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1 – 10 of over 1000Kechen Lv, Xinyu Yang, Tangqing Wu, Song Xu, Lanlan Liu, Lin Sun and Xinming Wang
High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose…
Abstract
Purpose
High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions.
Design/methodology/approach
The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer.
Findings
The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process.
Originality/value
The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering.
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Jing Liu, JiHao Cheng, Qian Hu, Feng Huang, JinQiao Xu and Bin Guo
The purpose of this paper is to clarify the influence of the cathodic polarized potential on the stress corrosion cracking (SCC) susceptibility of X120 steel in a simulated acidic…
Abstract
Purpose
The purpose of this paper is to clarify the influence of the cathodic polarized potential on the stress corrosion cracking (SCC) susceptibility of X120 steel in a simulated acidic soil solution and the different SCC mechanisms at different cathodic polarized potentials.
Design/methodology/approach
The SCC behaviors of X120 pipe steels at various potentials were investigated in a simulated acidic soil solution by slow strain rate tensile tests, electrochemical impedance spectroscopy and surface analysis techniques.
Findings
The fracture surface of X120 steel stretched in air showed a ductile fracture. Both elongation and tensile strength of X120 steel in the simulated acidic soil solution decreased compared to that obtained in air. A slight cathodic polarization increased the elongation and tensile strength of X120 steel; therefore, the SCC susceptibility was lower at −0.65 VSCE than that at OCP, anodic dissolution dominates the corrosion process. However, a strong cathodic polarization induced hydrogen embrittlement, decreasing elongation and tensile strength, therefore, the SCC susceptibility was highest at −1.1 VSCE, and hydrogen embrittlement became the dominant process.
Originality/value
The paper provides an essential insight into the mechanism of pipeline SCC for X120 steel in acidic soil environments.
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Yingying Li, Lanlan Liu, Jun Wang, Song Xu, Hui Su, Yi Xie and Tangqing Wu
The purpose of this paper is to study the corrosion behavior of Q235 steel in saturated acidic red and yellow soils.
Abstract
Purpose
The purpose of this paper is to study the corrosion behavior of Q235 steel in saturated acidic red and yellow soils.
Design/methodology/approach
The corrosion behavior of Q235 steel in saturated red and yellow soils was compared by weight-loss, SEM/EDS, 3D ultra-depth microscopy and electrochemical measurements.
Findings
Rp of the steel gradually increases and icorr gradually decreases in both the red and yellow soils with time. The Rp of the steel in the red soil is lower, but its icorr is higher than that in the yellow soil. The uniform corrosion rate, diameter and density of the corrosion pit on the steel surface in the red soil are greater than those in the yellow soil. Lower pH, higher contents of corrosive anions and high-valence Fe oxides in the red soil are responsible for its higher corrosion rates and local corrosion susceptibility.
Originality/value
This paper investigates the difference in corrosion behavior of carbon steel in saturated acidic red and yellow soils, which can help to understand the mechanism of soil corrosion.
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Jie Zhang, Jing Liu, Qian Hu, Feng Huang, ZhaoYang Cheng and JunTao Guo
The aim of this paper was to clarify the influence of tensile stress on the electrochemical behavior of X80 steel in a simulated acid soil solution and attempt to understand…
Abstract
Purpose
The aim of this paper was to clarify the influence of tensile stress on the electrochemical behavior of X80 steel in a simulated acid soil solution and attempt to understand mechanistic aspects of the corrosion behaviors of X80 under these conditions.
Design/methodology/approach
The electrochemical behavior of X80 steel at various tensile stresses was investigated in a simulated acid soil solution using electrochemical impedance spectroscopy, potentiodynamic scan measurements and surface analysis techniques.
Findings
The results show that as tensile stress was increased, the open-circuit potential decreased, the reaction activity increase, the reaction resistance (Rct)value became smaller by degrees, the corrosion product film resistance (Rf) first decreased and then increased and polarization current densities changed conversely. The corrosion product film was compact and continuous under the low stress, whereas it was relatively loose under high-stress conditions. Tensile stress promotes the movement of dislocations, which become active points when they move to the steel surface. The increase in the number of active points enhances the anodic dissolution rate and promotes the formation of corrosion product film whose blocking effect can decrease the dissolution rate. The corrosion rate of the specimen is determined by these two effects.
Originality/value
This research provides an essential insight into the mechanism of the electrochemical behavior of X80 steel in acid soil environments.
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JiaYu Zhou, Zili Li, JianGuo Liu, Xiao Xing, Gan Cui, ShouXin Zhang, Ran Cheng and YiShu Wang
The purpose of this paper is to quantify the influence of alternating current (AC) interference on hydrogen evolution reaction of X80 steel.
Abstract
Purpose
The purpose of this paper is to quantify the influence of alternating current (AC) interference on hydrogen evolution reaction of X80 steel.
Design/methodology/approach
The hydrogen evolution potential was obtained by cathodic potentiodynamic polarization curve. The instantaneous potential under AC interference was obtained by high-frequency acquisition with three-electrode system. Electrochemical impedance spectroscopy and Tafel polarization curves were used to study the influence mechanism of AC interference on instantaneous potential.
Findings
It was concluded that the hydrogen evolution reaction could occur on X80 steel under AC interference. There were critical AC current densities of about 100 to 200 A/m2, beyond which the cathode reaction of X80 steel changed from oxygen absorption to hydrogen evolution. Besides the pH value, the initial polarization potential EZ and impedance module of the steel/electrolyte interface under AC interference were also the factors that affected the critical AC densities in different solutions.
Originality/value
This research quantified the hydrogen evolution capacity of X80 steel under AC interference, which could be applied to clear the effect of AC interference on hydrogen evolution reaction.
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BaoZhuang Sun, Wenju Liao, Zhong Li, Zhiyong Liu and Cuiwei Du
To study the corrosion behavior of pipeline steel in coastal areas, a tidal seawater macro-cell corrosion device was built using a cycle soaking tank and a macro-cell corrosion…
Abstract
Purpose
To study the corrosion behavior of pipeline steel in coastal areas, a tidal seawater macro-cell corrosion device was built using a cycle soaking tank and a macro-cell corrosion facility to simulate the corrosion behavior of pipeline steel in a simulated coastal environment (dry and wet alternations during seawater-soil corrosion macro-cell processes).
Design/methodology/approach
The corrosion behaviors were studied via the weight loss method, electrochemical methods and morphological observations on corrosion.
Findings
The results show that during the initial stage of tidal seawater/soil macro-cell corrosion process of the X65 steel, the working electrode on the seawater side is the anode of the macro-battery. As corrosion progresses, the anode and the cathode of the macro-battery become inverted. As the area ratio and the dry – wet ratio increase, the time of anode and cathode inversion shortens. Galvanic current density decreases as the dry – wet ratio increases and increases as the area ratio increases. The corrosion process of macro-cell is affected by the reversal of anode and cathode. After the reversal of anode and cathode, the corrosion rate is mainly controlled by dry – wet alternating corrosion.
Originality/value
The corrosion behavior of a pipeline steel in a coastal environment was studied using a tidal seawater macro-cell corrosion device. The synergism effect between the tidal seawater and seawater-soil macro-cell on corrosion behavior was clarified.
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Abstract
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Yue Wang, Dan Wang, Meng Zhao, Fei Xie and Kaili Zhang
The purpose of this study is to find the multi-factor influence law of stress, strain rate and sulfate-reducing bacteria (SRB) on X70 pipeline steel in a simulated solution of sea…
Abstract
Purpose
The purpose of this study is to find the multi-factor influence law of stress, strain rate and sulfate-reducing bacteria (SRB) on X70 pipeline steel in a simulated solution of sea mud and the order of influence of the three factors on X70 steel to develop a scientific basis for pipeline corrosion protection.
Design/methodology/approach
This paper studied the effects of stress, strain rate and SRB on the X70 pipeline steel corrosion behavior in simulated sea mud solution through orthogonal testing, electrochemical experiments and morphological observations.
Findings
The results of this study showed that stress proved to be the most relevant element for corrosion behavior, followed by SRB and strain rate. At high stresses (301 MPa and 576 MPa), stress dominated the corrosion behavior of X70 pipeline steel. However, at low stress (82 MPa), SRB played the most important role.
Originality/value
Subsea pipelines are in a very complex environmental regime that includes stress, strain rates and SRB, which often cause pipeline pitting and perforation. However, most scholars have only looked into the influence of single factors on metal corrosion. So, the single-factor experimental results of previous studies could hardly be applied to actual working conditions. There is an urgent need to understand the multi-factor influence law of stress, strain and SRB acting together on the pipeline corrosion behavior, especially to determine the dominant factor.
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Longfei Song, Zhiyong Liu, Lin Lu, Xiaogang Li, BaoZhuang Sun and Huanlin Cheng
This paper aims to analyze a failure case of a P110 tube in a CO2 flooding well.
Abstract
Purpose
This paper aims to analyze a failure case of a P110 tube in a CO2 flooding well.
Design/methodology/approach
The chemical composition, microstructure and mechanical properties of the failed P110 tubing steel were tested, and met the API Spec 5CT standard. The fractures were investigated by scanning electron microscopy and energy dispersive spectroscopy.
Findings
Fracture was induced by stress corrosion cracking (SCC) and that the stress concentration caused by the mechanical damage played an important role in the failure. The failure case is a SCC failure affected by mechanical damage and galvanic corrosion.
Originality/value
The effect of the infiltration of groundwater was studied in the failure case. The stress concentration caused by the mechanical damage played an important role in the failure.
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L.M. Quej-Ake, A. Contreras, H.B Liu, J.L. Alamilla and E. Sosa
The purpose of this paper is to study the susceptibility to corrosion processes of X60, X65 and X70 steels immersed in sand-clay soil with pH 3.0, using electrochemical…
Abstract
Purpose
The purpose of this paper is to study the susceptibility to corrosion processes of X60, X65 and X70 steels immersed in sand-clay soil with pH 3.0, using electrochemical techniques, scanning electron microscopy (SEM), energy dispersive spectroscopy and X-ray diffraction (XRD).
Design/methodology/approach
Natural acidic soil sample was collected as close as possible to buried pipes (1.2 m in depth) in a Right of Way from south of Mexico. Both steels and soil were characterized through SEM and XRD. Then, open circuit potential was recorded for all steels exposed to soil at different exposure times. Thus, the electrochemical impedance spectroscopy (EIS) was traced, and anodic polarization curves were obtained.
Findings
The steel corrosion processes started when the active sites were exposed to natural acidic soil. However, corrosion rates decreased for three steels as immersion time increased, obtaining the highest corrosion rate for X60 steel (0.46 mm/year for 5 h). This behavior could be attributed to corrosion products obtained at different exposure times. While, 5 h after removing corrosion products, X65 steel was more susceptible to corrosion (1.29 mm/year), which was corroborated with EIS analysis. Thus, corrosion products for the three steels exposed to natural acidic soil depended on different microstructures, percentage of pearlite and ferrite phases, in which different corrosion processes could occur. Therefore, the active sites for carbon steel surfaces could be passivated with corrosion products.
Practical implications
The paper identifies the any implication for the research.
Originality/value
Some anodic peaks could be caused by metallic dissolution and was recorded using high positive polarization (high field of perturbation). In addition, the inductive effects and diffusion process were interpreted at low frequency ranges using EIS. According to X-ray diffraction (XRD), acidic soil had Muscovite containing aluminum and iron phases that were able to generate hydrogen proton at the presence of water; it might be promoted at the beginning of deterioration on low carbon steels. Steel surface cleaning after removing corrosion products was considered to study the possible diffusion phenomena on damaged steel surfaces using EIS.
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