Effect of Electrical Connection on Corrosion Behavior of Q235 Carbon Steel in Cross Zones in Marine Environment

The effect of electrical connection state on the corrosion behavior of Q235 carbon steel across full immersion zone and tidal zone in Qingdao sea environment were studied by measuring and analyzing corrosion rate, microstructure and rust layer composition. The results showed that under non-electric connection state, the corrosion rate of the sample in full immersion zone was lower than that of the sample in tidal zone, and the corrosion rate of the sample in tidal zone increased with the increase of exposure height. Under electrical connection state, the corrosion rate of the sample under the lowest tidal level line reached the peak value, while in tidal zone, the corrosion rate of the sample in middle tidal level area reached the lowest value. The areas with obvious differences in the corrosion morphology of the samples were mainly in the upper part of full immersion zone and whole tidal zone. There were obvious differences in the composition of the rust layer on the surface of the sample in tidal zone under two states. Under electrical connection state, there was the influence of rust layer. With the increase of exposure height, the content of Ca and Mg in the rust layer gradually increased.