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Al 5000 series alloys are being used in ship structural and automotive applications. However, these alloys become sensitized in the low temperature range of 50–80 °C due to the formation of beta phase at grain boundaries. The estimation of beta phase in Al 5000 series alloys aged at low temperatures is critical as it significantly affects the stress corrosion intensity factor, K1scc, which was observed to decrease with aging and reduces to 90% of its original value in fully sensitized condition. Here, we utilize transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, stress corrosion cracking studies and nitric acid mass loss testing to address this issue. In particular, we demonstrate the beta phase formation at relatively low temperatures by analyzing the peak shift of Al (Mg) solid solution during aging with respect to the as-received condition using high-resolution XRD, and compared these results with TEM studies. For complete sensitization, we determine the observed change in lattice parameter is 0.05% and 0.1% at 70 and 75 °C, respectively, with respect to the lattice parameter, corresponding to the as received condition. Knowing the exact supersaturation level from the peak positions, we estimate the thickness of beta phase at grain boundaries applying the parabolic growth law. Utilizing this method, one can estimate the beta phase fraction at the early stage in the low temperature range, which would be beneficial to increase the life cycle predictability of a ship. [ABSTRACT FROM AUTHOR]

6082-T6 aluminum alloy is a commonly used aluminum alloy material in the field of rail transit because of its good molding properties, high mechanical properties, excellent corrosion resistance and weldability. In the high temperature and humid environment, the temperature change is bound to affect the stress corrosion resistance of the aluminum alloy and their welded joint. However, the influence mechanism of temperature on its stress corrosion resistance has not been explained in the existing research. In this paper, the mechanical properties and stress corrosion behaviors of melt-inert gas welded (MIG) 6082-T6 aluminum alloy welded joints were systematically studied under various temperatures condition. Results indicated the temperature scarcely affected stress corrosion cracking susceptibility index (PSCC) of base metal, while significantly affected the welded joint and higher temperature caused lower PSCC. After slow strain rate tensile test, a corrosion layer was formed, which was a typical brittle-toughness mixed failure, and the degree of brittleness increased with the increasing of temperature. Electrochemical analysis showed that corrosion resistance of the joint slightly decreased due to aluminum alloy accelerated dissolution caused by increasing of temperature. The proposed research will provide a theoretical basis for solving aluminum alloys used in rail transit, ship accessories and other industrial fields. [ABSTRACT FROM AUTHOR]

This paper intends to enhance the corrosion resistance of coolant pipes in thermal fatigue conditions and lateral hydrostatic pressure in critical engineering environments. This research applies to circular coolant pipes under hydrostatic pressure of the LBE (lead-bismuth eutectic) boundary in nuclear power plants. The resistance against corrosion caused by liquid LBE is mainly formed by Fe12Cr2Si solid solutions coatings on the pipe. The silicon concentration in Fe12Cr2Si can interact with LBE as an effective oxidized compound such as SiO2 and Fe2SiO4 when the silicon concentration is above 1.25 wt%. The oxide film formed on the coating can resist the LBE corroding in the Fe12Cr2Si structure. The primary material for constructing a coolant pipe is T91 ferritic-martensitic alloys, and the surface anti-corrosion coating is Fe12Cr2Si solid solution. With a high-strength structure, FGC (functionally graded composite material) ensures that the pipe resists the corrosion from Liquid LBE. This study evaluates the thermal fatigue failure of coolant pipes and the silicon concentration when the pipe model is under thermal shock testing by a CO2 laser. The research result indicates that the FGM (functionally graded material) structure performs better in effectively raising the margin of safety and reserving the silicon concentration on the inner surface higher than 1.25 wt% as compared to the FGC structure. [ABSTRACT FROM AUTHOR]

This study analyzed the premature failure of a stainless-steel stack obtained from a mining company. The stack was manufactured using ASTM A240 Type 316L stainless steel. After one year of its service, massive leakages and cracks were observed near the welds. Following a visual examination of the stack, a representative sample was extracted and analyzed using visual and radiographic inspection, metallographic examination, scanning electron microscopy, energy-dispersive spectrometry, optical emission spectrometry, ferrite number analysis, and leak testing. Furthermore, corrosion mechanisms and the sequence of events leading to failure were determined. Two different mechanisms were identified: acid dew point corrosion caused by the condensation of H2SO4 and HCl at the inner walls of the chimney, followed by stress-corrosion cracking near the welded joints. [ABSTRACT FROM AUTHOR]

A 7075 aluminum alloy high-lock nut developed multiple cracks after 3 years of exposure to atmospheric conditions. To identify the root cause of the cracking, a comprehensive analysis was conducted, including chemical composition, macro- and micro-fracture analyses, microstructural analysis, mechanical performance verification, and residual stress testing. The results indicated that stress corrosion was the cause of the fractures. After assembly, the crimping part of the high-lock nuts exhibited significant residual tensile stress and stress concentration, which led to stress corrosion in the industrial atmospheric environment. A comparison of the residual tensile stress in high-lock nuts with wall thicknesses of 0.75 mm, 1.00 mm, and 1.25 mm revealed that the residual tensile stress at the crimping part decreased as the wall thickness increased. Additionally, stress corrosion testing demonstrated that high-lock nuts with a wall thickness of 1.25 mm did not undergo stress corrosion within 30 days. [ABSTRACT FROM AUTHOR]

As a new surface strengthening technology, laser shock peening (LSP) can effectively improve the stress corrosion resistance of metal surface. However, the martensitic transformation induced by traditional LSP has negative effects on the corrosion resistance of 304 stainless steel. In order to retard the martensitic transformation, the thermal laser shock peening (TLSP) tests of 304 stainless steel were carried out in this work. The residual stress, grain size, microhardness and martensite content of the surface layer of the specimens were measured. The stress corrosion sensitivity of the TLSP 304 stainless steel was studied by slow strain rate test (SSRT). The results show that high residual compressive stress, grain refinement and martensitic transformation occurred on the surface of the specimens after TLSP, and the martensite content is significantly lower than that of the traditional laser peening specimens. The stress corrosion sensitivity index of the specimens treated by TLSP is significantly lower than that of the untreated specimens. With the increase in the TLSP temperature, the stress corrosion sensitivity index of the specimens decreases, especially when the laser shock peening temperature rises above 50 °C, the stress corrosion sensitivity index decreases significantly. [ABSTRACT FROM AUTHOR]

In this paper, the corrosion resistance of sheet-gyroid porous structures with different porosities formed by LPBF under static and dynamic conditions was studied, and the mechanism of influence of medium flow on corrosion resistance was explored based on CFD simulation. It was found that the corrosion resistance of porous structures decreased with the increase in porosity in static and dynamic environments, which was mainly related to the increase in forming defects and the decrease in forming quality as the wall thickness of porous structures decreased with the increase in porosity. Under dynamic electrolyte conditions, the wall shear stress generated by the flowing medium on the surface of the porous structures will reduce the stability of the oxide film and increase the corrosion rate. The porous structures exhibited greater corrosion damage in the dynamic electrolyte solution. Based on CFD simulation analysis, it was found that with the increase in porosity, the channel size of porous structures increased, the curvature decreased, the average wall shear stress decreased, and the influence of medium flow on the corrosion rate of porous structure gradually decreased. The relationship model between average wall shear stress and corrosion rate growth rate was established, which provided data support for the subsequent design of porous structures for bone implantation. During the corrosion process, α-Ti and Ti2Cu phase form micro-galvanic corrosion, and the preferential dissolution of Ti2Cu phase leads to the gradual release of Cu2+, which is conducive to improving the antibacterial performance of Ti–Cu implants. [ABSTRACT FROM AUTHOR]

Owing to their excellent properties, duplex stainless steels (DSSs) may be selected for the H2S environment. Operational limits are not defined and depend on fabrication processes. In this work, the susceptibilities of two DSSs 2205 to sulfide stress corrosion (SSC) in saline solutions with three pH levels were investigated. The difference between materials is the fabrication route: hot rolled (HR) tubes and powder metallurgy with compacting and sintering final operations by hot isostatic pressing (PM‐HIP). The susceptibility parameters were evaluated by slow strain rate tensile tests (SSRT). Both materials suffered embrittlement in solutions with pH 3.5 and 4.5, but the susceptibility was slightly better in the HR. In the solution with pH 5.5, the HR fractured with ductile behavior, while the PM‐HIP was brittle. The better resistance of HR to SSC can be explained by microstructural features, such as the lower grain size and austenite island interspace. [ABSTRACT FROM AUTHOR]

This paper is devoted to presenting a micromechanical model for describing instantaneous and long-term mechanical behaviors of typical quasi-brittle rocks under lateral unloading conditions. The unified damage-friction coupling model is formulated in a combined linear homogenization and irreversible thermodynamics framework. Crack propagation and friction sliding are regarded as the two primary dissipation and coupling mechanisms, respectively related to material damage and plastic deformation. Rock damage due to microcracking is divided into two parts: an instantaneous part induced by variation in stresses and a time-dependent part caused by subcritical extension of microcracks due to stress corrosion. Both the instantaneous and long-term mechanical behaviors of rock are taken into account in a unified way, which closely resemble the excavation scenarios encountered in practical engineering. In addition, we conduct a series of experiments under unloading conditions to provide experimental data for model validation and analytical predictions. Highlights: A unified micromechanical model is presented to characterize the instantaneous and long-term mechanical responses under various loading and unloading stress paths. Short- and long-term mechanical behaviors of red sandstone under unloading conditions are investigated experimentally. Damage-controlled and time-controlled algorithms are provided to perform the numerical simulation. [ABSTRACT FROM AUTHOR]

To address the issue that 2205 duplex stainless steel (DSS) of reboiler tube bundle is prone to stress corrosion cracking (SCC) under high temperature, high chloride, and dissolved oxygen (DO), the SCC mechanism of 2205 DSS was investigated in this paper in an oxygen–chloride synergistic corrosion environment. To characterize the fracture morphology of SCC under different oxygen–chloride conditions, the slow strain rate tensile (SSRT) test was used. SSRT tests were performed on 2205 DSS in high temperature (100°C–200°C), high salt (0–150,000 mg/L), and different DO (0–20 mg/L) corrosive environments. As the DO (0–20 mg/L), chloride ion concentration (0–150,000 mg/L), and temperature (100°C–200°C) increased, so did the elongation, internal product work, and stress corrosion cracking tendency of 2205 DSS. A stress corrosion sensitivity index F(A) calculation model was established, incorporating the interaction of temperature, chloride ions, and dissolved oxygen. The rupture of the passivation film and the superposition of anodic dissolution are the failure mechanisms of 2205 DSS. Transgranular stress corrosion cracking is caused by the rupture of the passivation film, which accelerates the failure process and eventually causes 2205 DSS to rupture. [ABSTRACT FROM AUTHOR]

In this study, Al2024 metal matrix composites reinforced with Al2O3 of 0.063 - 0.200 mm particle size varying from 0 to 6 weight percentage were fabricated by vortex method. The effect of the Al2O3 particle on Al2024's corrosion behaviour has been investigated. The distribution of particles in all metal matrix composites appears to be quite homogenous, according to the SEM study of the microstructures. Weight loss corrosion studies have been performed on both MMC and corresponding base alloys using 0.05N and 0.1N HCl as corrosive media. The composites have a less susceptibility to pitting and corrosion than the matrix alloy, potentially because of the passive Al2O3 layer found in the MMCs. Using the potentiodynamic polarization test, the effect of reinforcement on the corrosion characteristics of composites in 0.05N and 0.1N HCl media was examined. The weight loss method was used to conduct stress corrosion tests for varying acidic medium temperatures (30oC - 55oC), normalcy (0.025 N-0.1 N), and exposure times (10-60 min). The rate of corrosion of Al2024 alloy was found higher than the Al2O3 reinforced Al2024 alloy. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency 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.)

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe 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.)

Abstract The creep failure of rocks is related to its microstructure, external loading and time. A nonlinear yield model was introduced to describe the variation in the cohesion and friction angle with plastic strain and intergranular stress. The mechanical properties and creep characteristics of deep granite were obtained by indoor tests, and a variable radius particle clump model was constructed based on the particle flow method. The bond-weakening-friction-strengthening model was combined with the parallel bond stress corrosion method to establish the bond-degradation creep model of granite. The creep failure time, creep rate and tension and shear fractures number of the parallel bond stress corrosion model and the bond-degradation creep model were compared and analyzed to verify the applicability of the model. The fracture evolution law of deep roadway surrounding rock was studied based on the bond-degradation creep model. The results show that the rock failure characteristics and tension-compression ratio obtained by the variable radius particle clump modeling method are closer to the actual situation. Compared with the parallel bond stress corrosion model, the creep failure time of the bond-degradation creep model is shorter, more microfractures are generated during the failure process, and the numerical creep curves are more consistent with the test curves. The deep roadway vault shear failure and sidewall plate crack failure characteristics calculated based on the bond-degradation creep model are basically similar to the actual project situation. The bond-degradation creep model can better simulate the creep damage process of rocks under high stress, and is more suitable for analyzing the fracture evolution law of surrounding rock in deep hard rock cavern.

Abstract 6082-T6 aluminum alloy is a commonly used aluminum alloy material in the field of rail transit because of its good molding properties, high mechanical properties, excellent corrosion resistance and weldability. In the high temperature and humid environment, the temperature change is bound to affect the stress corrosion resistance of the aluminum alloy and their welded joint. However, the influence mechanism of temperature on its stress corrosion resistance has not been explained in the existing research. In this paper, the mechanical properties and stress corrosion behaviors of melt-inert gas welded (MIG) 6082-T6 aluminum alloy welded joints were systematically studied under various temperatures condition. Results indicated the temperature scarcely affected stress corrosion cracking susceptibility index (P SCC) of base metal, while significantly affected the welded joint and higher temperature caused lower P SCC. After slow strain rate tensile test, a corrosion layer was formed, which was a typical brittle-toughness mixed failure, and the degree of brittleness increased with the increasing of temperature. Electrochemical analysis showed that corrosion resistance of the joint slightly decreased due to aluminum alloy accelerated dissolution caused by increasing of temperature. The proposed research will provide a theoretical basis for solving aluminum alloys used in rail transit, ship accessories and other industrial fields.

The exposure of reinforced concrete bridges to chloride induces a corrosion phenomenon, leading to pitting corrosion on the steel bars and subsequent stress concentration development within them. This process accelerates corrosion, resulting in structural degradation. The stress corrosion coupling effect of pitting steel bars was investigated in this paper. First, based on electrochemical theory, the stress corrosion correction factor (SCCF) was proposed for carbon steel bars to chloride attack, which was applicable throughout the elastic-plastic stage. Then, an electrochemical experiment of steel bars in concrete was conducted to obtain the parameters for the SCCF equation. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) measurements were performed at various strain levels to investigate the stress corrosion behavior of steel bars under simulated chloride ion intrusion conditions. Next, based on the experiment results, a time-varying stress corrosion model was established to examine the corrosion pits of the steel bars under load. Finally, a numerical model of stress corrosion in concrete-exposed steel bars subject to chloride erosion was developed. The impact of loading on the stress corrosion coupling effect and the relationship between the SCCF and the stress concentration factor (K) were discussed. The analyses confirmed an accelerated corrosion rate in steel bars under stress, particularly magnifying as the steel bar transitions into the plasticity phase. Furthermore, the stress corrosion coupling effect was amplified with increasing loads. Within the elastic range, the SCCF and K were basically linear. [ABSTRACT FROM AUTHOR]

Multiple corrosion defects on oil and gas pipeline elbows seriously threaten the safe and smooth operation of pipelines. In this work, a three-dimensional (3D) model of circumferentially aligned corrosion defects on the external surface of the elbow subjected to mechanoelectrochemical (M-E) interaction was developed. Subsequently, the M-E interaction law of circumferentially aligned corrosion defects under internal pressure was investigated. Then the influence of the geometries of circumferentially aligned corrosion defects on the M-E interaction was studied. The critical circumferential spacings between the defects were determined. The results indicate that due to the special characteristics of the elbow structure, the nonuniform distribution of stress under the action of internal pressure leads to different failure pressures at different locations of the elbow. The variation laws of defect width are the same as that of straight pipelines, under a fixed internal pressure or a defect depth, with the increase of the defect width, the maximum stress level and corrosion rate growth slow until both barely change. In addition, this work integrates the mechanical stress field with the electrochemical corrosion field, considering the specificity of the stress distribution in the elbow. A new interaction criterion to judge the critical circumferential spacing of the interaction between adjacent defects is defined. The new interaction criterion indicates that the circumferentially aligned corrosion defects of the elbow separate when neither the mechanical stress field nor the electrochemical corrosion field mutually interact, and can be evaluated as individual corrosion defects. This work complements the integrity evaluation model for elbows containing multiple corrosion defects and provides guidance for oil and gas piping systems integrity management. [ABSTRACT FROM AUTHOR]

Efficient and corrosion resistant 15 %PANI-NiB@Ti catalytic electrode was rapidly prepared by one-step mild electroless plating, which maintains its hydrogen evolution and morphological integrity in harsh environments. [Display omitted] • Highly efficient 15 %PANI-NiB@Ti is prepared via one step mild electroless plating method. • The doping of polyaniline significantly reduces the cracking phenomenon and improves the HER evolution performance of the electrode. • Excellent corrosion resistance enables the electrode to tolerate the harsh environment such as high temperature. The economic and reasonable design of highly stable and corrosion-resistant electrodes is fundamental to achieving the industrial-scale hydrogen productions via water electrolysis, but electrodes' premature failures are often caused by corrosion and stress damage. Therefore, these challenges are successfully solved by utilizing conductive and crack-resistant polyaniline "stabilizer" with a mild chemical plating process to construct the catalytic electrode on a titanium substrate (15 %PANI-NiB@Ti) in the present work. The 15 %PANI-NiB@Ti catalytic electrodes have been in continuous operation for 350 h at the current density of 200 mA cm−2 with the high efficiency of 98.4 % in a 323.15 K environment. With the high economy and universality, the catalytic electrodes have good catalytic performance and reliability in the extreme industrial environments, such as high temperature, air, and high current density. Except for the above advantages, the 15 %PANI-NiB@Ti catalytic electrodes also have good cracking resistance, which provides a novel and feasible approach to the industrial application of transition metal catalytic electrodes. [ABSTRACT FROM AUTHOR]

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]

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.

AbstractA mechanical property degradation model of material fatigue life varying with stress level and corrosion time was developed in this study. An acidified NaCl solution was used to accelerate the corrosion of stainless-steel samples, and the relationship between laboratory-accelerated corrosion and atmospheric corrosion was established using corrosion thickness loss parameters. Based on the results of a pre-corroded fatigue test, lgN–S–T surface models and a modified version of Miner’s rule for calculating nonlinear mechanical damage accumulation were proposed. Taking a real part of a high-speed train as an example, critical operating mileages considering material fatigue performance degradation under corrosion conditions were calculated, which were consistent with failure mileages of the census results. [ABSTRACT FROM AUTHOR]

The escalating demand for advanced structural materials with superior wear and corrosion resistance in aeronautical and military applications has spurred interest in amorphous alloys, particularly metallic glasses, due to their non-crystalline atomic configurations and exceptional mechanical properties. High-Velocity Oxygen Fuel (HVOF) spraying, a high-performance thermal spray technology, has emerged as a robust solution for enhancing the surface integrity of these materials by delivering dense, well-bonded coatings. This study investigates the integration of HVOF in reinforcing amorphous materials, with a specific focus on augmenting wear resistance under extreme mechanical stresses and improving corrosion protection in hostile environments. Key parameters such as particle velocity, flame temperature, and spray distance are analyzed to optimize coating quality while preserving the amorphous phase. The article delves into the microstructural evolution during deposition, assessing the resultant performance improvements through empirical data and computational models. Findings indicate that HVOF reinforcement significantly enhances the operational longevity of amorphous materials, positioning them as viable candidates for high-stress, corrosive conditions in military aviation, defense systems, and aerospace components. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department 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.)

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths 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.)

Coatings are essential for protecting steel structures from corrosion and mechanical stresses, especially under challenging environmental conditions. To this end, this study systematically examines the effects of temperature (−20 °C to 50 °C), strain rate (6.67 × 10−4 s−1 to 1.67 × 10−2 s−1), and intermediate coat thickness (140 μm to 700 μm, the layer between the primer and topcoat) on the uniaxial tensile properties of heavy-duty coatings for steel structures. Experimental and theoretical analyses were conducted to quantitatively assess the influence of these factors on the mechanical properties of the coatings. A multifactor constitutive model was developed based on the Sherwood–Frost model by integrating material characteristics and fitting experimental data, incorporating response functions for temperature, strain rate, and intermediate coat thickness. The results reveal that increased temperature causes temperature-induced softening, while higher strain rates lead to strain rate-dependent strengthening of the coatings. In contrast, the effect of layer thickness on mechanical properties follows a non-monotonic trend, influenced by the structural and material characteristics of the coatings, with the most significant mechanical response occurring at 560 μm thickness. These findings suggest that optimal coating design must consider multiple factors to enhance mechanical performance. Additionally, the correlation coefficients (r) between the model predictions and experimental results are 0.97 or higher, indicating the model's effectiveness in predicting and optimizing the mechanical performance of heavy-duty coatings under complex conditions. [ABSTRACT FROM AUTHOR]

Regarding the safety of casing during the production of hydrogen gas during the perforation operation in the curve section of ultra deep horizontal wells, the theoretical stress calculation formula near the perforation hole and the tensile strength, external extrusion strength, and internal pressure strength that three different sizes of casing can withstand were derived based on the plate hole theory and casing performance calculation formula; It also analyzed the stress distribution of the casing in the curve section before perforation operations, and found that under the worst working conditions, the stress on the casing body is less than the yield strength, and the high stress area of the casing is mainly concentrated in the axial direction. Increasing the wall thickness of the casing does not have a significant effect on reducing the high stress area, but reducing the diameter, density, curvature of the curve section, and using a single spiral distribution will effectively improve the stress distribution on the casing, which is more conducive to the safety of perforation operations in the curve section; Finally, physical and chemical properties and stress corrosion experiments were conducted on the casing used on site, and it was found that there will be a large number of pitting pits for the initiation of cracks in the casing underground. Therefore, an analysis was conducted on the crack propagation caused by the initial cracks generated by perforation operations. It was found that changing the initial crack length, angle, and casing wall thickness has little significance in reducing crack propagation, while reducing the curvature of the curve section has a significant impact on casing crack propagation. The research methods and achievements in the article provide theoretical guidance for the safety evaluation of casing during perforation operations in the curve section of ultra deep horizontal wells. • Analyzed the stress of casing in curved wells, it can guide construction operations. • Evaluated the casing after perforation, which can prevent downhole casing failure. • Corrosion experiments were conducted on casings with different chromium contents. • Explored the propagation of casing cracks after curved perforation operations. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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.)

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]