Corrosion Characteristics Of Carbon Steel Research Articles

Theoretical and experimental studies on the electrochemical behavior of steel in HCl solution in the presence of two bio-inhibitor mixtures

In this new study, the inhibitory effectiveness of two bio-inhibitor mixtures has been studied on the corrosion characteristics of carbon steel in an HCl environment. The inhibitors were derived from a plant seed (quinoa seed-QS) and an insect extract (Oestrus ovis larvae-OOL). The total inhibitor concentration was a variable factor even the ratio of bio-inhibitor concentration was a fixed parameter. The electrochemical behavior of steel substrate was investigated through the Tafel polarization and electrochemical impedance spectroscopy measurements. Fourier transform infrared spectroscopy and field emission scanning electron microscopy were performed to identify bonds and analyze the morphology of the corroded surface of the steel. Additionally, molecular dynamics (MD) simulation and quantum calculations were applied to investigate the inhibitory influence of utilized bio-inhibitors. The experimental results indicated that the corrosion resistance decreased to 85 % when the optimum total concentration of the bio-inhibitor was 1 g L−1. The Langmuir model was used to illustrate the adsorption mechanism on the steel surface when physical adsorption occurred. Quantum chemical calculations revealed that the QS-inhibitor adsorbed more effectively onto the metal surface than the OOLE-inhibitor, due in part to a lower energy gap and higher HOMO energy. MD simulation and Monte Carlo calculations further confirmed that the QS-inhibitor was adsorbed on the Fe (110) surface with higher adsorption energy than the OOLE-inhibitor.

Corrosion behavior and mechanism of carbon steel in industrial circulating cooling water system operated by electrochemical descaling technology

Electrochemical descaling technology (EDT) can significantly increase the concentration ratio of industrial circulating cooling water systems (CCWSs), thereby reducing water, capital, and energy consumption. However, our understanding of the impact of EDT on carbon steel corrosion in CCWSs is limited, which increases the risk of long-term operation. In this study, the influence of the EDT on the corrosion characteristics of carbon steel was comprehensively investigated in field CCWSs (E-CCWSs) and compared with a system using traditional chemical processes (C-CCWSs). The corrosion characteristics, corrosion products, and corrosion mechanism of carbon steel have been studied using various testing methods, including the weight loss method, electrochemical testing, Confocal Laser Scanning Microscopy (CLSM), Advanced Mineral Identification and Characterization System (AMICS), etc. The research showed that the corrosion behavior of carbon steel in a circulating water system was similar and could be divided into three stages: the initial stage (corrosion rate increased), middle stage (corrosion rate slowed down gradually), and later stage (corrosion rate was stable). Owing to the lack of the corrosion inhibitor film, the corrosion rate of carbon steel in the electrochemical circulating water system was faster in the initial stage. However, the rapidly thickened corrosion product layer had a protective effect on the carbon steel. The corrosion of carbon steel entered the middle and late stages faster, and the corrosion rate decreased rapidly and tended to stabilize. In the long term, the corrosion rate of carbon steel in the electrochemical system was slightly lower than that in the chemical system. E-CCWS encounter serious pitting problems. At 120 days, the pitting depth in electrochemical systems was 108.22 μm, almost twice as deep as that in chemicals (54.79 μm). This research has important reference value for corrosion prevention and risk assessment of EDT for practical applications.

Understanding the local pitting corrosion characteristics of carbon steel in CO2 corrosion environment using artificially machined pits

Carbon steel remains the most commonly used material in CO2 – containing oilfield, and other energy applications. Pitting corrosion is a prominent form of corrosion attack on carbon steel, and linked to the formation of non – protective iron carbonate (FeCO3) films and/or their breakdown. The conditions for local breakdown of FeCO3, and other fundamental aspects of pitting corrosion are still not clearly understood; particularly in relation to the evolution of the local chemistry within active pits. Local distribution of corrosion activities/species is likely to influence FeCO3 formation; evolution and properties to support and/or impede pit propagation. This study investigates the local corrosion environment within an artificially machined pits to understand the local pitting corrosion behaviour. It focuses on the local evolution of FeCO3 and pitting corrosion. Pits with specific geometry on X65 carbon steel samples are exposed to two different environments: pH of 4 and 5.9 for 168 h. Tests were performed at atmospheric pressure and 60 °C in 1 M NaCl solution. Linear polarization technique was implemented in combination with a suite of post-experiment surface analysis: Scanning Electron Microscopy, X-ray diffraction, 3D-profilometry and Raman spectroscopy for assessing overall corrosion rate, localised corrosion products and pitting characteristics. Results show that at both pH levels, more crystalline FeCO3 was formed within the pits than at the top surfaces. The size and compactness of FeCO3 decrease from the base of the pits towards the top surfaces, which correlates with the extent of pitting corrosion within the pit and the spatial variation in the local chemistry.

Biofilm Development on Carbon Steel by Iron Reducing Bacterium Shewanella putrefaciens and Their Role in Corrosion

Microscopic, electrochemical and surface characterization techniques were used to investigate the effects of iron reducing bacteria (IRB) biofilm on carbon steel corrosion for 72 and 168 h under batch conditions. The organic nutrient availability for the bacteria was varied to evaluate biofilms formed under nutritionally rich, as compared to nutritionally deficient, conditions. Focused ion beam-scanning electron microscopy (FIB-SEM) was used to investigate the effect of subsurface biofilm structures on the corrosion characteristics of carbon steel. Hydrated biofilms produced by IRB were observed under environmental scanning electron microscope (ESEM) with minimal surface preparation, and the elemental composition of the biofilms was investigated using energy dispersive spectroscopy (EDX). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was used to provide information on the organic and inorganic chemical makeup of the biofilms. Electrochemical techniques employed for assessing corrosion, by open circuit potential, linear polarization and potentiodynamic polarization tests indicated no significant difference in the corrosion resistance for carbon steel in IRB-inoculated, compared to the abiotic solutions of common Postgate C after 72 and 168 h. However, the steel was found to be more susceptible to corrosion when the yeast extract was removed from the biotic environment for the 168 h test. In the absence of yeast nutrient, it is postulated that IRB received energy by transforming the protective film of Fe3+ into more soluble Fe2+ products.

Iron sulphide formation and interaction with corrosion inhibitor in H2S-containing environments

Corrosion of carbon steel in H2S-containing environments poses serious challenges to operations in oilfield and geothermal applications. Carbon steels exposed to H2S-containing environments are often susceptible to pitting and uniform corrosion, and linked to the properties of iron sulphide (FeS) layers that forms at the corroding interface. This paper investigates the corrosion characteristics of carbon steel in H2S-containing environments focussing on the early stage kinetics of FeS formation and its interaction with corrosion inhibitors (CI). Experiments were conducted in 3.5 and 5.8 wt% NaCl solution at 80 °C in 10% H2S-90% CO2-containing environments. In-situ electrochemical responses were measured using the linear polarisation resistance (LPR) technique. This was combined with post-experiment surface analysis; scanning electron microscopy (SEM) and X-ray diffraction (XRD) to investigate the nature and morphology of formed FeS. 3D surface profilometry was used to investigate the pitting corrosion characteristics of carbon steel caused by FeS interaction with CI. The results show a fast kinetics of FeS formation by direct reduction of H2S(aq) with a distinct and easily identifiable morphology, and evidence of minimum level of ferrite dissolution. The early stages of FeS formation and its interaction with CI have a strong influence on the overall corrosion characteristics of carbon steel. A dose of 30 ppm of a commercial corrosion inhibitor (CI); salts of nitrogenous molecules with a fatty acid group, at the corrosion interface induced a competition for surface absorption between CI and emerging FeS. Over the 48 h duration of this test, the FeS formation process was delayed and the mechanisms of its formation quickly became the main driver of pitting corrosion. The amount of CI dosed in this study was not able to prevent FeS-induced pitting corrosion attack on the surface.

Corrosion characteristics of carbon steel in solutions of synthetic detergents

Data of corrosion rate are obtained experimentally, values of braking coefficient, protection degree of steel 10 in 3 % aqueous solutions of detergents ML-52, MS-8 and Labomid-203 are calculated. It is found that when the composition of synthetic detergents diethylene tetraborate ammonium (DETA) composition (NH4)2B4O7·2C2H8N2·2H2O concentration of 0.5 % wt., the corrosion rate of carbon steel is significantly reduced, and the values of the braking coefficient and the protection degree increase and reach almost significant values. By removing the potentiodynamic polarization curves, it is shown that in the presence of DETA, the dissolution potentials of steel 10 are shifted to the positive side relative to the potential in the background solutions and the anode process is predominantly slowed down. Corrosion-fatigue tests indicate increase in the coefficient of cyclic strength reserve of carbon steel in aqueous solutions of synthetic detergents with the addition of DETA. The results allow us to recommend the compound diethylene tetraborate ammonium as effective anticorrosive additive to synthetic detergents used to clean parts from technological contaminants in the repair of process metallurgical plants machines.

Corrosion Characteristics of Carbon Steel upon Exposure to Biodiesel Synthesized from Used Frying Oil

The use of biodiesel leads to corrosion of automotive material, which can potentially shorten engine lifetime. The study aims to investigate the effect of temperature and contact time on the corrosion characteristics of carbon steel upon exposure to biodiesel synthesized from used frying oil. The corrosion rate of carbon steel was analyzed based on weight loss measurement according to the standard of ASTM G31 as affected by temperature and contact time. The immersion temperatures used in this study were 30oC, 40oC, and 70o, respectively. The contact times studied were 30 days, 40 days, and 50 days respectively. The results show that the increase of temperature and contact time of biodiesel on carbon steel surface speeds up the corrosion rate. Maximum corrosion rate (0.083 mmy) was observed on the carbon steel contacted to biodiesel at 70oC for 50 days. The SEM results showed an irregular shape of the corroded carbon steel surface. XRD / FTIR analysis of carbon steel samples show the presence of peaks, detected as Fe2O3, FeO(OH) and Fe2O2CO3, as the corrosion products. Keywords: biodiesel; carbon steel; corrosion; FAME; used frying oil

Inhibition of corrosion in amine air cooled heat exchanger: Experimental and numerical study

The major challenges of CO2 capture by alkanolamines are associated with corrosion process. In this paper, the corrosion characteristics of carbon steel were analyzed in the air-cooled heat exchanger (ACHE) of a petrochemical plant in Kermanshah, Iran. The chemical analysis, weight loss method, electrochemical techniques, and eddy current measurements were applied to determine corrosion products and corrosion rate. Computational fluid dynamics was also applied to search for the links between the observed patterns of attack seen in the amine plant's heat exchanger tubes and the hydrodynamics inside the tubes. Validation of the computational fluid dynamics results was compared with the visualized model of the tubes in the first pass of ACHE header. It was found that the erosion–corrosion damage was a consequence of increased levels of turbulence at tubes' inlet, caused by a rapidly turning flow. An alternative flow correction was numerically investigated applying another nozzle in the first pass header of inlet flow and were recommended for implementation. As a result of the proposed configuration, the maximum wall shear stress was reduced from 90 Pa to 40 Pa in the inlet tube. Furthermore, the length of high wall shear stress region was decreased from 15 cm to 5 cm.

Electrochemical characteristics under cavitation-erosion for STS 316L in seawater

The offshore structure industry, which is emerging as a higher value-added business, has continued to evolve and expand. Much of this is contributed to development of new alloys with high corrosion resistance. Stainless steel, in particular, has significantly improved the corrosion characteristics of carbon steel. However, the protective film for corrosion protection of stainless steel is vulnerable to Cl− ions in seawater, leading to damages such as pitting corrosion and crevice corrosion. Especially, application of the material for underwater rotating body can cause physical erosion damage due to cavitation. This paper investigated the electrochemical characteristics of 316L stainless steel exposed to cavitation environment in seawater. The results revealed that the cavitation condition exhibited relatively high corrosion current density due to the breakdown of the protective film by either the impact pressure during bubble collapse or the micro-jet, suggesting that acceleration of corrosion damage was achieved compared to the static condition.

Localized Electrochemical Corrosion Characteristics of Carbon Steel in Seawater

The galvanic and potential distributions of carbon steel immersed in seawater were studied by wire beam electrode (WBE) technique. Results indicated that the corrosion of carbon steel in seawater tended to local corrosion. With immersion time increasing, local corrosion was more and more serious. During the initial immersion period, the top of the coupon near the water surface was main cathode. With the corrosion extended, corrosion products gradually gathered on the surface of the carbon steel. Potential differences between cathode and anode gradually became small. Cathode and anode redistributed on the surface of carbon steel. At last, the top and the bottom were cathode while the middle was anode. The areas of anode first increased and then decreased. The areas of cathode were in contrast.

Influences of the three‐phase boundary on the electrochemical corrosion characteristics of carbon steel under droplets

AbstractThe potential/current distributions of carbon steel were investigated under 0.001 M sodium chloride droplets of various sizes using a wire beam electrode. During the corrosion process, carbon steel exhibited heterogeneous electrochemical characteristics with the major anodes located near the edge of the droplets. The three‐phase boundary (TPB) plays a vital role in determining the electrochemical distribution and the corrosion degree of carbon steel. With the increase of droplet size, the average anodic current density and the corrosion degree decreased, which is believed to be due to the decrease of the TPB length per unit area.

Temperature dependence of the electrochemical corrosion characteristics of carbon steel in a salty soil

The electrochemical corrosion characteristics of carbon steel in a salty soil at different temperatures were studied by measurements and analyses of potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy. The results showed that the mass-transfer of dissolved oxygen plays an essential role in carbon steel corrosion, and the whole corrosion process is mix-controlled by both activation and mass-transfer steps. Passivity can be developed on carbon steel in the soil at low temperatures. With the increase of temperature, the passive current density increases and the passive potential range decreases. When temperature is elevated to a certain value, 50 °C in this system, passivity cannot be maintained and the steel is dominated by an active dissolution status. Anodic Tafel slope decreases continuously with the increase in temperature, which is mainly due to the enhanced electrode reaction rate at an elevated temperature. Simultaneously, cathodic Tafel slope increases with temperature continuously due to the decrease of the solubility of dissolved oxygen in soil. Since the diffusion activation energy is generally much smaller than the reaction activation energy, the effect of temperature on diffusion is far less than that on electrode reaction rate.

Aqueous Corrosion Behavior of Weathering Steel and Carbon Steel in Acid-Chloride Environments

Abstract Aqueous corrosion characteristics of carbon steel and weathering steel in aerated acid-chloride solutions were studied by using immersion weight loss tests, crevice corrosion tests, electr...

ボイラ給水模擬酸素処理条件下における炭素鋼の腐食特性

ボイラ給水模擬酸素処理条件下における炭素鋼の腐食特性

Corrosion characteristics of carbon steel in organic solvent containing fatty acids

AbstractThe corrosion characteristics of carbon steel in an organic solvent containing fatty acids were determined. The investigations were conducted by means of mass loss tests. Stable corrosion potentials could not be measured and electrochemical evaluations rendered meaningless results. Iso-octane was used as the solvent. The acids investigated include acetic acid, propionic acid, butyric acid, valeric acid, and hexanoic acid as well as all the heavier acids with an even number of carbon atoms up to and including stearic acid. Temperatures from 60 to 250°C and acid numbersfrom 5 to 25 mg KOH/g solution were investigated. It was found that corrosion by the heavier acids (hexanoic acid and heavier) are activation controlled while the lighter acids (valeric acid and lighter) have more complex characteristics owing to film formation.

Corrosion characteristics of carbon steel in organic solvent containing fatty acids

Corrosion characteristics of carbon steel in organic solvent containing fatty acids