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Abstract The influence of co-regulating Mo and Sn on the corrosion resistance of low alloy steel in tropical marine atmospheric was investigated. The combined addition of Mo and Sn has been found to significantly improve the corrosion resistance of low alloy steel, augmenting the protective capabilities of the rust layer. This combined addition promotes the formation of protective compounds like α-FeOOH and FeCr2O4 within the alloy rust layer. Furthermore, it facilitates the conversion of Cr, Ni and Cu into corrosion-resistant oxides such as Cr2O3, NiFe2O4 and CuO, thereby enhancing the density of the rust layer. Additionally, as corrosion progresses over time, higher levels of Sn addition lead to increased Sn content within the inner rust layer, consequently bolstering the protective qualities of the rust layer. This comprehensive understanding sheds light on the synergistic effects of Mo and Sn in fortifying the corrosion resistance of low alloy steel, offering insights for the development of advanced corrosion-resistant materials in marine environments.

The spatiotemporal distribution of atmospheric environmental severity in Tibet was evaluated and predicted based on polycarbonate (PC) chromatic aberrations. This study collected the annual average data (April 2021 to March 2022) of eight types of environmental factors from 10 typical atmospheric sites in Tibet. The climatic characteristics and climate distribution areas were analyzed to obtain accurate input to evaluate environmental severity. Natural environmental tests were conducted at 10 sites to analyze the regulation of PC degradation. The results showed that the gloss decreased and chromatic aberration gradually increased during PC aging, and mechanical properties, such as tensile strength and tensile strain at break, decreased with fluctuations. Thus, chromatic aberration was selected as a PC aging evaluation index owing to its excellent performance. Pearson’s correlation analysis was used to determine the information redundancy hidden in various environmental factors and geographic information coordinates. The environmental parameters were further optimized, and the factors highly related to PC aging were sunshine time, altitude, average relative humidity, and precipitation time. The “environmental material” mapping model with excellent training precision and generalizability was established using the Back Propagation Artificial Neural Network. By inputting the environmental data of 28 cities in Tibet into the well-built models, the severity was predicted and visualized to form spatial distribution maps using the Griddate interpolation method. The results showed that the low-altitude areas in eastern Tibet presented low severity. By training with different learning accuracies, the results revealed that low learning precision caused insufficient training and led to low prediction accuracy, whereas high learning precision led to overfitting and a prediction of the local minimum. The meteorological data of the 28 cities in Tibet were loaded into a well-trained artificial neural network model to predict the chromatic aberration value of PC aging in 28 cities in Tibet. A spatial distribution map of severity in Tibet was obtained based on the Griddate interpolation calculation. The results indicated that severity was much higher in summer than in winter, and the severity of the northwest area was the highest even in winter. The exact quantitative evaluations of severity played a significant role in the safety service for the equipment and facilities in Tibet.

Abstract Microorganisms are notoriously known to cause local corrosion and stress corrosion cracking (SCC), which seriously endangers the materials service safety. Cu can enhance antibacterial function of the material and reduce the vulnerability to hydrogen embrittlement (HE). However, the dilemma of how much Cu content generates the best resistance to microbiological corrosion and SCC arises. Here, we modified the Cu content in pipeline steel to obtain the best antibacterial effect to nitrate reducing bacteria Bacillus cereus and HE resistance. The findings offer a fresh perspective on how to design and prepare a steel that are both resistant to microbiological corrosion and SCC.

Multiphase stainless steel is a kind of stainless steel that obtains good mechanical properties. Nevertheless, the passive and pitting behaviors of multiphase stainless steel remain inadequately elucidated. This study aims to investigate the passive and pitting behaviors of multiphase stainless steel by employing Auger electron spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and electrochemical techniques. The conclusions drawn from this research are as follows: The main constituents of the passive film on multiphase stainless steel comprise FeO, Fe2O3, Cr2O3, and Cr(OH)2. The passive film on the martensitic phase displays largest thicknesses. The Cr content in the passive film of the ferritic phase is highest. Particularly, the passive film on the (111) orientation of martensitic phase is thicker than that on the (001) and (101) orientations. Pitting corrosion in multiphase stainless steel primarily initiates at phase interfaces and subsequently extends into the ferritic phase.

Ferritic stainless steels have been utilized in marine atmosphere and are found to be susceptible to pitting corrosion in our field investigation. Alloying is an important to modify the passive film on the surface and improve the pitting corrosion resistance. Nevertheless, how the addition of titanium modifies the passive film and affects the pitting corrosion resistance of ferritic stainless steels remain controversial. This study has elucidated these topics through microstructure analysis and corrosion properties analysis. The results demonstrate that titanium addition increases the pitting potential almost linearly. Titanium forms TiO2 in the passive film and reduces defect density of the passive film. Moreover, titanium addition induces the precipitation of the Laves phase, which promotes micro-galvanic corrosion. For the titanium-alloyed ferritic stainless steels, pitting corrosion predominantly occurs in the ferrite phase adjacent to the Laves phase. The influence mechanism of titanium on the pitting corrosion of the ferritic stainless steel has been established, which takes micro-galvanic corrosion induced by titanium addition into account.

In the present work, we introduced a novel way to study the Tafel slope of titanium in passive state based on potentiodynamic test with a break by potentiostatic polarization. The power law model as well as surface analysis methods such as AES and XPS were also introduced to character the thickness and composition of the film. Results indicate that the Tafel slope of titanium electrode in the passive state increases with the applied overpotential. The anodizing constant is found to be equal to about 0.24–0.46 Å/s and 4–10 Å/V. The results showing highly consistent with AES and XPS results. The passive film are mainly composed of TiO2 predominantly outer layer, and titanium sub-oxide, Ti(OH)x predominantly inner layer.

Abstract A comparison of microstructure and corrosion performance has been made between NiCrMoV/Nb steel under different heat treatments in artificial seawater. The microstructures as well as the volume fraction of austenite strongly affect corrosion resistance. Atomic force microscopy (AFM) results reveal that both retained/reversed austenite and the grain boundary have a higher Volta potential than the matrix. The morphology of pits and the nature of retained/reversed austenite were investigated by field emission scanning electron microscopy (FESEM). Results can be discussed in terms of a model that describes the microgalvanic effect and the change of morphology and content of retained/reversed austenite resulting from a heat treatment process. The role of the microstructure and retained austenite on corrosion resistance evolution in the corrosion process is discussed. The X-ray diffraction (XRD) results reveal that the corrosion products formed on distinct microstructures primarily contain lepidocrocite (γ-FeOOH), goethite (α-FeOOH) with little difference after long time immersion.

Abstract Bacillus cereus (B. cereus) is observed to have varying effects on the stress corrosion cracking (SCC) sensitivity of different microstructures in the simulated heat-affected zone (HAZ) of X80 steel. At open circuit potential (OCP), the SCC sensitivity of different microstructures increased from 3.40–7.49% in an abiotic medium to 10.22–15.17% in a biotic medium. At −0.9 V (SCE), it increased from 22.81–26.51% to 35.76–39.60%. The increment in SCC sensitivity upon exposure to B. cereus was highest in the coarse-grained HAZ (7.68 and 16.79% at OCP and −0.9 V, respectively), followed by the intercritical and fine-grained HAZs. Owing to differences in the phase composition, grain boundary type, dislocation density, and surface volta potential, the initial adhesion number and position of B. cereus in the microstructure of the HAZ were differed, resulting in different sensitivities to SCC.

The stress corrosion mechanism and susceptibility of X80 steel under a disbonded coating in a simulated acidic soil solution was investigated by a disbonded coating simulation device. According to the ex situ slow strain rate tension (SSRT) tests and potentiodynamic polarization measurement results, the environmentally assisted cracking (EAC) process was controlled by both anodic dissolution (AD) and hydrogen embrittlement (HE), and the range of critical potential values for different EAC mechanisms were also confirmed. Due to the accumulation of H+ and Cl− at the bottom of the crevice under the disbonded coating, the X80 steel exhibited the highest EAC susceptibility. A low strain rate provides sufficient action time and allows the adequate diffusion of hydrogen atoms on the steel surface, thereby resulting in an increase in the EAC susceptibility of X80 steel.

Photocatalytic technology is considered an ideal approach for clean energy conversion and environmental pollution applications. In this work, a bifunctional BiOBr/ZIF-8/ZnO photocatalyst was proposed for removing phenols in wastewater and generating hydrogen peroxide. Insights from scanning electron microscopy measurements revealed the well-dispersion of ZIF-8/ZnO was on the BiOBr layer, which could effectively prevent agglomeration of ZIF-8 and facilitate the separation of carriers. In addition, the optimal H2O2 yield of the BiOBr/ZIF-8/ZnO sample could reach 116 mmol·L−1·g−1 within 2 h, much higher than that of pure BiOBr (with the value of 82 mmol·L−1·g−1). The optimal BiOBr/ZIF-8/ZnO sample could also remove 90% of the phenol or bisphenol A in 2 h, and its kinetic constants were 3.8 times and 2.3 times that of pure BiOBr, respectively. Based on the analysis of the various experimental characterizations, the photocatalytic mechanism of the S-scheme BiOBr/ZIF-8/ZnO composite for the degradation of phenolic pollutants and generation of H2O2 was proposed. The formation of the heterojunction and the oxygen vacancy work together to significantly improve its photocatalytic efficiency. In addition, the BiOBr/ZIF-8/ZnO catalyst has a certain impact on the degradation of phenol in actual wastewater, providing a way to effectively remove refractory pollutants and generate H2O2 in actual water.

NiAl-precipitate-strengthening steels, utilizing the inexpensive and lightweight element Al instead of Co and Ti to form strengthening precipitates, have cost and weight advantages over conventional maraging steels. However, such steel can hardly achieve ultimate strength above 1600 MPa if without co-precipitation of other precipitated phases. The goal of current work is to explore a processing scheme that can further improve the strength over 1600 MPa without sacrificing ductility and explain the mechanism. With the optimization of processing scheme, Ni(Fe, Al)-maraging steel, as a new type of such steel, achieves strength of up to ~2.1 GPa and elongation of 9.31%. The strengthening mechanism is discussed and concluded based on the results of tensile tests and microstructural characterizations. The key factor of further enhancing the strength and ductility simultaneously is given.

The behavior and mechanisms of the stress-assisted microbiologically influenced corrosion (MIC) of X80 pipeline steel induced by sulfate-reducing bacteria (SRB) were investigated using focused ion beam-scanning electron microscopy (FIB). Electrochemical results show that SRB and stress have a synergistic effect on the corrosion of X80 steel. SRB accelerated the transformation of Fe3O4 into iron-sulfur compounds and may have caused the film breakage of X80 steel products. The obtained FIB results provide direct evidence that SRB promotes the corrosion of X80 steel.

The present work systematically investigated the initiation mechanism of localized corrosion induced by Al2O3-MnS composite inclusion in E690 steel under a simulated marine environment. The results showed that a micro-gap exists between the Al2O3-MnS inclusion and the matrix, and electron backscattered diffraction (EBSD) analysis revealed significant lattice dislocation zones around the Al2O3-MnS composite inclusion. The presence of the micro-gap and the lattice dislocation both promoted the localized corrosion initiation. The Volta potential of Al2O3 detected by scanning Kelvin probe force microscopy (SKPFM) was approximately 149.33 mV higher than that of the steel matrix, and the Volta potential of MnS was 10 mV lower than that of the steel matrix. The current-sensing atomic force microscopy (CSAFM) results showed that the Al2O3 was not conductive, while the MnS had good conductive properties. Therefore, it was not possible for a galvanic couple to be formed between Al2O3 and the adjacent steel matrix. A galvanic couple effect between the MnS and the adjacent steel matrix was directly demonstrated for the first time. The MnS acted as the anode phase for preferential dissolution in the corrosion process. The in situ immersion experiments and the Pourbaix diagram results confirmed that the dissolution of MnS was an electrochemical reaction process and the dissolution of Al2O3 was a chemical reaction.

The effects of hydrogen charging on the electrochemical and stress corrosion cracking (SCC) behavior of X70 steel in a simulated deep seawater environment were investigated by using electrochemical measurements, slow strain rate tensile (SSRT) tests, and corrosion morphology characterization through SEM. The results showed that the concentrations of the adsorbed hydrogen in X70 steel after precharging under different hydrostatic pressures increased gradually and tended to be steady with the charging time. High hydrostatic pressures promoted the hydrogen permeation of X70 pipeline steel by promoting the permeating rate and quantity. The SCC susceptibility of X70 steel decreased first and then increased with the hydrogen-charging current density. The area reduction loss (Iψ) and true strain loss (Iε) exhibited the lowest SCC susceptibility at the 25 mA/cm2 hydrogen-precharging current density. The elongation rate loss (Iδ) exhibited the lowest SCC susceptibility at the 50 mA/cm2 hydrogen-precharging current density.

Economics: What corrosion cost China in 2014 It is estimated that the effects of corrosion in China cost approximately $310 billion USD in 2014. Corrosion is a costly issue, justifying substantial expenditure into techniques to protect and mitigate susceptible metals from its effects, and research investment. China has seen rapid growth in its economy in recent times, driven in part by investment in industry. In order to understand the monetary impact of corrosion in China, The Chinese Academy of Engineering instigated a nationwide study led by the Institute of Oceanology, Chinese Academy of Sciences. It estimates that approximately $310 billion USD was lost to the consequences of corrosion and money spent addressing it in 2014, accounting for 3.34% of GDP. Transportation and electronics industries generated the highest costs. Several recommendations are made, including the need for a government-coordinated national strategy.

The influence of dissolved oxygen concentration (DOC) on the microbiologically influenced corrosion (MIC) of Q235 carbon steel in the culture medium of halophilic archaeon Natronorubrum tibetense was investigated. The increase of DOC from 0.0 to 3.0 ppm was found to strengthen the oxygen concentration cell by promoting cathodic reaction. Meanwhile, the increased DOC also promoted archaeal cell growth, which could consume more metallic iron as energy source and aggravated the localized corrosion. When the DOC further increased to 5.0 ppm, the uniform corrosion was dominant as the biofilms became uniformly presented on the steel surface. Combined with the stronger inhibition effect of oxygen diffusion by the increased biofilm coverage, the MIC of carbon steel in the 5.0 ppm medium was weaker than that in the 3.0 ppm medium. From weight loss and electrochemical tests, the results all demonstrated that the carbon steel in the 3.0 ppm medium had the largest corrosion rate.

Anatase TiO2 with {001} facets is much more active than that with {101} facets, which has been verified via experiments and theoretical calculations. Graphene has garnered much attention since it was initially synthesized, due to its unique properties. In this study, reduced graphene oxide (RGO)/{001} faceted TiO2 composites were fabricated via a solvothermal method. The composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrophotometry, photoluminescence and Raman analysis. The results revealed that the graphene oxide was reduced during the preparation process of the {001} faceted TiO2, and combined with the surface of {001} TiO2. The photocatalytic activities of the composites were evaluated through the degradation of basic violet, under both white light (λ > 390 nm) and visible light (λ = 420 nm) irradiation. The results indicated that the photocatalytic activities of the {001} faceted TiO2 were significantly improved following the incorporation of RGO, particularly under visible light irradiation. Theoretical calculations showed that the band structure of the {001} faceted TiO2 was modified via graphene hybridization, where the separation of photoinduced electron–hole pairs was promoted; thus, the photocatalytic activity was enhanced.

The corrosion process of AZ91D magnesium alloy in simulated haze aqueous solution has been studied by electrochemical measurements, immersion tests and morphology characterization. Results show that AZ91D was corroded heavily in simulated haze aqueous solution due to the loose and breakable product film on the surface providing little corrosion barrier. The effect of different ions was investigated. It was found that both N O 3 − and N H 4 + played an important role in the corrosion process. N O 3 − helped to form passive film to protect the matrix, yet N H 4 + consumed OH−, resulting in the absence of Mg(OH)2 and serious corrosion. Meanwhile, S O 4 2 − and Cl− had influence on pitting corrosion. Magnesium aluminum oxide and MgAl2(SO4)4·22H2O instead of Mg(OH)2 were the dominate products, which is different from the former study. Corrosion rate changed with time, especially in the first 3 h. A two-stage corrosion mechanism is proposed after considering both the corrosion process and the influence of ions.

In this study, electrochemical measurements, immersion tests, and slow strain rate tensile (SSRT) tests were applied to investigate the electrochemical and stress corrosion cracking (SCC) behavior of X70 steel in simulated seawater with the interference of different alternating current (AC) densities. The results indicate that AC significantly strengthens the cathodic reaction, especially the oxygen reduction reaction. Simultaneously, hydrogen evolution reaction occurs when the limiting diffusion current density of oxygen reaches, and thus, icorr sharply increases with the increase in AC density. Additionally, when AC is imposed, the X70 steel exhibits higher SCC susceptibility in the simulated seawater, and the susceptibility increases with the increasing AC density. The SCC mechanism is controlled by both anodic dissolution (AD) and hydrogen embrittlement (HE) with the interference of AC.

This study employs potential-monitoring techniques, cyclic voltammetry tests, alternating current (AC) voltammetry methods, and surface characterization to investigate the AC corrosion of cathodically protected X80 pipeline steel. In a non-passive neutral solution at pH 7.2, a sufficiently negative potential completely protects steel at an AC current density of 100 A/m2. In an alkaline solution at pH 9.6, more serious AC corrosion occurs at more negative cathodic protection (CP) potential, whereas without CP the steel suffers negligible corrosion. In addition, the interface capacitance increases with AC amplitude. Based on these results, the AC corrosion mechanisms that function under various conditions are analyzed and described.

Waterborne coating has recently been paid much attention. However, it cannot be used widely due to its performance limitations. Under the specified conditions of the selected resin, selecting the function pigment is key to improving the anticorrosive properties of the coating. Zinc phosphate is an environmentally protective and efficient anticorrosion pigment. In this work, zinc phosphate was used in modifying waterborne acrylic coatings. Moreover, the disbonding resistance of the coating was studied. Results showed that adding zinc phosphate can effectively inhibit the anode process of metal corrosion and enhance the wet adhesion of the coating, and consequently prevent the horizontal diffusion of the corrosive medium into the coating/metal interface and slow down the disbonding of the coating.

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples.

Waterborne coating is the most popular type of coating, and improving its performance is a key point of research. Cathodic delamination is one of the major modes of failure for organic coatings. It refers to the weakening or loss of adhesion between the coating and substrate. Physical and chemical characteristics of coatings have been studied via scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurements, Fourier transform infrared spectroscopy (FTIR), and secondary ion mass spectrometry (SIMS). Early heterogeneous swelling at the metal-coating interface in non-defective coated metals was elucidated using frequency-dependent alternating-current scanning electrochemical microscopy. Two types of coatings (styrene-acrylic coating and terpolymer coating) were compared. The effects of thickness, surface roughness, and chemical bonding on cathodic delamination were investigated.

A modelling effort was made to try to predict the life of downhole tubes or casings, synthetically considering the effect of service influencing factors on corrosion rate. Based on the discussed corrosion mechanism and corrosion processes of downhole tubes, a mathematic model was established. For downhole tubes, the influencing factors are environmental parameters and stress, which vary with service duration. Stress and the environmental parameters including water content, partial pressure of H2S and CO2, pH value, total pressure and temperature, were considered to be time-dependent. Based on the model, life-span of an L80 downhole tube in oilfield Halfaya, an oilfield in Iraq, was predicted. The results show that life-span of the L80 downhole tube in Halfaya is 247 months (approximately 20 years) under initial stress of 0.1 yield strength and 641 months (approximately 53 years) under no initial stress, which indicates that an initial stress of 0.1 yield strength will reduce the life-span by more than half.

This article discusses the key features of a newly developed national data-sharing online network for material environmental corrosion. Written in Java language and based on Oracle database technology, the central database in the network is supported with two unique series of corrosion failure data, both of which were accumulated during a long period of time. The first category of data, provided by national environment corrosion test sites, is corrosion failure data for different materials in typical environments (atmosphere, seawater and soil). The other category is corrosion data in production environments, provided by a variety of firms. This network system enables standardized management of environmental corrosion data, an effective data sharing process, and research and development support for new products and after-sale services. Moreover this network system provides a firm base and data-service platform for the evaluation of project bids, safety, and service life. This article also discusses issues including data quality management and evaluation in the material corrosion data sharing process, access authority of different users, compensation for providers of shared historical data, and finally, the related policy and law legal processes, which are required to protect the intellectual property rights of the database.