Role of NaCl, CO2, and H2S on Electrochemical Behavior of 304 Austenitic Stainless Steel in Simulated Oil Industry Environment

The electrochemical behavior of 304 austenitic stainless steel (304ASS) was studied by different methods such as potentiodynamic polarization, EIS, SEM, and Raman spectroscopy. Potentiodynamic polarization data suggest that 304 ASS could be more susceptible to corrosion due to the presence of H2S. The coexistence of H2S and Cl−-type ionic species in 304 ASS lead to a decrease in the corrosion resistance as compared to the H2S-free condition. It is seen that CO2 helps form a passive layer on the metallic surface, which eventually decreases its corrosion rate. Raman spectroscopy analysis shows that the passive layer developed under different condition consists of FeCO3, FeS2, Fe2O3, Fe(OH)2, etc. SEM images further confirm that elemental S− and Cl− can infiltrate the passive film and cause the passive film to deteriorate.

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Comprehending the role of individual microstructural features on electrochemical response and passive film behaviour in type 304 austenitic stainless steel

Corrosion Science ◽

10.1016/j.corsci.2020.109187 ◽

2021 ◽

Vol 180 ◽

pp. 109187

Author(s):

S.K. Pradhan ◽

P. Bhuyan ◽

L.R. Bairi ◽

S. Mandal

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Passive Film ◽

Electrochemical Response ◽

304 Austenitic Stainless Steel ◽

Type 304

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Electrochemical Properties of Passive Film Formed on Supermartensitic Stainless Steel in a Chloride Medium

CORROSION ◽

10.5006/3230 ◽

2020 ◽

Vol 76 (9) ◽

pp. 884-890

Author(s):

Renata B. Soares ◽

Wagner R.C. Campos ◽

Pedro L. Gastelois ◽

Waldemar A.A. Macedo ◽

Luís F.P. Dick ◽

...

Keyword(s):

Aqueous Solution ◽

Stainless Steel ◽

Passive Film ◽

Electrochemical Behavior ◽

Photoelectron Spectroscopy ◽

Oil And Gas ◽

Electrochemical Impedance ◽

Passive Layer ◽

Open Circuit ◽

Pitting Potential

The electrochemical behavior and the electronic properties of passive films formed on a super martensitic stainless steel (SMSS) used in oil and gas industries were investigated in aqueous 0.6 M and 2.1 M NaCl solutions with additions of sodium acetate and acetic acid (pH 4.5). Open-circuit potential transients, electrochemical impedance spectroscopy, cyclic voltammetry, and x-ray photoelectron spectroscopy were measured to characterize the passive film formed on SMSS. The electrochemical behavior of the steel in an aqueous solution of 0.6 M NaCl presented the highest pitting potential and the highest polarization resistance in relation to the NaCl/NaAc solution. The passive film of SMSS in an aqueous solution of NaCl presented a thickness of 18.40 nm, three times the thickness of the oxide film in NaCl/NaAc, and consisted of FeO, Cr2O3, MoO2, and spinels such as FeCr2O4 species that are a p-type semiconductor, but may also contain a small fraction of the Fe2O3 and MoO3 oxides. Additionally, it was shown that the passive layer after immersion in a saline solution also contains hydroxides such as FeOOH and Cr(OH)3.

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