The fatigue life of structural components is determined by the initiation of cracks and their propagation to critical dimensions. This report presents fatigue-crack-initiation and fatigue-crack-propagation data for pressure-vessel steels operating in a benign environment and at temperatures below the creep region. Available data indicate that the primary factor affecting fatigue-crack initiation is the ratio of the stress-intensity-factor range, delta K, to the square root of the notch radius, rho. This ratio is directly related to the maximum stress range at the tip of a notch. The threshold stress-in-tensity-factor range, delta K sub th, for nonpropagating fatigue cracks in martensitic, ferrice-pearlite, and stainless steels is shown to be essentially independent of the chemical composition or the mechanical properties of the steel, but is strongly dependent on the stress ratio, R. The primary factor affecting fatigue-crack-propagation rates is the applied stress-intensity-factor range. Equations are presented that can be used to calculate conservative estimates of fatigue-crack growth per cycle under constant-amplitude loading for martensitic, ferrite-pearlite, and stainless steels. An equation is also presented that can be used to calculate conservative estimates of fatigue-crack growth per cycle under variable-amplitude loading. Data obtained by testing pressure vessels and pressure-vessel components, and the results of surveys of pressure-vessel failures are discussed. It is concluded that the probability of fatigue failure of properly designed and fabricated pressure vessels is very low and that the most effective approach to keep this probability low is to minimize the magnitude of the stress (strain) concentration factors. This can be accomplished through proper design of details and through proper fabrication.

  • Corporate Authors:

    Welding Research Council

    345 East 47th Street
    New York, NY  United States  10017
  • Authors:
    • Barsom, J M
  • Publication Date: 1974-5

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Filing Info

  • Accession Number: 00054956
  • Record Type: Publication
  • Source Agency: Welding Research Council
  • Files: TRIS
  • Created Date: Jul 22 1974 12:00AM