Simulation of the effects of neutron irradiation on the fracture properties of pressure vessel weld metal

Su Wu, John Knott

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15 Citations (Scopus)


A degradation procedure has been devised to simulate the effect of neutron irradiation on the mechanical properties of a steel pressure-vessel weld metal. The procedure combines the application of cold prestrain together with an embrittling heat treatment to produce an increase in yield stress, a decrease in strain hardening rate, and an increased propensity for brittle intergranular fracture. Fracture tests were carried out using blunt-notch four-point-bend specimens in slow bend over a range of temperatures and the brittle/ductile transition was shown to increase by approximately 110 degreesC as a result of the degradation. Fractographic analysis of specimens broken at low temperatures showed about 30% intergranular failure in combination with transgranular cleavage. Predictions have been made of the ductile-brittle transition curves for the weld metal (sharp crack) fracture toughness in degraded and non-degraded states, based on the notched-bar test results and on finite element analyses of the stress distributions ahead of the notches and sharp cracks. The ductile-brittle transition temperature shift (DeltaT = 110 degreesC) between non-degraded and degraded weld metal at a notch opening displacement of 0.31 mm was combined with the Ritchie, Knott and Rice (RKR) model to predict an equivalent shift of 115 degreesC for sharp-crack specimens at a toughness level of 70 MN/m(3/2). (C) 2003 Elsevier Ltd. All rights reserved.
Original languageEnglish
Pages (from-to)807-815
Number of pages9
JournalInternational Journal of Pressure Vessels and Piping
Publication statusPublished - 1 Jan 2003


  • degradation
  • fracture toughness
  • steel
  • embrittlement
  • weld metal


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