Corrosion Behavior Of Steel Research Articles

The effect of microstructure on the initial corrosion behavior of low carbon steel in simulated coal solution

Abstract The service life of weathering steels in wagon body was determined by their corrosion resistance directly. This study investigated the influence of microstructure on the initial corrosion behavior of low carbon steels, systematically. The initial corrosion behavior of ferritic-bainitic (F+B) steel, bainitic (B) steel and ferritic-pearlitic (F+P) steel are thoroughly analyzed using coal leach solution immersion test, macroscopic and microcircuit electrochemical methods. The results revealed that F+B steel exhibited the highest corrosion resistance, with the potential of M-A islands surpassing that of ferrite. The initial corrosion initiates from the dissolution of the ferrite matrix, followed by detachment of the M-A islands. The potential of M-A islands is higher than that of bainitic ferrite lath, and the corrosion originates from ferrite dissolution in B steel. Moreover, F+P steel exhibited the largest potential difference between pearlitic and ferrite, leading to initiation of corrosion from the pearlitic corrosion of internal ferrite. Additionally, the multiphase characteristics of P in F+P steel exacerbates their corrosion susceptibility. Overall, the influence of microstructure on the initial corrosion behavior of low carbon steels can be attributed to the potential difference between different phases. Ferrite is the preferentially dissolved phase due to its negative potential difference.

Corrosion Behavior of N80 Steel in Underground Supercritical CO2 Environments

Corrosion Behavior of N80 Steel in Underground Supercritical CO2 Environments

A study on corrosion behavior of advanced weathering steel relying on Ni–Mo synergy under marine atmosphere

A new weathering steel suitable for low salinity conditions was developed in this paper. The corrosion evolution of test steel under simulated tropical marine atmosphere was studied by alternating dry/wet corrosion tests, electrochemical techniques, morphology characterization and component analysis. It was indicated that the relative corrosion performance ratio of Mo-alloyed Ni-advanced weathering steel is superior to that of 3Ni steel due to the adsorption of Mo's oxide by NiFe2O4 in the rust layer. This interaction prevents NiFe2O4 from disintegrating, enhances the density of the rust layer, and improves its protecti0ve properties.

Characterization of the oxide film formed on alumina-forming austenitic stainless steel in deaerated, DH, DO, and OT supercritical water

The effects of water chemistry (deaerated (DO < 10 ppb), dissolved hydrogen (DH 1.6 ppm), dissolved oxygen (DO 2 ppm), and oxygen treatment (OT 300 ppb O2 and 100 ppb NH3) on the corrosion behavior of alumina-forming austenitic stainless steel (AFAs) were systematically investigated. A dual-layer oxide scale composed of an inner Fe/Cr/Al oxide layer and an outer Fe-rich oxide layer was observed on the AFAs. Water chemistry was found to have a negligible effect on the inner Fe/Cr/Al oxide layer; however, the morphology of the outer Fe-rich oxide layer was found to depend significantly on the chemistry. No facetted and dense hematite, which effectively protected the alloy and led to lower weight gain (less oxidation) over prolonged exposure, was formed in the outer oxide layer in oxidizing environments (DO and OT). Conversely, columnar magnetite with a porous structure was formed in outer oxide layer in reducing environments (deaerated and DH) in the absence of oxygen, with a higher weight gain observed. The addition of NH3 increased the pH of the supercritical water (SCW), thereby promoting alumina dissolution and rendering the OT conditions undesirable for use in a supercritical water-cooled reactor (SCWR). This study provides valuable insight into the behavior of AFAs in SCW and highlights the importance of carefully controlling SCW chemistry to optimize material performance.

Corrosion behaviour and mechanism of acid-resistant steel in acidic solutions with different Cl− concentrations

This study aimed to enhance the corrosion resistance of low-alloy steel in acidic solutions with varying Cl− concentrations. A new acid-resistant steel incorporating Cu and Sb was developed. Various analyses, including immersion tests under different Cl− concentrations and pH values, corrosion weight loss tests, electrochemical tests, morphological observations, and X-ray diffraction (XRD) analysis, were conducted to investigate the corrosion behaviour and mechanism. The results show that in chlorine-containing acidic environments, acid-resistant steel undergoes chemical dissolution at the anode, with hydrogen gas precipitation at the cathode. The corrosion current density is influenced mainly by the pH and immersion time. The primary corrosion products include Fe2O3, Fe3O4, α-FeOOH, γ-FeOOH, Cu, and Sb oxides, and the intensities of the diffraction peaks of Sb2O3 and Sb2O5 increase as the pH decreases. Acid resistance primarily comes from the protective effects of Sb2O3 and Sb2O5. An increase in H+ concentration promotes uniform coverage of Sb2O3 and Sb2O5. A higher H+ concentration has a greater protective effect on the corrosion product layer than does an increased Cl− concentration, although the influence of Cu cannot be ignored.

Investigation of microbiologically influenced corrosion of low alloy steels with different Cr contents in simulated oilfield produced water

Microbiologically influenced corrosion has become a predominant cause of pipeline and equipment failure in oil and gas fields. This research examines the corrosion behavior of steels with varying chromium contents in simulated shale gas formation water environments. Weight loss testing, Scanning Electron Microscopy (SEM), Energy Dispersive x-ray Spectroscopy (EDS), Focused Ion Beam (FIB), Transmission Electron Microscopy (TEM), and x-ray Photoelectron Spectroscopy (XPS) were employed. The findings suggest that an elevated Cr content in steel results in a gradual reduction in its uniform corrosion rate in a CO2-SRB coexistence environment. This can be primarily attributed to the significant distribution of Cr content throughout the entire product film, including both biofilm and corrosion products, thereby enhancing the product film’s protectiveness. Additionally, the competitive corrosion between CO2 and SRB, as well as the influence mechanism of Cr on corrosion, were discussed.

How the multi-phase microstructure of a novel tool steel determines its corrosion behaviour in sulphuric acids

The corrosion behaviour of a Fe81Cr15V3C1 steel was analysed compared to commercial X90CrMoV18 (1.4112) in 0.01–1 mol/L H2SO4 solutions. The rapidly cooled steel comprises martensite dendrites, carbide networks (M7C3, MC) and austenite interdendritic areas. Electrochemical measurements with surface analysis (SEM, EDX, AES, GD-OES) revealed the phase impact on corrosion. Active corrosion of austenite occurs at martensite-carbide boundaries leading to narrow bands. A unique oxidation between passivity and transpassivity with dissolution along lamellar carbides and vanadyl(IV) cation release enhances with increasing acid concentration. Both steels exhibit similar corrosion resistance, a superior mechanical performance of Fe81Cr15V3C1 explains its potential for tool manufacturing.

The Corrosion Behaviors of X70 Steel Under the Effect of Alternating Current and Sulfate-Reducing Bacteria in Seawater

The influence of alternating current (AC) and sulfate-reducing bacteria (SRB) on the corrosion behaviors of X70 steel in seawater was investigated by different electrochemical tests and surface examination methods. It was found that the activity of SRB was affected by AC. When the AC current density sustains at the low level of 0 A/m2 and 50 A/m2, the activity of SRB is not high enough to produce a significant impact on the AC-induced corrosion process. As the current density increases to 80 A/m2 and 100 A/m2, SRB could alter the corrosion kinetics by forming a more intact film on the corrosion surface. However, the activity of SRB is inhibited by AC with the current density up to 200 A/m2. The intact corrosion product formed by SRB in high activity could influence the AC corrosion kinetics, but the product film can not prevent AC-induced corrosion. The localized corrosion was more significant under the effect of AC and SRB probably because the biofilm formed by SRB produced uneven electrochemical properties on the corrosion surface.

Effect of early CO2 curing on the chloride induced steel bars corrosion in cement mortars

Early CO2 curing acting as a new curing technique is an effective way to cut down on carbon footprint in cement industry. It also improves the strength development and long-term durability of concrete without reinforcement. Given the fact that reinforcement concrete is most widely used in construction and building fields, the carbon sequestration potential will be enhanced remarkably if this curing technology can be used in reinforced concrete. However, the impacts of early CO2 curing on the corrosion behavior of steels, which is the major concern for reinforced concrete exposure to chloride, is unclear yet. In this work, the permeability of chloride, threshold chloride value and corrosion behaviors of steels in cement mortar were determined to comprehensively study the effect of early CO2 curing on the chloride induced corrosion of steels. Early CO2 curing lowers the chloride ions permeability of mortars, in particular for the mortars with 28 day curing ages. Steels take longer time to form stable passive films in early CO2-cured mortar than in conventional moist-cured ones. Early CO2 curing reduces the chloride threshold concentration of mortar, in particular for the mortars that the whole cross section is carbonated, the reduction reaches ∼50%. However, it exerts few effects on corrosion induction phase of steel rebar. Moreover, early CO2 curing decreases the corrosion rate of steel bars in corrosion propagation phase and thus the overall corrosion rate of steels during the whole testing process due to slower chloride ingress rate. Thus, early CO2 curing can act as an alternative curing technique in the production of pre-cast reinforced concrete exposed to chloride.

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 &gt; fine-grained heat-affected zone &gt; intercritical heat-affected zone &gt; base metal &gt; 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.

Investigations on corrosion behavior of 316LN and 316L austenitic stainless steel under corrosion-deformation interactions

PurposeThis paper aims to explore the influence of corrosion-deformation interactions (CDI) on the corrosion behavior and mechanisms of 316LN under applied tensile stresses.Design/methodology/approachCorrosion of metals would be aggravated by CDI under applied stress. Notably, the presence of nitrogen in 316LN austenitic stainless steel (SS) would enhance the corrosion resistance compared to the nitrogen-absent 316L SS. To clarify the CDI behaviors, electrochemical corrosion experiments were performed on 316LN specimens under different applied stress levels. Complementary analyses, including three-dimensional morphological examinations by KH-7700 digital microscope and scanning electron microscopy coupled with energy dispersive spectroscopy, were conducted to investigate the macroscopic and microscopic corrosion morphology and to characterize the composition of corrosion products within pits. Furthermore, ion chromatography was used to analyze the solution composition variations after immersion corrosion tests of 316LN in a 6 wt.% FeCl3 solution compared to original FeCl3 solution. Electrochemical experiment results revealed the linear decrease in free corrosion potential with increasing applied stress. Electrochemical impedance spectroscopy results indicated that high tensile stress level damaged the integrity of passivation film, as evidenced by the remarkable reduction in electrochemical impedance. Ion chromatography analyses proved the concentrations increase of NO3− and NH4+ ion concentrations in the corrosion media after corrosion tests.FindingsThe enhanced corrosion resistance of 316LN SS is attributable to the presence of nitrogen.Research limitations/implicationsThe scope of this study is confined to the influence of tensile stress on the electrochemical corrosion of 316LN at ambient temperatures; it does not encompass the potential effects of elevated temperatures or compressive stress.Practical implicationsThe resistance to stress electrochemical corrosion in SS may be enhanced through nitrogen alloying.Originality/valueThis paper presents a systematic investigation into the stress electrochemical corrosion of 316LN, marking the inaugural study of its impact on corrosion behaviors and underlying mechanisms.

Effects of heat treatment on the nano-indentation, corrosion and cavitation erosion behavior of 17-4PH stainless steel by laser surface melting

The effects of heat treatment on the microstructure, residual stresses, nano-indentation behavior, the resistance to the corrosion and cavitation erosion (CE) of 17-4PH stainless steel (17-4PH SS) by laser surface melting (LSM) were thoroughly investigated. Experimental results showed that the samples were mainly composed of martensite phase, and the NbC precipitations formed after heat treatment. The distribution of NbC precipitations was more uniform in the sample (S3) after solution treatment 3 h at 1040 °C + aging treatment 3 h at 480 °C. The grain size was increased for the samples after heat treatment. This heat treatment processing significantly reduced the residual stresses generated from the LSM process, and the nano-indentation behavior of the LSM samples after heat treatment was improved compared to that of the LSM sample without heat treatment. The S3 sample displayed the highest corrosion resistance as indicated by the low corrosion current density (icorr), high pitting potential (Epit) and high polarization resistance (Rp). The CE resistance of samples after heat treatment in 3.5 wt% NaCl solution was higher than that of the sample without heat treatment. Among them, the S3 sample exhibited the highest CE resistance, and its CE mass loss was only 59.5 % of the sample without heat treatment. The excellent CE resistance resulted from the appropriate combination of mechanical properties, corrosion resistance and self-recovery ability of the passivation film.

Effect of endogenous chloride ion on the corrosion behavior of reinforcement embedded in sea-sand UHPC matrix in different immersion environments

Ultra-high performance concrete (UHPC) is an innovative cement-based composite material characterized by extremely high durability and mechanical properties, which provides a potential possibility of using non-desalted sea-sand as aggregate. However, the long-term steel corrosion behavior in UHPC prepared by simulated sea-sand under different immersion environments remains unclear, which is of great significance for the application of sea-sand UHPC in practical engineering. In this study, the pore structure of sea-sand UHPC matrix was measured using nitrogen adsorption/desorption method. The corrosion behavior of rebar in sea-sand UHPC with different endogenous chloride ion contents soaking in pure water and NaCl solution was characterized by linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP). The experimental results show that the initial UHPC pore structure is refined by incorporation of sea-sand, and is similar to that of ordinary UHPC at the later hydration. Regardless of the endogenous chloride ion content and immersion environment, the corrosion rate evaluated by corrosion current density (icorr) and polarization resistance (Rp) of reinforcement in UHPC is extremely low. The measurement of EIS shows that UHPC group has higher matrix resistance (Rc) and charge transfer resistance (Rct), while lower electric double layer capacitance (CPEdl) of reinforcement, which indicates that the steel in UHPC made of sea-sand is still in a state of passivation. However, the steel bar in comparison specimen OPC soaking in NaCl solution is in the corrosion stage. Furthermore, sea-sand UHPC possesses of excellent ability of anti-pitting corrosion of reinforcement after 180 days of immersion in NaCl solution.

Microstructural characterization and corrosion behaviour of heat treated standard stainless steels in tar sand

This paper aims to investigate the corrosion behaviour of heat-treated standard duplex stainless steel (UNS S32205) in the recovery of bitumen from Nigerian-rich tar sand, using sodium hydroxide (NaOH) as the process solution. Appropriate material family needs to be identified for the exploitation of tar sand resources to ensure sustainable extraction of bitumen. UNS S32205 offers exceptional mechanical properties and excellent corrosion resistance which makes it a great material choice for demanding applications, including offshore platforms and construction projects. Samples of UNS 32205 were heat-treated and immersed in the digested tar sand, maintaining a process temperature of 90°C. The microstructure of the corrosion coupons was studied using SEM/EDS (Scanning Electron Microscope/Energy Dispersive Spectroscope), and the corrosion rate of the samples was derived using gravimetric technique following ASTM G31 standard. The SEM micrographs indicated varying degrees of pits associated with the passivity of UNS 32205 and an imbalance between its ferrite and austenite phases due to the presence of secondary precipitates formed during heat treatment.The normalized sample, having a corrosion rate of 0.053 mm/year, exhibited the best corrosion resistance, followed by oil quenching (0.054 mm/year), then annealing (0.076 mm/year), and water quenching (0.077 mm/year), where they all showed improved corrosion resistance over the as-received sample having a corrosion rate of 0.078 mm/year.

Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

Stainless steel selection tool for water application: pitting engineering diagrams

Introduction: This work systematically investigates the effect of chloride level, temperature, and the water system’s oxidative power on the pitting corrosion performance of stainless steels in pH-neutral environments.Methods: Two test programs were set to a) develop a robust method for constructing the pitting engineering diagrams and b) construct the pitting engineering diagrams based on the obtained method from the first test program. The various electrochemical techniques were selected to assess and understand factors that affect the corrosion behavior of stainless steel. Extensive testing was performed with short-term electrochemical measurements and long-term immersion tests.Results and Discussion: The obtained results demonstrate that the electrochemical methods are sufficient to define pitting diagrams showing the boundaries between pitting and no pitting as a function of chloride concentration, temperature, and the water system’s oxidation potential. The laboratory long-term electrochemical test results correspond the best to real applications and clearly underline the importance of an induction time for pit initiation. Accordingly, two sets of pitting engineering diagrams were constructed based on the water system’s oxidation potential. Measurements at the applied potential of 150 mV vs. saturated calomel electrode (SCE) correspond to applications in sterile tap water, whereas the applied potential of 400 mV vs. SCE corresponds to slightly chlorinated water or water with some biological activity. Pitting engineering diagrams were proved to be very useful tools to aid material selection in water application. However, it is important to realize that additional factors, such as different surface conditions and the presence of other environmental species, crevice design, or weld will affect the exact position of the boundaries between pitting and no pitting.

Investigation of the Corrosion and Passive Behavior of HP-13Cr Stainless Steel in Formate Annulus Protection Fluid

Investigation of the Corrosion and Passive Behavior of HP-13Cr Stainless Steel in Formate Annulus Protection Fluid

Influence of hydrogen sulphide on the corrosion and hydrogenation of 07Cr16Ni6 steel

The effect of hydrogen sulphide concentration on the corrosion behaviour of 07Cr16Ni6 austenitic-martensitic stainless steel in a 5% NaCl + 0.5% CH3COOH solution was studied to determine the role of H2S in the corrosion product formation and corrosion mechanism. Unstable passivation of steel is detected in a solution containing &lt;100 mg/dm3 H2S. Steel corrodes in an electrochemically active state at &gt;100 mg/dm3 H2S. When the pitting potential is reached, pitting damage occurs at the grain boundaries. The corrosion rate decreases by ∼five times after exposition for 720 h due to the formation of nickel and iron sulphides on the surface. Corrosion is accompanied by the absorption of 4.2–17.5 ppm hydrogen, 62…70% of which is diffusible and can cause hydrogen embrittlement. The scheme of steel corrosion under the influence of different concentrations of hydrogen sulphide is proposed.

Corrosion behavior of Hastelloy alloys and stainless steel in the molten chloride salt NaCl-CaCl2-CeCl3

ABSTRACT Compatibility tests are carried out on Ni-based Hastelloy alloys and stainless steel under the influence of the molten chloride salt NaCl-CaCl2-CeCl3 to investigate the corrosion behavior of molten salts with structural materials. Weight change measurements before and after the reaction tests show that the Hastelloy alloys have better corrosion resistance than stainless steel. The effects of molten salt purification on the corrosion behavior in the Hastelloy alloys are explored. The composition of the reacting phases is identified from transmission electron microscopy analysis and the corrosion mode is homogeneous corrosion with Cr and Fe diffusion, followed by Mo and Ni elution.

Corrosion behavior and mechanism of FeCoNi high-entropy alloy compared with X100 pipeline steel in a simulated alkaline soil environment

In this work, the corrosion behavior of FeCoNi HEA and X100 pipeline steel in a simulated Golmud soil environment was systematically studied utilizing electrochemical tests, surface analysis techniques and immersion measurement. The results indicate that FeCoNi HEA possesses superior anti-corrosion property than X100 steel by comparing the charge transfer resistance (Rct), passive current density (ip) and corrosion morphology. The microstructure and surface film are the principal factors causing the difference in corrosion resistance of the two alloys. More intact, uniform and dense passive film enhances the anti-corrosion performance of the HEA, while the nonprotective, loose and defective corrosion product film covering the surface of X100 steel is not conducive to inhibiting the corrosion of the steel substrate. The appearance of inclusions within the HEA can generate the micro-galvanic corrosion effect with the matrix, which promotes the substrate as an anode to induce pitting. Furthermore, multiple phases of X100 steel exhibits higher electrochemical activity compared to the HEA with a single Face Center Cubic (FCC) phase, which accelerates the corrosion of the steel. Moreover, the matrix of the HEA primarily experiences selected dissolution of Ni element.