Localized Corrosion Of Carbon Steel Research Articles

An Online Monitoring Approach of Carbon Steel Corrosion via the Use of Electrochemical Noise and Wavelet Analysis

In this study, carbon steel was examined under different corrosive conditions using electrochemical noise (EN) as the primary method of investigation. The corroded carbon steel surfaces were examined using 3D profilometry to gather information about localized defects (pits). A post-EN analysis approach was used using the discrete wavelet transform (DWT) method, which emphasizes the necessity of employing wavelet analysis as a quantitative analysis approach for electrochemical noise. A well-established approach to extract features from wavelet scalogram images, based on the concept of local binary patterns (LBPs), was used to extract features from these wavelet images. The results demonstrated that electrochemical noise associated with wavelet transform analysis, particularly wavelet scalograms, is an effective tool for monitoring the localized corrosion of carbon steel.

Inhibition of Localized Corrosion Propagation on Carbon Steel: A Potentiostatic Study

The occurrence of localized corrosion in carbon steel pipelines, even when the uniform corrosion rate remains low, is a major concern in the hydrocarbon production and transmission industry. The propagation of these pits, caused by the galvanic coupling between the inhibited surface and the active pit, can lead to serious consequences such as financial loss, environmental damage, production interruption, and even loss of life. To better understand this phenomenon, this work focuses on using the potentiostatic technique to evaluate the tendency of localized corrosion propagation. The experiments were conducted using a primarily imidazolinium-based corrosion inhibitor in produced water conditions (5 wt% NaCl, pH 4.5, CO2-saturated) at 55°C and 80°C. The baseline results were obtained through linear polarization resistance and potentiodynamic polarization tests. The potentiostatic experiments were then conducted to artificially simulate different levels of galvanic coupling that could exist in case of active localized corrosion. The results showed that, at certain anodic potentials, increased inhibitor dosage was necessary to significantly decrease the current. However, at high current levels, further injections were insufficient, indicating that substrate dissolution may affect the adsorption of the inhibitor. This work provides insights into the role of inhibitors and important factors in stopping the propagation of localized corrosion of carbon steel. Further research, such as designing a proper zero-resistance ammeter setup, will be necessary to fully understand this complex phenomenon. The results show that the potentiostatic methodology can be a rapid and easy alternative to obtain electrochemical information and improve understanding of localized corrosion propagation.

The Effects of Chloride, Nitrate, and Nitrite on the Localized Corrosion of Carbon Steel in Simulated Concrete Pore Solutions

Localized corrosion is a precursor to the deterioration of carbon steel reinforcing bars in concrete. The localized corrosion of carbon steel in simulated concrete pore solutions was investigated by cyclic potentiodynamic polarization (CPP) technique. A four-factor, two-level, full factorial design and a five-factor, two-level, Plackett-Burman design were used to study the effects of OH−, Cl−, , , with Na+ and Ca2+ cations on the localized corrosion of carbon steel. The results show that the occurrence of localized corrosion can be evaluated by the type of CPP curves (negative, mixed, or positive hysteresis) and the difference between the open-circuit and repassivation potentials (OCP-Erp). The lowest (OCP-Erp), indicating a low risk of pitting corrosion, could be obtained with high OH−, high , and low Cl−, whereas the effect of was not significant. The corrosion activities near the OCP were measured using linear polarization resistance and electrochemical impedance spectroscopy methods. They indicated that NO2− and Cl− were the main factors influencing the corrosion rate. The cationic species did not have a significant influence on the electrochemical parameters.

Corrosion behaviors of carbon steel induced by life activities of Phaeodactylum tricornutum in a marine environment

AbstractMicrobiologically influenced corrosion induced by bacteria has been studied for many years. Corrosion is known to be sensitive to the presence of microalgae, such as Phaeodactylum tricornutum. However, the life activity of P. tricornutum that influences the general and localized corrosion of carbon steel is not fully understood. The current study uses a combination of immersion tests and electrochemical experiments with a detailed surface characterization to reveal the naturally formed corrosion products with/without the presence of P. tricornutum. The results show that samples suffer from pitting corrosion and the averaged pit depths are approximately 15 μm under a light–dark cycle condition or a 24‐h constant light condition. Meanwhile, the corrosion products are mainly comprised of γ‐FeOOH and Fe3O4 in a constant light condition. However, γ‐FeOOH, Fe3O4, and FeCO3 are found in a light–dark cycle. This study proposes the fundamental mechanisms of the effect of P. tricornutum life activities on the corrosion performance of Q235 carbon steel, to fulfill the knowledge gaps of the presence of microalgae inducing the general and pitting corrosion of carbon steel.

Mechanisms of localized corrosion of carbon steel associated with magnetite/mackinawite layers in a cement grout

AbstractCarbon steel electrodes covered with a specific low‐pH cement grout (pH ~10.7 at 20°C), designed for nuclear waste management applications, were immersed for 30 days in a 0.01‐M NaCl + 0.01‐M NaHCO3 solution (pH 7 measured at 20°C), in aerated conditions, at 80°C. The corrosion processes were studied by voltammetry and linear polarization resistance measurements while the corrosion product layers were analyzed by µ‐Raman spectroscopy and X‐ray diffraction. Most of the electrodes (75%) suffered from localized corrosion, a phenomenon associated with the formation of a heterogeneous Fe3O4/FeS layer. It is proposed that the mechanisms of the particular corrosion process observed here are associated with galvanic effects, the large magnetite‐covered zone acting as cathode and the locally mackinawite‐covered zones being anodic regions.

AC Corrosion of Carbon Steel under Cathodic Protection Condition: Assessment, Criteria and Mechanism. A Review.

Cathodic protection (CP), in combination with an insulating coating, is a preventative system to control corrosion of buried carbon steel pipes. The corrosion protection of coating defects is achieved by means of a cathodic polarization below the protection potential, namely −0.85 V vs. CSE (CSE, copper-copper sulfate reference electrode) for carbon steel in aerated soil. The presence of alternating current (AC) interference, induced by high-voltage power lines (HVPL) or AC-electrified railways, may represent a corrosion threat for coated carbon steel structures, although the potential protection criterion is matched. Nowadays, the protection criteria in the presence of AC, as well as AC corrosion mechanisms in CP condition, are still controversial and discussed. This paper deals with a narrative literature review, which includes selected journal articles, conference proceedings and grey literature, on the assessment, acceptable criteria and corrosion mechanism of carbon steel structures in CP condition with AC interference. The study shows that the assessment of AC corrosion likelihood should be based on the measurement of AC and DC (direct current) related parameters, namely AC voltage, AC and DC densities and potential measurements. Threshold values of the mentioned parameters are discussed. Overprotection (EIR-free < −1.2 V vs. CSE) is the most dangerous condition in the presence of AC: the combination of strong alkalization close to the coating defect due to the high CP current density and the action of AC interference provokes localized corrosion of carbon steel.

Multi-Physics Coupling Analysis on the Time-Dependent Localized Corrosion Behavior of Carbon Steel in CO2-H2O Environment

Localized corrosion of carbon steel in CO2-H2O environment is a long-standing challenge faced by the oil and gas industry, because of its unfeasible detection and high propagation rate. Numerical modelling can overcome the limitations of the spatial and temporal scales in the experimental studies, thus becoming a valuable complement. A multi-physics coupling model is established to investigate the evolution of localized corrosion of carbon steel in CO2 aqueous environment. The complex interactions among the kinetics of electrode reactions, multicomponent reactions, mass transfer and the deposition of corrosion products are coupled into the model, achieving a comprehensive and physically realistic description of the actual corrosion process. The arbitrary Lagrangian-Eulerian method is implemented to track the moving metal/solution interface. Special emphasis is put on the coupling mechanism among the underlying processes at different time and length scales. This study characterizes quantitatively the time-dependent corrosion behavior, including the distributions of potential and species concentration within the corroding pit, corrosion current density and pit morphology. The inherent relationship between the corrosion behavior and the local corrosive environment within the pit is revealed. The results indicate that the competition between the chemical effect and electrical effect determines the trend and distribution of corrosion current density. The pit shape and cathode/anode area ratio have a great influence on the corrosion behavior due to the coupled role of local solution chemistry and electrical field.

Characterization and prediction of carbon steel corrosion in diluted seawater containing pentaborate

This study addresses the influence of Na2B10O16, which may be used for criticality control of fuel debris in the Fukushima Daiichi Nuclear Power Station, on the corrosion behavior of carbon steel in diluted artificial seawater. The corrosion forms of carbon steel were categorized as uniform corrosion, localized corrosion, and passivity based on the balance between the dilution ratio of artificial seawater and the concentration of Na2B10O16. The changes in corrosion forms were arranged on a water quality region map. Passivity was maintained by adding 3.7 × 10−2 M or more of Na2B10O16 to artificial seawater with a dilution ratio of 100-fold or more. The criticality control of the fuel debris and corrosion mitigation of the carbon steel components may be achieved simultaneously in the water quality. The prediction of the corrosion form of carbon steel was attempted by the extended Larson–Skold Index (LSI) = ([Cl−] + 2[SO42−])/([HCO3−] + 2[B10O162−]). However, because the passivating action of B10O162− was remarkably stronger than that of HCO3−, the prediction was difficult under the simple addition of equivalent concentrations. The localized corrosion of carbon steel under the addition of Na2B10O16 preferentially occurred from the crevices of the test specimens, as was the case in stainless steel.

Effect of small amount of H2S on the corrosion behavior of carbon steel in the dynamic supercritical CO2 environments

The effect of small amount of H2S on the corrosion of carbon steel in both dynamic supercritical CO2 and aqueous phase was investigated. H2S changed the adsorbability of H2O on the steel surface, causing the adsorption of H2O on the whole steel surface, which accelerated the general and localized corrosion of carbon steel in supercritical CO2 phase. The small amount of H2S presented more significant effect in the aqueous phase—it changed the microstructure and compositions of the corrosion product scale, ultimately changed the dominated corrosion type of carbon steel from localized to general corrosion.

The Influence of pH on Localized Corrosion Behavior of X65 Carbon Steel in CO2-Saturated Brines

Pitting and localized corrosion of carbon steel is considered to be a complex process influenced by a wide range of parameters such as temperature, bulk solution pH, and chloride ion concentration. Solution pH is known to influence corrosion product characteristics and morphology in CO2- and H2S-containing corrosion systems. However, from the perspective of pitting corrosion in CO2-saturated environments, the extent to which bulk pH of solutions and the presence of corrosion products influence localized attack is still not clearly understood. This paper presents an investigation into the role of pH on the characteristics of corrosion product and pitting corrosion behavior of X65 carbon steel (UNS K03014) in CO2-saturated brine. Pitting corrosion studies were conducted over 168 h at 50°C in 3.5 wt% NaCl solutions at different bulk pH (buffered to pH values of 6.6 and 7.5 in some cases) in order to understand and correlate the role of pH on corrosion product morphology, chemistry, initiation, and propagation of pits within each distinct environment. Corrosion product composition and morphology are identified through a combination of electrochemical and surface analysis techniques, which include scanning electron microscopy and x-ray diffraction. The extent of corrosion damage of the carbon steel is evaluated through the implementation of surface interferometry to study discrete pit geometry, namely the size, depth, and aspect ratio. Results indicate that the process of pit initiation and propagation of carbon steel in CO2 corrosion environment is different depending upon bulk solution pH. At low pH (pH values starting at 3.8), pitting initiates faster and propagates steadily along with significant uniform corrosion resulting from the formation of an “amorphous” form of FeCO3. At higher pH, uniform corrosion is significant, while pitting initiates with increasing protection from crystalline FeCO3. At a pH value of 7.5, pitting corrosion initiation occurs after and/or during pseudo-passivation is achieved as a result of the formation of a “protective and pseudo-passivating” FeCO3 film.

Adsorption and corrosion-inhibiting effect of Dacryodis edulis extract on low-carbon-steel corrosion in acidic media

The inhibition of low-carbon-steel corrosion in 1 M HCl and 0.5 M H 2SO 4 by extracts of Dacryodis edulis (DE) was investigated using gravimetric and electrochemical techniques. DE extract was found to inhibit the uniform and localized corrosion of carbon steel in the acidic media, affecting both the cathodic and anodic partial reactions. The corrosion process was inhibited by adsorption of the extracted organic matter onto the steel surface in a concentration-dependent manner and involved both protonated and molecular species. Molecular dynamics simulations were performed to illustrate the process of adsorption of some specific components of the extract.

Evaluation and classification of seawater corrosiveness by environmental factors

According to the data of main environmental factors and the depth of localized corrosion of carbon steel and low alloy steels in China seas, combined with the result of grey interrelation analysis, double-factor method was proposed to evaluate and classify seawater corrosiveness. According to the temperature of seawater and the biologically adhesive area on steels, the corrosiveness of seawater from low to high level is classified into five levels (C1–C5), which was identified by the data of corrosion depth of carbon steel immersed in water for one year.

Effect of Environmental Variables on Localized Corrosion of Carbon Steel

Abstract Environmental conditions under which localized corrosion of carbon steel could take place in simulated groundwater were examined. Using specimens with crevices, it was determined that at potentials above the repassivation potential, the ratio of the chloride concentration to the total carbonate concentration, solution pH, and solution temperature played critical roles in establishing conditions that promote localized corrosion, as well as in influencing the rate of propagation. Preoxidation in air at 200°C for short times improved the resistance to localized corrosion, but was detrimental for longer times. Monitoring of the open-circuit potential of samples with crevices in air-saturated, alkaline (pH 11) solutions revealed that the repassivation potential could be exceeded and localized corrosion can occur under free corrosion conditions. Factors important to the use of carbon steel as a construction material for high-level radioactive waste disposal containers were discussed.