Prediction Method of Time-dependent Evolution of Atmospheric Corrosion at Weathering Steel and Its Welded Joints

To provide theoretical methods and countermeasures for solving the corrosion problems faced by weathering steel bridges in the application and development, aimed at the corrosion damage evolution characteristics of weathering steel in the atmospheric environment, an innovative time-dependent evolution model of atmospheric corrosion of weathering steel welded joints, based on the three-dimensional cellular automata technology, is developed using MATLAB. According to the chemical reaction of weathering steel in the atmospheric environment, the key elements in the weathering steel corrosion system are abstracted into four cellular types and divided into cellular grids in the model, and different cellular neighbor types are defined for the base material and the weld respectively, to simulate the corrosion evolution process of the representative volume element of weathering steel welded joints on the mesoscopic scale. The feasibility and effectiveness of the proposed method was verified by the atmospheric exposure tests. Furthermore, the corrosion dynamics and evolution law of corrosion pit of weathering steel welded joints were revealed; the effect of dissolved oxygen concentration and dissolution probability on corrosion damage were analyzed, and the prediction method of long-term corrosion evolution process was raised. The results show that the proposed time-dependent evolution model of weathering steel welded joint is stable and reasonable. When the time scale and lattice spacing are set to 0. 2 years and 100 μm, the experimental results show good agreement with the numerical results. The corrosion damage of weathering steel and its welded joints are mainly determined by the dissolution probability and the dissolved oxygen concentration. The average corrosion depth increases with both the dissolution probability and the dissolved oxygen concentration. The proposed time-dependent evolution prediction method of atmospheric corrosion at weathering steel and its welded joints can reproduce the atmospheric corrosion process, describe and identify the corrosion dynamics, corrosion morphology and pit distribution characteristics of the research objects to a large extent, and provide scientific basis for the continuous prediction of corrosion behavior of weathering steel and its welded joints in the long-term atmospheric corrosion process. © 2023 Xi'an Highway University. All rights reserved.