Erosion-enhanced Corrosion Research Articles

Understanding the effect of cathodic reaction on corrosion-enhanced erosion in sand-entraining electrolyte

In this study, the pure erosion behaviour of pure iron and its erosion-corrosion behaviour under different anodic polarization currents were investigated in various cathodic reactions (oxygen reduction, hydrogen ion reduction, and water reduction) using a cylindrical stirring system. The corrosion-enhanced erosion (C-E) rates were determined for each condition. The results revealed that pure iron displayed similar pure erosion behaviour across all three cathodic reactions. When the cathodic reactions involve hydrogen ion reduction or water reduction, the erosion-corrosion of pure iron manifested as uniform damage, with the reduction in hardness being the main cause of the C-E in this case. Conversely, in the case of oxygen reduction reaction as the cathodic reaction, the erosion-corrosion presented as pitting damage, with the reduction in hardness resulting from localized concentration of anodic current and the formation of easily worn protruding flaky iron structures at the edges of the pits as the main mechanism of the C-E. Moreover, linear and exponential relationships were found between the C-E rate and the anodic current density for uniform damage and pitting damage, respectively. Finally, the concept of surface equivalent hardness was proposed, along with the establishment of a mathematical model for surface equivalent hardness based on the relationships between the C-E rate and the anodic current density. Utilizing the surface equivalent hardness enables the evaluation of the erosion rate on material surfaces considering the coupled effect.

Interaction of erosion and corrosion on high-strength steels used for marine dredging engineering

In this work, the erosion–corrosion performances of three high-strength steel samples: high manganese austenitic steel (HMnS), dual-phase steel (D-PS), and martensitic steel (MS), which are potentially used to construct marine dredged pipelines were investigated in comparison to the Q235 carbon steel. The corrosion-enhanced erosion (C-E) and erosion-enhanced corrosion (E-C) were electrochemically studied in conjunction with surface and subsurface characterizations. Results showed that the fracture of the steel extrusions induced by micro-cutting was the main erosion-corrosion feature under normal sand impacts. The C-E played a significant role in the erosion–corrosion process, which resulted in the dissolution of the work-hardening layer and facilitated the subsurface crack propagation, particularly for D-PS and MS. Although the general E-C rate was low, the concentration of the major anodes at the highly eroded area significantly enhanced the erosion process. Evaluating erosion resistance solely based on hardness is significantly limited. The twinning deformation of the austenite grain in HMnS effectively hindered the crack propagation during the erosion–corrosion. The addition of Al and Cr elements improved the erosion–corrosion resistance of high-strength steels.

Synergistic effect between cavitation erosion and corrosion of Monel K500 alloy in 3.5 wt% NaCl solution

Cavitation erosion-corrosion simultaneously damaged the material through mechanical attack and electrochemical corrosion. In this work, experiments were performed on Monel K500 alloy in deionized water and 3.5 wt% NaCl solution using an indirect ultrasonic vibration system to investigate the synergistic effect between cavitation erosion and corrosion. Mass loss measurement and surface topography observation were used to identify the different stages of cavitation erosion. The electrochemical properties at different cavitation stages were analyzed by EIS technique. Results showed that the synergistic effect between cavitation erosion and corrosion exacerbated cavitation damage, and the weight loss rate in 3.5 wt% NaCl solution was about 10% higher than that in deionized water. The increase in ion diffusion and oxygen supply caused by violent agitation accelerated the surface corrosion process, resulting in corrosion-enhanced erosion. Mechanical damage to the material surface during the cavitation process also accelerated the corrosion process, indicating that cavitation-enhanced corrosion was the primary synergistic mechanism. Pure cavitation accounted for 90.75% of total mass loss, suggesting that mechanical deterioration dominated the overall cavitation erosion and corrosion process. Cavitation-enhanced corrosion accounting for 96.12% of the synergistic effect，was the main synergistic mechanism.

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.

Advanced Hadfield steel with Cr-optimization resists against corrosion and erosion-corrosion

This study investigated the effects of Cr-optimization on the corrosion and erosion-corrosion behaviors of Hadfield steel with 1.1 wt% C-13 wt% Mn in a neutral aqueous environment. A variety of experimental and analytical results showed that adding Cr can enhance the corrosion and erosion-corrosion resistance. However, the extent of improvement is limited under non-optimized alloying conditions, specifically when the Cr content is below or above 2 wt%. Only at the optimized Cr content of approximately 2 wt%, the superior corrosion and erosion-corrosion resistances are manifested by excluding coarse M7C3 and forming a thin oxide layer enriched with Cr primarily composed of Fe3-xCrxO4 on the surface during corrosion. The inhibiting characteristics of the corrosion scale contribute to have lower corrosion kinetics with higher polarization resistance and corrosion-enhanced erosion rates compared to conventional Hadfield steel and commercial carbon steels. With its favorable combination of long-term environmental stability in harsh corrosive and erosive environments, along with high-strength, hardness, ductility, and commercial availability, the newly designed Hadfield steel is a promising alternative to commonly used metallic materials in various industrial applications.

Evaluation of Corrosion and Erosion-Corrosion Behavior of X65 Pipeline Steel in Flowing CO2-Saturated Electrolyte

In this study, the corrosion and erosion-corrosion behaviors of X65 pipeline steel in the flowing CO2-saturated electrolyte were electrochemically studied using a rotation disk system. The results showed that the accumulation of the Fe3C layer in the electrolyte without sand particles enhanced the cathodic reaction, increasing the corrosion rate. The increase in flow velocity facilitated the rapid accumulation of a thick Fe3C layer, which linearly increased the corrosion rate with increasing rotation speed. The sand impacts removed the corrosion product layer and broke the exposed Fe3C network, resulting in a negative synergy of erosion-enhanced corrosion. The erosion-corrosion negatively affected ferrites compared with the pearlites in an electrolyte containing sand due to the weaker erosion resistance.

Study on the Effects of Fluid Parameters on Erosion-Enhanced Corrosion of 90/10 Copper–Nickel Alloy Using Wire Beam Electrode

This paper clarifies the effects of the fluid parameters of flow velocity, impact angle and sand impact frequency on the erosion-enhanced corrosion of 90/10 copper–nickel alloy by combining computational fluid dynamics (CFD) simulation, wire beam electrode (WBE) technology and electrochemical measurements. The results show that under the conditions without sand particles, erosion-enhanced corrosion is dominated by the impact angle and the flow velocity at lower (&lt;0.860 m/s) and higher (2.370~5.644 m/s) flow velocities, respectively, while both the two fluid parameters have noticeable effects on erosion-enhanced corrosion at intermediate flow velocities (0.860~2.370 m/s). In contrast, adding sand particles corresponding to the sand impact frequency can further increase the corrosion current density without changing the effects of the flow velocity and impact angle. It demonstrates that all three fluid parameters show great effects on the erosion-enhanced corrosion of 90/10 copper–nickel alloy under conditions with sand particles.

Erosion-Corrosion of Gathering Pipeline Steel in Oil-Water-Sand Multiphase Flow

This work studies a series of factors influencing erosion-corrosion in oilfield gathering pipelines steel using the home-made testing pipe flow loop. Results showed that steel was corroded in oil-water flow. The corrosion rate increased with the flow velocity on the whole, and the addition of solid particles would intensify the localized corrosion. For the erosion-corrosion test added with 2 wt% quartz sand at the velocity of 2 m/s, the portion of pure corrosion and pure erosion accounted for 47.50% and 70.83%, respectively. The erosion-enhanced corrosion was 16.67% of the total weight loss, while the corrosion inhibiting the damage from erosion accounted for 35.00%, so negative synergistic effects appeared in the oil-water-sand multiphase flow conditions.

Inhibition of the erosion-corrosion of elbow by synergistic action of swirling flow and inhibitor

The experiments of using inhibitors to inhibit the erosion-corrosion of elbows under the conditions of liquid-solid non-swirling flow and swirling flow were designed to evaluate the inhibition of erosion-corrosion of elbows under the combined action of swirling flow and inhibitors. The experiments were carried out by a circulating loop system in combination with a variety of test methods and computational fluid dynamics (CFD) simulation. It is demonstrated that the addition of inhibitors under non-swirling flow and swirling flow conditions can inhibit effectively the erosion-corrosion rate and its four components (pure corrosion, pure erosion, corrosion-enhanced erosion, and erosion-enhanced corrosion). The comprehensive inhibition efficiencies of the synergistic action of swirling flow and inhibitor on the four components of erosion-corrosion are higher than the inhibition efficiencies of inhibitor acting on the four components alone. The hydrodynamic characteristics of swirling flow produce the sand suspension effect and mass transfer enhancement effect which facilitate the adsorption of inhibitor on the working electrode surface and acting in conjunction with the oxide film to form a lamellar protective corrosion product layer with stronger integrity and compactness.

The Erosion–Corrosion Behavior of Eutectic High Chromium Cast Irons Reinforced by TiC Particles

In this work, high chromium cast irons (HCCIs) reinforced by TiC particles are designed and fabricated to improve the erosion–corrosion and wear resistances of materials for the pumping and handling applications. The TiC particles are formed by the in situ solidification method. The experimental results show that the hardness of as-cast HCCIs is improved significantly with TiC volume fraction. It can be as high as 63 HRC when the TiC volume fraction is 9.8%. The introduction of TiC increases the abrasive wear resistance of the HCCIs in both as-cast and heat-treated states. However, it is unexpected to find that the presence of TiC significantly reduces the erosion–corrosion performance. It suggests that corrosion-enhanced erosion is the dominant mechanism that controls the mass loss of the TiC-strengthened HCCIs.

Electrochemical Noise and Polarization Analyses on Corrosion of Al-Brass Alloy During Erosion-Corrosion

It is known that impingement of solid particles on the surface of alloys could cause an increase in corrosion rate during erosion-corrosion. The increase in corrosion rate by erosion could be studied using the common electrochemical technique of polarization. Electrochemical noise method, on the other hand, has been widely used to study the localized corrosion. This technique could provide useful data on the effect of single particle impact on the corrosion rate of materials. In the present paper, both techniques of polarization and electrochemical noise were used to study the corrosion behavior of Al-brass alloy during erosion-corrosion. The erosion-enhanced corrosion rate was calculated and the results obtained from these two techniques were compared. The erosion-corrosion tests were performed at various sand concentrations of 0–30 g/l and different particle sizes. Under sand concentrations lower than 10 g/l, the electrochemical noise technique as a proper method for analysis of localized corrosion showed higher accuracy in measuring the erosion-enhanced corrosion as compared with the polarization method. However, at the concentrated slurries, higher possibility of simultaneous impacts and, therefore, overlapping of the current peaks imposed some limitation for the electrochemical noise method. The polarization and noise analyses revealed that an increase in the particle size resulted in an increase up to 2.8 times in the erosion-enhanced corrosion rate of the alloy.

On a multiphysics approach to modelling the erosion–enhanced corrosion of low–alloy carbon steel in chloride containing environments

The effect of chloride on erosion-enhanced corrosion was studied experimentally and by a multiphysics algorithm developed to describe the erosion-corrosion interactions. API 5 L X65 steel was exposed to a slurry jet of different chloride content (0.005, 0.05 or 0.5 M) containing silica particles (250–350 μm). An electrochemical-transport-reaction model was used for numerical simulation of polarization curves. Visualization of the flow conditions was also carried out in this work. The effect of erosion on corrosion was found to be well described as a proportionality factor between the kinetics constants of the electrochemical reactions with and without the erodent. The presence of chloride was found to affect the system mainly through increased conductivity of the electrolyte.

An Overview of Major Experimental Methods and Apparatus for Measuring and Investigating Erosion-Corrosion of Ferrous-Based Steels

This paper firstly provides an overview of major efforts made over the past several decades on developing the test apparatus for the study of erosion-corrosion of ferrous-based steels. The merits and the application range of the set-ups, i.e., rotating disc/cylinder electrode system, slurry jet impingement rig, and test flow loop, are introduced. Secondly, the advantages and limitations of both non-electrochemical and electrochemical methods used for the measurement of erosion-corrosion are presented. Thereafter, the interaction between erosion and corrosion using a cyclic erosion-corrosion method was introduced. The synergy between erosion and corrosion for the steels under the passive state were analyzed on the basis of the breakdown and restoration of the passive film. In addition, the difference between the obtained erosion-enhanced corrosion and the corrosion-enhanced erosion using different experimental methods for steels under active corrosion was discussed. Finally, the interaction between the localized corrosion and erosion was studied through the dynamic change of the local current distribution revealed by the wire beam electrode.

Insights into the erosion-enhanced corrosion on electroless Ni–P coating from single particle impingement

The erosion-enhanced corrosion behavior of electroless Ni–P coating was investigated by single particle impingement coupled with in-situ electrochemical measurements. The transient anodic dissolution of Ni–P coating induced by the single particle impingement is enhanced with the rising impact velocity, followed by a rapid repassivation that obeys a bi-exponential decaying law. The coating demonstrates a good erosion-corrosion resistance due to its strong capability of repassivation that is scarcely affected by the changing hydrodynamics under the test conditions. The erosion-enhanced corrosion rate of Ni–P coating in flowing slurry is well predicted based on the repassivation kinetic parameters determined from single particle impingement.

The mechanism of erosion-corrosion of API X65 steel under turbulent slurry flow: Effect of nominal flow velocity and oxygen content

Erosion-corrosion (E-C) of carbon steel API 5L X65 by mineral quartz and alumina slurry is studied to understand the mechanism of corrosion-accelerated material's degradation. A rotating cylinder electrode is employed to simulate the E-C damage and for electrochemical characterization, observed at different flow velocities and contents of dissolved oxygen (DO). Microstructural inspection using SEM and EBSD reveals the extension of the work-hardened layer and other features of the sub-surface. The effect of nominal flow velocity is shown to be associated with an increment in average particles' impact angle and frequency of impacts at the faster flow. The increase in DO availability is shown to promote localized-type corrosion different from pitting, demonstrating the mechanism of erosion-enhanced corrosion.

Exploring the sintering process parameters on erosion-corrosion characteristics of Fe-Cr-Ni steels in artificial mine water

Abstract This study investigates the erosion-corrosion behaviour of spark plasma sintered Fe-Cr-Ni relating additive and synergistic effects on the sintering temperature and time in mining and mineral processing industries. All tests were carried out using a rotating cylinder electrode system. The relative density has a relationship with the hardness values of the sintered alloys. The results linked the effects of the stainless steel sintering parameters (temperature and time) on the total mass loss, pure erosion, erosion-enhanced corrosion, and corrosion-enhanced erosion conditions. No correlation exists between the erosion-corrosion components and the densification mechanism since the porosity of the samples does not influence the sintered alloys behaviour. The surfaces indicated localized attack which increased with increasing time but decreased as the sintering temperature increased.

Erosion-corrosion interactions of X65 carbon steel in aqueous CO2 environments

When sand is present in carbon dioxide (CO2) corrosion environments in carbon steel oil and gas pipelines, wear rates can be particularly severe. The wear mechanism when surfaces are exposed to impact by a solid-laden corrosive fluid is known as erosion-corrosion and consists of erosion and corrosion components with total erosion-corrosion degradation enhanced by interactions between erosion and corrosion. The causes of corrosion-enhanced erosion and erosion-enhanced corrosion of carbon steel, in this regime, are not fully understood and are the subject of study in this work in a 60 °C, pH 4.7, 2% NaCl solution, containing 1000 mg/L of sand particles with an average diameter of 250 µm, flowing through a submerged impinging jet (SIJ) nozzle at 20 m/s. Particle impact angles and velocities were predicted on the SIJ sample surface using computational fluid dynamics (CFD) to improve the understanding of how particle impingement contributes to erosion-enhanced corrosion and corrosion-enhanced erosion. Corrosion-enhanced erosion accounted for up to 20% of total erosion-corrosion degradation, with focused ion beam scanning electron microscopy (FIB-SEM) analysis showing that removal of work hardened layers and subsurface cracking were causes of enhanced degradation. Erosion-enhanced corrosion was not significant in the conditions tested.

On the Interaction Between Erosion and Corrosion in Chromium Carbide Coating

In this paper, the effects of slurry flow velocity and impact angle on erosion–corrosion (E–C) behavior of the chromium carbide coating in NaCl solution containing SiO2 particle were investigated. A jet impingement system was used. The mass loss test, polarization curve and surface characterization were employed to examine the coating performance. The erosion–corrosion regime of the Cr7C3-coated and uncoated specimens was determined. Results showed that pure erosion and corrosion-enhanced erosion were the dominant regime for the uncoated samples. However, both the erosion and corrosion contributed to the coating damage. Mass loss values of the coated and uncoated samples increase with flow velocity. In addition, coated and uncoated samples experience maximum mass loss at 45° and 90°, respectively. Finally, E–C degradation mechanisms were evaluated using scanning electron microscopy. The images indicate the abrasive wear mechanism and lips removal as well as plastic deformation for the uncoated sample. Also, brittle fracture, cracking and flake fragmentation were recommended as the main fracture mechanism for the chromium carbide coating.

The Effect of Dissolved Oxygen in Slurry on Erosion–Corrosion of En30B Steel

Synergistic effect between corrosion and wear has been widely recognized in many tribo-corrosion systems. In most wet application conditions, dissolved oxygen (DO) is a controlling factor to the dynamics of corrosion process and is therefore expected to have significant impact on the tribo-corrosion performance of materials. In this study, the effect of DO (0–24 ppm) on erosion–corrosion behaviour of En30B low-alloy steel has been investigated using a slurry pot erosion–corrosion test apparatus in a slurry containing 35 wt% silica sand and 3.5% NaCl solution at 30 and 45 °C. The synergistic effect and its contributing components, i.e. erosion-enhanced corrosion and corrosion-enhanced erosion, have been measured/analysed. The total erosion–corrosion loss and synergy of the En30B steel increases with DO in the slurry, initially rapidly at DO levels below ~5 ppm and then less rapidly at the higher DO levels. The synergistic effect is mainly due to corrosion-enhanced erosion with negligible contributions from erosion-enhanced corrosion. Temperature has a significant effect on the total erosion–corrosion loss. Total erosion–corrosion was 34% higher at 45 °C (in still air) than at 30 °C. Mechanisms for the observed phenomena have been discussed based on the concept of corrosion-accelerated micro-crack propagation.

Inhibition of the erosion-corrosion of a 90° low alloy steel bend

The inhibition effect of inhibitor on the erosion-corrosion (E-C) of a low alloy steel bend is investigated by weight loss, electrochemical measurements, and surface analysis. It is demonstrated that inhibitor can significantly reduce the E-C rate and effectively inhibit the four components (pure corrosion, pure erosion, corrosion-enhanced erosion, and erosion-enhanced corrosion) of E-C. The inhibition of corrosion is more pronounced than that of erosion. The inhibition efficiencies (IEs) for total E-C, pure erosion, corrosion-enhanced erosion, and erosion-enhanced corrosion at the intrados are higher than that at the extrados of the bend. The lower IEs at the extrados are due to the severe sand particle impact and detrimental hydrodynamics conditions at these positions.