Search

The effect of boron (B) on stress corrosion resistance of S31254 in the presence of residual stresses has been studied. The microstructure and corrosion resistance of S31254 containing B at different levels of cold deformation are analyzed in this study. In the results, it is shown that B favors the improvement of deformation uniformity of S31254. The grain boundary (GB) and slip bands have better corrosion resistance at 5% deformation, and the overall corrosion resistance is better than that of the undeformed state, with smaller passivation current density and narrower width of GB corrosion grooves, especially for the 40B samples. At 30% deformation, the overall corrosion resistance of 40B S31254 is better than 0B due to improved deformation uniformity. [ABSTRACT FROM AUTHOR]

There is a need for high-throughput, scale-relevant, and direct electrochemical analysis to understand the corrosion behavior and sensitivity of nuclear materials that are exposed to extreme (high pressure, temperature, and radiation exposure) environments. We demonstrate the multi-scale, multi-modal application of scanning electrochemical cell microscopy (SECCM) to electrochemically profile corrosion alterations in nuclear alloys in a microstructurally resolved manner. Particularly, we identify that both mechanically deformed and irradiated microstructures show reduced charge-transfer resistance that leads to accelerated oxidation. We highlight that the effects of mechanical deformation and irradiation are synergistic, and may in fact, superimpose each other, with implications including general-, galvanic-, and/or irradiation-activated stress-corrosion cracking. Taken together, we highlight the ability of non-destructive, electrochemical interrogations to ascertain how microstructural alterations result in changes in the corrosion tendency of a nuclear alloy: knowledge which has implications to rank, qualify and examine alloys for use in nuclear construction applications. [ABSTRACT FROM AUTHOR]

Electrodeposited chromium plating continues to be widely used in a number of specialized areas, such as weapons, transport, aerospace, etc. However, the formation of texture, hydrogen content and residual stress can degrade the serviceability and lead to material failure. The effect of post heat treatment processes on the relationship of texture, hydrogen content, residual stress and corrosion resistance of hexavalent [Cr(VI)] chromium coatings deposited on Cr–Ni–Mo–V steel substrates was investigated. Macrotexture was measured by XRD. Microtexture, dislocation density and grain size were studied by EBSD. With the increase of the heat treatment temperature, it was found that the fiber texture strength of the (222) plane tended to increase and subsequently decrease. Below 600 °C, the increase in the (222) plane texture carried a decrease in the hydrogen content, residual stress, microhardness and an increase in the corrosion resistance. In addition, crack density and texture strength were less affected by the heat treatment time. Notably, relatively fewer crack densities of 219/cm2, a lower corrosion current density of 1.798 × 10−6 A/dm2 and a higher microhardness of 865 HV were found under the preferred heat treatment temperature and time of 380 °C and 4 h, respectively. The hydrogen content and residual stress were 7.63 ppm and 61 MPa, with 86% and 75% reduction rates compared to the as-plated state, respectively. In conclusion, in our future judgement of the influence of heat treatment on coating properties, we can screen or determine to a certain extent whether the heat treatment process is reasonable or not by measuring only the macrotexture. [ABSTRACT FROM AUTHOR]

The stress corrosion behavior of Ti‐6Al‐3Nb‐2Zr‐1Mo (Ti6321, in wt%) alloy in seawater with different dissolved oxygen (DO) concentrations was investigated using X‐ray photoelectron spectroscopy, energy dispersive spectrometer, electrochemical measurements, and other advanced methodologies. The results indicate that when the DO concentration in seawater is insufficient, the passivation film will preferentially form on the α‐phase surface. Meanwhile, insufficient DO concentration leads to incomplete oxidation of the surface passivation film, resulting in an increase in surface defects. Hydrogen produced by reactions at crack tips is more likely to enter the surface of the titanium alloy through these defects, and under the influence of HEDE and HELP mechanisms, promote crack propagation. [ABSTRACT FROM AUTHOR]

The study of fracture mechanics is usually within the paradigm of a failure mode that needs to be avoided. However, both in nature and in modern technology, there exist several situations where an ability to fracture is essential. In this work, we consider the problem of machining highly ductile and strain-hardening metals, such as annealed Cu, Al and Ta. These metals are known by the moniker "gummy metals" due to the large forces and poor surface finish associated with machining them. We investigate a chemo-mechanical technique involving adsorption of organic monolayers on the metal surfaces that causes the metals to become relatively brittle. This transition from ductile to brittle results in > 50% drop in the cutting force and an order of magnitude improvement in the surface finish. Molecular dynamics simulations of the phenomenon show the organic monolayers impose a surface stress on the metal surface which results in arresting of the dislocations close to the surface. The results suggest that a deeper understanding of the underlying mechanism has implications in environment-assisted cracking, stress-corrosion cracking and hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

The corrosion fatigue behavior of welded joints is a critical concern in the transportation industry, which shortens their service life. In this paper, the corrosion damage of 5083/6005A welded joints exposed to different conditions (3.5% NaCl + 0.01 mol/L NaHSO3, 3.5% NaCl, 0.6 mol/L NaHSO3, and 3.5% NaCl + 0.01 mol/L NaHSO3-75 MPa) was investigated by using tensile and fatigue tests, polarization curves, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The findings indicate that elongation and fatigue life were most adversely affected by exposure to 3.5% NaCl + 0.01 mol/L NaHSO3-75 MPa. This was followed by the exposure to 3.5% NaCl + 0.01 mol/L NaHSO3, then 3.5% NaCl, with the mildest effects observed under 0.6 mol/L NaHSO3. The corrosion mechanisms were elucidated and the corrosion model was established through the analysis of corrosion morphologies and corrosion products. The corrosion fatigue fracture model was developed by analyzing the fracture surfaces. These findings provide references for preventing the corrosion-fatigue fractures of 5083/6005A welded joints, extending their service life, and enhancing the operational safety and reliability of trains. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the intricate and volatile nature of the service environment surrounding prestressing anchoring materials, stress corrosion poses a significant challenge to the sustained stability of underground reinforcement systems. Consequently, it is imperative to identify effective countermeasures against stress corrosion failure in cable bolts within deep underground environments, thereby ensuring the safety of deep resource extraction processes. In this study, the influence of various coatings on the stress corrosion resistance of cable bolts was meticulously examined and evaluated using specifically designed stress-corrosion-testing systems. The specimens were subjected to loading using four-point bending frames and exposed to simulated underground corrosive environments. A detailed analysis and comparison of the failure patterns and mechanisms of specimens coated with different materials were conducted through the meticulous observation of fractographic features. The results revealed stark differences in the stress corrosion behavior of coated and uncoated bolts. Notably, epoxy coatings and chlorinated rubber coatings exhibited superior anti-corrosion capabilities. Conversely, galvanized layers demonstrated the weakest effect due to their sacrificial anti-corrosion mechanism. Furthermore, the effectiveness of the coatings was found to be closely linked to the curing agent and additives used. The findings provide valuable insights for the design and selection of coatings that can enhance the durability and reliability of cable bolts in deep underground environments. [ABSTRACT FROM AUTHOR]

In this work, the stress corrosion cracking (SCC) behavior of X90 steel was investigated at various cathodic protection potentials by slow strain rate tensile tests, crack growth tests, electrochemical measurements and scanning electron microscope. The results show that the crack growth behavior of X90 steel in high pH soil environment is controlled by the microenvironment-electrochemical interaction at the crack tip. Under the combined action of anodic dissolution and hydrogen embrittlement, the SCC susceptibility decreases at first and then increases with the negative shift of cathodic protection potential. The pH value and Cl- concentration at the crack tip are affected by the potential outside the crack. Crack growth rate (CGR) is fundamentally affected by the cathodic protection potential, and the minimum CGR is − 850 mV/SCE. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to explore the influence of corrosion-deformation interactions (CDI) on the corrosion behavior and mechanisms of 316LN under applied tensile stresses. Design/methodology/approach: Corrosion of metals would be aggravated by CDI under applied stress. Notably, the presence of nitrogen in 316LN austenitic stainless steel (SS) would enhance the corrosion resistance compared to the nitrogen-absent 316L SS. To clarify the CDI behaviors, electrochemical corrosion experiments were performed on 316LN specimens under different applied stress levels. Complementary analyses, including three-dimensional morphological examinations by KH-7700 digital microscope and scanning electron microscopy coupled with energy dispersive spectroscopy, were conducted to investigate the macroscopic and microscopic corrosion morphology and to characterize the composition of corrosion products within pits. Furthermore, ion chromatography was used to analyze the solution composition variations after immersion corrosion tests of 316LN in a 6 wt.% FeCl3 solution compared to original FeCl3 solution. Electrochemical experiment results revealed the linear decrease in free corrosion potential with increasing applied stress. Electrochemical impedance spectroscopy results indicated that high tensile stress level damaged the integrity of passivation film, as evidenced by the remarkable reduction in electrochemical impedance. Ion chromatography analyses proved the concentrations increase of NO3− and NH4+ ion concentrations in the corrosion media after corrosion tests. Findings: The enhanced corrosion resistance of 316LN SS is attributable to the presence of nitrogen. Research limitations/implications: The scope of this study is confined to the influence of tensile stress on the electrochemical corrosion of 316LN at ambient temperatures; it does not encompass the potential effects of elevated temperatures or compressive stress. Practical implications: The resistance to stress electrochemical corrosion in SS may be enhanced through nitrogen alloying. Originality/value: This paper presents a systematic investigation into the stress electrochemical corrosion of 316LN, marking the inaugural study of its impact on corrosion behaviors and underlying mechanisms. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to study the formation mechanism of micro-arc oxidation (MAO) coating on AZ31 magnesium alloy and how the annealing process affects its corrosion resistance. Design/methodology/approach: This study involved immersion experiments, electrochemical experiments and slow strain rate tensile experiments, along with scanning electron microscopy, optical microscopy observation and X-ray diffraction analysis. Findings: The findings suggest that annealing treatment can refine the grain size of AZ31 magnesium alloy to an average of 6.9 µm at 300°C. The change in grain size leads to a change in conductivity, which affects the performance of MAO coatings. The MAO coating obtained by annealing the substrate at 300°C has smaller pores and porosity, resulting in better adhesion and wear resistance. Originality/value: The coating acts as a barrier to prevent corrosive substances from entering the substrate. However, the smaller pores and porosity reduce the channels for the corrosive solution to pass through the coating. When the coating cracks or falls off, the corrosive medium and substrate come into direct contact. Smaller and uniform grains have better corrosion resistance. [ABSTRACT FROM AUTHOR]

To cope with harsh working conditions, new corrosion-resistant coated steel wires with higher tensile strength have been developed. This study investigates the corrosion characteristics of a new zinc–aluminum alloy-coated steel wire under stress conditions. The particulate corrosion products generated by the oxidation of the coating in the initial stage of corrosion are converted into layer-structured corrosion products at the early stage of corrosion. Moreover, high-stress conditions have a significant influence on the critical conversion time from the coating corrosion stage to the iron matrix corrosion stage. Thus, the uniform corrosion depth (i.e., the mass loss rate) could be fitted with a continuous power function model rather than the previously used two-stage model owing to an ambiguous moment of conversion under stress conditions. The pitting corrosion depth could be fitted with a lognormal distribution in this study. The probability distributions for the aspect ratios of corrosion pits under different stress conditions tended to be consistent. Finally, the block's maximum pitting factor followed a Gumbel distribution with a scale parameter that changed linearly with the stress level and a location parameter related to the square of the stress level. [ABSTRACT FROM AUTHOR]

In this investigation, we explored the corrosion inhibition mechanism of an imidazoline quaternary ammonium salt (IQA) on J55 steel in simulated annulus environment through a series of experiments, including electrochemical testing, stress corrosion immersion experiments, and hydrogen permeation testing. Our findings reveal that IQA functions as a mixed-type inhibitor, exerting its inhibitory action through chemical adsorption. Notably, it exhibits a stronger inhibitory effect on the anodic dissolution reaction compared to the cathodic hydrogen evolution reaction. Despite the minor influence of tensile plastic strain on the average inhibition efficiency, it notably exacerbates pitting and initiates stress corrosion cracking. This underscores the limitation of average inhibition efficiency in accurately assessing IQA's efficacy against stress corrosion. Additionally, hydrogen permeation experiments and electrochemical testing demonstrate that plastic strain diminishes IQA's inhibitory effect on the cathodic hydrogen evolution reaction, facilitating hydrogen diffusion into the steel substrate and thereby exacerbating stress corrosion in J55 steel. Consequently, at low IQA inhibitor concentrations (as in this study, 12.5 mg L−1), despite high average inhibition efficiency, it proves ineffective in mitigating stress corrosion.

An accurate measurement of the bonding energy of an interface is important in many areas of applied research. We present a novel method for measuring the bonding energy, which is based on the principle of non-planar direct bonding, i.e., direct bonding of originally planar wafers onto non-planar substrates. We discuss in detail the advantages and disadvantages compared to the commonly used double cantilever beam method. To demonstrate the practical relevance, by using the example of glass wafers, the evolution of the bonding energy during different de-bonding steps is investigated, focusing on how the surface shape variations and the surface roughness affects water stress corrosion. We find that the bonding energy in the corroded state is not affected by the original surface shape variations and mid-spatial frequency range roughness, anymore. A molecular mechanism to explain this phenomenon is proposed. [ABSTRACT FROM AUTHOR]

Metalized film capacitors in a.c. applications suffer high frequency and high voltage, which will induce electrode corrosion, leading to capacitance degradation. The intrinsic mechanism of the corrosion is oxidation caused by ionic migration in the oxide film formed on the electrode surface. In this work, a D–M–O illustration structure for the nanoelectrode corrosion process is established, and thereby, an analytical model is derived to study the influences of frequency and electric stress on corrosion speed in a quantitative approach. The analytical results well conform to the experimental facts. It is found the corrosion rate rises with frequency and finally tends to reach a saturation value. The electric field in oxide has an exponential-like contribution to the corrosion rate. In the case of aluminum metalized films, the saturation frequency and minimum field required for corrosion initiation are, respectively, 3434 Hz and 0.35 V/nm calculated by the proposed equations. [ABSTRACT FROM AUTHOR]

Abstract High-strength bolts have become indispensable support materials in geotechnical engineering, but the incidence of safety accidents caused by bolt fractures under complex geological conditions is increasing. To address this challenge, this study focuses on a typical roadway in the Xinjulong coal mine, employing a combination of mechanical performance testing, microscopic and macroscopic analyses to investigate the failure mechanism of bolt breakage. The research indicates that the cracks in the failed bolts underground exhibit subcritical patterns, with the presence of oxides and Cl elements, and multiple intergranular fractures internally, consistent with the characteristics of stress corrosion failure. Additionally, inherent defects in the bolts are also a primary cause of failure. For instance, for type A bolts, the levels of P and S elements significantly exceed the normative requirements, forming inclusions, while the low content of elements like Si and V leads to reduced plasticity, toughness, and corrosion resistance. Furthermore, the excessive pitch in type A bolts leads to stress concentration and cracking under complex loads. The study concludes that the synergistic effect of stress corrosion cracking and inherent flaws in bolts are the main causes of failure. Therefore, it is recommended to enhance the reliability and safety of bolt support by optimizing the bolt shape and developing anti-corrosion bolts, thereby achieving long-term stability in underground engineering.

To investigate the variation law of corrosion damage of steel wires for bridge cables, the accelerated stress-corrosion test was carried out. The corrosion surface of steel wires was collected by virtue of a three-dimensional topography instrument, and the surface characteristic parameters of steel wires were also statistically analyzed under different corrosion ages and initial strains. Finally, the maximum pit depth of steel wires was estimated by the analysis method of extreme value. The results showed that the stress corrosion intensified the corrosion degree of steel wires under the same corrosion age, and the maximum discrepancy was nearly 20%. However, the high strain level had a lower influence on the growth rate of corrosion degree in the later stage of corrosion. The pit depth of steel wires more conformed to the lognormal distribution under the unstressed condition, while the corrosion depth of steel wires more closely conformed to the normal distribution under the stress condition. The fractal dimension could not only reflect the unevenness of the corrosion surface, but also be used as one of evaluation indicators of corrosion degree. The maximum pit depth obtained from the sampling inspection data was hazardous, and it was safe and feasible to take the results from the analysis method of extreme value. [ABSTRACT FROM AUTHOR]

During the major overhaul of a chemical plant, the pipelines were disassembled and cleaned. Upon reinstallation, an air-tightness test discovered that the flange of the tandem mixer had cracked at the 304 stainless steel (SS) welding joint, affecting normal production. In the present paper, the microstructure of the weld joint was analyzed using SEM equipped with an EDS detector, to explore the corresponding cracking mechanism. The results show that the cracks start on the inner surface of the flange and extend outside. The microstructure in the welding heat affected zone (HAZ) is coarse and carbides are occurring at the grain boundaries, which reduces the strength. The precipitation of carbides at grain boundaries also reduced the Cr content in the crystal, resulting in a decrease in the corrosion resistance of the passivation film on 304 SS. The HAZ showed lower elongation compared to the 304 SS substrate and the fused zone. Under the combined action of stress and corrosive media, the HAZ undergoes stress corrosion cracking. [ABSTRACT FROM AUTHOR]

Wheelset shafts are usually coated to protect them from mechanical and corrosive influences. However, damage during operation requires close inspection intervals to check permissible damage depths. The focus of this research is to investigate a possible increase in corrosion fatigue strength through inductive surface layer treatment for the wheelset shaft material EA4T (25CrMo4+quenched and tempered). For this purpose, process parameters for inductive surface hardening were identified and optimized in order to achieve a sufficiently high hardening depth and hardness of the surface layer on lightly notched test specimens. Subsequently, fatigue strength tests were carried out in air and in 5 % NaCl solution for the initial state and the hardened state. By comparing the fatigue strength results determined, the expected potential for increasing fatigue strength and corrosion fatigue strength was confirmed. In order to demonstrate stone chipping and corrosion stress, further tests were repeated with damage specifically introduced into the surface layer. The findings indicate the potential of surface layer hardening for significantly lower‐maintenance wheelset shafts in freight transport in the future. [ABSTRACT FROM AUTHOR]

The present study was performed on the stress corrosion cracking of F304 stainless steel immersed in boiling magnesium chloride solution. Earlier, the Stress Corrosion Cracking behaviour (SCC) of induced residual stress on F304 stainless steel has not been stated widely in the literature. Researchers have used different techniques to understand SCC behaviours. However, the ASTM G36 method is extensively used for SCC testing under U-bend. In this work, the residual stresses were induced by U-Bend, and then the SCC behaviour of F304 Stainless steel was observed in a chloride environment of boiling MgCl2.6 H2O. The combined effect of residual stress and corrosion environment were applied with the help of the U-bend technique. Further, the upper surface of the U-bend was focused on as an investigation area. XRD Stress Analyser measured the residual stresses. The selected spot of stress analysis was the upper surface, end of U-bend curvature, and lower end. Moreover, the heat treatment process was performed to reduce the effect of machining. The results reveal the SCC susceptibility, the magnitude of residual stresses, and elements composition around the cracked surfaces. Similarly, the study also highlights SCC behaviour under the influence of boiling magnesium chloride. [ABSTRACT FROM AUTHOR]

• Correlative microscopy is used to investigate complex corrosion systems. • X-ray microscopy offers valuable insights into the original shape of the nails. • This approach enhances the accuracy of investigations within the same region of interest. • The results reveal significant differences in the condition of archaeological iron nails from Motya. In this work, we employed correlative imaging techniques to investigate the complex corrosion systems in nails from the Phoenician-Punic site of Motya (Sicily, Italy), combining analytical chemistry and imaging tomography across multiple dimensions and scales. To accomplish this, we used correlative light and electron microscopy, micro-Raman spectroscopy, and X-ray microscopy. The results showed remarkable differences in the condition of the nails, with one nail well-preserved and thinly coated with oxyhydroxides, while the other nail exhibited extensive corrosion and degradation with distinct corrosion layers and the presence of soil minerals. Multiscale X-ray microscopy provided 3D imaging of the internal structures, revealing cracks and the original shape of the nails. This work contributes to the understanding of stress corrosion in metals and has implications for the development of strategies to prevent and control corrosion processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Pipeline transportation is an important engineering component, which is widely used in transporting gas and liquid resources. The safety of the pipeline became the central point of this study. Pipeline deformation caused by liquid storage pressure is of great significance to the safety of pipeline engineering. Previous studies mainly focused on pipe deformation under ring force and less on deformation caused by internal liquid. In this paper, the theoretical results of strain distribution are derived based on elastic mechanics, and the strain distribution equation is established. The effects of the liquid storage pressure, pipe diameter, and pipe length on pipe strain are investigated experimentally. The experimental results are in agreement with the equation. It is found that the strain increases linearly with the increase in reservoir pressure. Under the same length, the larger the pipe diameter is, the larger the pipe strain is when the pipe diameter is 5–10 mm. In the range of 10–15 mm, the average strain is basically unchanged. Under the same pipe diameter, the pipe length has little effect on the average strain. The strain is greatest in the middle of the pipeline and decreases gradually to both sides. The results have important guiding significance for pipeline protection and stress corrosion prevention. [ABSTRACT FROM AUTHOR]

Corrosion cracking is the destruction of metal under static stresses and an aggressive environment. Corrosion fatigue is destruction of the metals and the alloys under the impact of cyclic mechanical pressure and aggressive environment simultaneously. Stress corrosion is the least studied and systematized in terms of literature data on the impact of various aggressive environment (type, temperature, and concentration), composition and structure of the material, mode of heat treatment, method of obtaining and cleaning the casting, methodology for determination of corrosion under stress, as well as equipment for carrying out similar studies. The purpose of this paper is to present the methodology and equipment developed for corrosion cracking testing of cast alloys. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aimed to determine the susceptibility of polycarbonate and polymethylmethacrylate to corrosion cracking under specific operating conditions. The tests included static tensile and flexure, impact strength, and microscopic examination. Due to the synergistic effect of tensile stresses and seawater environment, numerous cracks are observed. Moreover, aging conditions did not significantly reduce the strength properties of the tested specimens; thus, higher resistance to stress corrosion cracking does not have a close relationship with the material's mechanical properties. [ABSTRACT FROM AUTHOR]

Protective epoxy coatings, as a result of their inherent brittleness, show insufficient resistance towards initiation and propagation of cracks, which can occur as early as during the curing process. To improve premature crack initiation resistance, it is essential to understand the underlying mechanisms. In this work, a solvent-based novolac epoxy, cured with a cycloaliphatic amine, was reinforced with either an epoxypropoxypropyl-terminated polydimethylsiloxane (PDMS), nanoparticles of strontium titanate (SrTiO3), or core-shell rubber (CSR) nanoparticles. The effects on coating property transients, curing-induced internal stress, and premature crack initiation susceptibility of the modifier types and CSR (MX 217 and MX 267) concentrations were investigated. In addition, using a digital microscope, the defect and crack morphology in coatings applied to rigid, flat substrates and inner 90-degree angles were characterized. Finally, to evaluate the anticorrosive barrier performance of the reinforced coatings, an electrochemical impedance spectroscopy analysis was employed. Despite a slightly reduced crack initiation susceptibility, the flexible PDMS chains, due to phase separation, resulted in a deteriorated barrier performance. The inclusion of SrTiO3 nanoparticles also led to a reduced anticorrosion performance, relative to a neat epoxy coating, with a slightly lower crack initiation susceptibility and a minor increase (around 0.2 MPa) in the average internal stress. For 5 wt% MX 217 and MX 267 CSR toughened coatings, the maximum internal stress and crack initiation susceptibility in the series, as well as an associated reduced corrosion resistance, were seen. In spite of a reduction in the elastic modulus, an improved barrier performance and a reduced internal stress and crack initiation susceptibility were observed for 25 wt% MX 217 and 37 wt% MX 267 CSR toughened coatings. To improve barrier properties and avoid premature crack initiation of epoxy coatings, guidelines on modifier selection are provided. [ABSTRACT FROM AUTHOR]

Background: Excessive levels of residual stresses (RS) in metallic components of flexible pipes can lead to failure by fatigue or stress-corrosion cracking (SCC) mechanisms. Accurate measurements of residual stresses are essential in order to support comprehensive integrity assessments of these structures. Objective: This paper aims at proposing a methodology for in-field evaluation of the residual stresses in the tensile armour of flexible pipes. This methodology is evaluated by comparing results from the contour method (CM), a portable (PXRD) and a benchtop (BXRD) X-ray diffractometer. Methods: A set of samples with a controlled RS state was used to evaluate PXRD depth-profiles by comparison with BXRD measurements. CM was used to investigate stress values elsewhere in the cross-section of the samples. PXRD was then used to measure the total stress on a full-scale flexible riser. Results: Strong texture was seen in XRD measurements due to the preferential orientation in the samples, but a method to overcome this is proposed. RS measurements with PXRD were in close agreement with BXRD values in all samples. Total stress profiles obtained by PXRD on a tensile armour of flexible pipe are given. CM did not provide reliable results in the near-surface region of shot-peened samples, but reasonable agreement was found with BXRD after manual adjustment of a smoothing parameter when depths from 0.3 mm to 1.5 mm were analyzed. Conclusion: A methodology has been established for non-destructive in-loco profiling of the total stress state in tensile armours of flexible pipes with PXRD; in a real application scenario it could provide valuable information that could help to understand damage initiation mechanisms. [ABSTRACT FROM AUTHOR]

Stress corrosion cracking (SCC) mechanism of X80 steel under cathodic protection in alternating wet and dry marine environment is studied by electrochemical test and slow strain rate tensile test. The results show that the cathodic potential of -850 mV reduces the corrosion current density of steel, and the corrosion current density increases with the decrease of applied potential. The effect of cathodic protection gradually decreases due to strain. Compared with no applied potential, the SCC susceptibility of steel at -850 mV potential is reduced by 14.28%, while the susceptibility at -1200 mV potential is increased by 71.42%, the specimens change from ductile fracture to brittle fracture. The protection effect of the applied potential is achieved by inhibiting the anodic dissolution of the steel. With the decrease of the potential, severe hydrogen evolution reaction is triggered, resulting in higher SCC susceptibility. [ABSTRACT FROM AUTHOR]

To study the corrosion behavior of coupled steel bars under applied stresses, experiments on the influence of applied tensile and compressive stresses on the corrosion of coupled steel bars in simulated concrete pore solutions were conducted. The corrosion processes of the individual steel bars and coupled steel bars with different stress levels, including three tensile stress levels (1/3fy , 2/3fy , and 3/3fy) and three compressive stress levels (−1/3fy , −2/3fy , and −3/3fy), were monitored regularly, by several electrochemical measurements, in chloride contained simulated concrete pore solution for 45 days. The experimental results showed that applied stresses had significant effects on the corrosion of steel bars. In a chloride-free environment, the applied tensile stress was found to protect the passive film. However, once corrosion initiated, the applied tensile stress would aggravate the corrosion, while the applied compressive stress might inhibit the corrosion. Microcell corrosion and macrocell corrosion were significantly influenced by the applied stresses. The applied stresses might alter the corrosion mode. Tensile-stressed steel bars and compressive-stressed steel bars showed the susceptibility to the pitting corrosion. By comparison, steel bars with applied tensile stresses tended to corrode more uniformly; however, those with applied compressive stresses were more likely to undergo localized corrosion. Reinforced concrete structures usually endure various loads such as traffic and wind loads. The external loads have been proven to influence the corrosion process of steels in concrete. However, the specific principles and results of the effect of external loads on the corrosion of steels have yet to be thoroughly studied. This study aims to investigate the corrosion process of steel under different stress levels in a simulated concrete environment. Compared with an experiment in practical concrete structures, an experiment in simulated concrete pore solutions has a shorter test cycle and the experimental phenomena are more obvious. The results show that the applied tensile stress will aggravate the corrosion of steel, while the applied compressive stress will restrain the corrosion process. Based on the research results, engineers should pay attention to the effect of external loads on the durability of structures in the design stage. Moreover, this study provides a reference for further experimental studies in practical reinforced concrete structures. [ABSTRACT FROM AUTHOR]

Second-stage gas turbine nozzles are an important part of the gas turbine due to their performance in hot temperature conditions. In this investigation, service-induced failure analysis and microstructural variations of different sides of a second-stage nozzle in a 100 MW gas turbine made of FSX-414 cobalt-based alloy were comprehensively studied to determine the conditions and mechanisms of the failure process. The primary carbides M3C2 and M7C3 types were converted to secondary carbides M23C6 type by phase transformation process and formed a continuous layer in the grain boundaries owing to high-temperature operation conditions. A network of cracks was created in the grain boundaries, leading to a fracture in the vane of the nozzle. The continuity and density of the produced carbides decreased ductility and toughness of the nozzle. The results demonstrated that hot oxidation and sulfidation occurred in the leading-edge zone. The aggregation and asymmetry of the combustion line and, consequently, the increasing temperature were the reasons for the damage. Some macrocracks were observed by visual inspection on the surface of the nozzle owing to exposure to high temperatures and placement in the path of the hot gas with high pressure. Based on the results, the continuous and coarse brittle M23C6 carbides on the grain boundaries were the major cause of the failure due to the crack growth caused by stress corrosion. These carbides provided appropriate paths for the growth of the crack through grain boundaries, leading to failure after the operational out-of-service condition of a second-stage gas turbine nozzle. Operational in over-hot conditions and an inappropriate filtration system were the main reasons for the operational-induced thermal fatigue failure process of the second-stage gas turbine nozzles. Based on the results, oxidation and microstructural variations were the main causes of the failure process of the second-stage gas turbine nozzles. [ABSTRACT FROM AUTHOR]

In the present study, we address an important and increasingly relevant topic in mining safety and efficiency, namely the stability of open-pit bench slopes subjected to daily heavy truck cyclic loading. Specifically, we focus on the stability of Zhahanur open-pit slope (Inner Mongolia region, China) and investigate the potential role of daily heavy truck cyclic loading in bench slope instability. To this end, we incorporate a stress corrosion model into the particle flow code to develop a time-dependent deformation model of the rock. With the established model, we quantitatively analyse the effect of heavy truck cyclic loading on the bench slope stability. Our results support the hypothesis that daily heavy truck loading can cause gradual downward deformation of a rock mass, leading to slope instability. To validate our numerical modelling results, we compare and analyse them with in situ monitoring data. Our study demonstrates the significant impact of daily heavy vehicles on bench slope stability in open-pit mines and provides a practical tool for assessing the long-term stability of open-pit bench slopes and optimising mining operations. [ABSTRACT FROM AUTHOR]

The stress corrosion behavior of 7xxx series aluminium alloys in different concentrations NaCl solution was studied, and numerical simulation was conducted in COMSOL Multiphysics based on experimental results. Different stresses were applied on the experiment pieces, the pitting crater deepened with the change of stress level. The corrosion rate increased with the raising stress. There is no positive correlation between stress corrosion degree and chloride ion concentration. The most severe corrosion occurs in 5.0 wt% NaCl solution instead of 6.0 wt% NaCl solution due to the increase of water film conductivity and decrease of solubility of oxygen under high Cl− environment. The finite element model was used to analyze the stress distribution on aluminium alloy surface, to describe the dynamic equation of anodic dissolution of metal due to elastic and plastic deformation. Corrosion occurs mainly in stress concentrated areas. When the stress loading exceeds a certain threshold, plastic strain occurs on the surface of both the specimen and the structural part, the corrosion current density increases instantaneously, and the corrosion behavior in the stress concentration area gradually intensifies. The survey can provide practical theoretical guidance for predicting stress corrosion and extending the service life of equipment in (harsh) marine environments.

In order to clarify the influence and regularity of CO2 partial pressure on the corrosion behavior of S135 steel in the CO2/H2S coexistence system， the corrosion simulation test of S135 steel in CO2/H2S coexistence systems was conducted by using high temperature and high pressure reactors.Meanwhile， the weight loss method， constant load method， X - ray diffraction (XRD)， scanning electron microscope(SEM)， energy spectroscopy (EDS) and three-dimensional profile scanner were used to study the effects of different CO2 partial pressures on the corrosion behavior rules of S135 steel in CO2/H2 S coexistence systems at 100 ℃.Results showed that as the CO2 partial pressure increased， the corrosion rate of S135 steel increased， and the yield strength damage became intensified.When the CO2 partial pressures were 5， 10， 15， and 20 MPa， the yield strength (σs) damage rate were 1.4%， 3.6%， 4.5%， and 15.9%， respectively.Additionally， the tensile strength (σb) damage rates were 1.2%， 3.4%， 5.2%and 15.4%， respectively.S135 steel underwent general corrosion under low CO2 partial pressure， and with the increase of CO2 partial pressure， the corrosion behavior developed into mainly general corrosion， supplemented by local corrosion.In the initiation stage， the stress corrosion cracking was dominated by local anodic dissolution (pitting corrosion).As the CO2 partial pressure increased， stress corrosion cracks were more likely to grow， and the stress corrosion sensitivity increased， which caused the corrosion process of the substrate became aggravated.

High-resolution transmission electron microscopy and atom probe tomography are used to characterize the initial passivation and subsequent intergranular corrosion of degraded grain boundaries in a model Ni-30Cr alloy exposed to 360 °C hydrogenated water. Upon initial exposure for 1000 h, the alloy surface directly above the grain boundary forms a thin passivating film of Cr2O3, protecting the underlying grain boundary from intergranular corrosion. However, the metal grain boundary experiences severe Cr depletion and grain boundary migration during this initial exposure. To understand how Cr depletion affects further corrosion, the local protective film was sputtered away using a glancing angle focused ion beam. Upon further exposure, the surface fails to repassivate, and intergranular corrosion is observed through the Cr-depleted region. Through this combination of high-resolution microscopy and localized passive film removal, we show that, although high-Cr alloys are resistant to intergranular attack and stress corrosion cracking, degradation-induced changes in the underlying metal at grain boundaries make the material more susceptible once the initial passive film is breached. [ABSTRACT FROM AUTHOR]

Mycenaean vitreous artifacts, such as beads and relief plaques, are highly susceptible to degradation, which can significantly alter their visual characteristics and pose challenges to their taxonomy. The visual manifestation of corrosion on vitreous artifacts, especially glass and faience, has often led to their misclassification, which, in turn, has a significant impact on their interpretation by researchers, often resulting in misleading notions. The present paper constitutes part of an overall study, implemented within the framework of the project, Myc-MVP: Mycenaean Vitreous Production, A Novel Interdisciplinary Approach Towards Resolving Critical Taxonomy Issues, which has employed a combination of established, state-of-the-art scientific methods to analyze and identify the specific compositional changes occurring at different spatial dimensions within surface layers, with the overarching aim of contributing to our understanding of the degradation mechanisms of vitreous artifacts and the relevant implications for the archaeological record. Importantly, these findings will yield useful data in devising strategies for the proper classification, management, and preservation of vitreous artifacts in the future. The present study focuses on investigating the relationship between the compositional changes in a subset of 12 (of the overall 126 objects entailed in the project) corroded vitreous artifacts from Mycenaean contexts in the Aegean and the way these are manifested visually, with the application of X-ray fluorescence and LED microscopy. We aim to decipher the nature of corroded objects with the aid of focused analysis. This study delves into degradation processes in glass artifacts, highlighting preservation variations and environmental influences like burial. Coloration, attributed to copper and cobalt oxide, shows some correlation with preservation quality. These chromophore agents potentially induce thermal stresses and corrosion. The complex interplay between chemical composition, environmental conditions, and preservation status underscores the need for comprehensive research. Analyzing the full artifact set using complementary techniques promises deeper insights for secure material classification and cultural heritage preservation. [ABSTRACT FROM AUTHOR]

This work aimed to ascertain the corresponding influences of several PVD-coated cutting tools on the susceptibility of the machined surface of super duplex stainless steel (SDSS) to stress corrosion cracking. Coatings comprised of AlCrN, AlCrN/TiSiN, and AlTiN were applied to cemented carbide cutting tools using the PVD method; these were then used to turn the outer surface of the SDSS tube section. During the cutting process, the material presents the following combination of features: (i) a tendency for strain hardening, reflected in microstructural modifications and residual stresses of the machined surface and (ii) high temperatures in the cutting region, reducing the tool life. The goal of this work was to evaluate the surface integrity (work hardening and corrosion behaviour) of the SDSS obtained after the machining process (finish turning) with cemented carbide tools coated with three different PVD coatings. [ABSTRACT FROM AUTHOR]

We propose a mathematical model for the determination of the period of subcritical crack growth in an oil pipeline operating under the action of constant internal pressure, hydroshocks, and soil corrosion with regard for the degradation of its material. The model is based on the first law of thermodynamics, i.e., on the balance of energy components and the rates of their variations, the mechanisms of electrochemical corrosion, and the analytic dependences of changes in the stress-corrosion characteristics of the material in the course of time (degradation). We determine the residual lifetime of an oil pipeline made of Kh60 steel. [ABSTRACT FROM AUTHOR]

This paper aims to study the effect of stress corrosion on the electrochemical behavior and corrosion mechanism of epoxy zinc-rich coating/steel substrate. The electrochemical impedance spectroscopy (EIS) was applied to characterize the corrosion behavior of the system under different stress conditions (σ1 = 0MPa; σ2 = 120MPa; σ3 = 180MPa and σ4 = 240 MPa), and appropriate equivalent circuits were established. Additionally, the von Mises stress distribution and potential distribution around the pitting pit at the coating-substrate interface were quantified by means of finite element analysis. The approach used different tensile strains and the depths of the pitting pit to relate the corrosion current density and corrosion rate to the corrosion process. The EIS results demonstrate that, given the same time, the failure time of the epoxy zinc-rich coating/steel substrate system with 240 MPa is shortened by 27.8% compared to the system without stress. Meanwhile, the finite element model confirms that the uneven potential distribution around the pitting pit is responsible for coating failure. In-depth profile of the corrosion rate shows an increasing trend over the distance from the opening. Then this local corrosion acceleration will cause further stress concentration, which in turn accelerates the corrosion process of the system. [ABSTRACT FROM AUTHOR]

Load bearing behaviour of beam‐series structures – Recommendations and remarks on the computational evaluation of beam series structures on the basis of experimental inverstigations The verification formats from the german guideline „Nachrechnungsrichtlinie" and its supplement are applicable for numerous bridge systems in the Western states of Germany (Republik of Germany until 1990). The transferability to a large part of the older bridge structures in the new German states (former German Democratic Republic) is problematic. The structures have special specifications or designs, as they were only executed in the former GDR. In particular, the so‐called beam‐row structures are still widespread, both in the stock of the state building authorities and of municipalities. Due to their frequency and their special design, adapted calculation approaches would greatly facilitate the evaluation of these structures. In the GDR, prestressing steel from Hennigsdorf was used almost exclusively, which is considered to be susceptible to stress corrosion cracking. Nevertheless, it is generally assumed that this type of structure is not affected by prefabricated structures today. The following article describes the background and calculation recommendations for this particular bridge type. The findings are based on experience gained from the dismantling of a beam‐row structure in the course of the A 19. Here, the unique opportunity arose to carry out investigations on a bridge superstructure that was designed as a beam‐row structure. The following article summarizes the elementary results and gives recommendations for the computational evaluation. [ABSTRACT FROM AUTHOR]

Duplex stainless steels are generally selected for applications where resistance to corrosion is the most important criteria. Several duplex stainless steel alloys are suceptible to environmental-assisted cracking and that is the subject of this invesitgation for hot-rolled alloy 2205. Duplex stainless steels (DSSs) are generally selected due to their corrosion resistance, but several environment-assisted cracking (EACs) are related to this material. Slow strain rate tests are used to evaluate the resistance to EAC, including hydrogen embrittlement and sulfide stress corrosion cracking (SSCC). In this work, a hot-rolled DSS was tested by slow strain rate tensile testing (SSRT) in two saline solutions containing H2S (10 kPa (0.1 bar) of partial pressure). Two pH levels (3.5 and 4.5) were adjusted with HCl and NaOH additions. The material was brittle in both pH levels, although the density of secondary cracks at pH 4.5 was slightly lower than at pH 3.5. This work was dedicated to analyzing the fracture surface and the secondary cracks developed in the SSRT. Lines of localized deformation of ferrite and austenite were found in the specimen tested with pH 4.5. The results were compared to the behavior of previous SSRT results and SCC failures of DSS harsh conditions. [ABSTRACT FROM AUTHOR]

Electromagnetic treatment (EMT) plays a critical role in the manipulation of microstructures and properties in aluminum alloys. This study aims to investigate the impact of EMT on stress corrosion cracking (SCC) resistance in 7075 aluminum alloy and to reveal the underlying mechanisms from both thermodynamic and kinetic perspectives. The results demonstrate that EMT has a significant positive effect on the stress corrosion resistance of the aluminum alloy. It effectively reduces the elongation loss from 11.2 to 2.6% and the SCC susceptibility index from 3.9 to 1.4%. This improvement can be attributed to two primary mechanisms: (1) the energy supplied by the electromagnetic field lowers the thermodynamic barriers for the dissolution of precipitates, even at temperatures below the critical threshold. This facilitates the dissolution and coarsening of precipitates, ultimately reducing the alloy's susceptibility to stress corrosion in various environments. (2) The activation energy provided by the electron wind force facilitates the movement and annihilation of dislocations, leading to a reduction in residual stresses and further enhancing the aluminum alloy's resistance to stress corrosion. [ABSTRACT FROM AUTHOR]

This paper focuses on the issues of sour water corrosion, CO2 corrosion, wet H2S corrosion, chloride ion corrosion, and stainless steel chloride stress corrosion cracking in gasification-scrubbing system of coal to hydrogen unit. The on-site corrosion monitoring results show that 15CrMo and 14CrlMo are belong to corrosion-resistant materials, while 06Crl3, S30403, S31603, and S22053 are fully corrosion-resistant materials. The laboratory corrosion evaluation results show that 15CrMo belongs to corrosion-resistant materials at less than 200 °C and non corrosion-resistant materials at not less than 200 °C; 06Crl3 is a good corrosion-resistant material at less than 250 °C, and a corrosion-resistant materials at not less than 250 °C; S30403, S31603, and S22053 are fully corrosion-resistant materials; chloride ions have a promoting effect on the corrosion of Q245R and 15CrMo. Based on the above researches, combined with the actual operation of the unit and engineering experience, a recommended plan for equipment and pipeline material selection has been developed, and corrosion control strategies have been proposed. [ABSTRACT FROM AUTHOR]

The properties of the intercritically reheated coarse-grained heat affected zone (ICCGHAZ) in X65 pipeline steel with large deformation are studied. The ICCGHAZ is composed of acicular ferrite, granular bainite and lath bainite. With the increasing t 8/5 (the time for specimens to cool from 800 °C to 500 °C), the sulfide stress corrosion cracking (SSCC) resistance with and without pre-strain both increases, and the secondary cracks propagate along the necklace-type martensite-austenite (M-A)/matrix interface or near the M-A constituents, and the fracture toughness decrease. When t 8/5 = 30 s, ICCGHAZ has the most ideal performance on fracture toughness and stress corrosion resistance. • The microstructures of ICCGHAZ with different welding heat input are observed. • The crack propagation path is less affected by the phase interfaces with the increasing t 8/5. • The fracture toughness decreases significantly with the increasing of t 8/5. • When t 8/5 = 30 s, the ICCGHAZ has the best performance on fracture toughness and SSCC resistance. [ABSTRACT FROM AUTHOR]

The tensile strength of rocks is affected by loading conditions, specifically direct and Brazilian tension, as well as water saturation. But the fundamental reasons for the differences between direct tensile strength σ td and Brazilian tensile strength σ tb , and their degradation induced by water saturation, are not yet fully understood. Here, we report a series of direct tensile and Brazilian tests performed on marble and granite rocks under both dry and water-saturated conditions. We employed the acoustic emission (AE) technique and further analyzed the recorded AE waveforms using a methodology based on the statistical analysis of dominant frequency to infer the intrinsic failure process of studied rocks under different water and loading conditions. Our results show that water saturation causes substantial reductions in both σ td and σ tb , with the reduction in σ tb being greater. A correspondence between AE waveforms distributed in high and low dominant frequency bands (H-type and L-type waveform) and rock failure types is found, that is, the H-type waveforms correspond to the micro-shear failures, and the L-type waveforms correspond to the micro-tensile failures. Based on this, the generation of abundant micro-shear failures is the cause of enhancement in σ tb in rocks compared to its σ td , and the reductions in σ td and σ tb for saturated rocks result from increasing micro-tensile failures. Furthermore, the friction-weakening effect induced by lubricating water films is responsible for the tensile strength reduction of saturated marble and granite under direct and Brazilian tension. The pronounced friction-weakening effect resulting from the widespread friction condition in the Brazilian test facilitates the σ tb loss. In addition to the friction-weakening effect, stress corrosion could also be a secondary cause of the tensile strength reduction of saturated granite. Highlights: The corresponding relationship between acoustic emission waveform types with micro-failure patterns is built. Reasons for the difference in measured tensile strength under direct and Brazilian tension are proposed. Water-weakening effects on the tensile strength of rocks under direct tension and Brazilian loading are revealed. [ABSTRACT FROM AUTHOR]