Time- and Fluence-to-fracture Studies of Alloy 718 in Reactor

  • C. Joseph LongEmail author
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)


A series of Alloy 718 specimens were irradiated in the Halden Reactor under mechanical tensile stresses and in a chemical environment and temperature representative of Pressurized Water Reactor service conditions. The specimens were miniature pin-loaded dogbones, heat treated using either a direct aging cycle or the same aging heat treatment preceded by a solution anneal. Applied stresses ranged between 920 and 1200 MPa. Fracture surfaces examined by SEM displayed a mixture of intergranular regions perpendicular to the applied stress and smoother regions at various angles to the applied stress. It is concluded that intergranular cracking proceeded until the stress on the remaining ligament was sufficient to cause prompt ductile fracture. Fluence at fracture occurred over a range of seven orders of magnitude, with no correlation to applied stress. Time at fracture spanned a much smaller range and was broadly, though weakly, inversely correlated with stress. It appears that time in the environment is a better predictor of failure than is fluence.


Alloy 718 Irradiation-assisted primary water stress corrosion cracking Halden 



Torill Marie Karlsen of IfE has been consistently helpful in providing her high level of expertise and patient with a very long decision cycle. Jeff Stokes of Columbia Fuel Fabrication Facility, Westinghouse, provided the heat treatment for the specimens.


  1. 1.
    J.N. Stevens et al., Hold down spring failure analysis, in 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, 2015Google Scholar
  2. 2.
    K. Leonard et al., Characterization of materials properties and crack propagation mechanisms in damaged alloy 718 leaf springs following commercial reactor exposure, in 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems—Water Reactors, 2015Google Scholar
  3. 3.
    K.J. Leonard et al. Analysis of stress corrosion cracking in alloy 718 following commercial reactor exposure. J. Nucl. Mat. 406 (2015)Google Scholar
  4. 4.
    W.L. Kimmerle, M.T. Miglin, J.L. Nelson, Stress corrosion cracking of alloy 718 in pressurized-water-reactor primary water, in Superalloy 718—Metallurgy and Applications, 1989Google Scholar
  5. 5.
    Society of Automotive Engineers Aerospace Material Specification 5699L, in Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, Foil and Plate 52.5Ni–19Cr–3.0Mo–5.1Cb (Nb)–0.90Ti–0.50Al–18Fe Consumable Electrode Remelted or Vacuum Induction Melted 1775 °F (968 °C) Solution Heat Treated Google Scholar

Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  1. 1.Westinghouse Electric Company LLCHopkinsUSA

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