scholarly journals Anodic Dissolution of API X70 Pipeline Steel in Arabian Gulf Seawater after Different Exposure Intervals

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
El-Sayed M. Sherif ◽  
Abdulhakim A. Almajid
Keyword(s):  
Anodic Dissolution ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Arabian Gulf ◽  
Open Circuit ◽  
General Corrosion ◽  
Sem Images ◽  
Current Time ◽  
X70 Pipeline Steel

The anodic dissolution of API X70 pipeline steel in Arabian Gulf seawater (AGSW) was investigated using open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), cyclic potentiodynamic polarization (CPP), and current-time measurements. The electrochemical experiments revealed that the X70 pipeline steel suffers both general and pitting corrosion in the AGSW solution. It was found that the general corrosion decreases as a result of decreasing the corrosion current density (jcorr), corrosion rate (Rcorr) and absolute currents as well as the increase of polarization resistance of X70 with increasing the exposure time. On the other hand, the pitting corrosion was found to increase with increasing the immersion time. This was confirmed by the increase of current with time and by the SEM images that were obtained on the steel surface after 20 h immersion before applying an amount of 0–.35 V versus Ag/AgCl for 1 h.

Effect of Stress on the Corrosion Behaviors of X70 Steel in NaHCO3/NaCl Solution

2011 ◽  
Vol 399-401 ◽  
pp. 134-138
Author(s):  
Chuan He ◽  
Xu Chen ◽  
Yang Xu ◽  
Zhi Yong Liu
Keyword(s):  
Applied Stress ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Impedance Spectrum ◽  
Open Circuit ◽  
Diffusion Control ◽  
Electrochemical Impedance Spectrum ◽  
X70 Pipeline Steel ◽  
Corrosion Behaviors

Electrochemical impedance spectrum (EIS) technology and microscope analysis were used to investigate the corrosion behaviors of X70 pipeline steel in 0.5 M NaHCO3 + 0.5 M NaCl mix solution. The effects of applied stress on the open circuit potential (OCP), polarization resistance and surface microscope were summarized. The results show that OCP of X70 steel decreased linely with applied stress increasing. The polarization resistance also decreased with the increase of stress. The electrode reaction on X70 steel surface changed from activation control to diffusion control and mixed control and corrosion resistance of X70 pipeline steel declined. The number and the diameter size of pit on the sample surface increase with applied stress increasing.

scholarly journals Comparison of the influence of nitrate ions on the electrochemical behaviour of iron and carbon steels in sulphate solutions

2002 ◽  
Vol 67 (6) ◽  
pp. 425-436 ◽  
Author(s):  
Houy Ma ◽  
Shenhao Chen ◽  
Chao Yang ◽  
Jingli Luo
Keyword(s):  
Electrochemical Impedance ◽  
Electrochemical Behaviour ◽  
Low Frequency ◽  
Open Circuit ◽  
Carbon Steels ◽  
General Corrosion ◽  
Impedance Spectra ◽  
Nitrate Ions ◽  
Capacitive Loop ◽  
Acidic Sulphate

The effect of nitrate ions on the electrochemical behaviour of iron (ferrite) and two carbon steels (martensite and pearlite) in sulphate solutions of different pH values was investigated by cyclic voltammetry polarization and electrochemical impedance spectroscopy. The pitting inhibiting effect of nitrate ions on ferrite in sulphate media is pH dependent. Nitrate ions were unable to inhibit the pitting on ferrite in neutral sulphate solutions, but did effectively protect passivated ferrite from pitting in acidic sulphate solutions. No pitting occurred on the surface of the martensite and pearlite specimens in sulphate solutions regardless of the pH of the solutions. At the open-circuit corrosion potentials, the three materials underwent general corrosion. The impedance spectra for the three materials measured in neutral sulphate solutions containing nitrates and chlorides at the corrosion potentials all showed a capacitive loop, while in acidic sulphate solutions their impedance spectra were greatly reduced in size and displayed at least a low frequency impedance loop (inductive or capacitive loop) besides the well-known high frequency capacitive loop. The variation of the impedance behaviour with pH is explained.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

Cathodic Protection Effect on the Assessment of SCC Susceptibility of X52 Pipeline Steel

2009 ◽  
Vol 1242 ◽  
Author(s):  
A. Contreras ◽  
E. Sosa ◽  
M. A. Espinosa-Medina
Keyword(s):  
Anodic Dissolution ◽  
Pipeline Steel ◽  
Open Circuit ◽  
Dissolution Mechanism ◽  
Extension Rate ◽  
Time To Failure ◽  
Elongation Ratio ◽  
Protection Effect ◽  
X52 Steel ◽  
Reduction In Area

ABSTRACTAssessment of anodic and cathodic potentials on stress corrosion cracking (SCC) of API X52 pipeline steel through slow strain rate tests (SSRT) was studied. The SSRT were carried out in a NS4 solution to simulated dilute ground water that has been found to be associated with SCC of pipelines. SSRT were performed and evaluated in air and in the NS4 solution at room temperature at an extension rate of 1×10-6 in/sec. Tests were performed at controlled electrochemical polarization potentials, both anodic and cathodic (100, 200, 400 mV) versus the open circuit corrosion potential. The results of reduction in area ratio (RAR), time to failure ratio (TFR) and plastic elongation ratio (PER) of the specimens tested in the soil solution indicate that X52 pipeline steel was susceptible to SCC at cathodic potentials. These specimens showed a brittle type of fracture with transgranular appearance. The SCC proceess and mechanism of X52 steel in the NS4 solution is mixed-controlled by both anodic dissolution and the hydrogen involvement. At positive potentials the SCC is based mainly on the anodic dissolution mechanism. When the applied potentials shifted negatively, the SCC on the steel follows mainly hydrogen embrittlement mechanism. This mechanism was confirmed through the internal cracks observed in the specimens.

Surface white spot and pitting corrosion of 316 L stainless steel

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guanghui Yi ◽  
Dajiang Zheng ◽  
Guang-Ling Song
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
White Spot ◽  
General Corrosion ◽  
Corrosion Performance ◽  
Content Type ◽  
White Spots ◽  
316 L Stainless Steel

Purpose The purpose of this paper is to address the concern of some stainless steel users. To understand the effect of surface white spots on corrosion performance of stainless steel. Design/methodology/approach White spots appeared on some component surfaces made of 316 L stainless steel in some industrial applications. To address the concern about the pitting performance in the spot areas, the pitting corrosion potential and corrosion resistance were measured in the spot and non-spot areas by means of potentiodynamic polarization and electrochemical impedance spectroscopy and the two different surface characteristics were analytically compared by using optical microscopy, laser confocal microscopy, scanning electron microscopy, x-ray diffraction, energy dispersive spectroscopy and auger energy spectroscopy. The results indicated that the pitting performance of the 316 L stainless steel was not negatively influenced by the spots and the white spots simply resulted from the slightly different surface morphology in the spot areas. Findings The white spots are actually the slightly rougher surface areas with some carbon-containing species. They do not reduce the pitting resistance. Interestingly, the white spot areas even have slightly improved general corrosion resistance. Research limitations/implications Not all surface contamination or roughening can adversely affect the corrosion resistance of stainless steel. Practical implications Stainless steel components with such surface white spots are still qualified products in terms of corrosion performance. Originality/value The surface spot of stainless steel was systematically investigated for the first time for its effect on corrosion resistance and the conclusion was new to the common knowledge.

scholarly journals Cr3C2-NiCr Coating for the Protection of API Steel Corrosion in Concentrated Sodium Chloride Solution

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 249
Author(s):  
El-Sayed M. Sherif ◽  
Magdy M. El Rayes ◽  
Hany S. Abdo
Keyword(s):  
Corrosion Resistance ◽  
Sodium Chloride ◽  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Protective Layer ◽  
Steel Corrosion ◽  
Corrosion Current ◽  
Cyclic Polarization ◽  
Current Time

In the present work, a layer of 75%Cr3C2−25%NiCr with thickness of 260 ± 15 µm was coated onto the API-2H pipeline steel surface using high-velocity oxy-fuel deposition. The effect of 75%Cr3C2−25%NiCr coating on the corrosion of the API steel after 1 h, 24 h, and 48 h exposure in 4.0% sodium chloride solutions is reported. The corrosion tests were performed using potentiodynamic cyclic polarization, electrochemical impedance spectroscopy, and chronoamperometric current–time techniques along with scanning electron microscopy and energy-dispersive X-ray analyses. The curves of polarization indicated that the presence of the coating increases the corrosion resistance of the steel through decreasing its corrosion current and corrosion rate. Impedance data showed that all resistances recorded higher values for the coated API steel. Chronoamperometric current–time measurements confirmed that the coated API steel has lower absolute current values and thus lower corrosion rate. All results proved that the presence of 75%Cr3C2−25%NiCr coating enhances the corrosion resistance of the API steel via the formation of a protective layer of Cr and Ni oxides, which could lead to decreasing the corrosion rate.

scholarly journals Electrochemical Investigation of Corrosion of X80 Steel under Elastic and Plastic Tensile Stress in CO2 Environment

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 949 ◽  
Author(s):  
Wei Wu ◽  
Hailong Yin ◽  
Hao Zhang ◽  
Jia Kang ◽  
Yun Li ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Tensile Stress ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Open Circuit ◽  
Co2 Corrosion ◽  
X80 Pipeline Steel ◽  
X80 Steel ◽  
Co2 Environment

An investigation into the electrochemical corrosion behavior of X80 pipeline steel under different elastic and plastic tensile stress in a CO2-saturated NaCl solution has been carried out by using open-circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy, and surface analysis techniques. The results show that the corrosion rate of X80 steel first increases and then slightly decreases with the increase of elastic tensile stress, whereas the corrosion rate sharply increases with the increase of plastic tensile stress. Both elastic and plastic tensile stress can enhance steel corrosion by improving the electrochemical activity of both anodic and cathodic reactions. Moreover, compared with elastic tensile stress, plastic tensile stress has a more significant effect. Furthermore, electrochemical reactions for CO2 corrosion and mechanoelectrochemical effect are used to reasonably explain the corrosion behavior of stressed X80 steel in CO2 environment.

scholarly journals Effect of Nitrogen on the Corrosion Behavior of Austenitic Stainless Steel in Chloride Solutions

2015 ◽  
Vol 9 (11) ◽  
pp. 119 ◽  
Author(s):  
W. A. Ghanem ◽  
W. A. Hussein ◽  
S. N. Saeed ◽  
S. M. Bader ◽  
R. M. Abou Shahba
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Electrochemical Impedance ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Partial Replacement ◽  
General Corrosion ◽  
Heat Treated ◽  
The Difference

The effect of partial replacement of nickel with nitrogen on the corrosion resistance of newly designed austenitic stainless steel samples without and with heat treated was investigated in 3.5wt% and 5wt% NaCl solution using open-circuit, potentiodynamic, cyclic anodic polarization and electrochemical impedance spectroscopy techniques. The results showed that, passivation in sample 1 where the highest addition of nickel and low addition of nitrogen is different from that for sample 4 where the nitrogen is greatest and the nickel is reduced almost to the third comparing sample 1. The difference in responses of heat treated samples to localized and general corrosion could be attributed to the difference in their phase compositions. The appearance of ferrite phase for samples (2, 4, 5 and 6) after heat treatment resulted in lowering the general and localized corrosion resistance than as forged samples in contrast with samples 1 and 3, where they still pure austenite. The obtained results are confirmed by surface examination.

Pitting corrosion and effect of Euphorbia echinus extract on the corrosion behavior of AISI 321 stainless steel in chlorinated acid

2019 ◽  
Vol 37 (3) ◽  
pp. 259-271 ◽  
Author(s):  
Y. Koumya ◽  
R. Idouhli ◽  
M. Khadiri ◽  
A. Abouelfida ◽  
A. Aityoub ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Electrochemical Impedance ◽  
Chloride Concentration ◽  
Analysis Data ◽  
Chloride Ions ◽  
General Corrosion ◽  
Visible Absorption ◽  
Pitting Potential ◽  
Aisi 321

AbstractStainless steel (SS) is a very corrosion-resistant alloy used in different industrial plants because of its chemical and mechanical properties. However, the high chloride concentration in sulfuric acid (H2SO4) may promote both general corrosion and pitting corrosion. The pitting corrosion susceptibility in SS in chlorinated H2SO4 and the effect of Euphorbia echinus extract (EEE) on both general corrosion and pitting corrosion have been studied using potentiodynamic polarization, electrochemical impedance spectroscopy, chronoamperometry, cyclic voltammetry, and scanning electron microscopy (SEM). The pitting potential has been found to shift slightly in the presence of chloride ions (Cl−) in H2SO4. Also, pitting corrosion initiation has been demonstrated in the recorded chronoamperograms as a linear straight line having a positive slope. EEE has reduced the general corrosion and the inhibitor adsorption was found to follow the Langmuir isotherm. SEM micrographs showed that the tested inhibitor has efficiently acted on pitting corrosion for different concentrations of Cl−. Also, the kinetic findings were in good agreement with the surface analysis data. Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectrophotometric measurements provided more insights on the interaction between the chemical functional groups of the inhibitor and the SS surface.

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