Multiaxial low-cycle fatigue and cyclic deformation of boron-added 9% Cr martensitic steel at 650 °C: Microstructural evolution, damage mechanisms, and life prediction
Abstract
In this article, the mechanical behaviour of the boron-added 9% Cr martensitic stainless steel COST FB2 was investigated under axial-torsional Low-Cycle Fatigue (LCF) loading at 650 °C for five loading paths: tension-compression, pure shear, proportional, cross, and non-proportional diamond loading paths. All loading paths resulted in cyclic softening associated with microstructural degradation involving lath coarsening and a reduction in dislocation density, with the extent depending on the loading path. Transgranular cracking was predominant for all loading paths, with oxidation-assisted cracking being more pronounced for loading paths involving shear strain. In addition, surface cracks generally propagated along planes of maximum shear strain range, indicating a shear-dominated failure mode. For the same equivalent strain amplitude, the fatigue lifetime was highest under tension-compression loading and lowest under cross and diamond loading paths. Finally, several damage models within the critical-plane framework were assessed, and the modified Fatemi–Socie damage parameter showed the best agreement between the observed and predicted lifetimes.
Publication Title
International Journal of Fatigue
Recommended Citation
Bartošák, M., Mára, V., Šulák, I., Ghadar, S., & Fatemi, A. (2027). Multiaxial low-cycle fatigue and cyclic deformation of boron-added 9% Cr martensitic steel at 650 °C: Microstructural evolution, damage mechanisms, and life prediction. International Journal of Fatigue, 214 https://doi.org/10.1016/j.ijfatigue.2026.109899
