Effect of Technology and Microstructure on Corrosion Behavior of Bridge Steels in Simulated Ocean Splash Zone Environment

The corrosion behaviors of bridge steels with different manufacturing technologies were investignated by electrochemiscal method and simulated splash corrosion test, and the corrosion rates of the steels in simulated splash and full immersion zone corrosion tests were compared. The results showed that the microstructure of the samples changed from non-equilibrium granular bainite to equilibrium temper sorbite after tempering. Because of the grain refinement and uniformity of structure, the corrosion resistance of temper sorbite microstructure was better than that of granular bainite microstructure in simulated ocean splash zone. The corrosion rate in simulated ocean splash zone was 6-10 times as much as that in simulated full immersion zone. Besides the external surrounding factors, the open circuit formed between reducing rust layer and parent steel and the potential difference between internal and external corrosion pit were the main factors of higher corrosion rate.