Stress corrosion behavior and post-corrosion mechanical properties of CM490 steel in simulated marine splash zone environment

To address the issue of substantial corrosion-stress coupling in the splash zone of marine floating photovoltaic (FPV) mooring systems, this study systematically investigates the stress-corrosion behavior of CM490 anchor chain steel and the evolution of its mechanical properties following corrosion. The investigation was conducted under simulated multi-environmental coupling conditions, including salt spray, ultraviolet (UV) radiation, and rainwater; moreover, accelerated corrosion tests with multiple stress levels were designed and performed. Through a combination of microscopic morphology analyses, three-dimensional pit scanning, mechanical property testing, and finite element simulations, the study elucidates the mechanism whereby stress significantly accelerates corrosion and its impact on material performance degradation. Under conditions of 0.3 σₛ (yield stress) and 0.6 σₛ , the corrosion depth of the steel after 180 d increased by 15.7 % and 23.6 %, respectively, relative to that in the stress-free state. Moreover, time-varying models for the mass reduction and bearing capacity reduction coefficients showed that the rate of bearing capacity degradation exceeded that of mass loss; additionally, the degradation was more pronounced at higher stress levels. Furthermore, a quantitative mapping relationship between the uniform corrosion depth and maximum pitting depth was constructed. Subsequently, a multi-stress, coupled residual-strength model factoring the stress-correction factor was proposed, and a time-varying expression for the bearing capacity prediction reduction coefficient was derived. Overall, this study provides theoretical basis and data support for the durability design and service life prediction of anchor chain steel utilized in marine mooring systems. • Stress-corrosion of CM490 steel in simulated marine splash zones was investigated. • Models for mass and bearing capacity reduction under different stresses were derived. • A quantitative mapping between uniform and maximum pitting depth was constructed. • A multi-stress coupled residual-strength model with stress correction was proposed.