Effect of Elevated Temperature on Low Cycle Fatigue and Tensile Strength of 12Cr Ferritic Steel

This research investigates the low cycle fatigue (LCF) and tensile properties of X20CrMoV12.1 steel which belongs to the group 12Cr ferritic steels at 538–566 °C. The tensile strength measured at elevated temperature exhibits a reduction of approximately 30% compared to values obtained at ambient conditions. Conversely, ductility properties show a significant increase under elevated temperatures. Fatigue strength at elevated temperatures is generally lower than at ambient conditions for similar strain amplitudes, with a pronounced reduction observed at low strain amplitudes. Fractographic analysis indicates that the observed reduction in fatigue strength at low strains is due to oxidation-induced microcrack initiations following prolonged exposure to high temperatures. The Basquin-Coffin-Masson models and Ramberg–Osgood models were utilized to characterize the LCF properties of the materials for each temperature condition. The transition fatigue life of sample performed at ambient air is approximately half that of those tested at elevated temperatures. The findings demonstrate that the influence of chromium content on improving the LCF properties of X20CrMoV12.1 material is insignificant compared to materials with lower chromium content under the elevated temperature range of 538–566 °C.