Dynamic strain aging and microstructural damage mechanism of austenitic stainless steel under thermomechanical fatigue in the temperature range of 250–400 °C

Thermomechanical fatigue tests were performed on austenitic stainless steel in the temperature range of 250–400 °C. Results show that the increase in strain amplitude reduces fatigue life and enhances the impact of phase angle. DSA is only observed in the tensile direction under out-of-phase while in the compression direction under other phase angles at a low strain amplitude. The slip bands with a high dislocation density enhance fatigue resistance, and dislocation tends to form cell structures at high strain amplitudes. Moreover, oxidation damage contributes a lot to the reduction of fatigue life at high strain amplitudes.