Corrosion Penetration Depth Research Articles

Atmospheric corrosion and mechanical property degradation of 2524-T3 aluminum alloy in marine environments

Atmospheric corrosion and the resulting mechanical property degradation of 2524-T3 aluminum alloy in marine environments with different environmental factors are investigated. 2524-T3 aluminum alloy exhibits the most severe corrosion in tropical marine atmosphere, attributed to the highest temperature, humidity, rainfall, Cl- deposition rate, and the longest time of wetness. The EIS results are closely related to the corrosion evolution process. The degradation sensitivity indexed by elongation, reduction-in-area, and tensile strength is correlated with the average corrosion-induced surface defect depth (D′ave), while the elasticity modulus is related to the maximum corrosion penetration depth (Dmax).

Влияние защитного покрытия на процессы коррозии металлических контейнеров для иммобилизации высокоактивных радиоактивных отходов

The article explores nickel-based protective coatings and their influen e on high-temperature changes occurring on the inner surface of steel containers designed for HLW immobilization provided their interaction with the melts of model waste form materials. It evaluates the corrosion behavior of container surfaces with a nickel-based protective coating depending on its application method, i.e., galvanic and chemical. The study indicates the factors governing the corrosion depth, i.e., the depth to which the container steel surface may get altered depending on 4 different waste form material compositions. The study demonstrates high efficien y of the galvanic method in terms of nickelbased protective coating application and the major influen e that high sodium and calcium content has on the depth of corrosion penetration into container surface.

Experimental Study on the Effects of Corrosion in Reinforced Concrete Incorporating Steel Fiber and Ultra-Fine Slag

Abstract: In this work, a thorough review of the literature was conducted with a primary focus on accelerated corrosion-induced corrosion. The report that follows compares different reinforced concrete mixtures following corrosion. By adjusting the transparent cover and reinforcement diameter, a simple reinforced concrete specimen, a specimen of reinforced concrete mixed with steel fiber, and a specimen of reinforced concrete mixed with steel fibre and ultra-fine slag were all produced. Using the accelerated corrosion method, the rate of induced corrosion, the flexural strength before and after corrosion, and the depth of corrosion penetration were compared.

Structure and properties of aluminized alloys of the Fe–Cr–Al system

The formation features of the aluminide coating structure on Cr15Al5 and Cr23Al5 alloys after aluminizing by immersing in aluminum and silumin melt are studied. The influence of Si on the transformation of the structure and phase composition of the aluminide coating under high-temperature heating conditions are studied. It is shown that aluminizing of the Fe–Cr–Al system alloys by immersion in an aluminum melt ensures the formation of a defect-free continuous coating on their surface, which is a crystallized eutectic mixture of Al + FeAl3 and a layered diffusion zone at the boundary with the substrate. Replacing the aluminum melt with silumin with 12 % Si leads to the appearance of the Al7Fe2Si ternary intermetallic compound in the coating composition, which almost completely replaces FeAl3. In the process of hightemperature transformation of the coating structure, the presence of Cr and Si at the initial stage leads to the appearance in the coating composition intermetallic compounds (Cr,Fe)5Al8, Cr3Si, Al7Fe2Si, Fe3(Si,Al)5 and Cr5Si3 along with Fe–Al binary, and at the final stage – does not affect the phase composition, forming solid solutions based on iron aluminides. It is shown that the oxidation of aluminide coating on the Fe–Cr–Al system alloys at its early stages is accompanied by the formation of a stable modification of α-Al2O3 aluminum oxide and (Fe,Cr)2O3 ternary oxide, and with long-term oxidation leads to the appearance of δ-Al2O3 metastable modification and FeAl2O4. It has been established that the Si-alloyed aluminide coating on the Cr15Al5 alloy has a lower corrosion penetration depth at 1100 °C. At the same time, the retention time of heatresistant properties for the aluminide coating on the Cr23Al5 alloy is ~20000 h, and on the Cr15Al5 alloy it is ~5000 h for the aluminide and 6000 h for aluminosilicide coatings.The study was supported by the Russian Science Foundation grant No. 21-79-10246, https://rscf.ru/project/21-79-10246/.

Corrosion characterization of the 6061 Al–Mg–Si alloy in synthetic acid rain using neutron tomography

Neutron tomography has gained increasing importance as an imaging technique for materials characterization. In general, neutron beams are able to show microstructure features of hydrogenous materials, even enfolded with thick metal layers. In the present paper, neutron tomography and observation of cross section images were successfully applied to investigate the corrosion features of the 6061 Al–Mg–Si alloy. The results showed good agreement between neutron 3D tomography and the cross section images obtained in the high attenuation areas of the samples, whereas significant differences in depth of corrosion penetration were obtained between the results from Neutron Tomography and 3D optical profilometry.

Effect of extrusion on the microstructure and corrosion behavior of Mg-Zn-Mn-(0, 1.5)Sr alloys in Hank’s solution

The microstructure, corrosion behavior, and cytocompatibility of as-cast and extruded Mg-Zn-Mn-(0, 1.5)Sr alloys in Hank’s solution are investigated. Grain refinement and preferred texture are confirmed after extrusion, while increase in dislocation density and fragmentation of Mg17Sr2 phases are the distinct features of Sr-free and Sr-containing alloys, respectively. Corrosion rate of Sr-free alloy is significantly accelerated by extrusion, while alloyed Sr eliminates this deterioration process. Alloying of Sr decreases the corrosion rate and enhances the cytocompatibility of the extruded Mg-Zn-Mn alloy without affecting the corrosion penetration depth, demonstrating the superiority of Sr alloying for the extruded magnesium alloy as implant materials.

Comparing the corrosion behaviour of AA2050 and AA7050 aluminium alloys by scanning vibrating electrode and scanning ion-selective electrode techniques

ABSTRACT The susceptibility to localised corrosion of the high strength alloys, AA2050-T84 and AA7050-T7451, used in the aerospace industry, was investigated in this study by localised electrochemical techniques, specifically, scanning vibrating electrode technique (SVET) and scanning ion-selective electrode technique (SIET), in 0.005 mol L−1 NaCl solution. The study was initially carried out using both alloys individually and then, coupling the two alloys and evaluating the effect of galvanic coupling between them. The results revealed that the AA2050-T84, being nobler than the AA7050-T7451, presented higher corrosion current density values when tested in isolation and the depth of corrosion penetration was significantly deeper in the AA2050-T84 alloy than in the AA7050-T7451. However, galvanic coupling of the two alloys resulted in cathodic protection of the AA2050-T84 alloy and a reduction in corrosion current densities on both alloys.

Evaluation of the Heat Resistance of the Fe-Cr-Al System Coatings

The influence of the chemical composition of aluminide coatings of the Fe-Cr-Al system on their heat resistance at 1100 °C was investigated. It is shown that the lowest oxidation rate is possessed by the coating obtained by aluminizing the Cr15Al5 alloy in the silumin melt, for which the depth of corrosion penetration after 500 h at 1100 °C did not exceed 2.5 μm. The depth of corrosion penetration after 500 h at 1100 °C in coatings with a higher chromium content (23 at.%) reaches 8.9 μm. A decrease in the content of chromium (up to 5 at.%) or aluminum (up to 10 at.%) in the surface layer is accompanied by a critical increase in the corrosion rate. The longest time of retention of heat-resistant properties at 1100 °C is possessed by the coating obtained by aluminizing the Cr23Al5 alloy in an aluminum melt.

The combined effect of stress and corrosion on mild steel

This paper reports confirmation of the effect of different levels of tensile stress caused by quasi-static loading on corrosion growth and the mechanical properties of corroded steel. Plastic stressed, elastic stressed and non-stressed specimens have been immersed into hydrochloride acid with acidity ranging from 0.00001 to 1 Molar. Corrosion behaviours of the test specimens are measured after 7, 14 and 28 days. The mechanical properties of steel are then measured at three grinding thicknesses (0, 0.5 mm, and 1.5 mm) at different stress and corrosion combined environments to determine the effect of stress and corrosion on mechanical properties of steel and the corrosion penetration depth. Results show that the applied stress, especially plastic stress, can accelerate corrosion and contribute to the growth of corrosion-induced delamination. The results demonstrate that there are higher degrees of degradation in mechanical properties and faster growth of corrosion penetration depth for plastic stressed steel than elastic stressed and non-stressed specimens over time. The relevant mechanisms are summarized in this paper. This paper attempts to explain of cause-effect relationships between the level of imposed stress, the level of corrosion and the mechanical properties of corroded steel.

Study of the Residual Bond Strength between Corroded Steel Bars and Concrete—A Comparison with the Recommendations of Fib Model Code 2010

As is well known, corrosion of steel reinforcement deteriorates the steel–concrete interface and causes concrete cracking, degrading significantly the bond strength. Several experimental studies have investigated the magnitude of residual bond strength due to corrosion, which affects either the function of corrosion-damaged steel bars or the surface crack width in concrete. As a result, linear and exponential correlation relationships have been proposed in order to predict the bond loss due to corrosion. Based on the results of an ongoing experimental campaign on the degradation of bond strength of RC specimens, combined with comparable outcomes from existing literature, this manuscript summarizes a database, comparing with the recommendations of Model Code 2010, to analyze and interpret the corrosion effect on the bond loss and highlights some points that need improvement in the current regulations. As indicated, the density of transverse reinforcement (stirrups spacing) has intense impact on the resulting bond loss due to corrosion. Hence, in order to quantify this aspect, the present manuscript introduces a discretization of confinement levels of RC elements, depending on the stirrups spacing. Based on this, regression analyses of data were conducted to extract fitting curves of bond loss, taking into account the amount of transverse reinforcement and predictive zones of residual bond strength in relationship to either corrosion penetration or surface crack width. Furthermore, the outcomes demonstrate that the corrosion penetration depth is an appropriate assessment tool to correlate the residual bond strength with the corrosion level, whereas the surface crack width on concrete is not yet an effective index, since there is a plethora of factors affecting the crack width. Due to this, more research is needed to improve the current level of knowledge on the surface crack width and link it with the corrosion damage of the steel bar and the residual bond strength due to corrosion.

THE INFLUENCE OF THE FE-CR-AL SYSTEM COATINGS CHEMICAL COMPOSITION ON THEIR HEAT RESISTANCE

The influence of the chemical composition of the Fe-Cr-Al system coatings on their heat resistance at 1100 °C was investigated. It is shown that the lowest oxidation rate is possessed by the coating obtained by aluminizing the Cr15Al5 alloy in the silumin melt, for which the depth of corrosion penetration after 500 h at 1100 °C was 2.5 μm. The depth of corrosion penetration in coating with a higher chromium content (23 at.%) reaches 8.9 μm. A decrease in the chromium content (up to 5 at.%) or aluminum (up to 10 at.%) in the surface layer is accompanied by a critical increase in the corrosion rate. Based on the kinetics of changes in the aluminum content in the surface layer, it was established that the coating obtained on the Cr23Al5 alloy has the highest heat resistance.

Monitoring of rebar corrosion in concrete structures using a lens-based plastic optical fiber (LPOF) sensor

Corrosion of reinforcement in concrete is one of the major causes for deterioration of concrete structures. This work presents an approach in the monitoring of concrete structures for damage induced by corrosion of steel in concrete using a lens-based plastic optical fiber (LPOF) strain sensor. The optical fiber sensor offers the advantage of being light weight, small in size, low-cost, immune to electromagnetic interference and it does not pose any spark hazard. The intensity-based optical fiber sensor used in this work consists of an emitter fiber, a ball lens, a receiving fiber and a light detector system. The light from the emitter fiber converges to focal point using the ball lens, before it enters the receiver fiber. A change in distance between the ball lens and the receiver fiber would lead to a change in the light intensity transmitted. The intensity change is correlated to the relative distance using a suitable calibration curve. Following the calibration of the sensor, it was used to monitor response of concrete members subjected to flexural loading. Subsequently, the sensor was tested for its ability to monitor corrosion of steel in concrete using an accelerated corrosion test set-up. The sensor shows promising results for detection of corrosion. The test results were used for identification of the corrosion propagation phase, which can be used for predicting the remaining service life of the structures. The optical fiber sensor strain readings were then correlated to the corrosion penetration depth to estimate the extent of damage during the corrosion of rebar. The test results show that it is possible to monitor concrete structures for damage due to flexural loading and corrosion of rebar using an intensity-based LPOF strain sensor.

Contesting crack modes modeling of reinforced concrete structure threatened by the progressive rust expansion in rebars in the presence of external load

Disastrous concrete cracks as initiated by rebars pit corrosion and the resulted rust expansion have continually threatened the vitality of the reinforced concrete structures. In investigating the effects attributed to the rust expansion, existing scholastic works have, however, either focused only on examining one type of major crack or disregarded the influence of the external loading. Therefore, various contesting crack modes of the reinforced concrete structure due to rust progressive expansion from the rebars pit corrosion under external load are analytically modeled in this paper. To begin, such a multi-factors incident has been formulated under the premise of a thick cylindrical section with plane strain conditions and the new consideration of external loading. Considered major contesting crack modes include those of vertical, diagonal, and horizontal. Furthermore, a novel experimentally complying expansion ratio relating the rust expansion with the corrosion penetration depth is introduced into the model. Concrete cover thicknesses are categorized via the fracture mechanics process zone length, LFPZ, in determining the crack mode. In conclusion, thin covers are dominated by the vertical crack whereas thicker covers may crack diagonally or horizontally, depending on LFPZ and the crack tip deformation state. The rust expansion reduces both the moment capacity and the critical crack time to reach the concrete cover surface. tcr, while the critical corrosion penetration depth increases with the concrete cover thickness. However, the horizontal crack when dominating can offset this concrete cover effect by significantly reducing tcr. Additionally, the rust expansion affects the concrete cracking more than the external load.

Performance of recycled aggregate concrete with rice husk ash as cement binder

This research aims to utilize rice husk ash as a cementitious materials in recycled aggregate concrete (RAC). Rice husk ash was ground until the particles remained on a No. 325 sieve were 4.6%wt. Then, the ash was used to partially replace cement at 20 to 50%wt of binder to cast concrete. The compressive strength, steel corrosion, and chloride penetration depth by the impressed voltage method of RAC were examined. The results revealed that the replacement of 20% of ordinary Portland cement (OPC) by ground rice husk ash (GRHA) enhances the compressive strength of the RAC to be greater than the RAC without GRHA at 60 days. Concrete with GRHA at 20 to 50%wt of binder significantly improved the steel corrosion and chloride resistance of the RAC. The utilization of GRHA at 50% to replace OPC gave the highest chloride penetration resistance and produced the lowest steel corrosion of the RAC. Although, the RAC with GRHA had less compressive strength than CT concrete, the concrete provided a positive effect of increasing the resistance of chloride penetration and lowering steel corrosion.

Estimation of the Corrosion Resistance of the Metal Coatings Formed by Powder Metallurgy

A method is suggested to restore the worn surfaces of the components of food-processing equipment, which operate in an aggressive medium and are subjected to corrosive mechanical wear, by electrocontact welding of metallic powders placed in metallic-network containers. A combined additive, which allows one to exclude the losses of adding powder, is used. The corrosion penetration depth in an aggressive medium for metal coatings with a cast-iron addition is studied experimentally.

Models for Prediction of Long-Term Corrosion of Cast Iron Water Mains

Corrosion of cast iron pipes buried in wet soils has long been associated with severe localized effects often attributed to microbiological influences and also with the chemical and physical properties of the soils. Despite more than 70 y of research effort, correlations have remained poor. Recently, the reasons for this have been elucidated, as reviewed briefly herein. Also, interpretation of data from actual cast iron pipes buried in a variety of soils for up to 129 y shows that two critical factors governing depth of local corrosion penetration are the type of soil and the compaction of that soil around the pipe. The latter influences the size of wet air-voids in the soil at the pipe surface. These cause differential aeration and associated severe localized corrosion. The other critical factor is the time of wetness of the soil/metal interface. This is related both to atmospheric precipitation (e.g., rain) and to soil permeability as governed by compaction. Microbiological corrosion has no influence unless essential nutrients continue to be available. These new views on an old subject permit the development of corrosion penetration models for longer-term corrosion.

Predicción del agrietamiento inducido por corrosión en hormigón armado mediante modelización por elementos finitos

Este trabajo propone un método de elementos finitos (FE) para calcular la profundidad de penetración por corrosión (rcrit) en las armaduras de acero, necesaria para originar la aparición de la primera grieta visible en el recubrimiento de hormigón. El análisis por FE se ha llevado a cabo utilizando el programa comercial ANSYS. El método de FE obtenido se ha desarrollado en función del espesor del recubrimiento de hormigón libre (C), el diámetro de la armadura (D), la longitud de la zona anódica (L), y el tipo de hormigón. Los resultados obtenidos muestran una gran influencia de la corrosión localizada (pequeñas zonas anódicas frente a grandes zonas catódicas) en la predicción del valor de rcrit. Esta influencia sólo puede ser analizada tridimensionalmente. El modelo de FE propuesto se validó utilizando datos de la bibliografía. La originalidad del procedimiento propuesto radica en la consideración de la dirección longitudinal en el análisis, para tener en cuenta la extensión de la zona anódica. El tipo de corrosión tiene una gran dependencia de la relación entre C/L, ocasionando corrosión uniforme para valores entre 0,02 < C/L < 0,1, y originando corrosión localizada para valores entre 0,5 < C/L < 4,0.

EIS study of oxidation heat‐treatment effects on corrosion behavior of Ni10Cu11Fe6Al metallic inert anode inside molten calcium chloride salt

In this research, the effects of oxidation heat‐treatment on the high‐temperature corrosion behavior of Ni10Cu11Fe6Al (wt%) alloy was investigated as a new inert anode in titanium electrolytic production. The alloys were prepared using vacuum induction melting (VIM) process and then exposed to the electrolysis in calcium chloride molten salt at 900 °C at −1.6 V versus graphite reference electrode for different immersion times. The cross‐section and surface of the alloys were characterized using scanning electron microscope (SEM), and their electrochemical behavior was investigated by electrochemical impedance spectroscopy (EIS). The results showed that the oxidized alloys have the greater number of porosities compared to those of the unoxidized alloys. Thus, the nickel‐based alloy became more sensitive to pitting resulting from oxidation. The corrosion penetration depth reached about 400 µm after 16 h of electrolysis for the oxidized alloys while being nearly 213 µm for the unoxidized alloys, which indicates the corrosion penetration depth increased by oxidation. Therefore, the oxidation during the electrolysis inside the molten salt offers better results for this alloy.

Space-time Gaussian models for evaluating corrosion-induced damages in reinforcing bars

Chloride-induced steel reinforcing bars corrosion is a problem of worldwide importance because, in addition to massive industrialization, a majority of human population inhabit marine atmosphere zones where salinity is the main source of built infrastructure deterioration. Reinforced concrete structures vulnerable to chloride-induced corrosion potentially experience two stages of damage, namely non-structural and structural. Till date, with regard to non-uniform corrosion, there is very limited information regarding the significant role played by the non-structural stage of damage in influencing the progression of structural damage. The present work examines the process of non-uniform chloride ingress into concrete due to the existence of the steel bars and its influence on the spatial and temporal variations in the depth of corrosion penetration. Mathematical models in the form of Gaussian functions are proposed to represent space-time variation in corrosion initiation, spatial spread of corrosion penetration depth and corroded bar morphologies, and are compared with literature data. A numerical inverse analysis procedure is introduced to predict space-time evolution of non-structural damage from experimentally observed spatial spread of structural damage. Further, applicability of superposition approach for the evaluation of corrosion-induced stresses around the steel–concrete interface of a corner reinforcing bar is explored and shown to introduce spatial and temporal errors while evaluating structural damages.

Mechanical aspects of simulating crack propagation in concrete under steel corrosion

This paper presents mechanical consequences in concrete caused by steel corrosion with various types of models. According to the simulation approach for rust expansion, numerical models are classified into hollow concrete model with applied radial displacement or pressure, concrete/steel composite with steel expansion and full model of concrete/rust/steel composite with rust layer expansion. Qualitative and quantitative comparisons of results from various models are made in order to assess their accuracy. In various models, besides the stress and displacement states in concrete are different, the corrosion level is also represented differently, which should be noticed when interpreting the modeling results of corrosion level-crack level relation. Under the same corrosion penetration depth, corrosion expansion represented by the free increase of steel radius due to corrosion in the analytical cylinder models and hollow concrete model is larger than the final rust thickness calculated in the full model. In addition, the final rust thickness around the steel perimeter and the rust thickness/corroded depth ratio is shown to be non-uniform under both uniform and non-uniform corrosion, which is caused by the local cracking in concrete.