Steel In Near Neutral Solution Research Articles

Characteristic and Mechanistic Investigation of Stress-Assisted Microbiologically Influenced Corrosion of X80 Steel in Near-Neutral Solutions.

The behavior and mechanisms of the stress-assisted microbiologically influenced corrosion (MIC) of X80 pipeline steel induced by sulfate-reducing bacteria (SRB) were investigated using focused ion beam-scanning electron microscopy (FIB). Electrochemical results show that SRB and stress have a synergistic effect on the corrosion of X80 steel. SRB accelerated the transformation of Fe3O4 into iron-sulfur compounds and may have caused the film breakage of X80 steel products. The obtained FIB results provide direct evidence that SRB promotes the corrosion of X80 steel.

Characteristic and Mechanistic Investigation of Stress-Assisted Microbiologically Influenced Corrosion of X80 Steel in Near Neutral Solutions

Characteristic and Mechanistic Investigation of Stress-Assisted Microbiologically Influenced Corrosion of X80 Steel in Near Neutral Solutions

Effect of Sign-Alternating Cyclic Polarisation and Hydrogen Uptake on the Localised Corrosion of X70 Pipeline Steel in Near-Neutral Solutions

The effect of sign-alternating cycling polarisation (SACP) on the localised corrosion of X70pipeline steel in solutions of various compositions was studied. Localised corrosion of steel at anodic potentials was accelerated with an increase in the duration of the cathodic half-cycle, in the presence of a promoter of hydrogen absorption in aqueous electrolyte, and with an increase in the concentrations of chloride and bicarbonate ions. It was pointed out that the corrosion rate is determined by the amount of hydrogen absorbed by the steel. A quantitative indicator to determine the intensity of localised corrosion under SACP was suggested.

The influence of half-cycle rectified sinusoidal alternating current (AC) on corrosion of X80 pipeline steel in an acid bicarbonate solution

PurposeThis paper aims to investigate the effect of alternating current (AC) on corrosion, it is not yet clear about the exact mechanism of the corrosion induced by AC. Previous reports indicated that AC corrosion was similar to the effect of continuous cathodic and anodic polarization on the corrosion process of the metals. Wan et al. studied the effect of negative half-wave AC on stress corrosion cracking behavior and mechanism of X80 pipeline steel in near-neutral solution.Design/methodology/approachThis study attempted to understand the AC-induced corrosion by imposing the half-cycle AC on the X80 pipeline steel in an acid bicarbonate solution. The AC corrosion mechanism was determined by weight loss and potentiodynamic polarization curve measurements, as well as surface characterization.FindingsThe results show that the positive half-cycle AC accelerated the uniform corrosion in the NaHCO3 solution, the negative half-cycle AC would decrease the uniform corrosion and local corrosion was increased and some Ca and Mg deposited on the surface of X80 steel, so the corrosion rate decreased by negative half-cycle AC. The corrosion product was composed of α-FeOOH under the application of positive half-cycle AC. The oxygen reduction led to a local increase of pH near the electrode surface and led to the formation of α-FeOOH, which enhanced the protectability of corrosion products.Originality/valueResearchers studied the effect of negative half-wave AC on stress corrosion cracking behavior and mechanism of X80 pipeline steel in near-neutral solution. However, the AC behavior and corrosion mechanism in acid solution are unknown. So to make clear about the corrosion behavior of metals in different polarization states and the mechanism involved, diode technology was used to research the AC corrosion, half-wave AC was applied on the metals after the full-wave rectified.

Effect of negative half-wave alternating current on stress corrosion cracking behavior and mechanism of X80 pipeline steel in near-neutral solution

The influence of various negative half-wave alternating current (AC) densities on the stress corrosion cracking (SCC) behavior and mechanism of X80 pipeline steel (widely used in West-East natural gas transmission) was investigated in typical NS4 near-neutral solution (used to simulate the electrolyte trapped under a disbonded coating) by data acquisition technique, electrochemical method, immersion tests, slow strain rate tensile tests, and surface analysis techniques. It was found that the negative half-wave AC could accelerate corrosion of the steel for the potential decreasing, current density increasing and generating the local anodic dissolution such as nucleated pits. The SCC susceptibility of X80 steel was relatively high for disturbing the local double-charge layer structure at 5A·m−2 current density. Besides, the negative half-wave AC could promote cathodic hydrogen evolution reaction, the SCC susceptibility was low for hydrogen-induced plasticity at 10 and 20A·m−2 and the SCC mechanism was collectively controlled by anodic dissolution (AD) and hydrogen embrittlement, but it was elevated for the hydrogen-induced local anodic dissolution and hydrogen-induced embrittlement above 30A·m−2 and the SCC mechanism was hydrogen embrittlement.

Effect of alternating current on stress corrosion cracking behavior and mechanism of X80 pipeline steel in near-neutral solution

The influence of alternating current (AC) density on stress corrosion cracking (SCC)behavior and the mechanism of X80 pipeline steel was investigated in NS4 near-neutral solution by slow strain rate tensile tests (SSRT), surface analysis techniques, data acquisition technique, and electrochemical measurements. Results showed that the SCC susceptibility of X80 pipeline steel was improved with the increasing of AC density, and the SCC mechanism was collectively controlled by anodic dissolution (AD) and hydrogen embrittlement (HE). When the AC density was below 10 A m−2, the corrosion enhanced because of a vibrating effect. However, when the AC density was no less than 30 A m−2, SCC susceptibility enhanced because of the hydrogen evolution reaction. With regard to potential acquisition, only a very small percentage about 1.5%–2% of AC was involved acting as faradaic current, which resulted in hydrogen evolution reaction and then improved the SCC susceptibility.

The Corrosion Characterization in Simulated Heat-Affected Zones of X80 Pipeline Steel in Near-Neutral Solution

The Corrosion Characterization in Simulated Heat-Affected Zones of X80 Pipeline Steel in Near-Neutral Solution

Monomers of lignin as corrosion inhibitors for mild steel: study of their behaviour by factorial experimental design

This paper investigates the role of monomers of lignin on the corrosion inhibition of mild steel and their main and interaction effects on the corrosion parameters. A combination of statistical analysis and interaction contour plots has been employed to obtain an in depth understanding of the corrosion variables. Electrochemical tests were performed on three lignin monomers namely p-coumaric acid (CA), ferulic acid (FA) and hydroxybenzaldehyde (HB) on mild steel in near neutral solution. The CA and FA showed better inhibition of more than 70%, especially at higher concentrations. A full factorial method was used to study the main and interaction effects on these monomers. P-coumaric acid and FA have shown good inhibition with the greatest interaction effect with each other on the inhibition efficiency. Although HB had the lowest effect on inhibitor efficiency (%IE), its interaction with other monomers was significant. An empirical equation has been derived from test results to describe the relationship between the variables. Analysis of variance on the corrosion parameter shows a normalised distribution and confirms the suitability of this model. Scanning electron micrographs also showed an increase in inhibition with the metal surface with increasing inhibitor concentration.

Corrosion Inhibition of Mild Steel in Near Neutral Solution by Kraft and Soda Lignins Extracted from Oil Palm Empty Fruit Bunch

Corrosion Inhibition of Mild Steel in Near Neutral Solution by Kraft and Soda Lignins Extracted from Oil Palm Empty Fruit Bunch

Evaluation of corrosion non toxic inhibitor adsorption for steel in near neutral solution: L(+) ascorbic acid

AbstractThe force of adsorption of a non‐toxic inhibitor on iron surface was studied by electrochemical quartz crystal microbalance (EQCM). The value of standard free energy of adsorption, as calculated from Freundlich‐Langmuir (LF) adsorption, indicates that L(+)ascorbic acid physisorbes on the iron surface at corrosion potential. At cathodic potential, the quantity of energy is more important. So, there is a slightly stronger interaction between inhibitor and iron surface. This behaviour can be explained by that this inhibitor occupies better the cathodic sites. The inhibition efficiency of ascorbic acid was carried out by the fact electrochemical impedance spectroscopy data (EIS). The film adsorbed on the surface is less protective for a long time of immersion.

Test method for the investigation of the susceptibility to cracking in near neutral pH solution

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Pitting of Type 304 stainless steee in the presence of a biofilm containing sulphate reducing bacteria

The effects of sulphate reducing bacteria (SRB) on pitting corrosion of Type 304 stainless steel in nearneutral solutions based on 0.1 M NaCl have been studied at ambient temperature. SRB are considered to have at least two potentially corrosive effects: they create a biofilm having a crevice like geometry on the metal surface and they produce hydrogen sulphide. Slow potentiodynamic scans were used to measure pitting potentials and pit current transients in 0.1 M NaCl solutions with and without H 2S, a modified Postgate growth medium inoculated with SRB, and an inorganic medium based on the Postgate medium. Measurements were made after an 8 day incubation or aging period. Results indicate that although H 2S enhances pitting corrosion, SRB have less effect on the pitting potential than would be expected from the levels of H 2S they produce. In fact, a decrease in the metastable pitting rate was observed suggesting that, rather than forming aggressive crevice environments in these tests, the biofilms had inhibitory properties. Analysis of current transients in terms of the pit stability product suggested that pits in commercial grades of stainless steel should possibly be considered as micro-crevices rather than ideal hemispherical cavities.

Investigations of Thiosulfate Accumulation on 304 Stainless Steel in Neutral Solutions by Radioactive Labeling, Electrochemistry, Auger Electron and X‐Ray Photoelectron Spectroscopy Methods

Thiosulfate accumulation on 304 stainless steel in near neutral solutions (pH ∼ 5.6) was studied using in situ techniques: electrochemistry and radiochemistry, as well as by Auger electron spectroscopy depth profiling and angle‐resolved x‐ray photoelectron spectroscopy in ultrahigh vacuum. It was found that thiosulfate accumulation is an irreversible process and occurs over a broad electrode potential range. Thiosulfate surface concentration is very small, below −1.0 V vs. Ag/AgCl reference. In the potential range from −1.0 to −0.50 V the surface concentration increases linearly with potential, reaches a maximum at −0.30 V, and at even more positive potentials, decreases to a slightly lower level. Ultrahigh vacuum spectroscopic measurements indicate that the irreversible surface behavior can be attributed to thiosulfate incorporation into the substrate passive film. The present data obtained with 304 stainless steel are compared to previous results published from this laboratory on thiosulfate adsorption on 316 stainless steel, and the role of molybdenum surface enrichment in the thiosulfate accumulation reversibility is discussed. The effect of chloride on thiosulfate accumulation was also investigated. At high concentrations of chloride, thiosulfate is desorbed from the surface due to chloride‐induced dissolution of the stainless steel. At very negative potentials, the thiosulfate surface concentration increases upon chloride addition, most probably due to the surface microroughening caused by chloride adsorption.

Influence of Hydrogen Carbonate and Chloride Ions on the Stability of Oxide Films on Mild Steel in Near-Neutral Solutions

Influence of Hydrogen Carbonate and Chloride Ions on the Stability of Oxide Films on Mild Steel in Near-Neutral Solutions

Influence of Hydrogen Carbonate and Chloride Ions on the Stability of Oxide Films on Mild Steel in Near-Neutral Solutions

AbstractIn near-neutral solutions, mild steel can be protected by two different passivating films, a ferric oxide film stable at more positive potentials and a magnetite film stable at more negative potentials. In air-saturated solutions of hydrogen carbonate ions at 25°c, as the concentration is increased in the range up to 1O−2 M, the ferric oxide film on steel becomes less stable at its Flade potential; in the range 10−2 to 10−l M, the ferric oxide film increases in stability at its Flade potential until eventually its breakdown is suppressed and at 10−1 M and above, corrosion inhibition occurs. However, inhibition may be unstable, since the stability of the magnetite film at its Flade potential decreases with increasing hydrogen carbonate concentration. In the presence of chloride ions, critical breakdown potentials are observed for both the ferric oxide and the magnetite passivaiing films, but the magnetite film is much more stable than the ferric oxide film. The inhibition of corrosion of steel in a...