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Microarc oxidation technology enhances magnesium alloy surfaces but faces cracks and micropores. Adding C6H10CaO6 and Ca(OH)2 only partially solves this. This study used immersion pulling to create a microarc oxidation/polycaprolactone composite film, examining its properties and degradation. The film transitioned from smooth to porous with calcium and phosphorus deposits. After 56 days, the Ca/P ratio approached the ideal 1.67, matching the biological environment. The polycaprolactone layer thinned in corrosive media, with hydrogen bubbles and film detachment. Surface sediments included Ca2P2O7 and hydroxyapatite (HA), important for biocompatibility. Cell experiments showed superior adhesion and proliferation on the composite film compared to controls. A degradation model revealed the film's protective role during three stages. In summary, the composite film exhibits excellent surface morphology and composition, promotes cell growth, and protects the magnesium alloy substrate during degradation. [ABSTRACT FROM AUTHOR]

Chloride profiles can be used to assess the durability of concrete structures against corrosion in the marine environment. However, the models proposed to adjust these chloride profiles are diverse and have varied complexities. Therefore, the objective of this article was to compare the performance of five chloride penetration models using a database with different profiles found in the literature. For this, 63 chloride profiles were selected. The response of the models was evaluated through a strong statistical analysis to compare the accuracy of these equations. The results demonstrated that standardized models based on Fick's second law should adjust only the data in the diffusion zone of the profiles by minimizing the sum of the squared residuals and applying a simple iteration, showing a coefficient of determination (R2) above 0.90, mean absolute error (MAE) below 0.20, and root mean square error (RMSE) close to 0.20. However, traditional models were less effective to fit the entire profiles (convection and diffusion zones), especially when a triple iteration was applied. For this case, Holliday's model showed better results (R2=0.84 , MAE=0.25 , and RMSE=0.30). Therefore, a new analysis method is suggested in this article to better adjust the chloride profiles by the diffusion models. The analysis of chloride profiles is an important tool to evaluate the service life of reinforced concrete structures. In this case, considering the reinforcement corrosion as the main degradation mechanism observed in these structures, the knowledge regarding the service life of field structures highlights the importance of research on this area, mainly if the structure is present in the marine environment, since the port infrastructure is vital to several international trade relations. Furthermore, artificial islands have been built to expand the marine infrastructure for tourists up to aeronautical purposes, thus increasing the number of structures exposed to this severe aggressive environment. Different models have been proposed to represent the chloride penetration in concrete structures, although many of them have difficulty representing the chloride penetration, adjusting only the diffusion zone by the solution of Fick's second law of diffusion for a semi-infinite medium. The full representation of the chloride profiles, with clear physical variables, has been the subject of research in the last years. In this sense, a general model based on the modified Holliday equation was successfully applied to chloride profile modeling in different coastal structures around the world, attesting its worldwide applicability. [ABSTRACT FROM AUTHOR]

Results of studying the properties of composite fluoropolymer-containing coatings formed by the cold spray (CS) method on the surface of constructional steel are presented. Different ways of protective coating formation are proposed. The composition of coatings was studied using SEM/EDX analysis. The incorporation of super-dispersed polytetrafluoroethylene (SPTFE) into the coating increases the corrosion resistance of the copper-zinc-based cold-sprayed coating. Analysis of the electrochemical properties obtained using EIS (electrochemical impedance spectroscopy) and PDP (potentiodynamic polarization) indicates that samples treated with SPTFE on a base copper-zinc coating showed lower corrosion current density and higher impedance modulus (jc = 8.5 × 10−7 A cm−2, |Z|f=0.1 Hz = 5.3 × 104 Ω∙cm2) than the specimen with cold-sprayed SPTFE (jc = 6.1 × 10−6 A cm−2, |Z|f=0.1 Hz = 8.1 × 103 Ω∙cm2). The best anticorrosion properties were revealed for the sample with a cold-sprayed base Cu-Zn layer annealed at 500 °C for 1 h, followed by SPTFE friction treatment and re-annealed at 350 °C for 1 h. The corrosion current density jc of such a coating is 25 times lower than that for the base Cu-Zn coating. The antifriction properties and hydrophobicity of the formed layers are described. Obtained results indicate that cold-sprayed polymer-containing coatings effectively improve the corrosion and wear resistivity of the treated material. [ABSTRACT FROM AUTHOR]

• The novel concept of the nondestructive thickness measurement of the plate-like structures subjected to corrosion degradation has been presented. • The study explores the influence of actuator-sensor distance on corrosion monitoring, emphasizing the crucial role of the number of sensors over their spatial separation. • The Bilateral and Rotational Central Symmetry Degrees are introduced as reliable indicators, demonstrating a consistent decrease with higher corrosion levels. • The experimental campaign was supported with numerical simulations conducted for plates with irregular thickness defined using random fields. Metallic structures often face degradation, and corrosion ranks among the most prevalent forms of deterioration. Accurate quantification of corrosion is crucial, especially for structures exposed to harsh environmental conditions, such as marine vessels and offshore installations. Because the traditional measurement methods based on scanning by ultrasonic gauge are time-consuming and provide only rough information on the thickness variability, there is a need to develop new robust and accurate diagnostics methods. This paper aims to investigate the corrosion monitoring of metal plates using guided wave propagation. Guided waves propagate within the entire volume of the specimen. If it is undamaged and isotropic, the velocity in all directions is the same, and the spreading wavefront takes a circular shape. The primary assumption presented in this paper is that the potential damage caused by corrosion leads to disturbance of this symmetry. The study shows Bilateral and Rotational Corrosion Symmetry Degree (BCSD and RCSD) functions, demonstrating a consistent decrease in symmetry values with increasing degree of degradation (DoD) caused by the corrosion process. The main aim of the study was to test the possibility of corrosion monitoring by using variable number of sensors comprising the transducer network. Also, the influence of the distance between the sensors affecting the size of the monitored area on the corrosion monitoring procedure was investigated. The paper contains the results of numerical and experimental campaigns conducted for corroded plates characterized by variable DoD and monitored using nine different transducers configurations. It is the first step in developing a novel measurement procedure specially designed for the ship and offshore industry. Therefore, because of the initial stage of the study, the last part of the paper discusses the limitations and drawbacks of the presented wave symmetry-based approach. [ABSTRACT FROM AUTHOR]

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• Degradation behavior of rust-prevention oil coating has been studied by EIS. • The obtained EIS data have been interpreted based on an equivalent circuit model. • EIS measurement for rust-preventive oil coating degradation study is applicable. • Adsorption capacitance relates well to protection performance of the oil coating. The traditional evaluation on anti-corrosion performance of a rust-preventive oil is often time-consuming and of high cost. In this investigation, electrochemical impedance spectroscopy (EIS) has been employed to understand the degradation behavior of rust-preventive oil in contact with NaCl electrolyte, with a focus on analyzing the electrochemical responses that correspond to a different frequency range in the obtained EIS spectra. The results indicate that the obtained EIS spectra can be generally divided into four frequency ranges. The high-frequency range is influenced by the continuous seepage of NaCl electrolyte, and the sub-high frequency range can reflect the presence of reversed micelle formed by corrosion inhibitor molecules and water molecules. Besides, the mid-frequency range is associated with the adsorption process of corrosion inhibitor molecules at the oil-film/metal interface, and the low-frequency range is associated with the diffusion process of dissolved ferrous ions. An extended immersion will result in a continuous seepage of electrolyte into rust-preventive oil coating and degrade the adsorption of corrosion inhibitor molecules, leading to a poor corrosion protection performance of the oil coating. Therefore, it is believed that the proposed design can provide a method in evaluating the degradation behavior and corrosion protection performance of rust-preventive oil to underlying steel substrate by EIS measurement under a lower amplitude. [ABSTRACT FROM AUTHOR]

In order to study and verify if the three corrosive irons of SO42−, Mg2+, and Cl− could promote or inhibit each other in concrete corrosion as time goes by, we take Metakaolin (MK) as the research object to explore the interaction mechanism among ions by testing the physical and mechanical properties, the ion content, the phase composition, and the microstructural changes of the MK concrete under the action of various ion combinations. The results show that during the initial and middle stages of the corrosion (40–80 days), SO42− and Mg2+ are in reciprocal inhibition relation, Cl− could inhibit the action of SO42−, and Mg2+ could promote the diffusion of Cl−. However, at the final stage of corrosion (120 days), SO42− and Mg2+ could mutually promote each other, and both irons could promote the diffusion of Cl−. Mg2+ could mainly produce magnesium hydroxide and M-S-H inside the concrete, SO42− mainly generates the ettringite and gypsum, while Cl− mainly produces Friedel salt and NaCl crystal.

The efforts to develop structural materials for biodegradable metal implants have lately shifted their focus from Magnesium and Iron base alloys towards Zinc. This was mainly due to the accelerated corrosion rate of Mg that is accompanied by hydrogen gas evolution, formation of voluminous iron oxide products with reduced degradation rate in the case of Iron implants and the crucial role of Zn in many physiological processes. However the mechanical properties and degradation capabilities of pure zinc in physiological environment are limited and do not comply with the requirements of biodegradable implants. The present study aims at evaluating the effect of 4%Fe on the in-vitro and in-vivo behavior of pure Zinc. This was carried out in order to address the inherent disadvantages of pure zinc in terms of mechanical properties and biodegradability. The results obtained clearly indicate that the biocompatibility and mechanical properties of the new material system was in accord with the prospective requirements of biodegradable implants. However the corrosion degradation of the new alloy in in-vivo conditions was quite similar to that of pure zinc in spite of the significant micro-galvanic effect created by Delta phase Zn11Fe. [ABSTRACT FROM AUTHOR]

Infrastructures and industrial buildings are commonly exposed to aggressive environments and damaged by corrosion. In prestressed reinforced concrete structures, the potential risks of corrosion could be severe since reinforcements are already subjected to high amounts of stress and, consequently, their load-bearing capacity could abruptly decrease. In recent years, some experimental studies have been conducted to explore the flexural behavior of corroded pretensioned reinforced concrete (PRC) beams, investigating several aspects of residual structural performance. Although many studies have been done in this area, there is no concise paper reviewing the state-of-the-art research. Accordingly, the main objective of this paper is to provide a review of the available experimental tests for residual capacity assessment of corroded PRC beams. Based on the state-of-the-art review, a degradation law for the flexural strength of corroded PRC beams is suggested.

Corrosion degradation of ship plates is predicted at different ship locations based on limited information on the local environmental conditions. The ship spaces are classified according to their chemical and physical characteristics that affect the corrosion behaviour. The parameters of the calibrated models, expressing the corrosion degradation from both sides of ship plates, are used to derive other parameters for corrosion models expressing the corrosion degradation at each side of the corresponding plates. The derived models are then used to develop corrosion models for other ship spaces, where no real corrosion measurement data are available. [ABSTRACT FROM AUTHOR]

In this work, the corrosion degradation of tinplate in contact with salty water is investigated by scanning electrochemical microscopy (SECM) electrochemical impedance spectroscopy (EIS). Experimental results indicate tin maintains at passive state during the exposure; however, pores and defects existed in tin coating leads to an exposure of carbon steel substrate to the electrolyte, in which localized corrosion tends to occur within the pore. A phenomenological model is proposed to interpret corrosion mechanism of tinplate in contact with salty food based on the proposed electrochemical equivalent circuit. [ABSTRACT FROM AUTHOR]

In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications. However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications. Recently, zinc and zinc-based alloys have been proposed as new additions to the list of degradable metals and as promising alternatives to magnesium and iron. The main byproduct of zinc metal corrosion, Zn2+, is highly regulated within physiological systems and plays a critical role in numerous fundamental cellular processes. Zn2+ released from an implant may suppress harmful smooth muscle cells and restenosis in arteries, while stimulating beneficial osteogenesis in bone. An important limitation of pure zinc as a potential biodegradable structural support, however, lies in its low strength (σUTS ~30MPa) and plasticity (ε < 0.25%) that are insufficient for most medical device applications. Developing high strength and ductility zinc with sufficient hardness, while retaining its biocompatibility, is one of the main goals of metallurgical engineering. This paper will review and compare the biocompatibility, corrosion behavior and mechanical properties of pure zinc, as well as currently researched zinc alloys. [ABSTRACT FROM AUTHOR]

In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications. However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications. Recently, zinc and zinc-based alloys have been proposed as new additions to the list of degradable metals and as promising alternatives to magnesium and iron. The main byproduct of zinc metal corrosion, Zn2+, is highly regulated within physiological systems and plays a critical role in numerous fundamental cellular processes. Zn2+ released from an implant may suppress harmful smooth muscle cells and restenosis in arteries, while stimulating beneficial osteogenesis in bone. An important limitation of pure zinc as a potential biodegradable structural support, however, lies in its low strength (σUTS ~ 30 MPa) and plasticity (ε < 0.25%) that are insufficient for most medical device applications. Developing high strength and ductility zinc with sufficient hardness, while retaining its biocompatibility, is one of the main goals of metallurgical engineering. This paper will review and compare the biocompatibility, corrosion behavior and mechanical properties of pure zinc, as well as currently researched zinc alloys.

The study presents experimental and numerical identification of corrosion degradation of thin-walled structural components employing guided wave propagation. The steel structural components are subjected to through-thickness varying corrosion degradation levels. The developed approach using the non-destructive guided wave-propagation quantifies the equivalent average corrosion degradation level by exploring a limited number of transducers. A group velocity dispersion curve reconstruction has been used to determine the corrosion-induced plate thickness reduction. Two case studies are used to examine experimentally the newly developed approach. In the first one, the dispersion curve and the assessment of the corrosion thickness reduction have been made using wave signals of various excitation frequencies. In the second one, the analysis was conducted only for two wave propagation signals and one excitation frequency which allowed for reconstructing the dispersion curve in a limited frequency range. A good agreement between the natural and estimated corrosion degradation levels was observed in both case studies. The present study develops a signal processing methodology, which can be used in the SHM systems. Several aspects still need to be further investigated before the developed approach can be applied to the complex ship hull structures' large size and complex geometry. • An algorithm for dispersion curve tracing using adjacent signals is presented. • Guided waves for the corrosion degradation level assessment are employed. • It is proved to outperform plate thickness reduction using group velocity curve. [ABSTRACT FROM AUTHOR]

This paper studies corrosion inhibition and compressive-strength effect of Rhizophora mangle L. leaf-extract on steel-reinforced concrete in 0.5M H2SO4, simulating industrial environment of wind-energy installations. Electrochemical monitoring and load- bearing/compressive-strength testing were employed for different concentrations of the leaf-extract admixed in duplicated samples of steel-reinforced concretes, immersed in the test-system. Analyses of the experimental test-results, as per ASTM G16- 95 R04, identified 0.1667% Rhizophora mangle L., per weight of cement, with optimum (very good) inhibition efficiency. Rhizophora mangle L. admixtures combined good inhibition efficiency with compressive-strength improvements in concretes. These bear implications for protecting wind-energy structures against corrosion-degradation in industrial environments. [ABSTRACT FROM AUTHOR]

The study presents an experimental investigation on the corrosion degradation level assessment using nondestructive wave-based methods. The degradation level of ship structural elements has been assessed in two different ways. The first one is based on the spectral decomposition and zero-crossing incorporated reconstruction of the dispersion curve approach of the antisymmetric Lamb wave mode and the best matching of the theoretical solution. The second approach was based on searching for a solution to the convex optimization problem. In the first case, the plate thickness is assumed to be constant and the phase velocity reconstructed curve is fitted to match the best solution in the all considered frequency domain. In the second case, the assumption about the varying plate thickness is set and the optimal thickness distribution resulting in any times of wave flight is defined. • Wave-based methods for the corrosion degradation level assessment are employed. • Plate thickness reduction is assessed using phase velocity curve reconstruction. • The constrained convex optimization in thickness reduction estimation is used. [ABSTRACT FROM AUTHOR]

Subsea pipelines are delicate infrastructures with high importance to the oil and gas industry. These structures are surrounded by an extreme environment, in which free spanning is a major issue that can lead to several unwanted events such as local buckling or vortex-induced vibration. Moreover, corrosion is inevitable problem to these structures. All these problems highly reduce the safety levels of subsea pipelines. Hence, this paper proposes a new framework for the probabilistic analysis of subsea pipelines subjected to both free spanning and corrosion degradation. For the subsea pipeline, new limit state functions are developed that include failure modes due to corrosion degradation and spanning loads caused by the maximum bending stress. In addition, new probabilistic burst pressure models for corroded pipelines have been included, taking into consideration pipeline steel grade strength as well as the surrounding uncertainty. The importance sampling method is proposed to estimate the reliability analysis results in terms of failure probability and reliability index. The proposed framework is applied on a real case study of API 5 L X65 subsea pipeline. The impact of several parameters on the reliability analysis outcome are investigated and discussed through several scenarios. Results indicate the importance of early-inspection data for planning the suitable operating regime of the pipeline in terms of internal pressure, which can be used to estimate the allowable critical spanning lengths and corrosion defect geometries to alert the appropriate actions to avoid failures. • The assessment of subsea pipeline exposed to spanning loads and corrosion degradation is introduced. • Importance sampling method is proposed for estimating the failure probability results. • The framework is demonstrated using inspection data from an API 5 L X65 subsea pipeline. • The impact of crucial factors on the case study's reliability analysis results is examined. [ABSTRACT FROM AUTHOR]

A contribution to analytical and numerical tools is presented that permits deterministic evaluation of structures’ behavior under multiparameter and/or cyclic mechanical, thermal and chemical loads. Particular structure elements undergo plastic and corrosive degradation and dissipate energy, which consists of irreversible contributions, like the work of inelastic strains. The construction and its units’ lifetime are estimated according to the dissipated energy criterion. Modeling and numerical implementation of degradation effects are discussed, including cyclic plasticity generated by mechanical and thermal loads, stress corrosion, electrochemical corrosion and low-cyclic corrosion.

The deterioration of the condition of process plants assets has a major negative impact on the safety of its operation. Risk based integrity modeling provides a methodology to quantify the risks posed by an aging asset. This provides a means for the protection of human life, financial investment and the environmental damage from the consequences of its failures. This methodology is based on modeling the uncertainty in material degradations using probability distributions, known as priors. Using Bayes theorem, one may improve the prior distribution to obtain a posterior distribution using actual inspection data. Although the choice of priors is often subjective, a rational consensus can be achieved by judgmental studies and analyzing the generic data from the same or similar installations. The first part of this paper presents a framework for a risk based integrity modeling. This includes a methodology to select the prior distributions for the various types of corrosion degradation mechanisms, namely, the uniform, localized and erosion corrosion. Several statistical tests were conducted based on the data extracted from the literature to check which of the prior distributions follows data the best. Once the underlying distribution has been confirmed, one can estimate the parameters of the distributions. In the second part, the selected priors are tested and validated using actual plant inspection data obtained from existing assets in operation. It is found that uniform corrosion can be best described using 3P-Weibull and 3P-Lognormal distributions. Localized corrosion can be best described using Type1 extreme value and 3P-Weibull, while erosion corrosion can best be described using the 3P-Weibull, Type1 extreme value, or 3P-Lognormal distributions. [ABSTRACT FROM AUTHOR]

Material degradation due to corrosion-fatigue was evaluated nondestructively using backscattered Rayleigh surface wave. A corrosion-fatigue test was carried out for the specimens made of thermo-mechanically controlled process steel in 3.5 wt.% NaCl solution at 25 °C. The Backscattering profile, which is the amplitude variation of backscattered ultrasound according to the incident angle, of the specimens were measured in water at room temperature after the corrosion-fatigue test. The velocity of Rayleigh surface wave, determined from the incident angle at which the profile of the backscattered ultrasound became maximum, decreased for the specimen that had the large number of cycles to failure in the corrosion-fatigue test. This fact implies that the corrosion degradation occurred at specimen surface in this specific test is dominantly dependant on the time exposed to corrosion environment. The result observed in the present work demonstrates the high potential of backscattered Rayleigh surface wave as a tool for nondestructive evaluation of corrosion degradation of aged materials. [Copyright &y& Elsevier]

This study investigated the corrosion behaviors of Ti6Al4V alloy during the hot salt and hot salt - water vapor tests. Ti6Al4V suffered from slight oxygen erosion at the initial stage, while chlorine greatly accelerated the oxide growth. The initial and accelerated oxidation reactions resulted in a continuous mass gain of Ti6Al4V during the hot salt test. Ti6Al4V experienced severe corrosion degradation during the hot salt - water vapor test. The reaction between oxides, chloride salt and water induced the formation of hydrochloric acid (HCl), while chlorine reacted with water to form HCl. The HCl subsequently reacted with the alloy to form gaseous chlorides, that volatilized to the outside and consequently led to a significant mass loss of Ti6Al4V. These results confirmed that the oxidation - hot salt - water vapor synergism effect showed a strong damage on the hot end components of titanium alloy during the marine service. • Corrosion damage mechanism of Ti6Al4V in marine environment was studied. • Ti6Al4V experienced a continuous mass gain during the hot salt test. • Oxidation-hot salt-water vapor synergism damage occurred in marine environment. • Ti6Al4V suffered from a severe mass loss during the hot salt-water vapor test. [ABSTRACT FROM AUTHOR]

In order to study and verify if the three corrosive irons of SO42−, Mg2+, and Cl− could promote or inhibit each other in concrete corrosion as time goes by, we take Metakaolin (MK) as the research object to explore the interaction mechanism among ions by testing the physical and mechanical properties, the ion content, the phase composition, and the microstructural changes of the MK concrete under the action of various ion combinations. The results show that during the initial and middle stages of the corrosion (40–80 days), SO42− and Mg2+ are in reciprocal inhibition relation, Cl− could inhibit the action of SO42−, and Mg2+ could promote the diffusion of Cl−. However, at the final stage of corrosion (120 days), SO42− and Mg2+ could mutually promote each other, and both irons could promote the diffusion of Cl−. Mg2+ could mainly produce magnesium hydroxide and M-S-H inside the concrete, SO42− mainly generates the ettringite and gypsum, while Cl− mainly produces Friedel salt and NaCl crystal. [ABSTRACT FROM AUTHOR]

Infrastructures and industrial buildings are commonly exposed to aggressive environments and damaged by corrosion. In prestressed reinforced concrete structures, the potential risks of corrosion could be severe since reinforcements are already subjected to high amounts of stress and, consequently, their load-bearing capacity could abruptly decrease. In recent years, some experimental studies have been conducted to explore the flexural behavior of corroded pretensioned reinforced concrete (PRC) beams, investigating several aspects of residual structural performance. Although many studies have been done in this area, there is no concise paper reviewing the state-of-the-art research. Accordingly, the main objective of this paper is to provide a review of the available experimental tests for residual capacity assessment of corroded PRC beams. Based on the state-of-the-art review, a degradation law for the flexural strength of corroded PRC beams is suggested. [ABSTRACT FROM AUTHOR]

Physically, corrosion damage results in a reduction in thickness and a change in surface geometry due to differential corrosion rates on the surface of a steel member. The effects of thickness reduction on the mechanical characteristics of structural steel have been investigated intensively, but the same cannot be said for the surface configuration. This study investigated the variation of corrosion thickness and surface roughness characteristics with increasing corrosion degradation and their contribution to a reduction in the tensile ductility of corroded steel. Twenty-two SS400 type steel plates were corroded by an underwater accelerated exposure (bubbling) test. Specimens were exposed for a varying number of days after which measurement and evaluation of thickness reduction and surface roughness characteristics were conducted. Then, the remaining load and elongation capacity were determined experimentally from the standard uniaxial tensile test. The distribution of the surface strains was studied employing digital image correlation techniques. Findings from this work revealed that surface unevenness due to corrosion causes stress concentration and uneven yielding, and strain localization after yielding during the tensile test. This translated to an early attainment of maximum load, resulting in reduced ductility in corroded specimens. A general trend is such that ductility decreases with increasing surface roughness. A plastic ductility loss of up to 80% is experienced when maximum surface height ratio, ζ sz ≥ 0.9 and average surface height ratio, ζ sa ≥ 0.15. Finally, empirical equations for estimating the remaining tensile ductility of corroded steel based on surface roughness characteristics were proposed. Unlabelled Image • Corrosion causes a reduction in thickness as well as a change in surface geometry. • Residual ductility for corroded steel decreases with increasing surface roughness. • Roughness causes stress/strain concentration, early yielding and strain localization. • Strain localisation leads to early necking initiation thus a reduction in ductility. • Ductility can be estimated empirically based on surface roughness characteristics. [ABSTRACT FROM AUTHOR]

• Accelerated corrosion experiments of semi-parallel wire cables were conducted. • Different cable dimensions, wire arrangements and HDPE sheath break modes were considered. • A FE model for the failure mechanism evaluation of corroded semi-parallel wire cables was established. • Corrosion extent relates to the distance from breakage and wire arrangements. • Brittle strength evaluation model is applicable for corroded semi-parallel wire cables. Previous investigations on corrosive evolutions are mainly based on the parallel wire stay cables, and related discussions on semi-parallel wire cables are limited. The semi-parallel wire cable has helical wire compositions and different wire bonding mechanisms, which may induce different corrosion degradation evolutions. In this study, the accelerated corrosion testes have been performed on semi-parallel wire cables with different high-density polyethylene sheath breaks. The corrosion evolution paths inside the cable were analyzed, and tensile loading tests were performed on corroded wires to get the degradation properties. The residual strength and failure process of corroded semi-parallel wire cables were studied with finite element methods. Due to the clamping effect from HDPE sheath and the tight wire arrangement inside the cable, the corrosive solution can hardly infiltrate to the inner layers. The corrosive extents varied significantly between wires at different layers and even between different sides of the same wire. With the corrosion distribution and mechanical properties of corroded wires, a finite element model for corroded semi-parallel wire cables was established. The helical wire composition, inter-wire contact and frictions, and the wire rupture features were all considered. Simulation results revealed that the high level of wire bonding effects in semi-parallel wire cables will induce the uneven wire force redistribution and helical shaped deformation, which effect may lead to faster strength degradation when comparing to parallel wire cables. [ABSTRACT FROM AUTHOR]

The work studies the ship structural corrosion degradation allowance, analysing several sets of corrosion thickness measurements collected from operating tankers. The corrosion degradation process is modelled by a time-dependent exponential function with parameters adjusted to real corrosion thickness measurement data. Corrosion margins of redundant ship structures with severe consequences of failure are derived based on two approaches, probabilistic closed-form solution and risk-based direct approach. The developed closed-form solutions for the corrosion allowance for different corrosion environments can be used in the design, avoiding a complex risk-based assessment. [ABSTRACT FROM AUTHOR]