Multiaxial fatigue behaviour and damage mechanisms of P92 steel under various strain amplitudes and strain ratios at high temperature

• Published in: International journal of fatigue 2022-05, Vol.158, p.106774, Article 106774
• Main Authors: Gao, Ning, Zhang, Wei, Yin, Peng, Liang, Fei, Zhang, Guodong, Xia, Xianxi, Zhao, Yanfen, Zhou, Changyu
• Format: Article
• Language: English
• Subjects: Amplitudes; Cyclic deformation; Damage; Damage mechanism; Dynamic strain aging; Fatigue failure; Fatigue tests; Heat resistant steels; High strength steels; High temperature; Materials fatigue; Multiaxial fatigue; Precipitation hardening; Strain amplitude; Strain analysis; Strain ratio
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2022.106774

•Increases in strain amplitude and strain ratio accelerate cyclic stress softening.•Dynamic strain ageing appears in the torsional direction at a high strain ratio.•The increase in strain ratio promotes the occurrence of planar slip of dislocation. High temperature multiaxial fatigue tests at different strain amplitudes and strain ratios were performed at 600 °C. Dynamic strain ageing (DSA) analysis and microstructure characterization were used to analyze the cyclic deformation and damage mechanisms. Results reveal that the increases in strain amplitude and strain ratio accelerate the cyclic softening. Moreover, the DSA behaviour shows a distinct dependence on the strain amplitude, strain ratio and loading direction. Furthermore, the increase in strain amplitude promotes subgrains growth and dislocation structure transformation. Particularly, the increase in strain ratio promotes the occurrence of planar slip of dislocation.