Corrosion Cracking of 316L Steel Under Fatigue Loading in High‐Temperature Binary Nitrate Salt: Effects of Loading Frequency

In this study, the corrosion‐fatigue behavior of 316L steel under various loading frequencies in molten nitrate salt at 565°C were conducted. The results indicate that the fatigue life of 316L steel was similar in air and molten salt environments at a low frequency (0.019 Hz). However, at the relatively higher loading frequencies (0.038, 0.076, and 0.152 Hz), a reduction in fatigue life was observed compared with that in air. Fatigue loading significantly accelerated the corrosion of 316L steel, and the extent of acceleration was dependent on the loading conditions. At 0.019 Hz, the cracking of the oxide layer in molten nitrate salts was limited due to the relatively low strain rate, whereas at 0.038, 0.076, and 0.152 Hz, it became considerably more severe. At higher loading frequencies (≥ 0.038 Hz), significant cracking of the oxide layer not only creates pathways for molten salt to corrode crack tips further, but also promotes multi‐site fatigue crack initiation.