Effective and Back Stress Evolution Upon Cycling Oxide-Dispersion Strengthened Steels

We report on the evolution of effective and back stresses upon cycling a 9Cr oxide-dispersion strengthened (ODS) steel at elevated temperatures by partitioning its hysteresis loops. We found that the trend of the cyclic stress response mainly originates from the back stress evolution, while the effective stress undergoes insignificant change with the cycle number. The effective and back stresses vary with both strain amplitude and temperature but with different magnitudes. These observations are discussed based on the previously reported microstructure evolution. Furthermore, comparison with its similar non-ODS counterpart and other ODS steels pinpoint the origins of their distinct fatigue behaviours.