Wire Beam Electrode Research Articles

Investigation on localized corrosion behavior of pipeline steel under AC interference in alkaline earth metal environment using wire beam electrode

The localized corrosion behavior of X65 steel under AC interference in alkaline earth metal environment was investigated using the detachable wire beam electrode (WBE). The AC/DC current distribution, electrochemical properties, and elemental distribution were traced through the WBE to characterize the localized corrosion behavior and mechanism. The results show that hydrogen evolution under high cathodic protection (CP) conditions leads to an uneven distribution of calcareous deposits, and areas not covered by calcareous deposits have higher JAC and Cl− concentrations. The synergistic effect of Fe3O4 dissolution reprecipitation process, hydrogen evolution and Cl− leads to severe localized corrosion.

The corrosion analysis of X80 pipeline steel welded joint using wire beam electrode and numerical simulation methods

PurposeThe purpose of this study is to characterize the galvanic corrosion behavior of a simulated X80 pipeline steel welded joint (PSWJ) reconstructed by the wire beam electrode (WBE) and numerical simulation methods.Design/methodology/approachThe galvanic corrosion of an X80 PSWJ was studied using WBE and numerical simulation methods. The microstructures of the coarse-grained heat affected zone, fine-grained heat affected zone and intercritical heat affected zone were simulated in X80 pipeline steel via Gleeble thermomechanical simulation processing.FindingsComparing the corrosion current density of coupled and isolated weld metal (WM), base metal (BM) and heat-affected zone (HAZ), the coupled WM exhibited a higher corrosion current density than isolated WM; the coupled BM and HAZ exhibited lower corrosion current densities than isolated BM and HAZ. The results exhibited that the maximum anodic galvanic current fitted the Gumbel distribution. Moreover, the numerical simulation results agreed well with the experimental data.Originality/valueThis study provides insight into corrosion evaluation of heterogeneous welded joints by a combination of experiment and simulation. The method of reconstruction of the welded joint has been proven to be a feasible approach for studying the corrosion behavior of the X80 PSWJ with high spatial resolution.

Dual pH and NIR-controlled release system for metal coating protection

Mesoporous materials are often utilized as nanocarriers to encapsulate corrosion inhibitors. However, the loading process is often complex, and the loading efficiency of corrosion inhibitors is unsatisfactory. In this research, we present a strategy for one-pot encapsulation of benzotriazole (BTA) in polypyrrole (PPy). The prepared composite material (PPy@BTA) can release corrosion inhibitors in response to acid and alkali stimulation and has the ability of near-infrared (NIR) photothermal response. Electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and wire beam electrode techniques were employed to confirm the self-healing property of the scratched coating embedded with PPy@BTA. Results indicated that the combination of NIR and pH-responsive self-healing effects endowed the composite coating with a long-term protection effect and repeatable self-healing behavior. This research broadens the scope of the use of PPy and provides new strategies for metal corrosion protection.

Unraveling short-term O2 contamination on under deposit corrosion of X65 pipeline steel in CO2 saturated solution

The impact of short-term O2 contamination on the deposit-covered pipeline steel under a CO2-saturated solution was investigated using steel coupon and wire beam electrode. Results show that the brief exposure to O2 destroyed the FeCO3 film, and converted it into porous iron oxides, weakening its protection property. However, upon CO2 reinjection, the dense FeCO3 film regrew soon underneath the damaged FeCO3 layer on the bare steel, restoring its protective properties. Conversely, the localized corrosion beneath the deposits persisted and worsened, fueled by macro-cell current between the bare steel and the deposit-covered steel.

The screening of reasonable copper and phosphorus content in weathering steel by a high-throughput experimental method

The effect of coupling of copper and phosphorus in steel on atmospheric corrosion behavior was investigated using high-throughput experimental methods. Wire beam electrodes and plates with discrete distribution of composition gradients were prepared through a selective laser melting method. By combining array electrode scanning tests and EPMA, the electrochemical properties and the relationship between different copper and phosphorus contents were rapidly determined. Plenty of data obtained were analyzed according to relevant standards and screened to identify compositional ranges corresponding with the relevant compositions of existing grades of steel. To further analyze the effect of copper and phosphorus on the corrosion behavior, dry/wet cyclic corrosion test were performed using plates. A combination of XRD, FTIR, SEM, EDS, and EPMA were used to analyze the corrosion behavior. It was observed that both copper and phosphorus promoted the formation of amorphous substances, supporting the proposed mechanism by previous researchers. Furthermore, in the absence of manganese interference, copper could accumulate at the metal/rust layer interface, rendering the rust layer cation-selective and effectively inhibiting the deep penetration of chloride ions. Moving forward, we expect to develop this high-throughput experiments to investigate the coupling effects of other elements on corrosion behavior.

Galvanic Corrosion Behavior of the X80 Steel Welded Joint

Wire beam electrode techniques and classical electrochemical techniques were used to investigate the effect of the area ratio of each part of the welded joint on the galvanic corrosion behavior. The results showed that the order of the corrosion current density of the different regions in the simulated X80 steel welded joint was as follows: coarse-grained heat-affected zone > fine-grained heat-affected zone > intercritical heat-affected zone > base metal > weld metal. As the area ratio of weld metal increased, the galvanic potential shifted positively, the maximum anode galvanic current density increased and the main anode galvanic effect increased. On the other hand, as the area ratio of the base metal and the heat-affected zone decreased, the coupled potential shifted negatively and the maximum anode galvanic current density decreased. The galvanic corrosion intensity of the simulated X80 steel welded joint increased as the area ratio of the weld metal decreased and increased as the area ratio of the heat-affected zone and base metal increased. To enhance corrosion resistance, it is advisable to choose a shape with a larger groove to increase the WM area in the welded joint. Additionally, selecting a welding method with lower heat input and a higher energy density can help reduce the HAZ area in the welded joint.

Comparison of the Cathodic Protection of Epoxy Resin Coating/Zinc-Rich Coatings on Defective Areas under Atmospheric and Immersion Conditions: The Secondary Activation of Zinc Particles

The cathodic protection provided by epoxy coating/epoxy zinc-rich coatings on defective areas under atmospheric and immersion conditions was studied via a Q235 wire beam electrode (WBE), scanning electron microscopy, X-ray diffraction, and surface morphology analysis. The results showed that the cathodic protection processes under the two test conditions displayed significant differences. The effective protection time of the defective area under the atmospheric condition was 1.7 times that under the immersion condition. Compared with the immersion condition, zinc particles in zinc-rich coatings under the atmospheric condition exhibited higher cathodic protection efficiency. The possible activation mechanism of zinc particles under the two conditions was elucidated.

Galvanic Corrosion of E690 Offshore Platform Steel in a Simulated Marine Thermocline

Marked changes in temperature, pH, dissolved oxygen (DO) content, and nutrient content typically occur in marine thermoclines, which are key factors that affect the corrosion of metals. Offshore platforms require marine metals to be exposed to deep-sea environments and thus increase their penetration into the marine thermocline. This study investigates the galvanic corrosion of E690 steel in a marine thermocline using a simulated marine thermocline (SMT). Specifically, the corrosion of E690 steel was analyzed using the wire beam electrode (WBE) technique, linear polarization (LP), corrosion morphology, and weight loss measurement. Results indicated that the SMT had a stable multilayer structure, and the variations in temperature, DO, pH, and nutrient concentration in the SMT were similar to those in the natural marine thermocline. There were two forms of E690 steel corrosion in the SMT: galvanic corrosion and seawater corrosion. The corrosion rate of seawater corrosion was influenced by the DO concentration. Galvanic corrosion occurred after the intrusion of E690 steel into the marine thermocline. The driver of galvanic corrosion was the difference values for Ecorrs of E690 steel at various depths of the marine thermocline. The Ecorr of E690 steel was influenced by the temperature, pH, and DO of the seawater, in the following order: DO >> T > pH. The continuous reduction in Ecorr with depth contributed to large-scale galvanic corrosion, and the oscillation variation in Ecorr with depth was the reason for small-scale galvanic corrosion. The primary anodic regions of galvanic corrosion were located in the area with the fastest temperature variation in the thermocline, and the position of the anodic regions rose with time. The anodic regions gradually expanded with time. The proportion of galvanic corrosion in the average corrosion rate could increase up to approximately 80% in the stable anodic region. There were many hemispherical corrosion pits on the surface of the single electrodes that were at the depths of 75 cm, 105 cm, and 135 cm. These single electrodes comprised a long-term, sustainable anodic region of galvanic corrosion.

Investigation on chloride ion diffusion in concrete affected by sodium D-gluconate via wire beam electrode technique

The effects of various concentrations of sodium D-gluconate (SD) on chloride ion diffusion in concrete were investigated using both the wire beam electrode (WBE) technique and the finite element method. WBEs were encapsulated within concrete and immersed in a 3.75 mol/L NaCl solution which contained either 0.0461 mol/L or 0.0152 mol/L SD. Observations indicated that the passive film on the part of WBEs was destroyed by chloride ions on the 14th day, with the surface potential falling below −0.47 VSCE. Furthermore, the number of active corrosion electrodes was less at 0.0461 mol/L SD than at 0.0152 mol/L SD. Simulated chloride ion concentrations on WBEs were in agreement with the experimentally obtained values, demonstrating the viability of WBEs as non-destructive tools for assessing chloride ion concentrations in concrete.

Localized corrosion propagation of steel in cracked mortar and long-term corrosion of steel reinforcement in cracked concrete in seawater environment

A custom-designed wire beam electrode (WBE) covered by cracked mortar was applied to study the localized corrosion propagation of steel reinforcement in seawater. Additionally, steel-reinforced concrete specimens with cracks were monitored by EIS methods to study the long-term corrosion of steel in a real marine environment for 1920 days. The results revealed that corrosion initiates from the crack and then propagates to other electrodes through the steel-mortar interface. The number of anodic areas first increases and then decreases. The corrosion current density of steel reinforcement in cracked concrete increases exponentially with prolonged exposure time in a real marine environment.

Waterline corrosion behaviors of carbon steel covered by organic coating with artificial defects in seawater

The waterline corrosion behaviors of carbon steel covered by organic coating with artificial defects at and under the waterline simultaneously in simulated artificial seawater were studied by the wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) technologies. It was first proposed that the corrosion process of the metal substrate covered by organic coating under the waterline was mainly divided into three stages: no significant corrosion reactions of the metal substrate occurred; the cathodic reaction occurred with relatively slight corrosion on the metal substrate; cathodic delamination of the coating occurred, and the metal substrate was further corroded. Due to the different concentrations of dissolved oxygen, the corrosion reactions of the two exposed electrodes at the waterline and under the waterline were dominated by cathodic and anodic reactions, respectively. For the electrodes under the waterline, on account of the anodic dissolution reaction of the metal substrate, the cathode to anode polarity reversal occurred. In addition, for the yellow corrosion products, the main components were α − Fe2O3, β − FeOOH and γ − FeOOH, while α − Fe2O3 and Fe3O4 were the main components of the black corrosion products. γ − FeOOH participated in the cathodic reaction to form Fe3O4, which resulted in the reduction of the anodic current density at the electrode surface.

Electrochemical Study on the Macro-Cell Corrosion of Pipeline Steel Partially Covered by Different Kinds of Mineral Deposits.

This study presents the impact of mineral deposits (SiO2, Al2O3, and CaCO3) on the corrosion behavior of X65 pipeline steel in CO2-containing brine solution with low pH. The study investigates the initiation and propagation of under deposit corrosion (UDC) using a wire beam electrode (WBE) partially covered by different mineral deposit layers, in conjunction with electrochemical measurements and surface characterization. The results indicate that the corrosion behavior varies, depending on the characteristics of the deposit. During the test period, the Al2O3-covered steel acted as the main anode with more negative potential, while the bare steel acted as the cathode. The SiO2-covered steel acted as the cathode with more positive potential and a localized FeCO3 layer formed beneath the silica mineral. The CaCO3-covered steel initially acted as an anode with a more negative potential but transformed into the cathode at the end of the test. Additionally, shallow and small pits were observed beneath the deposits with the depth in the sequence Al2O3 > SiO2 > CaCO3.

Design of P110 steel wire beam electrode for high temperature and pressure environment and application for revealing corrosion mechanism

PurposeThe purpose of this work is to design the wire beam electrode (WBE) of P110 steel and study its corrosion behavior and mechanism under high temperature and pressure.Design/methodology/approachPackaging materials of the new type P110 steel WBE and high pressure stable WBE structure were designed. A metallurgical microscope (XJP-3C) and scanning electron microscopy (EV0 MA15 Zeiss) with an energy dispersive spectrometer were used to analyze the microstructure and composition of the P110 steel. The electrochemical workstation (CS310, CorrTest Instrument Co., Ltd) with a WBE potential and current scanner was used to analyze the corrosion mechanism of P110 steel.FindingsAccording to the analysis of Nyquist plots at different temperatures, the corrosion resistance of P110 steel decreases with the increase of temperature under atmospheric pressure. In addition, Rp of P110 steel under high pressure is maintained in the range of 200 ∼ 375 Ωcm2, while that under atmospheric pressure is maintained in the range of 20 ∼ 160 Ωcm2, indicating that the corrosion products on P110 steel under high pressure is denser, which improves the corrosion resistance of P110 steel to a certain extent.Originality/valueThe WBE applied in high temperature and pressure environment is in blank. This work designed and prepared a WBE of P110 steel for high temperature and pressure environment, and the corrosion mechanism of P110 steel was revealed by using the designed WBE.

Nanoindentation analysis of corrosion products and induced expansion stress in reinforced concrete exposed to marine environments

Reinforced concretes are widely used in construction owing to their ultrahigh mechanical properties and long-term durability. However, the corrosion of steel bar within concrete poses a substantial threat to the structural integrity of buildings, impeding advancements in ocean engineering and necessitating expensive maintenance measures. In this study, the corrosion mechanisms of reinforced concrete under marine environments were investigated. The elastic modulus of corrosion products and the identification of rust compositions in different corrosive environments were comprehensively investigated using nano indentation technique and microscopic characterizations. The average young's modulus of rust products in chloride, sulfate, and chloride-sulfate composite solutions were measured to be 47.6 GPa, 37.59 GPa, and 61.52 GPa, respectively. And the analysis identified the presence of two distinct layers of rust product, providing valuable insights into the corrosion process. In addition, the real-time and in-situ monitor of corrosion expansion stress shows that the rust expansion stress generated in chloride solution was almost twice as high as that under sulfate solution and 1.3 times higher than that in the composite solution. The advanced wire beam electrode technique was employed to compare and analyze the different stages of depassivation, pitting corrosion and corrosion rate during the whole process. The corrosion process under chloride solution showed larger and more serious corrosion than under sulfate solution, with the anodic peak current spreading and reaching 4.00 μA cm-2 after 300 days. This work reveals valuable insights into the corrosion behaviour of reinforced concrete in three corrosive conditions and can be used to inform the development of strategies for corrosion prevention and mitigation.

In-situ electrochemical testing and fluid dynamics simulation of pipeline defects under flow accelerated corrosion

The pipeline defects of flow accelerated corrosion (FAC) on the corrosion behaviors and localized corrosion mechanisms on different locations of the depressions and the welded joint with weld reinforcements were investigated using wire beam electrode (WBE) techniques and fluid dynamics simulations. The results revealed that the swirling vortex inside the depression and the local jet impact by the fluid separation in the weld reinforcement can accelerate the localized corrosion. Also, the depressed upper and trailing edge regions and the weld toes on both sides of the weld reinforcement experience considerable pressure fluctuations, enhancing interfacial mass transfer processes and inducing cavitation for severe localized corrosion failure. Furthermore, the galvanic corrosion strength factor (g) indicated an enhanced susceptibility of localized corrosion in depression and welded joints with weld reinforcement.

Crevice corrosion behavior and mechanism of laser additive manufacturing nickel-based alloy under wedge-shaped crevice by using wire beam electrode

PurposeThe purpose of this study is to investigate the crevice corrosion behavior and mechanism of laser additive manufacturing (LAM) nickel-based alloy under wedge-shaped crevice.Design/methodology/approachFirst, the opening size of the wedge-shaped crevice was designed to 0.1, 0.3 and 0.5 mm by controlling the thickness of silicon rubber and the double-side adhesive tape. Then, one side of the glass sheet was stuck on the silicon strip and keep the electrodes of Rows 1 and 2 outside the crevice as a reference, and the opposite side was stuck to the wire beam electrode by silica gel.FindingsThe current density with a maximum value of 5.7 × 10−6 A/cm2 was observed at the crevice opening of 0.5 mm, while the lowest value of 9.2 × 10−7 A/cm2 was found at the crevice opening of 0.1 mm. In addition, the corrosion resistance at the inside of the crevice is higher than that at the outside and the middle of the crevice. It means that the internal width of the wedge-shaped crevice tends toward 0, which hinders the migration of ions in the corrosive medium. The generation of corrosive products further reduce the crevice size to cause the inhibition of corrosion at the inside of the crevice as well.Originality/valueThe multilayer and multipath LAM component is prepared to show the complex microstructure, which made the corrosion behavior and mechanism at wedge-shaped crevice nondeterminacy.

Corrosion Behavior of Alkyd-Resin-Coated Carbon Steel under Cathodic Polarization in Both Static and Flowing Seawater

The effect of cathodic polarization on the corrosion behavior of alkyd-resin-coated carbon steel with an artificial coating defect was researched using a wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) in both static and flowing simulated solutions. The microscopic morphology and chemical structure of the organic coating were characterized by scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR) to reveal the degradation mechanisms of organic coatings under different polarization potentials. The study found that the failure process of the alkyd coating could be accelerated by cathodic polarization. After 312 h of immersion, the impedance under −1100 mV was one order of magnitude lower than that under the open-circuit potential (OCP). The coating delamination became serious with the negative shifting of polarization potential, and the delamination area ratio under −1100 mV in both static and flowing seawater rose to 23% and 14%, respectively. Interestingly, the flowing condition of the immersion solution that combined with cathodic polarization exhibited a synergistic effect, which could accelerate (in the earlier stage) and then alleviate the delamination of the coating. Furthermore, the results showed that both the diffusion of the corrosion particles and the anodic dissolution reaction of the metal could be significantly affected by cathodic polarization and the flowing condition of the solution, which provides a possible approach to gain insight into the delamination of organic coating.

Internal localized corrosion of X100 pipeline steel under simulated flow conditions

In this paper, a wire beam electrode (WBE) was used to explore the local corrosion processes of X100 pipeline steel in simulated solution containing HCO3− in static and flow conditions. The results indicated that the WBE's current density mapper was remarkably consistent with the polarization curves. Therefore, WBE is an efficient online corrosion monitoring approach. The WBE discovered undetectable pitting and passivation qualities within the X100 pipeline steel under static conditions. However, the corrosion current density of X100 steel was substantially higher under flow conditions than under static ones. The addition of HCO3− ions significantly decreased the corrosion resistance of the X100 steel. In the 0.3 mol/L HCO3− simulated solution, dynamic corrosion was 92 times faster than static. The corrosion of X100 steel was enhanced by the combined effects of fluid movement and HCO3− ions. Additionally, X100 steel produced significant irregular edge pitting when the critical level of HCO3− was 0.2 mol/L under dynamic conditions, and an erosion theory was proposed to explain this phenomenon.

Investigating Corrosion of Low Alloy Steel Detection Method based on Wire Beam Electrode

A wire beam electrode (WBE) method for investigating the local corrosion has been demonstrated by mapping non-unifore corrosion processes occurring on low alloy steel in solution of H3BO3 concentrations. It was found that low alloy steel from the sporadic points at the beginning of the test, the local corrosion range is the largest when it develops for 24 h and obvious local corrosion appeared, then it decreases when it reaches 48 h. To sum up, it is feasible to study the behaviors of low alloy steel localized corrosion with WBE.

Understanding the interaction between erosion and corrosion of pipeline steel in acid solution of different pH

The pure corrosion, erosion-corrosion and pure erosion behaviors of X65 pipeline steel in acid NaCl solution of different pH levels (ranging from 1.5 to 5.0) were studied using a rotation disc system, aiming to understand the interaction between erosion and corrosion of pipeline steel operating in acid slurry. The corrosion and erosion-corrosion performances of the steel were electrochemically measured in conjunction with surface characterizations. The pure erosion performance was studied by applying cathodic protection to eliminate the corrosion component. The propagation of the localized erosion-corrosion at different pH levels were probed using wire beam electrode. Results show that pH = 3.5 is a critical value for the transition of cathodic reaction under erosion-corrosion. In the acid fluids of pH < 3.5, the reduction of H+ is the main cathodic reaction, leading to a general erosion-corrosion feature with scattered small pits, which are initiated from the inclusions. Negative erosion-enhanced corrosion (E-C) is found at pH < 3.5 due to the wear of Fe3C networks. The oxygen reduction becomes the main cathodic reaction in the acid slurry of pH ≥ 3.5, resulting in the formation of erosion-corrosion pits and craters. The removal of the rust layer would result in positive E-C performance at pH > 3.5. Significant localized erosion-corrosion would occur at pH ≥ 3.5, where fixed major anodic sites are visualized. Obvious erosion-corrosion pits and craters would form with the occurrence of oxygen reduction. More serious corrosion-enhanced erosion (C-E) prefers to occur at the pitting areas where high macro-cell currents are registered.