Influence of frequency on high-temperature fatigue behavior of 17-4 PH stainless steels

Jui Hung Wu, Chih Kuang Lin

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20 Scopus citations

Abstract

The effect of frequency (2 and 20 Hz) on the high-cycle fatigue and fracture behavior was investigated at 573-773 K for 17-4 PH stainless steels in three conditions: Condition A (unaged). H900 (peak-aged) and H1150 (overaged). S-N results indicated that at 573 and 673 K, there was generally no difference in fatigue strength between 2 and 20 Hz, except for H900 at 673 K where the fatigue strength at 2 Hz was lower than that at 20 Hz. At 773 K, the fatigue strength of condition at 2 Hz was lower than that at 20 Hz due to the occurrence of creep mechanism at this low frequency. At 773 K and 2 Hz, the fatigue fracture mode exhibited a mixed mode involving transgranular and intergranular cracking and the grain boundary cavities were also observed. At a given temperature and frequency, the fatigue strength for the three conditions generally took the following order: H900 > Condition A > H1150, except for Condition A at 773 K in the long life regime where the fatigue strength was close to that of H1150 due to a precipitate-coarsening effect. With the exception of Condition A tested at 673 K, the fatigue strength of each condition was decreased with increasing temperature as a result of a reduction in yield strength. At both frequencies, the fatigue strength of Condition A at 673 K was greater than that at 573 K as a result of an in-situ precipitation-hardening effect. Fractography observations indicated that the fatigue crack initiation site, crack propagation path and fracture surface morphology were functions of testing temperature, loading frequency and applied cyclic stress level.

Original languageEnglish
Pages (from-to)713-721
Number of pages9
JournalMaterials Transactions
Volume44
Issue number4
DOIs
StatePublished - Apr 2003

Keywords

  • 17-4 PH stainless steel
  • Creep
  • Frequency effect
  • High temperature
  • High-cycle fatigue

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