## 1 Introduction
[15; 16; 17; 18] studied the effect of corrosion on the mechanical properties of ship steel plates with a yield strength of 235 Mpa and found that modulus of elasticity, yield strength, tensile strength, and elongation after the fracture of the steel plate decreased with the increase in the degree of corrosion and corrosion made the steel plate more brittle; a new stress-strain relationship was proposed to consider the influence of corrosion and residual stress on the mechanical properties of the steel plate. [PERSON] et al. [19] studied the same batch of corroded ship steel plates and found that the fatigue strength of the uncorroded sample was 86 Mpa and the fatigue strength of the corroded sample was between 50 MPa and 100 Mpa. The increase in the surface roughness of the steel plate caused by corrosion was directly related to the deterioration in the fatigue life. [PERSON] et al. [20] experimentally studied the mechanical behaviors of weathering steels Q420 qNH and Q420 qNHY in a marine environment and found that local corrosion or pitting can affect the yield strength, ultimate strength, and corresponding strains, especially elongation. Modeling of the development of fatigue cracks and the numerical prediction of the remaining fatigue life have also been studied extensively. [PERSON] et al. [21] experimentally studied the fatigue behavior of Q345 qD ordinary carbon-steel butt-welded splices. As a result, combined from linear elastic fracture mechanics and finite element analysis, a numerical method to predict the remaining fatigue life of steel specimens with initial defects was proposed. [PERSON] et al. [22] combined the Monte Carlo method, the rainflow counting technique, and the Palmgren-Miner rule and proposed a method to evaluate the residual life of a nearly 100-year-old exterior-riveted crane support truss; the Monte Carlo method is used to generate a time-dependent load based on the operation of the overhead crane, and detailed numerical modeling is based on the rainflow counting technique and the Palmgren-Miner rule and is used to assess the fatigue resistance and estimate the residual life. [PERSON] et al. [23] Proposed a linear corrosion prediction model based on [PERSON]'s linear cumulative damage concept to solve the difficulty of implementing accelerated corrosion tests, and combined with the fatigue test results, a fatigue damage prediction model that considers corrosion factors is established, and the law of fatigue damage and stiffness degradation of the structure under a corrosive environment is determined. [PERSON] et al. [24; 25] found, through experimental research, that the fatigue properties of corroded and uncorroded Q345 qDNH weathering-steel non-load-carrying fillet welded specimens all met the requirements of the Chinese design code JTG D64-2015 \"Specifications for Design of Highway Steel Bridge\" with a certain safety margin; the fatigue strength of the atmosphere-exposed corroded specimens was reduced by 26.2% compared with the uncorroded specimens; however, the value was still 13.9% larger than the prescribed design fatigue strength. In addition, based on the finite element method and fracture mechanics, and with the help of FEA software Abaqus and fracture mechanics analysis software FRANC3D, it was found that the 3-dimensional initial cracks can be equated to 2-dimensional semi-elliptical initial cracks, and the remaining fatigue life can be reasonably accurately calculated. The influences of initial crack size, initial crack shape, and initial crack location on the remaining fatigue life were studied, and the influence of the initial crack size on fatigue behavior was found to be significant, while the influences of initial crack shape and initial crack location were found to be insignificant. Consequently, a fatigue-life assessment method for corroded weathering steel at the specimen level was established and verified. [PERSON] et al.