Eutectic high entropy alloy (EHEA) is made up of alternatively ranged matrix and strengthening phases. The combination of eutectic and high entropy features endows EHEA extremely excellent mechanical properties, which may break the limit for strength-ductility compatibility and show a broad application prospects in various engineering fields. However, during the real service, the dual-phase structure of EHEA may result in a heterogeneous oxide scale, thus affecting its corrosion performance. The unknown effect of such heterogeneity affects the further application in high temperature application. Therefore, this study systematically analyzes the high-temperature oxidation behavior of different EHEAs, identify the factors (temperature, oxidation time, alloying elements) that affects corrosion, summarizes the high-temperature oxidation mechanism, compares the oxidation resistance between EHEA and conventional alloys and points out the future research direction, all of which may provide a reference for the future study and practical application of EHEA.

The corrosion behavior of HR3C steels with and without aluminizing beneath simulated coal ash deposits with varying content of alkali metal sulfate (Na₂SO₄ + K₂SO₄) and chloride (KCl) salts was comparatively studied in a gas mixture of SO₂,O₂, H₂O and CO₂ at 700^oC. The corrosion form of steels is oxidation with internal-sulfidation and -oxidation. When there is no chloride salt in the ash deposits, the corrosion depth of the alloy increases linearly with the mass fraction of Na₂SO₄ + K₂SO₄. However, the aluminized HR3C steel only underwent slight oxidation. When the content of alkali salts remains unchanged, while the content of KCl increases successively to 0.5%, 1% and 2% (mass fraction), the corrosion degree of HR3C is intensified in a jumping manner, but the aluminized ones still maintain good corrosion resistance.

Corrosion behavior of high temperature alloy GH4169 under tensile stress while beneath a solid NaCl deposit film was studied in water vapor containing air at 600°C to simulate the service conditions of aircraft engine compressors in the marine environment. The results show that the applied tensile stress accelerates the corrosion of GH4169 in the environment, resulting in the formation of a complex mixture of NiCr₂O₄, NaNbO₃, Fe₂O₃, NiO, Cr₂O₃, Al₂O₃ and NiFe₂O₄ on the alloy surface. The applied tensile stress could induce active internal corrosion of GH4169. The internal corrosion products were discontinuous granular Cr₂O₃ and a small amount of Fe₂O₃ and NbO. After normal heat treatment the GH4169 alloy tends to have non-uniform intergranular corrosion, while the solid-solution heat-treated ones exhibited a relatively uniform internal corrosion zone. The active corrosion process leads to the formation of Cr and Fe depletion regions in the matrix, and the Cr and Fe vacancies in this region lead to the deteriorated stability of Ni-Cr-Fe cells.

The synergistic effect of 2,2-dibromo-3-hypoazopropionamide (DBNPA) and rhamnolipid (RL) on the corrosion behavior of X80 pipeline steel in solutions containing sulfate reducing bacteria (SRB) Desulfovibrio bizertensis SY-1 was investigated. The results showed that compared with a sterile solution, the mass loss and pitting depth of X80 pipeline steel significantly increased in the presence of Desulfovibriobizertensis SY-1, while corrosion product FeS was detected on steel surface. However, the addition of DBNPA effectively inhibited the growth of planktonic and sessile bacterial cells, thereby retarding the corrosion process on X80 pipeline steel. Notably, when 150 mg/L DBNPA and 500 mg/L RL were co-added in the solution, the corrosion rate of X80 pipeline steel decreased by 77.8% compared to that in the SRB (p = 0.009) containing solution, whilst, by 50% compared to that in the SRB containing solution with addition of 300 mg/L DBNPA alone. Furthermore, this combination also led to an approximately 84.7% reduction in corrosion current density even after 15 days' immersion compared to that in the SRB containing solution, and about 20.5% reduction compared to that in the SRB containing solution with addition of 300 mg/L DBNPA alone. Therefore, these findings found that the cooperative addition of 150 mg/L DBNPA and 500 mg/L RL can effectively inhibit the corrosion of X80 pipeline steel induced by Desulfovibrio bizertensis SY-1. The results may provide references for selecting and utilizing biocides.

Addressing the issue of crack formation in SiO₂ coatings during high-temperature oxidation, a supplementary Zr layer was applied onto the SiO₂ coating surface through magnetic sputtering. This study revealed that the Zr layer, upon oxidation, transformed into ZrO₂, may effectively amend the cracks and voids that emerged during the sintering process of the SiO₂ coating. Furthermore, it mitigated the thermal expansion coefficient (TEC) disparity between TiAl and SiO₂ coatings. In addition, the ZrO₂-SiO₂ skeleton structure formed during the oxidation process may be able to improve the stability of the coating structure. The resultant Zr-SiO₂ composite coating significantly impeded oxygen inward diffusion from the ambient environment to the Ti45Al8.5Nb substrate, even the outward diffusion of alloy elements in the early stage of oxidation, which notably enhancing its resistance against high-temperature oxidation. Notably, limited growth of oxide particles was observed on the alloy, with a negligible increase in the thickness of oxide scale. Additionally, following a period of 100-hour oxidation at 900^oC, mutual element diffusion from both the substrate and coating led to the formation of a three-layered interdiffusion zone (Ti, Nb)O₂/Ti₅Si₃ + Al₂O₃ + Nb₃Al/TiN. This interdiffusion zone notably bolstered the bond strength between the composite coating and the Ti45Al8.5Nb substrate.

In this study, the galvanic corrosion behavior of T2 Cu-alloy and Q235 steel in solutions containing Na₂SO₄ and NaCl with various amount of Cl^- was investigated by electrochemical tests and corrosion product analysis. The results show that T2 Cu-alloy acts as cathode, while Q235 steel as anode for the galvanic couple, therefore Q235 steel experiences corrosion with accelerating rate; With the increasing of Cl^- concentration, the galvanic current density (I_g) of the galvanic couple exhibits a maximum due to the decrease of dissolved oxygen content in the solution, the decrease of oxygen diffusion coefficient and the increase of solution conductivity etc.; As the area ratio of T2 Cu-alloy to 235 steel increases, I_g increases significantly, indicating that the galvanic corrosion reaction is controlled by cathodic reaction; When the temperature increases from 25^oC to 50^oC, I_g increases and a maximum occurs at lower Cl^- concentrations; galvanic potential (E_g) shifted negatively with the increasing Cl^- concentration as influenced by dissolved oxygen. The results of this study may provide a reference for understanding the influence of Cl^- concentration on galvanic corrosion of Cu-coated carbon steel metal containers.

The requirements of power system for the corrosion resistance, conductivity and cost of grounding materials are increasing, so it is crucial to develop a new type of grounding materials. Herein, the cast iron was surface modified by carburization with epoxy resin as the carbon source, while controlling heating rate, holding temperature and time. The effect of heat treatment parameters on the microstructure, composition and corrosion resistance of the cast iron before and after carburization were comparatively charachterized by means of XRD, SEM, metallography, Raman spestroscopy, and electrochemical corrosion test. The results showed that there was an obvious carburization coating formed on the cast iron surface, which was mainly Fe₃C, thereby the corrosion resistance of the carbuurized cast iron was significantly improved. The best carburizing parameter is to heat up from room temperature to 750^oC at a rate of 5^oC/min, followed by furnace cooling. The carburization treatment to certain extent process can significantly enhance the corrosion resistance and conductivity of the cast iron, which met the functional requirements of grounding materials.

The passivation behavior of Cr10Mo1corrosion-resistant rebar steel and ordinary HRB400 rebar steel either as bare steels in a Cl^- free simulated concrete pore solution, or as rebar steels embedded in a concrete made of cement and reagent sea-sand in an artificial seawater 3.5% NaCl solution were studied by electrochemical technology and microscopic analysis technology, meanwhile the resistance probe technology was used to establish a rapid evaluation method of rebar corrosion. The results show that the corrosion resistant rebar steel exhibits better passivation behavior in the simulated pore solution with pH 11.5. In the second testing circumstance, the passivation film resistance value of the corrosion-resistant rebar steel is larger than that of the ordinary rebar steel, correspondingly, the corrosion current density of corrosion-resistant rebar steel is also smaller than that of the ordinary one. Results of EDS and XRD characterization show that due to the presence of Cr element, Cr₂O₃ generated by passivation reaction makes corrosion-resistant rebar steel exhibit better corrosion resistance. In order to rapidly evaluate the corrosion behavior of corrosion-resistant rebar steel, the resistance probe method was adopted to assess the corrosion rate of corrosion-resistant rebar steel in the second testing circumstance environment of seawater sand concrete. Consequently, the annual corrosion rate of corrosion-resistant bar steel was acquired to be 0.0047 mm/a. While the corrosion rate acquired by mass loss method dose further confirm that this resistance probe method may suitably be used to rapidly evaluate the corrosion behavior of steel bars within concretes.

The corrosion inhibition performance of the agricultural and forestry waste of coffee skin extract (CSE) in 0.10 mol·L^-1 trichloroacetic acid (Cl₃CCOOH) for plate of a cold rolled steel (CRS) was investigated by mass loss method, electrochemical tests, infrared spectroscopy (FTIR), scanning electron microscope (SEM), contact angle and surface tension measurements. The results show that the inhibition efficiency of 500 mg·L^-1 CSE can reach as high as 93.7% at 20^oC. The adsorption of CSE on CRS follows Langmuir adsorption isotherm at 20^oC and 30^oC, while follows Freundlich adsorption isotherm at 40^oC and 50^oC. The standard Gibbs free energy (ΔG⁰) is in the range of -30~-41 kJ·mol^-1. The adsorption type of CSE on CRS is the mixed adsorption mainly by chemisorption. CSE is a cathodic-type inhibitor. With the presence of CSE in 0.10 mol·L^-1 trichloroacetic acid solution the charge transfer r reactance increases, while the interface double layer capacitance reduces for the steel surface. As a subsequence, the corrosion degree and roughness of the steel surface decrease significantly, but its hydrophobicity is enhanced. FTIR confirms that CSE contains a large number of polar groups such as O atoms and aromatic rings. As the CSE concentration increases, the surface tension of the corrosive Cl₃CCOOH solution gradually decreased, and the conductivity of the solution increased. After the immersion of the test steel in the solution, the surface tension of the solution is increased, while its conductivity decreased.

Micro-nano structures were constructed on basalt flakes by alkali etching. Then nanosized ZnO-particulates were coated on the modified basalt flakes in assistance with silane coupling agent and stearic acid modifying agent. A super-hydrophobic, anti-corrosion and antibacterial composite coating consisted of basalt@ZnO and epoxy was prepared on Q235 carbon steel. The results show that the superhydrophobic basalt@ZnO/epoxy coating has a large water contact angle (approximately 152°). The modification of stearic acid could delay the occurrence of photocatalytic reaction and the release of reactive oxygen species, thus delaying the expression of antibacterial properties of ZnO. The anti-bacterial adhesion function of the composite coating is realized from two aspects: the hydrophobic mechanism of the superhydrophobic surface and avoiding the mass death of bacteria near the coating in a short time. After immersion in 3.5% NaCl solution for 14 d, the corrosion resistance of the superhydrophobic coating is 2 orders of magnitude higher than that of the plain epoxy coating, indicating that superhydrophobic basalt@ZnO/epoxy coating has superior barrier properties against corrosive media.

The F-PANI material was synthesized by modifying polyaniline (PANI) with perfluorodecyl triethoxysilane (FAS), which was subsequently blended with silicone resin (SR) to fabricate a functional F-PANI coating that exhibits both photo-thermal and superhydrophobic properties. The coating displays a contact angle of 150.8^o and a rolling angle of 3^o, along with superior mechanical strength, self-cleaning ability, and anti-corrosion performance. Upon exposure to 1 Sun irradiation at 20^oC, the F-PANI coating can attain a surface temperature of 83.5^oC within five minutes. Additionally, the coating demonstrates excellent photo-thermal features even at low temperatures. By 1 Sun irradiation at -25^oC, water droplets on the F-PANI coating were observed to be completely freezed after 830 s, showing a significantly slower freezing rate than the SR coating. Furthermore, the F-PANI coating exhibits defrosting and de-icing capability by 1 Sun irradiation at -15^oC.

The stress corrosion cracking behavior of two advanced high-strength steels (ultrafine bainite steel, Q&P steel) of the same composition in an artificial marine environment 3.5%NaCl solution was studied by means of microscopic characterization (SEM, XRD, EBSD), electrochemical test and slow strain rate stress corrosion test. The results show that being subjected to treatment with isothermal process,the aquired ultrafine bainitic steel presents significantly refined bainitic ferrite laths, companied with more thin film-like residual austenite herewith, presents higher strength and elongation at break. The bainite ferrite lath and residual austenite form a micro-electric couple, the lower potential of bainite ferrite acts as an anode thus suffered from dissolution, while the active dissolution site induces the initiation and propagation of cracks. In addition, ultrafine bainitic steel has fine grain, low stress during plastic deformation, thereby, lower stress corrosion sensitivity, which is due to the passivation of cracks caused by thin film residual austenite. Being subjected to treatment with quenching-partitioning process, the resulted Q&P steel presents thick and short martensitic lath with less amount of thin film residual austenite. However carbon in martensite is partially transferred to the residual austenite, nevertheless, the martensite and residual austenite also form a micro-electric couple, which significantly increases the electrochemical corrosion rate. The blocklike residual austenite in Q&P steel structure may be broken into brittle martensite under the action of stress, causing stress concentration leading to crack nucleation, dislocation accumulation and residual stress, which further promotes crack initiation and propagation.

The evolution of corrosion damage characteristics of AA7075-T651 Al-alloy under combined force-chemical interaction was clarified via a combination of cellular automaton method and mechanical numerical simulation software, aiming to simulate the evolution process of corrosion damage of Al-alloy under different load levels, and to revealing the effect of mechanical stress on the variation of corrosion growth rate and morphological characteristics evolution of the Al-alloy as well. The results show that compared with the corrosion of Al-alloy without external load, the number of cells lost due to the corrosion and the maximum corrosion depth or width under the action of force-chemical coupling are significantly increased, while the maximum ratio of corrosion depth to width of the corrosion damage characteristics are significantly increased. It can be seen that the ratio of depth to width gradually increases with the increase of load level. It can be seen that the tensile stress causes the corrosion pit to show a faster growth trend in the longitudinal direction, which in turn causes the stress concentration coefficient to increase, causing the bottom of the corrosion damage characteristic to change from elastic deformation to plastic deformation, ultimately accelerating the corrosion process of the Al-alloy.

The corrosion of oil tube goods related with the oil enhanced recovery technology of air injection is very serious issue. Herewith, the corrosion and passivation behavior of TC4 Ti-alloy in a simulated downhole liquid in high-temperature and high-pressed O₂ + CO₂ environment were studied via a high temperature autoclave with electrochemical measurements. The investigation shows that TC4 alloy has good corrosion resistance in high temperature and high pressure O₂ + CO₂ environment. The passive film of TC4 alloy has n-type semiconductor characteristic, which is mainly composed of TiO₂ and Al₂O₃. The protective property of the passive film formed on the substrate is weakened with the increase of Al₂O₃ content in the film. The results of electrochemical tests show that anodic polarization improve the quality of the passive film formed on the surface of TC4 Ti-alloy. With the decreasing O₂ content in the system, the defects in the passive film increase, while the compactness of film decrease, and thereby the protective property of the film is weakened.

Herein, FeCoCrNiMn high entropy alloy coatings were prepared on 304 stainless steel, using atmospheric plasma spraying technique. The tribo-corrosion behavior of the coating was studied in simulated seawater. Results show that the FeCoCrNiMn high entropy alloy coating was composed of single FCC phase with an average hardness 221.1HV_0.2, in contrast, that of the 304 stainless steel is 159.1HV_0.2. The tribo-corrosion test results showed that in 3.5%NaCl solution, the wear volumes of FeCoCrNiMn high entropy alloy coating under loads 5 N and 10 N differentiated by 17%, which were 1.21 × 10^-2 mm³ and 1.42 × 10^-2 mm³ respectively. The main wear mechanism was believed to be corrosive wear and oxidative wear. The wear volumes of the coating under loads 5 N and 10 N in deionized water differentiated by 11%, which were 1.15 × 10^-2 mm³ and 1.28 × 10^-2 mm³ respectively. The main wear mechanism was also adhesive wear and oxidative wear. The wear volume in NaCl solution higher than in deionized water might suggest that the corrosion effect of NaCl solution promote the wear process. Meanwhile, in NaCl solution, the open circuit potential of the wear samples under lower load could be restored to close to the level before friction motion in a short time during the static soaking stage. However, the open circuit potential of wear samples under higher load increased slowly and was difficult to return to the level before friction motion due to more severe mechanical damage. This phenomenon might indicate that the mechanical damage caused by wear would accelerate the corrosion process.

The corrosion inhibition performance of Tween-80 for a cold rolled steel in amino sulfonic acid solution was studied by mass loss method, potentiodynamic polarization measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), as well as measuring the conductivity and surface tension of corrosion inhibitor containing solutions. The results showed that Tween-80 had a good corrosion inhibition effect on cold-rolled steel in amino sulfonic acid solution. The corrosion inhibition efficiency of Tween-80 in 0.10 mol/L amino sulfonic acid solution at 30^oC can reach as high as 94.33%. The standard adsorption Gibbs free energy (ΔG) is -29.94~-33.79 kJ/mol for the inhibitor adsorption on the surface of cold-rolled steel, it indicates that Tween-80 is a mixed adsorption dominated by chemisorption, and it follows the Langmuir adsorption isotherm equation. Therefore, Tween-80 is a mixed inhibitory corrosion inhibitor. After adding Tween-80, the surface tension of the solution decreases sharply. With the progress of corrosion inhibition of the steel, the conductivity of the solution increases, then gradually decreases and tends to be flat, which finally slightly lower than the conductivity before the steel immersion in the solution. AFM and XPS results confirmed that Tween-80 can effectively suppress the corrosion, while form an adsorption film on the surface of steel to achieve corrosion inhibition effect.

The present study aims to investigate the passivation behavior of steel bar subjected to tensile stress in a simulated concrete pore solution (SCPS). The passivation behavior of the stressed steel was studied by electrochemical techniques including open circuit potential, linear polarization resistance, cyclic voltammetry, electrochemical impedance spectroscopy and electrochemical noise measurement. The passive film of the stressed steel was characterized by XPS. Results indicated that the applied tensile stress enhanced the redox activity in highly alkaline SCPS, where the enhancement was proportional to the level of tensile stress. Nevertheless, the increment of tensile stress led to passive film with a higher value of Fe²⁺/Fe³⁺ and therefore a poorer protectiveness. As such, tensile stress especially high stress level of tension (over 60% yield strength) significantly reduced the resistance of passive film, the noise resistance, as well as the polarization resistance, leading to a higher value of current density of the passive steel.

The corrosion resistance of the as-forged AZ80 Mg-alloy subjected to solid solution treatment, and aging treatment for different time was investigated by means of hydrogen evolution method, mass loss method and electrochemical tests etc. Meanwhile, the microstructure and phase composition of the alloy, as well as the morphology and composition of corrosion products were also characterized by OM, SEM and XRD, especially in terms of the effect of microstructure variation and second phase precipitates on the corrosion behavior of the as-aged AZ80 Mg-alloy. The results indicate that varying aging time can effectively adjust the precipitation behavior of the second phase in the forged AZ80 Mg-alloy. Aging treatment can improve not only the corrosion resistance, but also mitigates the anisotropy in the corrosion performance of the Mg-alloy. For the specimen after the peak-aging treatment, a dense second phase with a network structure can be formed in its matrix, which results in the effective improvement of the corrosion resistance and uniformity of the specimen surface. Meanwhile, the difference in average corrosion rate between the cylindrical oriented surface and the basal oriented surface is minimized.

The adsorption behavior of S and Cl on γ-FeM(111) (M = Cr, Ni, Mn, Mo, Cu, Ce) surface and its influence on the corrosion performance of the latter, as well as the effect of the applied tensile and compressive stress on the surface stability of the γ-FeM(111) were studied by first principles calculation method. The calculation results show that S and Cl are most easily adsorbed at hcp- and fcc-sites on γ-Fe(111) surface, as a result from this, the electronic work function of S and Cl adsorbed surfaces decreases, accordingly, the corrosion resistance becomes weak for the γ-FeM(111) absorbed with S and Cl. The surface of γ-FeM(111) alloyed with M = Cr, Ni, Mn, Mo, Cu, Ce is resistant to Cl corrosion. Among the alloying elements, Mo, Cu and Ce can synergistically improve the resistance to S and Cl corrosion. Under compressive stress, the electron work function of the γ-FeM(111) (M = Cr, Ni, Mn, Mo, Cu, Ce) surface adsorbed with S and Cl increases, while the electron work function decreases under tensile stress. The joint action of S, Cl and tensile stress greatly reduces the surface corrosion resistance.

AC electrified rail transit system will lead serious electrochemical corrosion to surrounding buried metal pipelines, which will severely threaten the structural integrity and service reliability of buried oil and gas pipelines. Numerical simulation is an effective method to study the distribution and variation of stray current corrosion macroscopically. In view of this, this paper proposed a numerical simulation model of AC stray current corrosion for buried metal pipeline based on the coupling of physical fields. Through the interaction of electric field and electrochemical field, the distribution patterns of rail potential and current density on the surface of buried metal pipeline during static and dynamic periods is analyzed. The effect of buried depth, relative angle and relative distance between metal pipeline and AC electrified rail transit system on the surface current density distribution were studied. Results show that in a given period the dynamic characteristics of AC signal and dynamic characteristics of overall change of traction current both have an important influence on the evolution process of AC corrosion of buried metal pipeline, and the buried depth, relative angle and relative distance are important factors that cannot be ignored to evaluate the AC corrosion effect for buried metal pipeline.

The chemical composition of the solution inside the crevice influences the initiation and development of crevice corrosion significantly, and the crevice geometry is an important factor which determines the chemical composition of the solution inside the crevice. Herein, the crevice corrosion behavior of 2205 duplex stainless steel in a NaCl solution was investigated by means of a home-made set for measurement of the solution composition and electrochemistry inside the crevice. The variation of Cl^- and H⁺ concentration during the crevice corrosion incubation period, and the anodic dissolution behavior of the electrode inside the crevice during the development period were characterized. Further, the effect of crevice gap size and solution volume of occluded area on the solution composition and corrosion behavior of occluded area were revealed. Results show that with the decrease of crevice gap or solution volume of occluded area, the enrichment rate of Cl^- and H⁺ increase significantly and the concentration of H⁺ increases by 2 orders of magnitude. The anodic dissolution rate of electrode inside crevice increases with the decrease of the potential drop inside the crevice.

The Cu-containing Fe-Mn-Cr-Ni medium entropy alloy (MEA) was prepared by selective laser melting (SLM) and followed by post aging treatment, and then its microstructure and corrosion performance in 1 mol/L NaOH solution were studied. The results show that the Cu-rich phase at grain boundaries of SLM-MEA is preferentially dissolved after aging at 300^oC, which inhibits the dissolution of the active site and improves the corrosion resistance. Compared with the SLM alloy, the corrosion current of the alloy after being aged at 300^oC decreased by 37.37% and the polarization resistance increased by 2 times. As the aging temperature increased, the Cu-rich precipitates migrate from grain boundaries to the interior of the cellular sub-crystal. Cr-rich carbides coarsened with the increasing temperature, which weakened the protective ability of the passivation film. In addition, the dissolution of Cu-rich precipitates in the alloy aged at 300^oC increased the cation ratio of Cr + Ni to Fe + Mn in the passivation film, which was 1.2 times that of the as prepared SLM alloy, and promoted the formation of a denser and continuous passivation film.

In predicting corrosion-induced cracking of reinforced concrete, traditional empirical formulas used are varied with limited precision of prediction. To address these limitations, this paper presents a method based on the stacking of models to predict the cracking of reinforced concrete due to corrosion induced expansion. Firstly, 223 sets of test data on the cracking of reinforced concrete due to corrosion induced expansion were collected from published articles and processed in advance. Next, Bayesian optimization of hyperparameters, model training, and evaluation were conducted separately based on Support Vector Regression (SVR), Random Forest (RF), and Extreme Gradient Boosting (XGBoost) algorithms. Determination coefficient (R²), mean absolute error (MAE), and root mean square error (RMSE) were utilized for a comparative analysis of the prediction performances of three machine learning models. On this basis, a prediction model integrating multiple algorithms with the Stacking method was proposed. Finally, the generalization performances of the proposed prediction model and traditional empirical formula models were verified, and the XGBoost model was employed to analyze the interpretability of the proposed model. As revealed in the results, the proposed model has better prediction accuracy and generalization performance than other machine learning models. The interpretability analysis result demonstrates that the prediction of the proposed model logic matches the practical engineering experience. This finding is conducive to improve the prediction accuracy of thecorrosion-induced cracking of reinforced concrete, and can provide scientific theoretical guidance for decision-makers in practical engineering.

The effect of B and Ce micro-alloying on secondary phase precipitation and corrosion resistance of S31254 super austenitic stainless steel were studied by OM, SEM, EDS and electrochemical tests. The results show that the addition of B and Ce can inhibit the precipitation of secondary phase in the aging process and change the morphology of precipitated phase along the grain boundary. The B and Ce micro-alloying can also improve the free-corrosion potential and pitting potential of the S31254 super austenitic stainless steel, promote the rapid formation of passive film, improve its stability synchronously, thus improve the pitting and intergranular corrosion resistance of the steel. Therefore, it follows that the synergistic effect of both B and Ce co-alloying on precipitation inhibition and corrosion resistance of S31254 is significantly more pronounced when compared to the addition of a single B element.

For a barrier-type corrosion-resistant coating on Q235 carbon steel plate, the functional relationship of the cathodic delamination resistance versus the coating thickness and testing time may be acquired by means of cathodic delamination tests according to standards such as ISO 12944-6, ISO 11507 and ISO 9227 etc. The feasibility of using electrochemical impedance as an indicator for coating performance was analyzed and demonstrated. The variation of the electrochemical impedance of the coating during cyclic aging process was further assessed, and the numerical relationship of electrochemical impedance against the coating thickness and aging time was analyzed. Finally a lifetime prediction model for the coating was established. The results showed that the predicted lifetime shows a good comparability with the designed service lifetime of the barrier-type corrosion-resistant coating.

A nickel based single crystal high-temperature alloy was subjected to two different heat- treatments, namely complete heat treatment (CH) and long-term aging after complete heat treatment (CH-LA).Then their hot corrosion behavior beneath a 75%Na₂SO₄ + 25%NaCl mixed salt film in air at 900℃ was studied by means of metallographic microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) methods, in terms of the surface morphology, phase composition, and element distribution of the alloy after 100 h corrosion. The results indicate that fine γ-particles with good cubic degree are uniformly distributed on the matrix γ' phase for the CH alloy. While the γ'-phase was deformed coarsened, and rafted, meanwhile spherical, needle like, and short rod like TCP phases did precipitated for the CH-LA alloy. The corrosion kinetics curves of the two different heat-treated alloys are similar to parabolas or segmented parabolas. The corrosion rate of CH alloy is relatively small, while a continuous Al₂O₃ outer oxide scale is formed on the surface, and Al internal oxidation and Cr, Ni internal sulfidation occur in the inner layer, and slight spallation of the corrosion product scale was observed. The CH-LA alloy shows a relatively high corrosion rate with significant spallation of the formed surface corrosion products, which is a thick composite oxide scale with an extremely thin Al₂O₃ scale on the surface, beneath that, there is a zone of internal oxidation of Al and internal sulfidation of Cr and Ni.

The stress corrosion cracking (SCC) behavior of 316L stainless steel in HF solution was investigated by means of slow strain rate test (SSRT) and microscopy characterization. Results revealed that 316L stainless steel showed intense stress corrosion susceptibility in HF solution, correspondingly the mechanical property was greatly shortened for the tested steel. Stress corrosion is caused by the initial tear of the corrosion product film and the subsequent pitting corrosion caused by the synergistic action of mechanics and chemistry. The crack initiation of 316L stainless steel in HF solution shows the characteristics of multi-sites of initiation, i.e. the grain boundary, slip step and phase boundary between δ ferrite and matrix are the main sites of crack initiation. In all, mechanical deformation induced the rupture of corrosion products was essentially the inducement of SCC of 316L stainless steel in HF solution.

Usually, early failures of anti-corrosion coating for marine engineering equipment are difficult to be detected in time, and indeed such failures are potential safety hazard. Herein, defects in coatings on steel plate were detected via electromagnetic induction infrared thermal imaging system, aiming in realizing non-destructive visual detection of coating defects. Meanwhile, qualitative evaluation criteria for different type of coating defects were proposed, according to the comprehensive assessment of the acquired infrared thermal images in terms of the color brightness difference throughout the image, the temperature difference between defects and their adjacent area, as well as the shape of defects in the acquired infrared thermal images. The established criteria of coating defect types may be used to identify defects occurred in coatings during their service process in marine environment, and the reliability of the criteria is verified by the Kelvin probe measured potential distribution and visible light images of the relevant coatings.

The structure and composition of oxide scales formed on casting billets of 304 austenitic and 430 ferritic stainless steel after being held in air at 1240^oC for 4 h were characterized by means of field emission scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometer. The adhesive strength between the oxide scale and the matrix was assessed via 3D micrometer scratch. The oxidation mechanism of the steels in actual working condition was discussed. The results show that the oxidation kinetics of the two stainless steels follow a parabolic low, and the oxidation rate of 430 stainless steel is significantly higher than that of 304 stainless steels. The oxidation products of the two stainless steels have a typical three-layered structure: i.e. the oxide scale composed of an outer layer and an inner layer, as well as an internal oxidation layer beneath the outer oxide scale. But the morphologies of the inner layer of oxide scale and internal oxidation layer for the two stainless steels are different. The inner layer of oxide scale of 304 stainless steel is relatively dense, while there exist obvious pores and cracks in the inner layer of oxide scale of 430 stainless steel, which is conducive to the inward diffusion of oxygen, so that accelerates the oxidation process. The internal oxidation layer of 304 stainless steel is mainly distributed as scattered blocks; while that of 430 stainless steel is distributed as continuous root-like shape, which enhances the adhesion between the oxide scale and the matrix.

The corrosion behavior of SA210C steel beneath surface deposit film of mixed salts of Na₂SO₄∶NaCl = 3∶1, 1∶1 and 1∶3 in air at 600^oC was studied by means of corrosion kinetics curve measurement, as well as characterization of composition, microstructure and morphology of the corrosion products by XRD, SEM and EDS. The results show that the corrosion products on the surface of SA210C steel consists mainly of Fe₃O₄ and Fe₂O₃, and the mass gain and the thickness of corrosion products scale are positively correlated with the mass proportion of NaCl in the mixed salt film. When the mass ratio of NaCl to Na₂SO₄ in the mixed salt film is 1∶3, the corrosion products on the surface of SA210C steel have obvious cracking and delamination, and the corrosion products are seriously spalling. When the mass ratio of NaCl to Na₂SO₄ is 3∶1, penetrating cracks are observed in the corrosion products scale and internal corrosion occurs in the base metal.