原油船货油舱CO₂-O₂-H₂S-SO₂干湿交替环境低合金钢腐蚀行为研究

Corrosion behavior of carbon steel and Cr-Cu-Ni low alloy steel with rust forming in simulated CO₂-O₂-H₂S-SO₂ wet-dry environment of cargo oil tanks of crude oil tankers for 98 days were investigated using corrosion rate by mass loss method, scanning electron microscope, X-ray diffraction, and electrochemical measurement. The results showed that the corrosion rate of Cr-Cu-Ni low alloy steel was higher than carbon steel in initial period, while with the increase of corrosion time, it tended to be lower than carbon steel. The corrosion current density of Cr-Cu-Ni low alloy steel reduced greatly from 67.4 μA/cm² to 11.7 μA/cm² after a period of corrosion, while the corrosion current density of carbon steel decreased little. The rust layer of carbon steel contained large cracks throughout the cross-section of it, while the rust of Cr-Cu-Ni low alloy steel was compact due to the small size of rust particles, with smaller cracks in cross-section of the rust. The rusts of both carbon steel and Cr-Cu-Ni low alloy steel were composed of amorphous corrosion products, α-FeOOH, small account of γ-FeOOH, Fe₃O₄ and element S. Compared to the rust of carbon steel, the rust of Cr-Cu-Ni low alloy steel had a high content of the amorphous corrosion product and a high α/γ value (the content ratio of α-FeOOH to γ-FeOOH), leading to high rust compactness.