With the continuous development and utilization of Marine resources,the demand for high-strength steel continues to increase.The cantilever beam,pile leg and lifting electric gear of the offshore platform need the strength of high-strength steel to reach 690 MPa or more,and the corrosion resistance should be better.E690 steel is cur-rently a high strength steel with high comprehensive performance for offshore platforms.With the continuous improvement of the depth of Marine resources development,the environment of high-strength steel used for offshore platform is more and more severe,and it is subjected to seawater erosion and biological fouling in the seawater immer-sion area for a long time,but also to withstand the damage of waves,low temperature and ocean currents and other harsh sea conditions,the corrosion problem is becoming more and more prominent.Based on the array electrode tech-nology,the corrosion exposure experiment of E690 steel was carried out in the full immersion area of Zhanjiang solid sea environment.The corrosion rate,corrosion morphology and polarization curve of E690 steel were tested and ana-lyzed under the electric connection state.The results show that at the beginning of the exposure experiment,the cor-rosion current density increases and the corrosion rate increases with the increase of the depth.Due to the influence of temperature and dissolved oxygen,E690 steel formed a macroscopic corrosion battery under electric connection,and galvanic corrosion occurred.The lower sample had a higher corrosion rate as the anode metal,while the upper sample was protected as the cathode,and the corrosion was light.With the extension of exposure time,the corrosion current density and corrosion rate of E690 steel decreased significantly at the later stage of the experiment.The pro-tective effect of corrosion products and attached organisms on the substrate inhibits the anodic dissolution reaction of E690 steel,which is the main factor affecting metal corrosion,while the galvanic corrosion had little effect.
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