Fatigue crack initiation and growth behavior within varying notch geometries in the low-cycle fatigue regime for FV566 turbine blade material

Benjamin M.D. Cunningham, Mitchell Leering, Yuhui Fan, Chao You, Andrew Morris, Philippa A.S. Reed, Andrew R. Hamilton, Michael E. Fitzpatrick

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Abstract

Plain bend bars made from FV566 martensitic stainless steel were extracted from the root of ex-service power plant turbine blades and several industry-relevant notch geometries were introduced. Some of the samples were shot peened. The notched bend bars were loaded plastically in the low-cycle fatigue regime and finite element (FE) modeling carried out to investigate the effects of changing notch geometry, combined with shot peening, on fatigue behaviors such as crack initiation, short crack growth, and coalescence. Shot peening damaged the notch surface, accelerating initiation behaviors, but had a lifetime-extending effect by retarding short crack growth in all tested notch geometries. At a total strain range higher than 1.2%, the lifetime extension benefit from shot peening was diminished due to compressive residual stress relaxation in the notch stress field. Notch geometry (and the associated varying constraint levels and stress/strain gradients) was found to have no notable difference on fatigue life when tested at identical notch-root strain ranges.

Original languageEnglish
Article number14036
Pages (from-to)2845-2863
Number of pages19
JournalFatigue and Fracture of Engineering Materials and Structures
Volume46
Issue number8
Early online date16 May 2023
DOIs
Publication statusPublished - Aug 2023

Bibliographical note

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.

Funder

Engineering and Physical Sciences Research Council (EPSRC), UK, Grant/Award Number: EP/N509747/1; Natural Science Foundation of Jiangsu Province, Grant/Award Number: BK20210302

Keywords

  • constant amplitude
  • low cycle fatigue
  • notch field
  • notches
  • short crack growth
  • stainless steel

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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