Evaluation of the Pitting Corrosion of Modified Martensitic Stainless Steel in CO2 Environment Using Point Defect Model

Abstract

Pitting corrosion is a significant concern for the broader application of stainless steel in modern industries in which metal and metal alloy are detached preferentially from susceptible parts on the surface, resulting in the creation of holes in passivated alloys that are exposed to an aqueous, neutral electrolyte containing corrosive species. Exposure of SS to brines leads to the localized loss of surface passivity and the onset of isolated pitting, which render the equipment or piping unfit for service. In the present study, the passive layer behavior and the pitting corrosion of the modified martensitic stainless steel (MMSS) were evaluated in a saturated CO2 environment (pH~5) with different NaCl concentrations and temperatures, using various electrochemical techniques. It was found that by increasing the temperature up to 60 °C, the corrosion resistance of the MMSS increased; however, the corrosion rate dramatically increased at 80 °C, indicating the destruction of the oxide layer. According to the point defect model (PDM) results, the calculated values of polarizability (α), metal cation diffusivity (D), and the rate of annihilation of cation vacancies (jm), reveal a strong dependence on the solution temperature.

Selective Initiation of Corrosion Pits in Stainless Steel Using Scanning Electrochemical Cell Microscopy

“…14,24−27 However, most investigate low scan rates (<10 mV/s) in bulk solutions. 24,26,28 Therefore, the effect of the scan rate on E corr is investigated in microcapillaries (Figures 1c and S2) and compared to bulk solutions (Figure 1d) to determine the optimal scan rate for SECCM experiments.…”

“…High scan rates (>10 mV/s) are employed in SECCM to expedite the collection of a large number of electrochemical measurements and to mitigate the accumulation of corrosion products that may block the end of the microcapillary tip . Many studies work to determine the exact effects of scan rate on PDP curves and the measured E corr values. ,− However, most investigate low scan rates (<10 mV/s) in bulk solutions. ,, Therefore, the effect of the scan rate on E corr is investigated in microcapillaries (Figures c and S2) and compared to bulk solutions (Figure d) to determine the optimal scan rate for SECCM experiments.…”

Localized corrosion in selective laser melted SS316L in CO2 and H2S brines at elevated temperatures

“…The point defect model (PDM) expanded this idea to develop a framework to discern passive film growth along with film breakdown and pit initiation with respect to point defects generated in the oxide layer 44 , 47 , 48 . The occupation of Cl − ions in oxygen vacancy sites at the film/solution compensates for the loss of oxygen vacancies by generating cation vacancy and oxygen vacancy pairs through a Schottky-pair reaction or via cation abstraction 44 , 48 – 50 . The cation vacancies generated move to the metal/film interface, where they are annihilated by cation injection into the film from the substrate.…”

Electrochemical Corrosion Behavior of 310S Stainless Steel in Hot Concentrated Tap Water

“…Tap water contains anions (e.g., Cl − , HCO 3 − , SO 4 2− ) and cations (e.g., Ca 2+ , Mg 2+ ), which play important roles in the corrosion of heating tubes [9][10][11][12]. Cl − ions must adsorb on the metal surface and subsequently cause the breakdown of passive films and the occurrence of pitting corrosion.…”