[en] Highlights: • Environmental damage per cycle was more severe at low strain rates. • Mechanical fracture resulted in branching at high strain rates. • High dislocation density near crack tip at low strain rates was related to HELP. • A thin oxygen penetration layer was the initial state of the oxide film. - Abstract: The corrosion fatigue (CF) behavior and crack tip characteristic of 316LN stainless steel in 325 °C water at different strain rates were investigated under a strain amplitude of 0.6%. With decreasing the strain rate from 0.4% s⁻¹ to 0.0004% s⁻¹, the CF life decreased linearly in log-log plot. More obvious reduction of CF life at low strain rate was due to the environmental damage. The morphology of cracks and the dislocation density near the crack-tip front exhibit a significant different under different strain rate conditions. The hydrogen enhanced localized plasticity mechanism is discussed to explain the micro-damage process at different strain rates in high-temperature water.