Corrosion Process Of Steel Research Articles

Effects of water content on the corrosion behavior of NiCu low alloy steel embedded in compacted GMZ bentonite

Buffer material and metal disposal containers are the key engineering barriers in the geological disposal of high-level radioactive waste. The durability of disposal containers largely depends on the water content in buffer material. This work focused on investigating the corrosion evolution of NiCu low alloy steel in compacted GMZ bentonite with different water contents for 270 d by using weight loss, electrochemical measurements, and various methods for analyzing corrosion products. As the water content increased from 13% to 20%, the water in the bentonite transformed from an unsaturated to a critical saturated state, and the corrosion rate of NiCu steel clearly increased. In these two systems, the oxygen could migrate to the thin liquid film on the steel surface through the air pores in the bentonite in the gas phase and undergo cathodic reduction. Meanwhile, it oxidized the ferrous hydrolysis products into ferric corrosion products and formed a rust layer, which could block the diffusion of oxygen. At that moment, the cathodic process of NiCu steel corrosion changed to rust reduction. When the water content continually increased to 30% and 40%, the compacted bentonite was in a saturation state, and the corrosion rate of NiCu steel was significantly decreased. This was because most pores among the bentonite particles were occupied by a large amount of free water, which hindered the diffusion of oxygen and inhibited its cathodic reduction. Furthermore, it restrained the oxidation of ferrous corrosion products, which greatly weakened the cathodic depolarization of rust, leading to the cathodic process being dominated by the hydrogen evolution reaction.

Understanding the role of alloying elements Cr, Ni in erosion–corrosion process of nuclear grade austenitic stainless steel 304 L by total reflection X-ray fluorescence

Stainless steel (SS) has gained an indispensable position as one of the most widely used industrial material. In nuclear industry, it is one of the technologically most important structural materials used in pressure tube, containment vessel and reprocessing-related applications. In fact, SS 304 L is the workhorse material of the reprocessing plant which faces the hostile conditions of acid, temperature as well as high radiation dose. These conditions can affect the erosion-corrosion behavior of the material and can lead to poor mechanical properties. This also affects the life of the reactor components. In the present study, a systematic work has been carried out to develop an in-depth understanding of the Corrosion Rates (CRs) with respect to the loss of major and minor elements from SS into the corrosive nitric acid medium using Total reflection X-Ray Fluorescence (TXRF). The effect of acid molarity as well as temperature, on the erosion-corrosion behavior of SS304L was studied. The TXRF studies have revealed that the CR was maximum in 2 M HNO3 and minimum in 8 M, showing that as the nitric acid molarity has an important role to play in the corrosion and as the molarity increases, the passivation of SS 304 L also increases. This observation was further corroborated with the concentrations of Fe, Cr and Ni, which had leached into the nitric acid medium. The role of alloying elements, Cr and Ni, in the passivation of SS was also studied. The effect of temperature showed that at 45 °C, the rate of corrosion was minimum, as compared to at 25 °C and 90 °C which reveals that the formation of chromium oxide passive layer was thermodynamically most favorable at this temperature.

Corrosion of carbon steels subjected to chloride and sulfate in simulated concrete pore solutions with different pH

The present study explores low-carbon steel corrosion in simulated concrete pore solutions with varying pH, focusing on the influence of chloride and/or sulfate ions. Employing electrochemical techniques, ToF-SIMS, XRD and DFT calculations, the results reveals that higher pH strengthens the passivation film and reduces corrosion by limiting corrosive ions adsorption. Notably, sulfate triggers corrosion at higher thresholds, while chloride alone significantly elevates corrosion rates. The presence of both ions shows mitigated corrosion risk due to competitive absorption onto steel interface of sulfate. The two-stage mechanism involving competitive adsorption and catalytic corrosion is initially proposed and elucidates the interaction mechanism of chloride and sulfate during steel corrosion process.

Revealing the Mechanism of O<sub>2</sub> and Pressure Effects on the Corrosion of X80 Carbon Steel Under Supercritical CO<sub>2</sub> Conditions

Pipeline transportation is widely used due to its ability to improve the efficiency of CO<sub>2</sub> transportation in Carbon Capture, Utilization, and Storage (CCUS). Within the transport pipelines, CO<sub>2</sub> fluid exists in a supercritical state and often contains various impurity gases such as O<sub>2</sub> and H<sub>2</sub>O, which can easily cause steel corrosion, affecting the safety of pipeline operations. In this investigation, we examine the corrosion behavior of X80 carbon steel within a water-saturated supercritical CO<sub>2</sub> environment utilizing weight loss experiments, electrochemical tests, and surface analysis techniques. Furthermore, we explore the impact of pressure and oxygen on the corrosion process of X80 steel. The results indicated that X80 steel underwent severe corrosion under the experimental conditions, with FeCO<sub>3</sub> as the primary corrosion product. Both the introduction of oxygen and an increase in pressure accelerated the steel's corrosion, and the addition of oxygen led to the formation of a new corrosion product, Fe<sub>2</sub>O<sub>3</sub>. Electrochemical test results showed that changes in pressure did not significantly alter the electrochemical corrosion characteristics of the steel, but the introduction of oxygen decreased the electrochemical reaction resistance of X80 steel. Combined with surface analysis, the following conclusions were drawn: In a 50°C supercritical CO<sub>2</sub> environment, the anode reaction of X80 steel corrosion is the active dissolution of iron, while the cathode reaction involves the dissolution and ionization of CO<sub>2</sub>. Changes in pressure do not alter the corrosion mechanism, but the introduction of oxygen leads to oxygen corrosion reactions in the system, accelerating the anode reaction rate and thus increasing the degree of corrosion.

Study on electrochemical corrosion dynamics of cathode dic shield in concrete crack

Abstract Corrosion of steel reinforcement is a primary factor that negatively impacts the service life and safety of bridges made of concrete. Cathodic protection techniques are widely used to protect reinforcing bars in concrete against corrosion. However, it is inevitable that corrosion cracks will develop in the concrete during long-term operation, which will significantly shorten the cathodic current protection distance and increase the degree of corrosion of the rebar within the cracks. Therefore, electrochemical experiments and characterization of corrosion forms were carried out based on the company’s design of a rectangular connection device, we studied HRB500 steel in 3 wt.% corrosion behavior in rectangular joints under different CP current densities in NaCl solution. The results showed that with increasing experimental time, the corrosion in the crevice transitioned from activation corrosion to oxygen concentration corrosion, with the open-pore potential of the HRB500 steel inside the crevice appearing as a positive shift and the open-pore potential outside the crevice shifting from positive to negative. When implementing cathodic protection, the corrosion of HRB500 steel within the crevice is activated, while the corrosion outside the crevice changes from anodic to mixed controlled corrosion and from full to pitting corrosion. With the increase of CP current density, the corrosion process of HRB500 steel outside the gap is mainly dominated by cathode control, then gradually weakens, and the corrosion form changes from pitting to comprehensive corrosion.

Performance of a Composite Inhibitor on Mild Steel in NaCl Solution: Imidazoline, Sodium Molybdate, and Sodium Dodecylbenzenesulfonate

Mild steel corrosion is a significant challenge in oil and gas exploitation. Inhibitors are frequently employed to minimize the corrosive impact on mild steel. Mixing corrosion inhibitors is an effective method in reducing the dosage of toxic compounds and expanding the potential applications of inhibitors in NaCl solutions. Herein, a mixed corrosion inhibitor composed of imidazoline (IM), sodium molybdate, and sodium dodecylbenzenesulfonate (SDBS) for mild steel in a 3.5 wt% NaCl solution are investigated by orthogonal experimental design and electrochemical measurement. The imidazoline compound was synthesized and identified using Fourier transform infrared (FTIR) spectroscopy. The inhibitory effect is improved by higher concentrations of sodium molybdate and is further enhanced with the addition of 10 mg/L of SDBS. The electrochemical impedance spectroscopy indicates that the combination of IM (100 mg/L), sodium molybdate (50 mg/L), and SDBS (100 mg/L) results in excellent performance with electrochemical impedance (1.8 kohm·cm2). The mild steel surfaces after electrochemical measurement were analyzed using scanning electron microscopy (SEM). The information can contribute to the development of corrosion inhibitors with high performance or to understand the influence of mixing inhibitors on corrosion processes of mild steels.

Steel corrosion process in ultra-high performance concrete monitored by fiber bragg grating sensor

The steel corrosion in Ultra-High Performance Concrete (UHPC) would cause degradation of structural performance or even structural failure. It is an urgent need to monitor and predict the steel corrosion in UHPC, however it is still a tough task. In this paper, Fiber Bragg Grating (FBG) sensors are applied for monitoring the steel corrosion process in UHPC, by combining with steel bar, which is equidistant winding with the sensors, and connected with power supply for accelerating corrosion. The UHPC specimens embedded with steel bars are surrounded by sodium chloride (NaCl) solution, and the steels are artificially corroded with different current densities for investigation. The steel corrosion in Original C60 and Marine Concrete 60 (Marine C60) are applied for comparison. The volume expansion coefficient for monitoring the steel corrosion process, is carried out by FBG sensors, and further comprehensively monitored by three grating sensors. The results suggest that the steel corrosion process in UHPC is slowly with current density lower than 100 μA/cm2, and largely increases with current density higher than 500 μA/cm2, the volume expansion coefficient of corroded steel in UHPC is in range of 2.02–2.62 in this test, which is much different from Original C60 and Marine C60.

Insights into the role of H2O2 on corrosion behavior of NiCu low alloy steel in simulated Beishan groundwater

Steel containers used for geological disposal of high-level radioactive waste will be gradually thinned or even perforated due to corrosion, which will lead to radiolysis of nuclides when they contact with infiltrated groundwater and produce H2O2. This work focused on investigating the influence of H2O2 concentration (0%, 0.001%, 0.01%, 0.1% and 1% by volume) on the corrosion behavior of NiCu low alloy steel as the candidate material for containers was comparatively studied by combining corrosion weight loss test, corrosion product analysis, morphology characterization, thermodynamic analysis and electrochemical measurements. As [H2O2] = 0.001%, H2O2 inhibited the formation of γ-FeOOH and enhanced the compactness of rust layer, which effectively blocked the migration of aggressive ions and slowed down the cathodic reduction reaction of rust, thus improving the corrosion resistance of NiCu steel. With the increase of [H2O2] (0.01%→1%), the cathodic process of NiCu steel corrosion was promoted by the increase of dissolved oxygen involved in cathodic depolarization. Meanwhile, the relative content of Fe3O4 in the rust increased, while Fe6(OH)12SO4 and Fe6(OH)12CO3 decreased obviously, which led to the loose and porous rust layer, thus accelerating the corrosion of NiCu steel.

Evaluation of the Corrosion Activity of Reinforcement in Drainage Gallery of Concrete Dam using Half-cell Potential (HCP)

Dams are essential structures for water management, providing various benefits crucial for human survival and economic growth. However, steel corrosion in concrete dams poses a significant threat, leading to structural deterioration and potential collapse. Detecting corrosion in the early stage is critical to prevent catastrophic failures. This study investigates corrosion risk in a concrete dam's drainage gallery using half-cell potential (HCP) measurements, a common method for assessing corrosion activity in reinforced concrete. The electrochemical process of steel corrosion in concrete, influenced by factors like chloride or carbonation exposure and temperature, is discussed. The HCP method is a nondestructive technique for determining the corrosion rate of steel reinforcement in concrete structures. It involves measuring the potential difference between reinforcing steel and reference electrodes; typically, a copper/copper sulphate electrode is used. The potential difference between the two electrodes is then used to calculate the corrosion rate of the reinforcing steel. The HCP method is a reliable and cost-effective way to identify potential corrosion problems before they become severe. The present study used CorMap II® to measure HCP on the upstream face of the dam's drainage galleries. Results indicate predominantly low corrosion risk across tested locations, with minimal uncertainty. However, interpretations must consider environmental factors' influence on measurements. The study's findings offer valuable insights for future corrosion assessments and underline the importance of preventive measures for concrete dam integrity.

Corrosion behavior of Q345 steel in a simulated industrial atmosphere

Abstract The corrosion process of Q345 steel in simulated industrial atmospheric surroundings using NaHSO3 as the corrosion medium was performed. Corrosion weight loss, X-ray diffraction (XRD), electron probe microanalysis (EPMA), laser scanning confocal microscopy (LSCM), and scanning electron microscopy (SEM) were utilized to investigate the corrosion behavior of Q345 steel samples at various corrosion times. The results indicate that, in the industrial atmospheric acceleration system, the corrosion law of Q345 steel follows an exponential function model and that as the corrosion period lengthens, the rate of corrosion declines steadily. γ-FeOOH, α-FeOOH, Fe3O4, Fe3O2, and FeO make up the majority of the corrosion products on the surface of rust layer, and the rust layer structure is generally loose in the first stages of corrosion. As the corrosion time lengthens, the corrosion products transform from needle-like to cluster-like and the rust layer will become thicker. In addition, there is a segregation of the elements Cr, S, and O in the rust layer of Q345 steel.

In silico evaluation for the design of coumarin-type compounds based on phenol and naphthol rings as a coating in carbon steel corrosion processes: DFT B3LYP calculations, synthesis and electrochemical characterization

Corrosion is a natural electrochemical process that converts metals into their most stable form, oxides. Coating metals with paints is done most effectively if oxide scales are removed, which is done by exposing the metals to corrosive media such as HCl, H2SO4, HNO3, and NaCl. However, corrosive solutions also attack the metal surface, and adding an inhibitor to the acid environment becomes necessary. Inhibitors can be inorganic or organic and are evaluated through techniques such as Potentiodynamic Polarization (PDP) and Impedance Spectroscopy (EIS). This work evaluated coumarin-type organic molecules compounds as potential corrosion inhibitors through the DFT B3LYP calculations of quantum descriptors. The results were analyzed using Principal Components Analysis (PCA), it is established that the values of inhibitory efficiency of 1, and 33, showed that the corrosion of the metallic surface which can be seen in the inhibitory efficiency values 1 (57,14 %) and 33 (82,86 %), it is evident that 33 has the highest effect respect other coumarins being identified as phenol and naphthol derivatives. These compounds were synthesized employing sequential reactions from the respective phenol: Pechmann cyclization, nitration, and reduction reactions. Then, the compounds were evaluated as anti-corrosive agents for carbon steel in the presence of 1.0 M HCl. The cathodic and anodic current densities in the HCl solution containing coumarin 1 exhibit lower values than the 33 and the Blank solutions. The obtained data reveals that as the amount of coumarins 1 (3.2 mg), and 33 (2.8 mg) increases, the corrosion current density (icorr) decreases to values of 3.08 and 4.90 mA.cm-2, respectively. These results were validated through the electrochemical evaluation of the molecules obtained by Potentiodynamic Polarization (PDP), Impedance Spectroscopy. (EIS) and Scanning Electron Microscopy (SEM).

Corrosion behavior of X65 steel in gaseous and liquid CO2 transport environments containing multiple impurities and different H2O content

The mechanism of H2O content in different CO2 phase states on the corrosion of pipeline steel was studied by using high-pressure corrosion simulation tests, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and water chemistry simulation calculations. The results show that the corrosion mechanism of X65 steel did not change significantly under different CO2 phase state systems, and the corrosion products were similar. As the H2O content of the system increased, the sulfur-containing products in the corrosion products increased and the degree of corrosion worsened. Additionally, because the aqueous phase formed by the liquid CO2 system contained more corrosive substances, which promote the electrochemical corrosion process of X65 steel, the corrosion degree of X65 steel in a liquid CO2 system was significantly higher than that of X65 steel in a gaseous CO2 system.

Corrosion of Q235 carbon steel induced by sulfate-reducing bacteria in groundwater: corrosion behavior, corrosion product, and microbial community structure.

Microbiologically influenced corrosion (MIC) is one of the reasons leading to the service failure of pipelines buried in the soil. In this work, the effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of Q235 carbon steel in groundwater was investigated by electrochemical methods, surface analysis, and biological analysis. The results show that SRB utilizes iron as electron donor to sustain the vital activities of organic carbon-starved groundwater during the 14-day experimental period. The microbial community composition analysis at the genus level demonstrate that the diversity and richness decrease after corrosion, and the dominant SRB species has changed from Desulfovibrio to Desulfosporosinus. Moreover, the impedance of the carbon steel in the presence of biofilm was 1 order of magnitude higher than that of other periods in the electrochemical test, indicating that the biofilm and formed ferrous sulfide layer impeded the occurrence of corrosion. Although the 3D topography indicated that the surface of carbon steel was more uneven and pits were increased in the presence of SRB, the average weight loss (0.0396 ± 0.0050 g) was much higher than that without SRB (0.0139 ± 0.0007 g). These results implied that the growth of SRB makes the corrosion process of Q235 carbon steel more complicated.

Deep learning-based extraction and quantification of features in XCT images of steel corrosion in concrete

The corrosion of rebars in concrete has been regarded as one of the most predominant factors for the degradation of reinforced concrete (RC) structures. The accurate predictions of corrosion damages are the basis for the safety assessment of in-service RC structures and the enhancement of new structure designs. X-ray computed tomography (XCT), known for its non-destructive capabilities, has been widely utilized to understand the corrosion process inside the concrete, offering three-dimensional (3D) visualization and aiding in the identification of the parameters in the predictive model of steel corrosion. This study uses U-Net, a deep learning network, to detect various phases of steel corrosion evolution in concrete, including the identification of rebar, corrosion products, pores, cement mortar, and corrosion-induced cracking. A galvanostatic accelerated corrosion test was conducted to simulate rebar corrosion within the mortar. The XCT test was performed, producing a series of XCT images that revealed the corrosion-induced cracks in the concrete. This set of images formed a comprehensive training database for the U-Net model. The performance of the model was significantly improved by data augmentation within the training dataset, thereby enabling it to recognize corrosion-induced cracking and pores. The U-Net model proved effective in accurately segmenting the XCT images into different phases, demonstrating a high accuracy rate of 99.18% on the validation dataset. A mean Intersection over Union (IoU) of 82.1% and a mean F1 score of 89.1% are observed on the test dataset, showing superior segmentation performance on XCT images. This significant advancement has automated the process of visualizing and 3D reconstructing the steel corrosion process inside the concrete. Concurrently, it has enabled the quantification of the volumetric expansion coefficient of corrosion products. The findings reveal spatial and temporal variations in this coefficient due to the migration of the corrosion product through the cracks.

The study of riboflavin-mediated indirect electron transfer process in corrosion of EH40 steel induced by Methanococcus maripaludis

The riboflavin-mediated indirect electron transfer process during EH40 steel corrosion was investigated in Methanococcus maripaludis medium. The results showed that exogenous riboflavin participates in the process of EH40 steel corrosion induced by M. maripaludis. The presence of riboflavin promotes pitting corrosion of EH40 steel in M. maripaludis medium, but this trend is mitigated by increasing concentrations of riboflavin. Both anodic and cathodic processes of EH40 steel corrosion are enhanced in M. maripaludis media with riboflavin. The speed of transportation of electron on EH40 steel surface through riboflavin reduction is faster than proton reduction.

Time-dependent performance assessment of mountain tunnels considering the hazards associated with squeezing soft rock and nonuniform steel corrosion in RC lining structure

Mountain tunnels buried in squeezing soft rock inevitably undergo a rapid degradation with time due to creep behaviors of surrounding rock. The performance of tunnel would become more exacerbated when steel corrosion occurs in lining structures. High failure risk of tunnel lining within a short time after construction would significantly shorten its service life. Since the properties of rock mass in space and the corrosion of reinforcements in space–time exhibit a high uncertainty in practices, it is necessary to perform a reliable performance assessment of tunnels by incorporating the concept of random field-based reliability analysis. In this study, a novel approach for reliability assessment of mountain tunnels under the hazards associated with creep behavior and non-uniform steel corrosion is presented. A creep constitutive model of rock is introduced firstly; Random field-based modeling for the spatial-variant properties of rock mass is proposed; and a spatio-temporal approach for describing the spatial variability and stochastic process of steel corrosion is established. Numerical simulation for the deteriorated mountain tunnel is implemented by integrating the FLAC3D with MATLAB. In an illustrative example, both deterministic and probabilistic analysis on structural performance were conducted. The time-dependent deformation, axial forces and bending moments of lining structure are investigated.

High-precision in situ 3D ultrasonic imaging of localized corrosion-induced material morphological changes

We present an ultrasonic research technique that can carry out in situ, direct monitoring of the 3D morphologies of corrosion substrates. The technique has a customizable lateral resolution, an ultra-high axial resolution of 100 nm, and an experimentally proven measurement accuracy. In using the technique to monitor the localized corrosion processes of carbon steel under constant DCs, it was observed that during each of the experiments conducted in alkaline environments, iron dissolution accelerated for a certain period of time and then slowed down. Based on the various features of the ultrasonic signals acquired and the XRD spectra of the corrosion products obtained, it was deduced that an increase in iron dissolution rate as such was accompanied by the depositing of solid corrosion products onto the substrate used and driven by the formation of Fe3O4, which consumed electrons. After a while, the corrosion product layer collapsed and the formation of Fe3O4 was halted.

Corrosion process of stainless steel in natural brine as a source of chromium and iron - the need for routine analysis.

The corrosion of the installations carrying high salinity water is particularly important in the case of utility and therapeutic waters, such as natural brine. The analysis of such complex systems is challenging in the context of routine analysis of Fe and Cr. Both elements can be determined by UV-Vis spectrophotometry after only 1 : 100 dilution and liquid-liquid extraction (LODFe = 0.03 mg L-1) or thermal chloride stripping (LODCr = 0.02 mg L-1). The corrosion process was characterized. Electrochemically accelerated corrosion showed uneven decomposition of the steel components - Cr is less easily released to the solution than Fe. Iron comprises 53% of the dissolved part, and Cr comprises 8.6%, while the steel originally contained 62% of Fe and 18% of Cr. During the short-term (one week) contact of the brine with stainless steel, the amounts of Fe and Cr released to the brine were insignificant from the perspective of its therapeutic value.

Mechano-electrochemical interaction of high-strength pipeline steels with Al-Ti deoxidization and Mg-Ca compound treatment

The micro-zone interface of inclusions with the steel matrix of X70 high-strength pipeline steel with Al-Ti deoxidization and Mg-Ca compound treatment in the tropical marine environment was investigated. Results revealed that the Volta potential difference increased in proportion to the residual stress at the interface of inclusions with the steel matrix. The early corrosion behavior of pipeline steel was investigated by immersion testing and corrosion morphology assessment. Three stages of the early corrosion process of pipeline steel were elucidated based on micro mechano-electrochemical (M-E) interaction. Thermodynamic and kinetic models of M-E interactions at the micro-scale were proposed.

Effect of H2O Content on the Corrosion Behavior of X52 Steel in Supercritical CO2 Streams Containing O2, H2S, SO2 and NO2 Impurities

In this study, the corrosion behavior of X52 pipeline steel affected by H2O content in supercritical CO2 streams containing O2, H2S, SO2 and NO2 impurities was investigated by the weight loss test and surface characterization. The corrosion differences of the steel in impure supercritical CO2 streams containing different H2O contents were analyzed. The influence of the variation of H2O content on the corrosion mechanism of steel in the complex impurity-containing supercritical CO2 streams was discussed. The results show that the H2O content limit is 100 ppmv in supercritical CO2 streams containing 200 ppmv O2, 200 ppmv H2S, 200 ppmv SO2 and 200 ppmv NO2 at 10 MPa and 50 °C. The impurities and their interactions significantly promote the formation of corrosive aqueous phase, thereby exacerbating the corrosion of X52 steel. The corrosion process of X52 steel in the environment with a low H2O content is controlled by the products of impurity reactions, whereas the impurities and the products of impurity reactions jointly control the corrosion process of the steel in the environment with a high H2O content.