Cyclic softening behaviour of a P91 steel under low cycle fatigue at high temperature

A. A. Saad*, W. Sun, T. H. Hyde, D. W. J. Tanner

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

48 Citations (Scopus)


This paper describes a model used to represent the cyclic mechanical behaviour of P91 martensitic steel. Low cycle fatigue tests were conducted at 600 degrees C using a thermo-mechanical fatigue test machine. A unified, Chaboche viscoplasticity model, was used to model the behaviour of the steel. The microstructure of the steel at different life fractions of the tests was investigated using scanning and transmission electron microscope images. The viscoplasticity model, with two stages of softening period, has resulted in better prediction capability for the cyclic behaviour of the steel for an initially undamaged material prior to crack initiation.

Original languageEnglish
Pages (from-to)1103-1108
Number of pages6
JournalProcedia Engineering
Publication statusPublished - 2011


  • P91 steel
  • FE prediction
  • Cyclic softening
  • Microstructural evolution
  • Viscoplasticity model


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