Notch size effects on high cycle fatigue limit stress of Udimet 720

Weiju Ren, Theodore Nicholas

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Notch size effects on the high cycle fatigue (HCF) limit stress of Ni-base superalloy Udimet 720 were investigated on cylindrical specimens with three notch sizes of the same stress concentration factor Kt = 2.74. The HCF limit stress corresponding to a life of 106 cycles was experimentally determined at a stress ratio of 0.1 and a frequency of 25 Hz at room temperature. The stresses were calculated using finite element analysis (FEA) and the specimens analyzed using scanning electron microscopy (SEM). Test results show that at the same Kt value, notch size can slightly affect the HCF limit stress of U720 when notch root plasticity occurs. FEA and SEM results reveal that the notch size effects are influenced by a complicated combination of the stress and plastic strain fields at the notch tip, the nominal stress, and the effects of prior plastic deformation on fatigue crack initiation.

Original languageEnglish
Pages (from-to)141-152
Number of pages12
JournalMaterials Science and Engineering: A
Volume357
Issue number1-2
DOIs
StatePublished - Sep 25 2003
Externally publishedYes

Funding

The authors would like to express their appreciation to the US Air Force for the financial support of this program, and to Ken Goecke, David Maxwell and Dale Osborne of University of Dayton Research Institute for technical support whenever needed. Thanks also go to Dr Tim Gabb of NASA Glenn, Drs Paul Browning and Eric Ott of Caterpillar Co. for supply of experimental materials and technical discussion. W. Ren is supported under the RMAT-5 program administered by Systran Federal Corporation.

Keywords

  • High cycle fatigue
  • Ni-base superalloy
  • Stress concentration factor
  • U720, notch

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