A multi-scale crystal plasticity model for cyclic plasticity and low-cycle fatigue in a precipitate-strengthened steel at elevated temperature

Dong Feng Li, Richard A. Barrett, Padraic E. O'Donoghue, Noel P. O'Dowd, Sean B. Leen

Research output: Contribution to journalArticlepeer-review

Abstract

In this paper, a multi-scale crystal plasticity model is presented for cyclic plasticity and low-cycle fatigue in a tempered martensite ferritic steel at elevated temperature. The model explicitly represents the geometry of grains, sub-grains and precipitates in the material, with strain gradient effects and kinematic hardening included in the crystal plasticity formulation. With the multiscale model, the cyclic behaviour at the sub-grain level is predicted with the effect of lath and precipitate sizes examined. A crystallographic, accumulated slip (strain) parameter, modulated by triaxiality, is implemented at the micro-scale, to predict crack initiation in precipitate-strengthened laths. The predicted numbers of cycles to crack initiation agree well with experimental data. A strong dependence on the precipitate size is demonstrated, indicating a detrimental effect of coarsening of precipitates on fatigue at elevated temperature.

Original languageEnglish
Pages (from-to)44-62
Number of pages19
JournalJournal of the Mechanics and Physics of Solids
Volume101
DOIs
Publication statusPublished - 2017

Keywords

  • Crack initiation
  • Cyclic softening fatigue
  • Finite element
  • Strain gradient-based crystal plasticity
  • Tempered martensite ferritic steels

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