Corrosion Level Research Articles

Experimental investigation on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium-stainless steel dissimilar materials

The electromagnetic welding (EMW), often known as magnetic pulse welding, is a solid-state welding technology that is used to join two different materials using high-velocity impact. In this study an attempt was made to join the Titanium(Ti)- Stainless Steel(SS 304) materials with the help of multi turn disc coil along with the field shaper. A comparative investigation was conducted on the joint’s microstructure, as well as its mechanical and corrosion properties. Inverted optical microscopy (OM) and x-ray diffraction (XRD) were used to do the microstructural characterization of the joint. The micro-Vickers hardness test was used to analyse the material’s mechanical properties. In addition, electrochemical experiments were run on the Ti-SS 304 EMW junction as well as the component materials to establish how resistant they were to corrosion. Using an electrochemical impedance analyzer, the levels of corrosion that were caused by the structures were measured while they were submerged in a solution of nitric acid at room temperature. The microstructural pictures revealed a wave-like pattern at the material’s interface, which is evidence of strong adhesion between the components. The micro vickers hardness of the joints was within the permitted range, as was the corrosion rate.

Experimental investigation into corrosion effect on buckling and low-cycle fatigue performance of high-strength steel bars

The reinforcement in marine RC structures will inevitably be corroded under long-time erosion of chloride ions, which will weaken steel mechanical properties and then structural seismic resistance. The new metallurgical technology is adopted for manufacturing high-strength steel bars (HSSB), but that may affect the corrosion resistance of steel bars at the same time. This paper experimentally investigates the effects of corrosion on monotonic and low-cycle fatigue properties of HSSB HTRB600 and normal strength steel bars (NSB) HRB400E. The HRB400E and HTRB600 steel bars were corroded to different corrosion rates by electrochemical accelerated corrosion technique. The monotonic tensile and compressive, as well as low-cycle fatigue tests of corroded steel bars were conducted to investigate the effects of corrosion on steel mechanical properties, of which corrosion levels (0–20% target corrosion mass loss), slenderness ratios (L/D=6, 8, 10, 12) and strain amplitudes (2%, 4%) are considered. Test results show that, the corrosion morphology of steel bars under electrochemical accelerated corrosion is basically consistent with that observed under natural corrosion. Compared with uncorroded HRB400E and HTRB600 steel bars, 20% corrosion mass loss leads to 38% and 35% decrease in tensile strength, as well as 33% and 28% reduction in buckling stress, respectively. The HTRB600 steel bars present slightly superior monotonic tensile and compressive corrosion resistance than HRB400E steel bars. Corrosion obviously decreases the low-cycle fatigue (LCF) life of steel bars, resulting in reductions of 44% and 36% in LCF life at 20% corrosion mass loss for HTRB600 and HRB400E steel with a L/D of 6, respectively. Moreover, the HTRB600 steel bars present more significant corrosion degradation in total hysteretic dissipated energy, compared with HRB400E steel bars. The combined effect of corrosion and inelastic buckling further exacerbates the deterioration of LCF performance of steel bars. The corresponding deterioration models are proposed to determine the LCF life and energy dissipation capacity of corroded steel bars.

Prediction of residual performance of corroded RC beams from observed surface cracks by 3D RBSM with MPC

Corrosion of reinforcing steel in concrete structures can significantly compromise their performance. Accurately estimating this deterioration for in-service structures is challenging due to uncertainties surrounding the distribution of internal corrosion and cracking patterns, compounded by the limitations of destructive testing. This research proposes a novel approach to predict the remaining load-bearing capacity of corroded reinforced concrete (RC) structures based on the pattern of surface cracks caused by corrosion. The method integrates a model predictive control (MPC) algorithm with a three-dimensional Rigid Body Spring Model (3D RBSM) to estimate internal corrosion levels from observed cracks and a normal 3D RBSM simulation to predict the residual performance. The proposed system is validated through analysis of four corroded beam specimens based on experimental work reported in the literature. In use, the MPC algorithm first estimates a corrosion distribution in a RC beam and generates simultaneous corrosion-induced crack and stress predictions. This information is then used to predict residual load-bearing capacity. The system accurately forecasts the non-uniform corrosion distribution, flexural capacity, and load-displacement curves of a specimen, offering insight into the performance differences among the specimens and demonstrating its potential to assess the serviceability of existing RC structures with corrosion issues.

Temporal and Spatial Variation Study on Corrosion of High-Strength Steel Wires in the Suspender of CFST Arch Bridge

The corrosion and degradation behavior of high-strength steel wires during service directly affect the safety and usability of suspenders in steel pipe concrete arch bridges. In this study, three different types of specimens were fabricated using steel wires extracted from the suspenders of an 11-year-old in-service arch bridge and subjected to accelerated corrosion tests with acetic acid. Considering the differential diffusion processes of corrosion factors caused by varying degrees of damage to the suspender sheath, the spatial corrosion variability of steel wires at different positions within the suspender cross-section was investigated. Experimental results indicated a two-stage characteristic in the corrosion process of individual galvanized steel wire samples. In the first corrosion stage, the microstructure on the corroded steel wire surface evolved from a dense crystalline structure to a porous one. In the second corrosion stage, corrosion products accumulate on the steel wire substrate, subsequently further aggregating into sheet-like structures. The maximum pitting factor of individual steel wire samples from a specific area could be described by a Type I extreme value distribution. In the time-dependent model that was established, the location parameter and scale parameter exhibited an exponential decrease during the first corrosion stage and a linear decrease during the second corrosion stage. In the absence of sheath protection, the coefficient of variation in corrosion among adjacent steel wires in the suspender followed a normal distribution. The spatial corrosion variability of the wires inside the suspender is significantly influenced by the shape of the suspender sheath damage. As the corrosion time increased, the overall discrepancy in corrosion levels among different layers of wires diminished.

Seismic performance evaluation and numerical analysis of CFDST long columns with local corrosion under eccentric compression

In this study, the seismic performance of locally corroded CST and CFDST long columns was evaluated by quasi-static tests. The effects of four levels of corrosion and two types of cross-sections on damage patterns, horizontal load-displacement curves, and seismic indexes were assessed. ABAQUS software was used to conduct extended simulations on long columns of CFDST, analyzing the impact of each parameter on seismic performance. Experimental results indicated that the horizontal load-displacement hysteresis curves of the CFDST long columns within the specified corrosion parameters exhibit robust characteristics, demonstrating improved seismic performance and energy dissipation capacity while preventing sudden damage due to local buckling. The parametric analysis showed that increasing the diameter-to-thickness ratio of the outer steel pipe and decreasing the hollow ratio significantly impact the peak load, whereas increasing the axial compression ratio and eccentricity results in non-uniform specimen damage and reduced peak load.

Investigation of corrosion-induced cracks using corrosion products quantified by an X-ray technique and FE analysis of single- and multiple-rebar beams

The effects of corrosion methods, galvanostatic (GS) vs. artificial climate environment (ACE), on the relationships between corrosion products and corrosion cracks of corroded reinforced concrete beams are investigated. The experimental results show that the GS method induces smaller corrosion crack width. A novel quantitative detection method of corrosion product thickness using X-ray and digital image processing techniques is proposed for investigating the continuous development of corrosion products. As the corrosion level increases, a smaller steel-to-rust volume expansion ratio caused by continuous leakage and a lower oxidation degree of corrosion products for the GS specimens are the major reasons for the smaller corrosion cracks. Regarding the effect of rebar arrangement on the development of corrosion-induced cracks, the expansion stress from corner-located rebars restrained the growth of corrosion products and further limited the propagation of corrosion-induced cracks of the center rebar. Estimated corrosion crack width via FE analysis using measured corrosion products as input show good agreement with experimental results.

Characterization of Corrosion-Induced Fracture in Reinforced Concrete Beams Using Electrical Potential, Ultrasound and Low-Frequency Vibration

The paper deals with the non-destructive experimental testing of the reinforced concrete beams under progressive corrosion. A series of experiments using electrical potential, ultrasound and low-frequency vibrations techniques are reported. Electrical potential and natural frequencies were used to characterise and monitor the corrosion process at its initial state. The P-wave velocity measurements were proved to be effective in quantitative assessment of the level of corrosion as it progresses. The possibility of early detection of damage using a proposed damage index and diagnostic framework is promising for possible applications in the non-invasive diagnostics of reinforced concrete elements.

New insights on the analysis of the causes of glossy lustre on the surface of ancient Chinese bronze mirrors

Ancient Chinese bronzes, particularly bronze mirrors, often develop a fatty, oily, or greasy film on their surface, known as patina. This film can appear silvery, green, or black. Bronze mirror samples from the Spring and Autumn Period (770–476/403 BCE) to the Ming Dynasty (1368–1644 CE) were analyzed using a systematic approach that included super depth of field three-dimensional microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM–EDS), Raman spectroscopy, and THM-Py-GC/MS. The analysis indicates the presence of advanced organic acid lead in the matrix of ancient bronze mirrors. The ancient existence of the lost wax method combined with the mould method of bronze casting technology is verified through simulation experiments and ancient literature. Ancient bronze mirrors may have utilized this technique, with advanced organic acid lead remaining in the mirror mould that entered the bronze mirror matrix during pouring. The Lead organic acids in bronze mirrors readily precipitate on the surface and cover the mirror. The change in the greasy sheen on the surface of the bronze mirror may be related to the degree of corrosion. If the mirror's corrosion level is low, the organic acid lead film remains transparent. If the level of corrosion is significant, the organic acid lead film may darken in color due to oxidation, aging, hydrolysis, or microbial activity.

A REVIEW OF PREDICTIVE MAINTENANCE APPROACHES FOR CORROSION DETECTION AND MAINTENANCE OF MARINE STRUCTURES

Corrosion is a natural phenomenon that deteriorates and damages the surface of metallic material. Over time, the surface of the material deteriorates due to electrochemical reactions with the surrounding environment. If corrosion is not identified early on, it can become a major financial burden for industries, costing billions of dollars. Despite swift technological developments, preventing and maintaining corrosion progression with reactive maintenance remains difficult. Due to that, predictive maintenance has been developed to predict the deterioration, degradation, and fault over the remaining useful life of the material by using real-time data, historical data, simulation, modelling, and failure probability. Predictive maintenance allows inspectors to monitor the health and predict the corrosion level of the material. However, it is hard to predict the unexpected degradation of the material from the developed prediction model without considering the harsh environment and other external factors. Hence, there is a need to investigate these problems and their effect on predictive maintenance for corrosion detection and maintenance. Therefore, this paper reviews and compares the state-of-the-art predictive maintenance solutions developed to solve corrosion issues in various applications, industries, and academic research. The challenges and opportunities for the predictive maintenance application of corrosion detection and maintenance are also presented. This review will provide new and additional knowledge that can be used to develop prediction models for corrosion detection and maintenance, which will help prevent unexpected failures.

Analysis of the Effectiveness of the Application of Corrosion Inhibitors to Steel Re-Bars Embedded in Concrete

Reinforced concrete is the most widely used material in the construction of building structures, being noted for its versatility and low cost. However, the durability of reinforced concrete structures can be compromised by the corrosion of steel re-bars, especially in the presence of chlorides. To address this challenge and promote sustainability, the use of corrosion inhibitors has been researched as a way to extend the lifespan of structures. This study assessed the effectiveness of using a commercial corrosion inhibitor on steel re-bars embedded in types of concrete with different chloride percentages, using electrochemical methods to measure the corrosion rate and potential. The results indicate that, in the absence of corrosion inhibitors, corrosion rates become unacceptable with chloride percentages equal to or higher than 0.8% by weight of cement. The application of inhibitors significantly reduced the corrosion rate, particularly at chloride percentages of 0.8% and 1.2%, maintaining the re-bars in a passive state or at moderate levels of corrosion. However, for chloride percentages higher than 1.6%, high levels of corrosion were observed, even in the presence of inhibitors. The findings suggest that the use of inhibitors can be an effective strategy in preventing corrosion in reinforced concrete structures, contributing to their structural integrity and long-term sustainability.

Numerical Investigation on Strengthening of Steel Beams for Corrosion Damage or Web Openings Using Carbon Fiber Reinforced Polymer Sheets

Fiber-reinforced polymers (FRPs) have been widely used to strengthen steel structures, which could suffer from corrosion or the introduction of web openings, for utilities such as ductwork, plumbing, electrical conduits, and HVAC systems. The present numerical study involves the application of unidirectional carbon FRP (CFRP) sheets to steel I-beams, damaged due to corrosion or web openings, to regain their lost load-carrying capacity. Finite element analysis (FEA) was utilized to develop and validate three beam models against existing experimentally tested specimens. Subsequently, a parametric study was conducted investigating the effect of various corrosion levels and the number of circular web openings on the yield and ultimate load capacities of the beams. The optimum number of CFRP layers needed to strengthen corroded beams was determined and six CFRP strengthening scenarios were adopted to determine the best configurations to retrofit steel beams with openings (SBWOs). The results revealed that corrosion, introduced by thinning the bottom flange, reduced both yield and ultimate load capacities, with a nearly perfect linear reduction in ultimate load for each 2.5% thickness loss. The optimum number of CFRP layers depended on the level of corrosion damage. Furthermore, while maintaining a constant total opening area, beams with a greater number of smaller circular web openings demonstrated higher yield and ultimate load capacities than those with fewer larger openings. Out of the six adopted CFRP strengthening scenarios, three configurations that involved applying CFRP sheets to both flanges and the web effectively restored the strength of SBWOs, when adequate CFRP layers were used.

Local–overall buckling behavior of corroded intermediate compression-bending H-section steel columns

The primary aim of this paper is to assess the impact of corrosion damage on intermediate H-section steel columns subjected to combined compression and bending about the strong axis. The study conducted a comprehensive investigation into the corrosion-induced transition in the buckling behavior of steel columns through experimental and numerical analyses. Six H-section Q355 steel intermediate columns were designed, with five undergoing an artificial spray-accelerated corrosion process. The three-dimensional scanning technology was employed to quantify the general corrosion and corrosion pits. Eccentric compression tests were carried out on intermediate H-section steel columns to investigate the effect of the different corrosion levels on the failure mode and load-displacement curves, as well as to determine local buckling load based on the load-strain curves. The test results showed that the corrosion characteristic parameters of each cross-section of the steel column exhibited irregularity and variation in all locations, reflecting the heterogeneity of corrosion. The density of corrosion pits exhibited a decreasing trend with increased corrosion duration. Corrosion remarkably reduced both the ultimate carrying capacity and local buckling capacity, with the most severely corroded specimen exhibiting an average cross-sectional area loss rate of 37 %, resulting in a 43 % and 51 % reduction in ultimate load and buckling load compared to the uncorroded specimen. Furthermore, the corrosion features substantially influenced the failure mode, resulting in a transition from overall buckling to local buckling or local-global interaction buckling. A numerical methodology was developed to incorporate the actual surface morphology of corrosion, and the reliability of the modeling method was validated through comparison with experimental results, further revealing the failure mechanism of corroded intermediate H-section steel columns under compression and bending about the strong axis.

Asymmetric deterioration of reinforced concrete marine piles subjected to nonuniformly localized corrosion: Experimental study

Reinforced concrete (RC) marine piles usually suffer from local stiffness deterioration caused by chloride attack in splash and tidal zones. Moreover, pre-existing concrete cracks and defects at the steel–concrete interface usually lead to nonuniformly localized corrosion, which has seldomly been discussed. In this study, the effects of nonuniformly localized corrosion on the lateral behaviours of piles were experimentally studied. The localized electrochemical chloride erosion (LECE) technique was employed, and the corrosion level was represented by the number of corroded steel bars and the length of the corroded sections. Results show that the nonuniform localized corrosion caused asymmetric force–displacement hysteresis curves and changed the failure mode of pile structure under cyclic loading. The highly contrast mechanical responses suggest the importance of the loading directions in assessing the mechanical behaviours of corroded piles. Skeleton curves, stiffness degradation and energy dissipation capacity were further analysed to investigate the bearing capacity of corroded piles. These findings can benefit the comprehensive understandings and assessment of the asymmetric stiffness deterioration of corroded marine RC piles.

Effect of Corrosion on R.C.Columns

Reinforced Cement Concrete is one of the most important structural materials used in the construction industry worldwide. It is expected that these structures will serve for a long period of time. But there are many instances of premature failure of RC structures, raising doubts about its durability. Most of these failures are attributed to the corrosion of reinforcement embedded in concrete. Generally, concrete provides an environment, which should ideally protect the embedded steel. This is true provided the quality of the concrete is good and sufficient cover is provided to the reinforcement. Concrete of low water-cement ratio and good compaction has low permeability that minimizes penetration of corrosive agents like oxygen, carbon-di-oxide, chloride ions etc. Corrosion of reinforcement is an international problem that causes extensive damages to various types of structures. The present project work deals mainly with corrosion of reinforcing steel in concrete columns in saline environment. The influence of concrete mix, concrete cover and reinforcing bar diameter on the rate of corrosion and the loss of bond due to corrosion level of reinforcing bars are also investigated.

Shear Capacity on Corroded Fly Ash Reinforced Concrete Beam Using Galvanostatic Method

Corrosion can be triggered by a chemical reaction to the materials, establishing reinforced concrete's failure. For a long time, researchers have tried to find out how to prevent corrosion, a main structural construction issue. As a technology of waste material, fly ash has predominance, i.e., it is safer and greener than Portland cement. The finer size of fly ash can be an advantage in filling the concrete materials well. This research is about using fly ash as supplementary material on reinforced concrete beams and the galvanostatic method to accelerate corrosion. This research will compare the shear strength after corrosion of each normal beam and fly ash as a supplementary beam. A shear test of fly ash and a normal reinforced beam has been applied. Results showed that fly ash beams have 14% higher compressive strength and 3% higher shear strength with 14% smaller crack width than normal beams after corrosion. It also has a 3,5 times lower rate and 62% level of corrosion than normal beam

Classification of Corrosion Severity in SPCC Steels Using Eddy Current Testing and Supervised Machine Learning Models.

Steel Plate Cold-Rolled Commercial (SPCC) steel is known to have long-term durability. However, it still undergoes corrosion when exposed to corrosive environments. This paper proposes an evaluation method for assessing the corrosion level of SPCC steel samples using eddy current testing (ECT), along with two different machine learning approaches. The objective is to classify the corrosion of the samples into two states: a less corroded state (state-1) and a highly corroded state (state-2). Generative and discriminative models were implemented for classification. The generative classifier was based on the Gaussian mixture model (GMM), while the discriminative model was based on the logistic regression model. The features used in the classification models are the peaks of the perturbated magnetic fields at two different frequencies. The performance of the classifiers was evaluated using metrics such as absolute error, accuracy, precision, recall, and F1 score. The results indicate that the GMM model is more conducive to categorizing states with higher levels of corrosion, while the logistic regression model is helpful in estimating states with lower levels of corrosion. Meanwhile, high classification accuracy can be achieved based on both methods using eddy current testing.

An experimental study into the degradation of elastic, plastic and fracture properties of a pre-corroded ductile material at elevated temperatures

Carbon steel is one of the most commonly used engineering materials. However, the mechanical properties of steel deteriorates due to exposure to harsh environments like corrosive surroundings and high temperatures. Extensive studies have been done to understand the exclusive effect of corrosion and high temperatures on tensile and fracture properties, although their combined effect has not been addressed. The present work aims to experimentally investigate this by conducting tensile and fracture tests at elevated temperatures on pre-corroded ductile steel. Pre-corroded steel was considered with corrosion levels up to 55%. Empirical relationships were established to quantify the degradation in tensile and fracture properties. An unloading compliance approach using a single specimen was utilized to determine the J-integral fracture toughness and also establish traction separation relation for mode I. The results reveal that the combined influence increases the degradation in fracture toughness, but it restricts the degradation in tensile properties.

Experimental behaviour of hybrid carbon steel – stainless steel bolted connections subjected to electrochemical corrosion

To minimise cost in practical applications whilst still obtaining a satisfactory performance, stainless steel is often employed in aggressive marine environments to ensure the durability of the structure, whilst parts of the structure less susceptible to corrosion employ conventional carbon steel. When the two materials are in direct contact in the connection region, galvanic corrosion can occur over time thus leading to an increased level of corrosion of the less noble carbon steel parts and an associated degradation in the structural performance. A comprehensive experimental study on the shear behaviour of hybrid carbon steel – stainless steel bolted connections subjected to electrochemical corrosion is presented in this paper. A total of 30 bolted connection specimens were designed and assembled from hot-rolled carbon steel and stainless steel plates. Two bolt grades, the high strength bolts 10.9 and the precipitation hardening stainless steel bolts 10.9 were used to connect the plates. Employing the electrochemical corrosion method, the specimens were subjected to various levels of corrosion by adjusting the duration over which the specimens were sunk in the corrosive medium, which resulted in both different corrosion morphology as well as different levels of mass loss of the carbon steel plates due to corrosion. The corroded connection specimens were thereafter tested to failure under shear exhibiting 4 different failure modes. The load versus deformation curves were recorded and are reported herein, whilst the observed failure modes were also documented. It was revealed that increased level of corrosions led to decreased levels of bolt pretention forces and ultimate resistances of the connections, albeit the severity of the degradation strongly depended on the adopted joint configuration and resulting failure mode.

Optimized deep learning for steel bridge bolt corrosion detection and classification

Corrosion of steel bridge bolts poses a major threat to structural integrity. As a key component, bridge bolts are susceptible to corrosion and detachment, necessitating close monitoring during maintenance. However, the vast number of corroded bolts presents challenges. Conventional detection relies on subjective visual inspection without unified assessment criteria. Fast and accurate localization and classification of bolt corrosion levels thus became a research priority for bridge maintenance. This study puts forward a new two-stage corrosion detection method, integrating Deep Convolutional Generative Adversarial Network (DCGAN) and improved You Only Look Once version 5 (YOLOv5) networks, which enables rapid categorization of bridge bolts by different corrosion extents, providing an intelligent solution for bridge maintenance. First, in the image preprocessing stage, a DCGAN with least squares loss generates simulated corroded bolt images through adversarial learning to expand the dataset. Second, three corrosion levels are defined based on visual features and percentage of surface rust, with this classification scheme applied in dataset annotation. Finally, the annotated images are input into an enhanced YOLOv5 model named YOLOv5-SE for corrosion identification. To improve accuracy, Squeeze-and-Excitation blocks are added after each residual block in the YOLOv5 backbone. Comparative experiments prove YOLOv5-SE's superior performance over YOLOv5 and other models like Faster R-CNN and VGG16. A pytorch system enables model deployment for corrosion detection. The integration of DCGAN simulation and attention-optimized YOLOv5-SE enables precise classification and localization of corroded bolts. This study represented a significant step towards intelligent upgrades in steel bridge maintenance.

Influence of Organic Coating Thickness on Electrochemical Impedance Spectroscopy Response

Electrochemical Impedance Spectroscopy (EIS) is a non-destructive and powerful technique for characterizing corrosion systems, allowing for the evaluation of surface reaction mechanisms, mass transport, kinetic evolution, and corrosion levels of materials. This study aims to analyze the progression of corrosion using EIS, with a focus on the influence of organic coating thickness. For this purpose, layers of high-purity epoxy paint were applied to carbon steel plates with thicknesses of 50 µm, 80 µm, and 100 µm. During the research, a direct correlation was observed between coating thickness and corrosion resistance, emphasizing the importance of identifying the optimal thickness for each type of coating. Additionally, it was found that thicker coatings may experience electrode penetration due to the tensions generated during deposition, resulting in cracks between the layers, while thinner coatings allow electrolyte penetration as they do not provide adequate protection to the base steel. Therefore, the 80 µm thickness demonstrated greater resistance to corrosion compared to the other tested thicknesses.