can be divided into three layers, i.e., the outer layer is mainly NiO and CoO, the middle layer is mainly a mixture of Cr,Ni and Ta oxides, and the inner layer is Al2O3. The γ' free layer occurs adjacent to the oxide layer, and the plastic deformation and γ' phase dissolution around the hole edge facilitate recrystallization formation.

Key words: film cooling holes, creep, single crystal superalloy, rafting, recrystallization

CLC Number: