Multiscale Analysis of Corrosion Fatigue Crack Propagation Mechanism of High‐Strength Steel in Seawater Atmospheric Environment

ABSTRACT E690 high‐strength steel is widely used in ocean engineering due to its excellent properties. However, it is highly susceptible to fracture and failure under the coupled effects of corrosion and fatigue in marine environments. This paper investigates the corrosion fatigue fracture mechanisms through experimental and theoretical analyses. First, a series of corrosion fatigue tests on E690 steel specimens were conducted to study the crack propagation behavior, and the crack growth parameters were fitted using the Paris equation. Second, scanning electron microscopy was employed to analyze the corrosion fracture characteristics of the E690 steel specimens. Lastly, finite element analysis and molecular dynamics simulations were used to examine the crack propagation process and failure mechanisms from multiscales. The results show that under the influence of corrosion, dislocation accumulation at the crack tip leads to a plastic deformation mechanism dominated by dislocations during crack propagation. Furthermore, the combined effects of anodic dissolution and hydrogen embrittlement accelerate crack growth. In dry air conditions, loading frequency has no significant impact on the crack growth rate, whereas, in corrosive environments, the coupling of low frequency and corrosion shortens the corrosion fatigue life.