Abstract
The pitting susceptibility of passive films formed on X70, X80, and X100 pipeline steels was investigated by means of electrochemical noise (EN) and Mott-Schottky measurements. The EN results were analyzed according to the shot-noise theory and stochastic theory. Pit initiation process was analyzed quantitatively using the Weibull distribution function. Pit growth process was simulated by Gumbel distribution function. The experimental results of Mott-Schottky plots showed that the passive films formed on the three pipeline steels displayed an n-type semiconductor character, and the passive film for X100 pipeline steel has the lowest donor density (ND) among the three passive films. The EN results demonstrated that X100 pipeline steel had the lowest pit initiation rate and pit growth probability, which implied that the X100 pipeline steel had the lowest pitting susceptibility.
Highlights
In the recent years, extensive attentions have been paid to supply oil and gas in a more economic and safer way because of the continuously growing demand in energy consumption
The corrosion resistance for pitting of the passive film formed on X100 pipeline steels was investigated by means of electrochemical noise analysis combining with conventional electrochemical techniques with comparison of its counterpart X70 and X80 pipeline steel; the EN data were analyzed according to the stochastic theory and shot-noise theory, and the pitting corrosion was distinguished from uniform corrosion, and the pit initiation and pit growth process were estimated using Weibull and Gumbel distribution function, respectively
Electrochemical impedance spectroscopy (EIS) is an important technique to investigate the protective character of passive films against corrosion [25, 26]
Summary
Extensive attentions have been paid to supply oil and gas in a more economic and safer way because of the continuously growing demand in energy consumption. Some research related to the passive films and pitting of X70 and X80 pipeline steel has been performed [10,11,12,13], little attention has been paid to analyze the pitting corrosion of X100 pipeline steel in high pH soil environment [21, 22]. The corrosion resistance for pitting of the passive film formed on X100 pipeline steels was investigated by means of electrochemical noise analysis combining with conventional electrochemical techniques with comparison of its counterpart X70 and X80 pipeline steel; the EN data were analyzed according to the stochastic theory and shot-noise theory, and the pitting corrosion was distinguished from uniform corrosion, and the pit initiation and pit growth process were estimated using Weibull and Gumbel distribution function, respectively. The pitting susceptibility of three passive films was compared based on the EN data
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