Influence of citric acid passivation treatment on the marine atmospheric corrosion resistance of L80-13Cr stainless steel

In offshore oil and gas extraction, 13Cr stainless steel is commonly used for manufacturing downhole tools, which is susceptible to corrosion in marine atmospheric storage environments. To improve the corrosion resistance of 13Cr stainless steel in marine atmospheric environments, a citric acid passivation process was developed in this study for surface passivation treatment of L80-13Cr stainless steel. By a combination of electrochemical tests, neutral salt-spray tests, and marine atmospheric corrosion tests, the influence of this passivation process on the corrosion resistance of L80-13Cr stainless steel was investigated. The study also analyzed the reasons for the improvement of marine atmospheric corrosion resistance due to passivation treatment. The results demonstrate that this passivation treatment significantly enhanced the electrochemical corrosion resistance, salt-spray corrosion resistance, and marine atmospheric corrosion resistance of L80-13Cr stainless steel. Additionally, it increased the thickness of the passive film, preventing the stainless steel from significant corrosion in marine atmospheric environment for 90 d. Characterization of the passive film indicates that the citric acid passivation treatment notably increased the content of Cr2O3 in the passive film, while also significantly increasing the electrical resistance and thickness of the passive film, effectively strengthening the corrosion resistance of L80-13Cr stainless steel.