Low-Cycle Fatigue Behavior and Microstructural Damage Mechanisms of 316L Austenitic Stainless Steel in Cryogenic Environments

This study focuses on the low-cycle fatigue behavior and microstructural damage mechanisms of 316L austenitic stainless steel in cryogenic environments to enhance understanding of its fatigue performance and failure mechanisms over a wide temperature range. Uniaxial tensile and strain-controlled low-cycle fatigue tests were performed at 293 K, 173 K, and 77 K; microstructural evolution and damage mechanisms were explored via interrupted tests combined with multiple microscopic techniques and quantitative martensite analysis. The results show that the room temperature fatigue stress response has three stages, while low temperatures induce continuous cyclic hardening that stabilizes quickly; fatigue life increases with lower temperature and strain amplitude, more notably at high strains. Low temperatures enhance strength, increase hardness, slightly reduce plasticity, but maintain good toughness, suppressing crack initiation and propagation with ductile fracture. The findings clarify cryogenic fatigue damage mechanisms, providing experimental and theoretical support for cryogenic pressure-bearing component design and safety assessment.