Different Degrees Of Corrosion Research Articles

Corrosion failure analysis and solutions of aluminum alloy gas path plate used in sanding device of high-speed train

During the maintenance of a high-speed train, it was frequently found that the anodized aluminum alloy gas path plates in the sanding device had different degrees of corrosion. In this paper, SEM, EDS, XRD and LAD-EDTEST spectrometer were used to analyze the macro and micro morphology, elements and phases of corrosion product, element compositions of the matrix and assembly problem of the gas path plates. The mechanism of delamination spalling corrosion caused by local pitting corrosion of anodized aluminum alloy gas path plate was described. In addition, the properties of the coatings produced by different surface treatment methods and different substrate materials were compared. The test results indicate that the corrosion protection level of the micro-arc oxide coating is higher than that of the anodic oxide coating, which is mainly composed of γ-Al2O3 and contains a certain amount of α-Al2O3. Compared with 2A12-T4 aluminum alloy, the micro arc oxidation (MAO) coating of 6082-T6 aluminum alloy has lower porosity, higher hardness, higher corrosion potential, lower corrosion current, and better corrosion resistance, and 6082-T6 aluminum alloy is more suitable for use as the gas plate material. Meanwhile, it is proposed that the MAO coating with 35 μm can obviously improve the corrosion resistance of the gas path plate.

Analysis of Mineralization and Disease Characteristics of Bronzes Unearthed in Archaeology

Bronze artifacts unearthed by archaeologists are affected by underground burial environment and other factors, and most of them have different degrees of corrosion. Bronze artifacts unearthed by archaeologists have different degrees of mineralization. Establishing a data analysis database for basic structure and disease analysis of mineralized bronze artifacts is a necessary prerequisite for developing targeted reinforcement materials and realizing accurate protection. Based on the characteristic analysis of the mineralized bronzes, this paper systematically analyzed the mineralization and disease characteristics of the mineralized bronzes by Confocal Super Depth-of-Field Microscope(CSDTM), scanning electron microscopy (SEM), energy spectrum analysis(EDS) and XRD, and compared and analyzed the microscopic morphology, composition and phase structure of the bronzes under the same burial environment, so as to provide support for subsequent targeted protection and reinforcement.

Ultrasonic testing and Monitoring of Hydrogen blistering and Hydrogen-induced Cracking of LPG Storage Tanks

Due to the presence of various corrosive chemicals in LPG (liquefied petroleum gas, or propane) storage tanks, it is very likely to cause different degrees of corrosion in the tank and derive various defects. This article analyzes the main characteristics and types of defects found in storage tanks and provides an overview of ultrasonic testing and monitoring of defects such as hydrogen blistering and hydrogen-induced cracking.

Performance degradation of steel rebar considering corrosion spatial variability in concrete

The corrosion of steel bars is the main issue affecting the durability of reinforced concrete structures, which is nonuniform owing to the material properties and external environmental effects. In this study, the performance degradation of steel rebars in concrete is estimated considering corrosion spatial variability. With the aid of a three-dimensional measurement technique, a finite element model based on the scanning result was established to examine the corrosion effect on the tensile behaviour of the corroded bars, which was validated with the experimental results and digital image correlation observation. To assess the deformation behaviour of the corroded steels, a semi-analytical model was developed based on the cross-sectional area distribution and material properties. Subsequently, the spatial weight loss distributions with different degrees of corrosion were generated using a random field model. The model parameters were determined by combining engineering judgement and estimation of the experimental results. Finally, probabilistic model of degraded performance was established using the deterministic assessment and simulated steel weight loss distribution.

Research on the Effects of Acid Rain and Improvement Measures

With the continuous development of industrial production, transportation and people's life all over the world, acid rain has become one of the major problems that seriously threaten the world environment. In this paper, the causes of acid rain, the effects of acid rain and the measures to control acid rain are studied. The influencing factors and forming process of acid rain were further expounded. Acid rain also affects buildings, animals, plants and humans to varying degrees - acid rain can cause different degrees of corrosion to buildings; Affecting the reproductive system of aquatic plants and causing egg defects in birds; It affects plant structure, physiological function and living environment. Therefore, in order to deal with acid rain, countries have implemented corresponding measures. This paper mainly introduces the Acid Rain Program (ARP) of the United States and the tax policy of Sweden. The treatment of acid rain is definitely not a simple thing, and people need to further explore more efficient and concise methods in the future. The purpose of this study is to clarify the serious impact of acid rain on society, economy and human life, and to arouse people's attention to acid rain and environmental protection.

Experimental and numerical study on the degradation law of mechanical properties of stress-corrosion steel wire for bridge cables

In this paper, the stress corrosion and monotonic tensile test of corroded steel wire were carried out. The effects of different corrosion ages and stress levels on failure modes, stress-strain curve and mechanical properties of corroded steel wire were discussed. Then, a finite element model of steel wire considering real surface morphology was established, and the surface stress distribution and the failure of steel wire under different corrosion degrees were compared. The relationship between stress triaxiality and critical equivalent plastic strain to different corrosion parameters was given. Finally, the degradation model of mechanical properties of corroded steel wires was established. The results showed that the failure patterns of steel wires with different degrees of corrosion were mainly divided into three types: cup cone shape, milling cutter shape and splitting shape. The shear lip zone of fracture section basically disappeared with the increase of stress corrosion, and the location of fiber area was transferred from the inside to the surface of steel wire. The decrease in strength and elastic modulus of the specimen under stress corrosion was four times and three times greater than that under non-stress corrosion, respectively. In addition, the crack position of specimen changed from the inside of section to the location of corrosion pit with the increase of corrosion degree. The fracture equivalent plastic strain decreased gradually, while the stress triaxiality increased. When the degree of corrosion reached 19.53%, the fracture equivalent plastic strain decreased by 55.41% from 0.314 to 0.140, and the stress triaxiality increased by 23.53% from 0.390 to 0.510. The influence of uniform thickness loss on the stress triaxiality was less than that of pit depth-width ratio. The larger the depth-width ratio, the larger the maximum stress triaxiality corresponding to the failure element. The constitutive model proposed in this paper could reflect the degradation law of mechanical properties of corroded steel wires.

An Assessment of the Structural Performance of Rebar-Corroded Reinforced Concrete Beam Members

This paper aims to determine the effects of local corrosion at three different corrosion areas, the (1) entire area, (2) the constant moment area, and (3) the constant shear area, on the flexural performance of RC beams. To analyze this, an experimental study was carried out to prepare two series of RC beams (200 × 300 × 2800 mm) created with three different degrees of corrosion, inducing local rebar corrosion. Furthermore, two series of experimental tests were conducted under different loading types: monotonic and cyclic loading. It was observed that the strength capacity reduction grew in the RC specimens with induced corrosion in the order of the (1) entire area > (2) the constant moment area > (3) the constant shear area, as the average corrosion rate increased. Our test results further showed that the yield and ultimate strength were kept nearly equivalent to the uncorroded RC specimen, with average corrosion rates of 10% and 15%, respectively. Over these corrosion rates, the yield strength and ultimate strength dropped significantly. Compared to the test results under a monotonic loading condition, the structural capacity under a cyclic loading condition decreased, with a more pronounced tendency for each corrosion case as the corrosion rate increased. Longitudinal cracks developed throughout and adjacent to the corrosion areas as the corrosion rate increased. Thus, we can infer that strength reductions may be strongly influenced by these longitudinal cracks.

The Effect of Bleaching Agents on Color Change in Different Section Shapes in Beech And Fir Woods

Aim of study: It is an investigation of the effects of bleaching processes on the color change in the wood of tree species. Tree species Eastern Beech (Fagus Orientalis Lipsky.) and Eastern Black Sea Fir (Abies Nordmanniana subsp.) were used in the study. Sodium hydroxide-hydrogen peroxide, oxalic acid, peracetic acid diluted 1/3, peracetic acid diluted 1/6 were used as bleaching agents. Trial samples were prepared in accordance with standards and color change measurements were made.
 Area of study: Surface treatments on wooden materials
 Material and methods: In the study, two wood species and one varnish type were used; Color changes were tested by applying various bleaches to the wooden material by rubbing method.
 Main results: As a result of the study, differences were observed in all cross-section shapes in beech wood bleaching measurements with 1/6 diluted peracetic acid, and differences were observed in cross-section shapes in fir wood bleaching measurements. The best bleaching of fir wood was achieved with peracetic acid.
 Main results: As a result of the study, differences were observed in all cross-section shapes in the beech wood bleaching measurements with 1/6 diluted peracetic acid, and in the cross-section shapes in the fir tree bleaching measurements. The best bleaching of fir wood was achieved with peracetic acid.
 Highlights: The bleaching process allows the wooden material to easily acquire a homogeneous color. Since the cell arrangements are different in different cross-sectional shapes, the bleaching rates are different from each other. While there is not much difference in the color changes in the wood material when bleached with oxalic acid, the samples are bleached as a result of bleaching with sodium hydroxide-hydrogen peroxide and peracetic acid. Significant changes have occurred in color changes. The reason for this difference is due to the different degrees of corrosion of bleaching agents.

Mechanical Performance of Artificially Rusted Q500MC Structural Steel Subjected to High Temperature

Steel is prone to rusting in a corrosive environment, which results in a reduction of the effective bearing section of the steel structure. The stress concentration at the location of rusting causes brittle fracture of the steel structure during service. Although there is valuable research on the mechanism of corrosion and corrosion failure, research on the high-temperature mechanical properties of corroded steel is still limited. In this study, one-sided artificial accelerated corrosion of Q500 steel was performed, and a high-temperature steady-state tensile test was conducted on it. The degradation law and influencing factors of the high-temperature mechanical properties of corroded steel were discussed and analyzed using scanning electron microscopy (SEM) to quantify the corrosion surface morphology, and the volume corrosion ratio was used to characterize the degree of corrosion. The results showed that when the temperature was below 500°C, the attenuation of the ultimate load of corroded steel was influenced by the combined effect of temperature and corrosion. When the temperature exceeded 500°C, the influence of corrosion on the attenuation of the ultimate load tended to decrease due to the reduction in the material properties of steel. Furthermore, after the temperature exceeded 500°C, the elongation of the corroded section of the specimen increased gradually with the increase in temperature, and the elongation tended to be consistent even at different degrees of corrosion.

Wind-Induced Responses of Corroded Angle-Steel Transmission Tower

Corroded transmission towers, whose load-bearing capacities are lowered, are suffering from wind-induced damage. By simulating the member corrosion through section thinning, the structural dynamic finite element model of an angle-steel transmission tower with a corrosion depth of 0 mm to 1.4 mm was established using ANSYS/LS-DYNA software. The incremental dynamic analysis method was used to study the collapse mode of the tower under different degrees of corrosion, as well as the effects of corrosion on structural self-vibration characteristics, wind-induced member stress, and tower-top displacement. The results show that with the corrosion deepening, the first three vibration frequencies decrease, and the torsional mode becomes the first mode. When the corrosion depth is smaller, the overall structure failure occurs under strong wind. The failure starts at the most unfavorable oblique rod between the upper and middle cross arm, then expands to the rods under the lower cross arm. When the corrosion depth is larger, the overall structure failure occurs restrictedly between the upper and middle cross arm. Internal axial force and bending moment redistribution happen when corrosion deepens. Under the critical failure state, the oblique rods are always at a high stress level, while the stresses of the main rods decrease. Corrosion has a stronger impact on component strength and stability than on structural stiffness.

A study on static properties of high-performance steel after corrosion damage

This paper experimentally investigates the mechanical properties of high-performance steel (690 MPa) under different corrosion degrees. The tensile specimens are examined by indoor salt spray accelerated corrosion tests with varying durations. Tensile tests are performed on the corroded specimens to obtain the corrosion kinetics (corrosion rate) model and residual mechanical properties under different degrees of corrosion, and the correlations between residual mechanical properties and corrosion weight loss rate are discussed. In addition, the paper will adopt Q235 steel as the control to compare the difference in corrosion characteristics between conventional-strength steel and the new high-performance steel under the same corrosion conditions and to compare their corrosion kinetics curves. The paper will establish a new constitutive model for high-performance steel and calibrate the relevant parameters. A new constitutive model was proposed based on the modification of Ramberg-Osgood model. On this basis, the paper will obtain a prediction expression of constitutive parameters considering the degree of corrosion damage. It is found that that the proposed corrosion model is suitable for the new high-performance steel under atmospheric corrosion.

Study on the Mechanical Properties of Corroded Steel Strands at Deflection Angles

The purpose of this study is to investigate the performance changes in steel-stranded hangers under complicated loads in moist or corrosive environments. First of all, corrosion tests were carried over three time periods (360 h, 720 h, 1080 h) on glossy and galvanized steel strands and different levels of corrosion were obtained. Subsequently, tensile tests were carried out on strands with different degrees of corrosion (including no corrosion) at different deflection angles. The test results showed that the ultimate bearing capacity of the uncorroded steel strand at the deflection angle decreased by 21.8%, while the ultimate bearing capacity of the glossy strand with the longest corrosion time decreased by 27.1%. For the same corrosion time, the ultimate bearing capacity of the glossy steel strand decreased at a higher rate than that of the galvanized steel strand. In addition, numerical simulations show that the angle of deflection reduces the ultimate bearing capacity of the steel strand. It is also found that both deflection angle and corrosion pit depth have a positive correlation on the maximum stress of the pit, and that the stress of the pit is highest near the fixed end. This study provides meaningful guidance for the design and maintenance of bridge hangers, which can extend the service life of the hangers.

Effect of corrosion on soil-structure interfacial shearing property and bearing capacity of steel foundation in submarine soil environment

As a common type of foundation in ocean engineering, steel foundation encounters great corrosion risk and serious safety hazards throughout its lifecycle. Besides reducing the thickness of steel members, corrosion also has a significant impact on the soil-structure interfacial shearing property by changing the roughness characteristics of steel surface, and eventually affects the bearing capacity of steel foundation in submarine soil environment. In this study, electrolytic accelerated corrosion experiments are conducted first to prepare corroded steel samples suffered different degrees of corrosion. Then, the effect of corrosion on the soil-steel foundation interfacial shearing property is investigated by interfacial shearing experiment and discrete element numerical simulation. The analysis results show that the interface shearing strength under different corrosion degrees can be regarded as following Mohr-Coulomb strength theory. The shearing strength parameters, i.e. the interfacial cohesion and interfacial friction coefficient, increase with the corrosion degree. Finally, the influences of corrosion on the bearing capacity of a steel pipe pile foundation are studied by finite element simulation, with considering the steel thickness reduction and the variation of soil-steel interfacial shearing strength. The numerical results demonstrate the necessity of considering the variation of the interfacial shearing property induced by corrosion.

Experimental Study and Numerical Simulation of the Tensile Properties of Corroded Bolt-Sphere Joints

In order to study the mechanical behavior of corroded bolt-sphere joints and predict the bearing capacity of the joints in a corrosive environment, bolt-sphere-connection and bolt-sphere-joint specimens with differing degrees of corrosion were obtained by accelerated corrosion. The tensile properties of the corroded bolt-sphere connections and the bolt-sphere joints with members were tested, respectively, and the effects of different degrees of corrosion on the tensile properties of bolted spherical joints were studied. Finally, a numerical simulation of the corroded bolt-sphere connections and bolt-sphere joints with members was carried out, and the main factors affecting the tensile performance of the corroded bolt-sphere joints was clarified; the degradation law of the tensile properties of the bolted sphere joints with service time was established.

Quantitative evaluation of surface cleanliness of weathering steel treated by continuous wave laser

A 3 kW continuous-wave (CW) laser was used for the laser cleaning of weathering steel with artificial corrosion pits. Specimens with different degrees of corrosion were obtained by NaCl deposition in artificial pits of 10 mg/m2, 100 mg/m2 and 1000 mg/m2 through constant dew point dry and wet cycles for one year. To develop quantitative evaluation methods that can be applied on-site, the cleanliness of the laser-cleaned surface was evaluated through visual observation, turning time, and photographic analysis. The results reveal that the photometric analysis based on the CIE L*a*b* color space can be used to evaluate the surface cleanliness of surfaces treated with a CW laser, which is consistent with the results of the turning time test. The color difference of the surface before and after the laser treatment can be used as a quantitative index to evaluate cleanliness. The proposed laser surface treatment procedures can provide a reference for cleaning corroded weathering steel structures and achieve cleanliness of more than 80 % and a longer turning time.

Experimental Study on the Overall Stability of Corroded H-Shaped Steel Beams

The degradation of the overall stability of corroded rolled H-shaped steel beams under bending conditions has not been extensively studied. In the present study, monotonic tensile tests and overall stability tests were conducted on seven rolled H-shaped steel beams that were subjected to electrochemical corrosion in order to discuss the influence of corrosion on the material’s mechanical properties and the overall stability of steel beams under bending conditions. The test results have indicated that the strength, the elastic modulus, and the elongation of the steel declined with an increase in the corrosion rate of the steel beams, and an obvious plastic deterioration phenomenon was observed. In addition, all of the steel beams with different degrees of corrosion were subjected to overall flexural–torsional buckling failure. The stiffness and the overall stability ultimate bearing capacity of the corroded steel beams decreased with the increase in the corrosion rate, and the overall stability of the test beams with a high design corrosion rate degraded significantly. Furthermore, by using the finite element numerical simulation analysis software ABAQUS, a double-reduction corrosion model of the sectional dimensions and the material’s mechanical properties was established. The overall stability ultimate bearing capacities of the steel beams that were subjected to three-point bending and the corresponding load–lateral displacement curves were analyzed. In addition, the finite element numerical simulation results were compared with the test results for verification. Subsequently, the influence of the initial bending on the overall stability ultimate bearing capacity of the steel beams was analyzed by virtue of the verified finite element model. This study will provide a test basis for the evaluation of the bearing capacity of existing rolled H-shaped steel members, as well as an experimental basis and finite element model reference for the follow-up study on the degradation of the mechanical properties of the corroded rolled steel members.

Corrosion of catalyst in high resolution: Layered transition metal dichalcogenides electrocatalyse water splitting and corrode during the process

Among the vast field of 2D materials, transition metal dichalcogenides (TMDs) have emerged as promising materials for electrocatalysis. Many of them, such as MoS2, were found to be potent electrocatalysts for the hydrogen evolution reaction (HER), which is vital for making electrochemical water splitting, a green route for obtaining hydrogen, economically feasible. In this work, we investigated the morphological and (electro)chemical changes undergoing in synthetic bulk crystals of MoS2, TiS2, and TiSe2 during HER. Local electrochemical changes were observed using scanning electrochemical microscopy (SECM). Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were utilized to monitor morphological changes. Furthermore, the chemical composition of the materials was analyzed using X-ray photoelectron spectroscopy (XPS) and electron dispersive X-ray spectroscopy (EDS). Changes in the atomic structure were studied using X-ray diffraction (XRD). Our experiments showed different degrees of corrosion occurring in these materials, with the magnitude of corrosion decreasing in the order TiSe2 > TiS2 > MoS2. These findings are of tremendous importance for the development of transition metal dichalcogenide electrocatalysts, which are touted to replace platinum for hydrogen evolution reaction.

Corrosion Fatigue Test and Performance Evaluation of High-Strength Steel Wires Based on the Suspender of a 11-Year-Old Concrete-Filled Steel Tube Arch Bridge

In this study, based on an actual project, the steel wire in the suspender of a concrete-filled steel tube arch bridge was selected from appropriate samples to perform acetic acid-accelerated salt spray tests, and steel wire samples with different corrosion degrees were obtained. A laser microscope was used to measure the roughness of the samples, and three corrosion samples were randomly selected from each group for grinding. Fatigue tests were performed on steel wire samples with different degrees of corrosion and polished steel wire samples, and the fatigue fracture was observed and analyzed. The results showed that few cracks on the steel wire surface could be eliminated by grinding, and the fatigue life of the specimens could be increased. Finally, the stress-life-mass loss rate (S-N-η) probability model based on the Weibull distribution was obtained using the measured fatigue data, which can be further referenced in the planning of the inspection of suspender service status, steel wire corrosion protection, and fatigue life prediction, etc.

Electrochemical behavior of 2205 duplex stainless steel in simulated solution containing high concentration Cl− and saturated CO2 at different temperatures

2205 duplex stainless steel (DSS) has good corrosion resistance due to its typical duplex organization, but the increasingly harsh CO2-containing oil and gas environment leads to different degrees of corrosion, especially pitting corrosion, which seriously threatens the safety and reliability of oil and gas development. In this paper, the effect of temperature on the corrosion behavior of 2205 DSS in a simulated solution containing 100 g/L Cl− and saturated CO2 was investigated with immersion tests and electrochemical tests and combined with characterization techniques such as laser confocal microscopy and X-ray photoelectron spectroscopy. The results show that the average critical pitting temperature of 2205 DSS was 66.9 °C. When the temperature was higher than 66.9 °C, the pitting breakdown potential, passivation interval, and self-corrosion potential decreased, while the dimensional passivation current density increased, and the pitting sensitivity was enhanced. With a further increase in temperature, the capacitive arc radius of 2205 DSS decreased, the film resistance and charge transfer resistance gradually decreased, the carrier density of the donor and acceptor in the product film layer with n + p bipolar characteristics also increased and the inner layer of the film with Cr oxide content decreased, while the outer layer with Fe oxide content increased, the dissolution of the film layer increased, the stability decreased, and the number and pore size of pits increased.

Predictive Study of Flow-Accelerated Corrosion Characteristic Parameters Based on the Neural Network

Corrosion of equipment by corrosive media is widespread in the processing of inferior crude oil. In hydroprocessing reactor effluent systems, corrosive media are very destructive to heat exchangers and air coolers during flow and cooling because of the high-temperature and -pressure environment. A fire and explosion in the air cooler or heat exchanger are highly likely when their tubes leak. Currently, there are no effective direct detection and prediction means to evaluate the corrosion risk in real time, creating significant hidden threats to the safe operation of the equipment. Therefore, this paper proposes a condition expansion method based on a Gaussian distribution. The distribution laws of characteristic corrosion parameters under various working conditions were studied, and the corrosion risk of the equipment was evaluated. A three-layer back-propagation neural network model is constructed to predict the characteristic corrosion parameters. After testing, the model is shown to have superior predictive accuracy and generalization performance. It can also meet the demand for real-time equipment corrosion prediction. The proposed method can serve an essential role in guiding engineers to take correct and timely prevention and control measures for different degrees of corrosion to reduce losses.