Corrosion Behavior Of X80 Steel 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.

Synergistic effect of microorganisms and a direct current electric field on X70 steel corrosion in a near-neutral solution

In this paper, the corrosion behavior of X70 steel in the near-neutral simulated soil solution (NS4 solution) under the synergistic effect of sulfate reducing bacteria (SRB) and a direct current electric field (DCEF) were explored. The corrosion rate was determined with the electrochemical technique and the corrosion morphology and corrosion products were respectively characterized by SEM and XPS. In the sterile solution, corrosion morphology of X70 steel was pitting and the corrosion rate increased with the increase in DCEF intensity and exposure time. When DCEF was absent, the corrosion rate of X70 steel in bacterial NS4 solution was faster than that in the sterile solution and the corrosion morphology was general corrosion. The acceleration effect of DCEF on corrosion was more significant than that of SRB. Under the synergistic effect of SRB and DCEF, when DCEF intensity increased below 500 V/m, the metabolic activity of SRB was gradually enhanced and the corrosion rate of X70 steel decreased. The protective effect of biofilm weakened the acceleration effect of DCEF on corrosion and the corrosion behavior was controlled by SRB corrosion. When DCEF intensity increased above 1000 V/m, SRB cells were inactivated and the corrosion rate of X70 steel increased. The corrosion behavior of X70 steel was controlled by DCEF. Based on the above research results, preventative actions were proposed.

Inhibitory effect of marine Bacillus sp. and its biomineralization on the corrosion of X65 steel in offshore oilfield produced water

The issue of material failure attributed to microbiologically influenced corrosion (MIC) is escalating in seriousness. Microorganisms not only facilitate corrosion but certain beneficial microorganisms also impede its occurrence. This study explored the impact of marine B. velezensis on the corrosion behavior of X65 steel in simulated offshore oilfield produced water. B. velezensis exhibited rapid growth in the initial stages, and the organic acid metabolites were found to promote corrosion. Subsequently, there was an increase in cross-linked “networked” biofilms products, a significant rise in the prismatic shape of corrosion products, and a tendency for continuous development in the middle and late stages. The organic/inorganic mineralized film layer formed on the surface remained consistently complete. Metabolic products of amino acid corrosion inhibitors were also observed to be adsorbed into the film. B. velezensis altered the kinetics of the X65 steel cathodic reaction, resulting in a deceleration of the electrochemical reaction rate. The mineralization induced by B. velezensis effectively slowed down the corrosion rate of X65 steel.

Corrosion mitigation behavior of mild steel in supercritical CO2 environments with varying the solution volume

The corrosion behavior of X70 steel in CO2 saturated water at 60 °C and 10 MPa was investigated by limiting the exposed solution volumes. When the specific solution volume to the exposed area was smaller than 10 mL/cm2, it revealed the formation of protective FeCO3 layer, leading to a significant corrosion reduction. The time-sensitive nucleation and the spatial growth of FeCO3 grains governed the overall performance of corrosion product layers. The solution volume dependency was further explained by a diffusion-controlled deposition mechanism. It suggested a possible way to prevent CO2 corrosion in harsh environments by generating stable FeCO3 layers.

Corrosion Behavior of X80 Steel in a Simulated Soil Solution Under Square-Wave Current Interference

The buried pipeline is disturbed by the dynamic direct current (DC) stray current with the subway as the main leakage source, which has the safety risk of accelerating corrosion, resulting in pipeline failure, which not only causes economic losses but also threatens personal safety. Therefore, it is necessary to study the corrosion behavior of pipeline steel under dynamic DC interference. The corrosion behavior of X80 steel under dynamic DC interference were studied by a mass loss test, alternating current impedance, circuit simulation, x-ray diffraction, and a Pourbaix diagram. Combined with the corrosion efficiency and Pourbaix diagram of the Fe-H2O system, the reversible process and reduction process mechanism in the Faraday process are proposed. The reason why the corrosion efficiency slows down in the process of non-Faraday is analyzed by the electric double-layer model of equivalent circuit calculation. In addition, based on the above corrosion process, the corresponding conceptual model of the corrosion mechanism is proposed. The experimental results show that with the asymmetry of positive and negative half-cycle interference duration and the increase of current density, the corrosion efficiency, and current corrosion efficiency of X80 steel decrease, and local corrosion intensifies. The length of the negative half-cycle interference affects the capacitive charge-discharge effect at the metal/solution interface and the reduction reaction process of corrosion products, resulting in corrosion slowing down and corrosion efficiency reduction. This is also an important reason for the reduction of corrosion mass loss observed in the experiment compared with steady-state DC.

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.

Accelerated deterioration corrosion of X70 steel by oxidation acid-producing process catalyzed by Acinetobacter soli in oil-water environment

Deterioration corrosion occurs between the external surface of oil pipelines and aerobic oil-degrading microorganisms in oil fields. Microorganisms with aerobic oil pollution remediation capabilities may catalyze more serious anaerobic microbial corrosion due to the carbon source supply. In this study, Acinetobacter soli strains were isolated from oil-contaminated environments, and their role in the deterioration corrosion behavior of X70 steel in an oil-water environment was investigated using the EDS multipoint scanning method. The presence of oil controls the deposition of carbon and phosphorus and diffusion of oxygen, leading to significant adhesion attraction and initial growth inhibition of biofilm on the metal surface. A. soli facilitates oxygen transfer and iron ion dissolution, thereby accelerating the pitting corrosion of X70 steel. This corrosion of the X70 steel, in turn, further accelerates the microbial degradation of oil, inhibiting the appearance of calcareous scale in the later stage of corrosion. The corrosion of X70 steel is influenced by microbial degradation, and the specific corrosion behaviors are related to the activity of A. soli in the petroleum environment. This study sheds light on the corrosion mechanisms of X70 steel by A. soli at different stages, providing insights into the interactions between microorganisms, oil pollution, and metal corrosion in oil fields.

CO2 Corrosion Behavior of X70 Steel under Typical Gas–Liquid Intermittent Flow

CO2 Corrosion Behavior of X70 Steel under Typical Gas–Liquid Intermittent Flow

Effects of cathodic protection potential on microbiologically induced corrosion behavior of X70 steel in a near-neutral pH solution

Sulfate reducing bacteria (SRB) are considered as one of the main causes for the failures of buried metal pipes. Although many researchers reported that more negative cathodic protection potential was required in environments containing SRB, SRB would increase the concentration of hydrogen adsorbed on steel surface and thus lead to hydrogen embrittlement. In the study, the optimum cathodic protection (CP) potentials of X70 steel in bacterial and sterile media were evaluated with electrochemical impedance spectroscopy. The morphology and composition of corrosion products were characterized by a scanning electron microscope (SEM), an energy dispersion x-ray spectrometer (EDS), and an x-ray photoelectron spectrometer (XPS). The corrosion morphology of X70 steel in NS4 medium was pits and the corrosion in the bacterial medium was more serious than that in the sterile medium. The corrosion products of X70 steel were FeOOH and Fe2O3 in the sterile medium, whereas its corrosion products in the bacterial medium were FeOOH and FeS. When CP potential was −775 mV, SRB growth was promoted and the optimal protection effect on X70 steel was achieved in the bacterial NS4 medium. Pits were still observed under the biofilm and the corresponding corrosion mechanism was extracellular electron transfer (EET). When CP potential was −875 mV, X70 steel realized the optimal protection in the sterile NS4 solution. However, CO2 hydrolysis and SRB metabolism in the bacterial medium resulted in hydrogen-induced pits. When CP potential was −1025 mV, the growth of SRB was inhibited and severe hydrogen evolution corrosion occurred on X70 steel in bacterial and sterile NS4 media. The optimal CP potential for pipeline steel in the sterile medium may lead to hydrogen corrosion in the bacterial medium when H+ concentration was high.

Effect of marine Streptomyces on corrosion behavior of X65 steel in simulated offshore oilfield produced water system

The effects of marine Streptomyces on the corrosion process of X65 steel were investigated by a complete characterization of metabolites using untargeted metabolomics, combined with surface analysis and electrochemical measurements. The results showed that the organic acid produced by Streptomyces accelerated the average corrosion rate of X65 steel in the early stage, but the formation of special “honeycomb” corrosion product structure promoted the enrichment of protein/polysaccharide in metabolites on the metal surface in the middle stage, and the biomineralized film was denser, which slowed down the corrosion especially localized corrosion. In the later stage, the corrosion was intensified due to the shedding of the protective film layer, but no obvious pitting corrosion was observed. In addition, the unique antimicrobial-like metabolites have potential applications in the field of microbiologically influenced corrosion inhibition by microbial control methods.

Insight into sulfate-reducing bacteria corrosion behavior of X80 pipeline steel welded joint in a soil solution

The effect of sulfate-reducing bacteria (SRB) on the corrosion behavior of X80 steel welded joint in a soil solution was studied. The results indicated that SRB enhanced the corrosion of X80 steel welded joint. The corrosion behavior in the heat affected zone (HAZ) was quite different from those of in the weld metal (WM) and base metal (BM). The HAZ was an active region that could be preferentially and more quickly corroded. Macro-galvanic corrosion in the welded joint had a significant effect on the MIC behavior of the X80 steel welded joint, leading to the preferential corrosion of the HAZ.

Pitting corrosion behavior of X70 steel in weakly alkaline solution under dynamic DC interference

Stray current discharged into the soil when subway trains operate will lead to fluctuation in the pipe-soil potential, which causes severe corrosion. In this work, the pitting corrosion behavior of X70 steel in a weakly alkaline simulated soil solution under different potential fluctuation ranges was studied. The influence of the fluctuation of the pipe-to-soil potential on the passivation film and pitting corrosion was studied using electrochemical measurement and surface characterization. X70 steel has passivation characteristics in the weakly alkaline solution. The passivation film is in a dynamic process of continuous growth or growth-dissolution due to the alternating polarization. The critical factor in inducing pitting corrosion is the failure to produce stable and dense passivation film or the instantaneous polarization potential exceeding the range of passivation potential. The passivation film's density determines the pitting's initiation and development trend. It is preliminarily found that the charge transfer resistance at the initiation stage of pitting has a good exponential function relationship with the pitting rate at the stable development stage, which is of great significance for the qualitative evaluation of the pitting rate.

Corrosion of X80 steel in the co-existence of sulfate reducing bacteria and permeating hydrogen

PurposeThis study aims to shed light on the corrosion behavior of X80 steel when sulfate-reducing bacteria (SRB) and permeating hydrogen interact.Design/methodology/approachIn this study, electrochemical tests were conducted between 25 and 55 °C, and the surface morphology of the specimen was observed using scanning electron microscopy and three-dimensional photos. The composition of the oxide film was characterized by X-ray photoelectron spectroscopy (XPS).FindingsUnder the condition of 6 MPa simulated natural gas (15% H2), the content of S-containing compounds (FeS and FeSO4) in the corrosion products on the surface of the specimen decreases from 60.8% to 54.4%. This finding indicates that hydrogen permeation inhibits the metabolic processes of SRB in this environment. By comparing the hydrogen-uncharged specimen, it was found that under the condition of 6 MPa simulated natural gas (15% H2) hydrogen charging, the uniform corrosion on the X80 surface was weakened, and the protection of the oxide film on the specimen surface in this environment was better than that without hydrogen charging.Originality/valueTo the best of the authors’ knowledge, most of these existing studies have focused on the effect of hydrogen on the mechanical properties of materials and very little is known about corrosion behavior in the hydrogen environment. In this study, a self-designed small gas phase hydrogen charging device was used to study the X80 surface corrosion behavior in the environment of the H2-doped natural gas pipeline.

Effect of Alcaligenes sp. on corrosion behavior of X65 steel in simulated offshore oilfield-produced water.

In this paper, the effect of Alcaligenes sp. on the corrosion process of X65 steel was investigated by using non-targeted metabolomics techniques for comprehensive characterization of metabolites, combined with surface analysis techniques and electrochemical testing. The results showed that the organic acids produced by Alcaligenes sp. accelerated the corrosion process of X65 steel in the early stage, and the presence of Alcaligenes sp. promoted the deposition of stable corrosion products and minerals in the middle and late stages. In addition, proteoglycans and corrosion inhibiting substances were enriched on the metal surface, which enhanced the stability of the film. The combined effect of multiple factors makes the mixed film of biofilm and corrosion products more dense and complete, which effectively inhibits the corrosion of X65 steel.

Corrosion behavior and mechanism of X80 pipeline steel welded joints under high shear flow fields

The internal-pipeline local corrosion in the welded joint region has been a widely concerning issue, particularly under the synergistic effect of high shear stress and electrochemical corrosion, which can easily result in pipeline rupture. Classical electrochemical testing techniques and wire beam microelectrode (WBE) are used to investigate the local corrosion behavior of X80 steel welded joints in a CO2-saturated NACE solution at different flow rates (velocities of 3 m/s, 5 m/s and 7 m/s), and the corrosion product composition and characteristics are analyzed via scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and three-dimensional (3D) measuring laser microscopy. The results show that different welded joint zones exhibit different corrosion degrees. The heat-affected zone (HAZ) shows the worst corrosion resistance, whereas the base metal (BM) and weld metal (WM) show similar corrosion resistances. The HAZ is an anode that corrodes unsatisfactorily at high flow rates, and the enhanced wall shear stresses peel off part of the dense corrosion product film, promoting the development of local corrosion. Therefore, the HAZ zone is a weak link in the X80 steel welded joints. This study provides scientific guidelines for the corrosion protection of long-distance oil & gas pipelines.

Effect of alternating current and Cl- ions on corrosion behavior of X70 steel in NaCl solution

The combined effect of alternating current (AC) and Cl- on the corrosion behavior of X70 steel was studied by conducting electrochemical experiments and evaluating corrosion morphology characteristics. The results show that the effect of AC on the corrosion behavior of steel was related to Cl- concentration. The extent of potential that negatively shifted when AC was applied decreased with increasing Cl- concentration. The corrosion rate enhanced as AC increased when the Cl- concentration within 0.3 mol/L, but decreased with AC current density as the concentration of Cl- further increased. The double-layer capacitance increased with the increase in Cl- concentration. When the concentration of Cl- exceeded 0.3 mol/L, the charge-transfer resistance increased with AC current density. When the concentration of NaCl was below 0.3 mol/L, the corrosion process was mainly controlled by AC, and when the concentration of NaCl increased to 0.5 mol/L, the corrosion process was mainly controlled by dissolved oxygen. AC may inhibit the diffusion of oxygen when the concentration of NaCl solutions exceeded 0.3 mol/L. This reduced the progress of cathodic reaction, resulting in a decrease of the corrosion rate. Therefore, with the increase in Cl- concentration, the effect of AC on the corrosion process of X70 steel was weakened. In addition, the effect of Cl- concentration and AC on the dissolution and diffusion of oxygen in the solution affected the corrosion process. Moreover, the corrosion morphologies indicate that the pitting of X70 steel was aggravated by both Cl- and AC, but the effect of AC on pitting is more significant than Cl-.

Effects of AC interference on the corrosion behavior of X70 steel in seawater and acidic solutions

Effects of AC interference on the corrosion behavior of X70 steel in seawater and acidic solutions

Coupling Effect of Hydrostatic Pressure and Erosion on Corrosion Behavior of X70 Steel in Simulated Seawater.

The corrosion behavior of X70 steel under the coupling effect of pressure and erosion in simulated seawater was investigated by using corrosion loss, electrochemical tests, SEM, AFM, XPS, and Raman spectroscopy. The coupling effect of pressure and erosion could induce changes in the amounts and compositions of the corrosion products and increase pitting. The rate of the combined corrosion of X70 steel represents a downtrend, which still displays a higher corrosion rate than only immersion at the same pressure. This means that the coupling of pressure and erosion will accelerate corrosion, but the effect of erosion is weakened by pressure. The larger the pressure is, the more erosion is weakened. The pressure reduces the water cutting force by increasing the liquid viscosity and reduces the surface hardness changes under high pressure by generating magnetite, which is closely bound to the substrate.

Unraveling the effect of O2, NO2 and SO2 impurities on the stress corrosion behavior of X65 steel in water-saturated supercritical CO2 streams

The stress corrosion behavior of X65 steel in water-saturated supercritical CO2 streams with various impurities was explored. The stress demonstrates a significant acceleration effect on the corrosion, especially the localized corrosion, which mostly depends on impurity type. O2 scarcely raises the SCC susceptibility of X65 steel, whereas SO2 and NO2 greatly enhance its SCC susceptibility due to their strong corrosion effects. The SCC process of X65 steel in SO2-containing environment is dominated collectively by local anodic dissolution, hydrogen embrittlement and stress, while the couple effect of local anodic dissolution and stress plays a leading role in SCC in NO2-containing environment.

Effect of sulfate-reducing bacteria from salt scale of water flooding pipeline on corrosion behavior of X80 steel

As a means to enhance the recovery of oil reservoirs, waterflooding is widely employed in field development. However, because injected water contains solid impurities and incompatible characteristics, water injection pipelines often suffer from scaling and blocking. In addition, because these pipelines are typically buried in underground soil, microbial bacteria are derived from humid and oxygen-deficient environments, causing serious microbial corrosion on the basis of scaling corrosion. The objective of this study was to analyze the corrosion behavior under the combined effect of sulfate-reducing bacteria (SRB) and the scale layer (CaCO3) induced inside a water injection pipeline. With an X80 steel pipeline as the experimental material and an oilfield injected water simulation solution as the experimental medium, this study conducted weight-loss tests and electrochemical experiments. Combined with the experimental results, scanning electron microscopy, electrochemical impedance spectroscopy, element and phase analyses, and 3D corrosion morphology reconstruction technology were used to explore the changes and mechanism of corrosion behavior under the combined effect of CaCO3 scale layer and SRB in water injection pipelines used in oilfields. The study results showed that a nonuniformly distributed CaCO3 scale layer can provide sites for SRB metabolic activity and also serve as a channel for the exchange of corrosion ions. The corrosion rate of the water injection pipeline increased significantly under the combined effect of the CaCO3 scale layer and SRB, and pitting corrosion under the biofilm/scale layer was serious. In the presence of iron oxides, SRB could interact with CaCO3, causing microbial dissimilation and reduction of iron oxides, forming a loose FeS product film, and accelerating the corrosion process of steel pipelines.