Effects of chloride ion concentration on the LCF performance of 316L austenitic stainless steel in high-temperature pressurized water

This investigation examines the influence of the chloride ion concentrations (0.05%–5%) on the low-cycle fatigue (LCF) behavior of 316L austenitic stainless steel (316L SS) under high-temperature pressurized water (HTPW) conditions. Experimental results indicate that chloride ions substantially decrease fatigue life, with maximum reductions reaching ∼55% relative to pure water conditions. To enable quantitative fatigue life assessment, a progressive modeling approach is developed and validated. Initially, the strain amplitude effect is incorporated into the environmental fatigue correction factor under pure water conditions. Building on this foundation, the effect of chloride ion concentration is introduced to establish a logarithmic predictive model that demonstrates accuracy across the 0.05%–5% range. Validation experiments at intermediate concentrations (0.3% and 3%) yield prediction errors within 10%. Analysis of the cyclic stress response (CSR) reveals that chloride addition shortens the peak stress saturation stage and accelerates stress degradation. Fractographic examination reveals that increasing chloride concentration accelerates fatigue degradation mechanisms, characterized by expanded fatigue striation spacing and increased oxide particle coarsening. These findings advance the mechanistic understanding of chloride-mediated corrosion fatigue. Overall, a logarithmic predictive model is proposed to predict the fatigue life of 316L SS in chloride-containing HTPW environments, with improved predictive accuracy for the 316L SS.