Effect Of Atmospheric Corrosion Research Articles

Insights into the degradation mechanism of Fe-40Ni-15Co superalloy exposed to marine atmospheric and high-temperature conditions

This study investigated the corrosion and oxidation mechanism of the Cr-free Fe-40Ni-15Co superalloy with exposure to a tropical marine atmosphere for one year and a subsequent high temperature of 650 °C for 300 h. The degradation behavior of the samples was evaluated based on surface characterization and analysis. In the tropical marine atmospheres, the corrosion process of the Fe-40Ni-15Co superalloy presented an initial localized type after one month of exposure and gradually developed into uniform. The corrosion products were mainly comprised of Fe2O3 and NiO, suppressing the pitting process. During the high-temperature oxidation process, all samples presented super-parabolic oxidation kinetics. Except for the initial active oxidation due to salt deposits, the corrosion products after atmospheric exposure could significantly enhance the oxidation resistance at 650 °C. An explanation for the degradation mechanism of the Fe-40Ni-15Co superalloy was developed based on the synergistic effects of atmospheric corrosion and high-temperature oxidation.

The Effect of Exposure Condition on the Composition of the Corrosion Layers of the San Carlone of Arona

The Colossus of San Carlo Borromeo, named San Carlone for its large dimensions, represents a unique opportunity to study the long-term effects of atmospheric corrosion on patina formation on historic copper sheets. The sculpture’s large dimensions, complex geometry, direct visitor interaction, and exposure conditions generate different microclimates. The purpose of this study is to understand how and to what extent these microclimates affect the formation of the copper patinas. The results show that microclimates play a key role in patina formation: in external surfaces exposed to rain, the main constituent is brochantite, whereas a wider variety of corrosion products have been found in sheltered and internal surfaces, such as antlerite, atacamite, copper oxalate, posnjakite, and anglesite.

Effect of static elastic stress on the corrosion behavior of 7A04 aluminum alloy exposed to real marine atmospheric environment

Aluminum alloy structural materials are widely subjected to the interactive effect of atmospheric corrosion under thin liquid film and elastic stress during the actual service. This study utilized the real marine atmospheric environment as the corrosion environment of thin liquid film for 7A04 aluminum alloy, and the specially designed outdoor device was used to apply varying levels of static elastic tensile stress at the same time, and then the corrosion damage behavior of 7A04 alloy under the interactive effect was studied. The research indicates that the 7A04 alloy suffers from pitting and exfoliation corrosion under the test conditions. The applied elastic tensile stress can accelerate the corrosion damage process of 7A04 alloy, and the degree of acceleration increases with increasing stress levels and exposure time. Moreover, the applied stress can also significantly accelerate the deterioration of the mechanical properties of 7A04 alloy, which has a more prominent effect on the elongation after fracture. Additionally, the corrosion mechanism of 7A04 alloy under the interactive effect was also discussed in this paper.

The Effect of Atmospheric Corrosion on Steel Structures: A State-of-the-Art and Case-Study

Atmospheric corrosion can seriously affect the performance of steel structures over long periods of time; thus, it is essential to evaluate the rate of corrosion and subsequent modification of dynamic properties of a structure over different time periods. Standards and codes represent the general guidelines and suggest general protection techniques to prevent structures from corrosion damage. The available models in the literature propose the thickness reduction method that accounts for the exposure time of structures in corrosive environments. The purpose of this study is to review the existing corrosion models in the literature and report as well as compare their effectiveness in low (C2 level), medium (C3 level) and high (C4 level) corrosivity class in accordance with the ISO standard. Furthermore, the influence of corrosion loss during the lifetime of a structure is studied through a realistic case study model using FEM (finite element method) in both linear and nonlinear regions. The results showed that the corrosion can considerably affect the dynamic characteristics of the structure. For instance, the vibration period rose up to 15% for the C4 class and 100-year lifespan. Additionally, the corroded structure presented higher acceleration and drift demand, and the base reaction forces were reduced up to 60% for the same class and time period.

Critical Assessment of the Effect of Atmospheric Corrosion Induced Hydrogen on Mechanical Properties of Advanced High Strength Steel

Hydrogen absorption into steel during atmospheric corrosion has been of a strong concern during last decades. It is technically important to investigate if hydrogen absorbed under atmospheric exposure conditions can significantly affect mechanical properties of steels. The present work studies changes of mechanical properties of dual phase (DP) advanced high strength steel specimens with sodium chloride deposits during corrosion in humid air using Slow Strain Rate Test (SSRT). Additional annealed specimens were used as reference in order to separate the possible effect of absorbed hydrogen from that of corrosion deterioration. Hydrogen entry was monitored in parallel experiments using hydrogen electric resistance sensor (HERS) and thermal desorption mass spectrometry (TDMS). SSRT results showed a drop in elongation and tensile strength by 42% and 6%, respectively, in 27 days of atmospheric exposure. However, this decrease cannot be attributed to the effect of absorbed hydrogen despite the increase in hydrogen content with time of exposure. Cross-cut analysis revealed considerable pitting, which was suggested to be the main reason for the degradation of mechanical properties.

PROTECTIVE PROPERTIES OF OIL PRODUCTS RECEIVED OF WASTE

The protective properties of petroleum products obtained with the use of secondary raw materials, in particular plastic oils and polymer-containing bitumen, are investigated. The technology of obtaining plastic oils, was to conduct thermal degradation of polymeric wastes of polyethylene, polypropylene and polystyrene under laboratory conditions at atmospheric pressure in a batch reactor, with subsequent removal from the products of high-boiling fractions (onset of boiling > 320 °C), which match to plastic lubricant by their properties. Bitumen, in turn, was obtained by compounding high-boiling oil residues, in particular oil sludge with 10% by weight of polymeric additives of polypropylene and expanded polystyrene. For these products, resistance to atmospheric corrosion arising from the operation or storage of materials with metallic surfaces in open air, and environmental corrosion, which arises from the location of technological equipment and communications in the soil, especially in the presence of moisture, was investigated. In the process of researching it was found that both plastic oils and tested bitumen with all types of polymers have high protective properties. They prevent the formation of grade 3 metal sheets in aqueous solutions of 10 % NaCl and 3 % Na2SO3 corrosion cells, which mimic the effects of atmospheric corrosion. The study of the influence of electrochemical corrosion was carried out using polarization dependences obtained under laboratory conditions, using the potentiostat P-45X. To determine the protective properties we used working electrodes made of carbon steel grade St3 (Celsius = 0.14 cm2), reinforced in a frame of epoxy resin ED-5 with a hardener polyethylene polyamine with a deposited layer (layer thickness 0.1 mm) of the investigated of petroleum products that were placed in 0.5 M NaCl solution.It was determined that during the studies for 30 days, in the considered range of values, there was no change in the current density at a constant value of the potential (2.5 V), indicating the absence of electrochemical corrosion and the high protective properties of petroleum from secondary raw materials.

Tests on axial strength of circle CFST stub columns under marine atmosphere in cold region

This paper aims to study the compressive behavior of circular concrete-filled steel tubular stub columns under marine atmosphere in cold region. The specimens after salt spray corrosion and freeze-thaw cycles were tested under axial compressive load where steel grade, corrosion rate and freeze-thaw cycles were considered. The experimental phenomena and results are discussed in detail. Current design methods for circular concrete-filled steel tubular stub columns were modified to consider the effect of atmospheric corrosion and freeze-thaw cycles. The results show that the corrosion rate, the cycle number and steel strength have little effect on the failure pattern of circular CFST stub columns, neither on the failure pattern of core concrete. The ultimate strength of specimens is reduced approximately linearly with the increase of corrosion rate and freeze-thaw cycles regardless of steel strength. Strength reductions of the specimens using Q235 steel are smaller than those of the counterparts using Q345 steel. The ultimate displacement and ductility indexes of the specimens are decreased by corrosion rate and freeze-thaw cycle. The enhancement factor φ tends to increase with the increase of test period which indicates that confinement effect contributes to resist the strength reduction due to corrosion and freeze-thaw cycle. Various design standards combined with the reduction factor proposed based on experimental results are adopted to predict the ultimate strength of CFST stub columns under atmospheric corrosion and freeze-thaw cycle.

Long-term atmospheric pre-corrosion fatigue properties of epoxy primer-coated 7075-T6 aluminum alloy structures

Atmospheric exposure tests of epoxy primer-coated 7075-T6 structures were carried out in the coastal environment for 7, 12 and 20 years. These structures included plate specimens, center hole plate specimens, and cold-expanded hole specimens. The characteristics of surface corrosion, atmospheric sediments, and corrosion products of specimens were studied. The P-S-N curves of plate specimens exposed for different years were then measured by the single-point test. In addition, the degradation characteristics of fatigue life of specimens with holes after different years of exposure were investigated. Finally, the mechanism of the effect of atmospheric corrosion on the fatigue properties was analyzed.

Effect of coastal atmospheric corrosion on fatigue properties of 2024-T4 aluminum alloy structures

To investigate the effect of atmospheric corrosion on the fatigue properties of 2024-T4 aluminum alloy structures during the whole corrosion period, atmospheric and accelerated pre-corrosion fatigue tests were carried out. Field exposure tests were carried out for 7, 12, and 20 years. A laboratory accelerated corrosion test method was proposed to simulate the whole atmospheric corrosion period from initial pitting to the subsequent exfoliation corrosion, and the reliability was verified through an analysis of the corrosion morphology, corrosion products, and thickness variation. Pitting and intergranular corrosion occurred after a short exposure to atmospheric corrosion, and intergranular corrosion was the dominant corrosion damage mode. The fatigue cracks initiated at the deepest boundary of intergranular corrosion. The fatigue life decreased dramatically during the initial stage of atmospheric corrosion and then decreased more slowly. Finally, the mechanism through which atmospheric corrosion affected the fatigue properties was analyzed.

Study on the effect of atmospheric corrosion on mechanical properties with impact test: Carbon steel and Galvanized steel

The present work presents the behavior of carbon steel and galvanized steel against atmospheric corrosion after 3 years of exposure at seven locations around the region of Valparaiso, Chile. Results show a relation between corrosion rates and environmental and meteorological conditions, categorized as CX for the Quintero zone, and C3 and C2 in the remaining six zones. Corrosion rate behaviors and material toughness losses were modeled using power functions and neural networks, found to be a function of environmental exposure time. Losses were greater for carbon steel in coastal and industrial environments, reaching 70 to 80%. This effect was reduced in galvanized steel, not exceeding 15% over the same period of exposure. The relationship between corrosion rate and loss of toughness of both materials was modeled using neural networks.

Effect of atmospheric corrosion on Al and Ti thin film deposited on steel surface in urban region

Pure metals Aluminum (Al) and Titanium (Ti) thin films have been deposited on steel by using physical vapor deposition. The effect of these protective layers on atmospheric corrosion steel surface have been investigated after exposure the samples for one year to urban atmosphere. The rust morphology observed using Scanning Electronic Microscope (SEM) analysis consists of a cotton ball structure for the steel samples coated with Al, and flowery structure for samples coated with Ti. The Raman spectroscopy (RS) used in this study consolidates deeply the information about the structure of the rust layer. The Al coating shows the predominance growth of iron oxide as goethite. However in case of uncoated steel or Ti coating, the oxide structure was principally lepidocrocite. Raman shifting to high wavenumber values gave stretching corresponding to diaspore. The comparison of Raman bands for the Ti coating on steel to the literature suggests that in our case the Ti films are not converted to a protective layer of anatase or rutile during exposure. This result can explain the important growth of the rust layer in atmosphere and suggest that Ti acting as a getter for atmospheric pollutant. However, the Al steel coating present an interesting resistant to atmospheric corrosion.

Performance evaluation of a reticulated shell with atmospheric corrosion damage

The study on damage evaluation induced by atmospheric corrosion of engineering structures has attracted more and more international concern over the past three decades. However, the effects of atmospheric corrosion on reticulated shells have not been systematically investigated. In this regard, the performance assessment of a reticulated shell subjected to atmospheric corrosion damage is actively conducted in this study. The atmospheric corrosion model of shell elements is first presented, and a refined exponential model for estimating the corrosion depth of steel materials is developed by using the pattern recognition technique. The sensitivity of stiffness matrix to element thickness is established by using Euler–Bernoulli beam element. The sensitivity of mass matrix to element thickness is developed based on lumped mass assumption. Then, the expression of natural frequency sensitivity to element thickness and mass is derived by considering the section loss induced by both the inner and outer surface corrosion. In addition, the explicit expression of frequency sensitivity to mass of spherical joints is also established in detail. The nonlinear static structural analysis is conducted to evaluate effects of atmospheric corrosion on the stress of structural elements. A real reticulated shell constructed in northern China is taken as the example structure to examine the feasibility of the proposed approach and to assess the potential damage caused by atmospheric corrosion to the structure.

Effect of Atmospheric Corrosion on the Mechanical Properties of SAE 1020 Structural Steel.

Resistance to atmospheric corrosion in different environments located in Chile and the corrosion’s effect on the mechanical properties of SAE 1020 steel were studied. Atmospheric corrosivity categories at each station under study were determined. These categories were C2, for Laja; C3 and C4, for the Arica and Antarctic stations, respectively; and the most aggressive, C5 and higher at Quintero. These specific environments significantly influenced the mechanical responses of steel exposed for 36 months. Rupture elongation, the modulus of toughness, ultimate tensile strength, and hardness of the material all decreased as a function of environmental atmospheric aggressiveness. Lowered ductility is the result of the increased corrosion rate due to the high deposition of chlorides. This is due to the morphology of material degradation, which consequently occurs as pores, microstrains, and other defects that promote early rupture of the steel.

Degradation of silver near-field optical probes and its electrochemical reversal

Deterioration of the outstanding optical properties of elemental silver due to atmospheric corrosion compromises its use in the field of plasmonics. Therefore, more chemically inert, but more lossy, metals (e.g., gold) are often used as a compromise. Silver tips for near-field optical microscopy are only utilized by specialized laboratories with in-house tip production facilities. This article presents a time-dependent study of the effect of atmospheric corrosion on the electromagnetic enhancement of solid silver tips. It was found that chemical degradation renders them unusable for tip-enhanced Raman spectroscopy (TERS) within the first two days after production. Furthermore, we present a simple electrochemical method for recovering the enhancing effect of corroded silver tips, as well as for storing freshly prepared probes, for example, for easy shipment. The present work greatly simplifies the experimental aspects of near-field optical microscopy, which should make near-field optical techniques, and, in particular, TERS, more accessible to the scientific community.

Atmospheric corrosion effects of air pollution on materials and cultural property in Kathmandu, Nepal

Carbon steel, zinc and limestone samples were exposed in Kathmandu for one year. Their corrosion was measured at ten locations and related to SO2, NO2, O3, HNO3 and PM concentrations and climatic factors. Corrosion rates vary considerably and are correlated mainly with the SO2 concentration. Estimated policy targets for SO2 are most stringent for limestone, in the range 3 to 6 μg m−3. The Kathmandu carbon steel and limestone samples matched a general pattern from exposures at more than twenty sites in Asia and Africa. At these Asian/African sites corrosion of copper is generally higher than corrosion of zinc. This is in contrast to experiences from European conditions where corrosion of zinc is higher than corrosion of copper.

Effects of Atmospheric Corrosion on the Car Park Roof Structure

The effects of the outdoor climatic conditions are observed in all constructions. Steel members of such constructions are affected negatively by urban atmospheres in a synergy with the effects of industrial pollutants. In very exposed buildings the impact of such effects is so significant that diagnostic assessment of their state and technical expertise is required. The paper presented shows the actual state assessment and the verification of structural reliability of the existing load-bearing structure of an exterior car park roof, emphasizing the estimation of corrosion losses in the steel structure that have considerably lowered its lifespan and obstructed its safe operation.

Studies of Evaluation of Hydrogen Embrittlement Property of High-Strength Steels with Consideration of the Effect of Atmospheric Corrosion

Hydrogen embrittlement of high-strength steels was investigated by using slow strain rate test (SSRT) of circumferentially notched round bar specimens after hydrogen precharging. On top of that, cyclic corrosion tests (CCT) and outdoor exposure tests were conducted prior to SSRT to take into account the effect of hydrogen uptake under atmospheric corrosion for the evaluation of the susceptibility of high-strength steels. Our studies of hydrogen embrittle properties of high-strength steels with 1100 to 1500 MPa of tensile strength and a prototype ultrahigh-strength steel with 1760 MPa containing hydrogen traps using those methods are reviewed in this article. A power law relationship between notch tensile strength of hydrogen-precharged specimens and diffusible hydrogen content has been found. It has also been found that the local stress and the local hydrogen concentration are controlling factors of fracture. The results obtained by using SSRT after CCT and outdoor exposure test were in good agreement with the hydrogen embrittlement fracture property obtained by means of long-term exposure tests of bolts made of the high-strength steels.

Voltage Controlled Current Source for Atmospheric Corrosion Measurements

Although the effects of atmospheric corrosion may be the most evident of all corrosion processes, obtaining accurate in-situ measurements that can be used to predict corrosion rate accurately is a difficult task. The authors present the design and construction of an analogue circuit that can operate as a potentiostat / galvanostat and allow electrochemical noise measurements intended for a multimodal portable corrosion measurement system for remote monitoring. The actuator section was simulated and tested in the laboratory for galvanostat/potentiostat operation. The experimental results agreed with simulations. The circuit was also used for electrochemical noise measurements using galvanized steel and stainless steel electrodes. An increased electrochemical noise measurement was obtained for corroded electrodes compared to intact electrodes. The results suggest that the proposed circuit can be used to build portable, multimodal equipment, capable of producing ± 75 mA @ ± 5V (maximum) for in-situ monitoring of environmental corrosion levels.

Evaluation on Environmental Corrosion Damage of Steel Domes

The evaluation on environmental corrosion damage of steel domes is carried out in this study through an integration of knowledge in material science and structural analysis. The refined exponential model for estimating corrosion of steel materials is presented based on long-term experimental data available. The formula for relating structural natural frequency sensitivity to structural member thickness is then derived to assess the sensitivity of natural frequency to variation of member thickness due to corrosion. The nonlinear static analysis is conducted to evaluate effects of atmospheric corrosion on the stress of structural members and the safety of steel space structures. A real steel dome built in China is taken as the case study to examine the feasibility of the proposed approach and to assess the potential corrosion damage to the structure..

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.