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Initiation and propagation of localized corrosion induced by(Zr,Ti,Al)-O_(x) inclusions in low-alloy steels in marine environment

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Journal of Iron and Steel Research International 2021年第4期28卷 453-463页

作者： Wen-zhui Wei Kai-ming Wu Jing Liu Lin Cheng Xian Zhang The State Key Laboratory of Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science in Metallurgical ProcessCollaborative Innovation Center for Advanced SteelsWuhan University of Science and TechnologyWuhan 430081HubeiChina

The effects of inclusions on localized corrosion of Zr–Ti deoxidized low-alloy steels in marine environment were investigated by various analytical techniques including scanning electron microscopy with X-ray microanalysis(SEM/EDS),confocal Raman microscopy(CRM),and in situ scanning vibrating electrode technique(SVET).It was found that complex(Zr,Ti,Al)-O_(x)inclusions were responsible for the initiation of localized *** corrosion pref-erentially occurred at Fe matrix adjacent to these inclusions and formed *** the early stage of corrosion,catalytic-occluded cells and the diffusion of chloride ions played a major role in the propagation of corrosion,further accelerating the dissolution of Fe matrix and(Zr,Ti,Al)-O_(x)*** SVET and CRM results,it revealed that the maximum anodic current density in local area gradually decreased with prolonged exposure time,indicating that corrosion products covered the steel surface and lowered the propagation rate of *** the later stage of corrosion,the barrier effect of corrosion products played an important role in inhibiting localized corrosion.

关键词： (Zr,Ti,Al)-O_(x)inclusion Localized corrosion Low-alloy steel marine environment Scanning vibrating electrode technique

Degradation and Mechanism of the Mechanics and Durability of Reinforced Concrete Slab in A marine environment

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China Ocean Engineering 2016年第2期30卷 257-270页

作者：吴胜兴刘冠国卞汉兵吕维波蒋建华 College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Jiangsu Engineering Research Center for Cracking Control of Building Hohai UniversityNanjing 210098China Jiangsu Transportation Research Institute Co.Ltd. Nanjing 211112China Laboratoire LEM3(UMR CNRS 7239) Universite de LorraineIle du Saulcy57045 Metz Cedex 01France Nanjing City-Town Architecture Design&Consultants Co.Ltd. Nanjing 210009China

An experimental research was conducted to determine the corrosion and bearing capacity of a reinforced concrete（RC） slab at different ages in a marine *** show that the development of corrosion-induced cracks on a slab in a marine environment can be divided into three stages according to crack morphology at the bottom of the *** the first stage,cracks *** the second stage,cracks develop from the edges to the middle of the *** the third stage,longitudinal and transverse corrosion-induced cracks *** corrosion ratio of reinforcements nonlinearly increases with the age,and the relationship between the corrosion ratio of the reinforcements and the corrosion-induced crack width of the concrete is *** flexural capacity of the corroded RC slab nonlinearly decreases with the age,and the model for the bearing capacity factor of the corroded RC slab is *** mid-span deflection of the corroded RC slab that corresponds to the yield of the reinforcements linearly increases with the increase in corrosion ***,the mechanisms of corrosion morphology and the degradation of the mechanical properties of an RC slab in a marine environment are discussed on the basis of the basic theories of steel corrosion in concrete and concrete structure design.

关键词： marine environment RC slab corrosion bearing capacity deflection

Reliability-based service life prediction of existing concrete structures under marine environment

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Journal of Central South University 2015年第9期22卷 3608-3614页

作者：吴灵杰周拥军寇新建蒋萌 School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University

Chloride-induced corrosion of the reinforcement is considered as one of the major mechanisms resulting in the reduction of structural resistance of reinforced concrete structural elements located in marine and other aggressive environments. A study of reinforced concrete structures located at the Fangcheng dock in the Beibu Gulf port, China, was present. The result from field survey indicates that the concrete cover depth and chloride diffusion coefficient fit best normal distribution and lognormal distribution, respectively. The service life of structure is about 55 a, while initiation time is 45 a. Sensitivity analysis indicates that the most influential factor of the structure service life prediction is concrete cover, followed by diffusion coefficient, diffusion decay index, critical chloride concentration, surface chloride concentration, current density and localized pitting corrosion. Finally, the effects of diffusion decay index and critical chloride concentration on structure service life prediction are discussed.

关键词： chloride existing concrete structure service life marine environment

Effect of Retained Austenite on Corrosion Behavior of Ultrafine Bainitic Steel in marine environment

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Acta Metallurgica Sinica(English Letters) 2023年第5期36卷 717-731页

作者： Xian Zhang Li Gong Yanpeng Feng Zhihui Wang Miao Yang Lin Cheng Jing Liu Kaiming Wu Hubei Province Key Laboratory of Systems Science in Metallurgical Process The State Key Laboratory of Refractories and MetallurgyCollaborative Innovation Center for Advanced SteelsWuhan University of Science and TechnologyWuhan430081China School of Chemistry Chemical Engineering and Life SciencesWuhan University of TechnologyWuhan430070China

In this study,the impact of retained austenite on corrosion initiation,propagation,and resistance of ultrafine bainitic steels in marine environments based on the one-step and two-step bainitic isothermal transformation was investigated using a combination of theoretical calculations and experimental *** to the results,the microstructure of ultrafine bainitic steels was composed of parallel arranged bainite ferrite(BF)and retained austenite(RA).The fraction of the block RA was significantly reduced,whereas the amount of the film RA increased through the two-step bainitic *** the initial stage of corrosion,micro-galvanic effects occurred between the multiphases due to the difference in nobility,leading to the selective dissolution of BF sheaves,which is adjacent to the block RA in the one-step bainitic ***,uniformly distributed film RA in the two-step bainitic steel acted as a barrier against corrosion *** electrochemical measurements and neutral salt spray tests revealed a relatively lower corrosion rate for the two-step bainitic steel,indicating a higher corrosion resistance than the one-step bainitic *** corrosion products layer mainly consisted ofα-FeOOH,γ-FeOOH,and Fe_(3)O_(4),which were stable and favorable for the formation of a protective rust layer.

关键词： Ultrafine bainitic steel Retained austenite marine environment Corrosion behavior First principle modeling

Bio-inhibitive effect of an algal symbiotic bacterium on corrosion of magnesium in marine environment

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Journal of Magnesium and Alloys 2023年第12期11卷 4603-4618页

作者： Yuqiao Dong Guang-Ling Song Yuqing Xu Dajiang Zheng College of Materials Xiamen UniversityXiamen 361005China Department of Ocean Science and Engineering Southern University of Science and TechnologyShenzhenChina State Key Laboratory of Physical Chemistry of Solid Surfaces Xiamen University422 S.Siming RdXiamen361005China The University of Queensland School of Mechanical and Mining EngineeringDivision of Materials EngineeringSt LuciaQld 4072 Australia Institute of Corrosion Science and Technology Guangzhou510530GuangdongChina

It is a longstanding and challenging task to develop sustainable environment-friendly and cost-effective corrosion-protection technologies for Mg alloys, especially under marine conditions in which corrosion can normally be significantly accelerated by bacterial activity. However,this paper reports on the corrosion of highly active Mg interestingly inhibited by an algal-symbiotic bacterium Bacillus altitudinis. The corrosion of Mg in the presence of the bacterium drastically reduced by one order of magnitude after 14 days of immersion. This means that the algal-symbiotic bacterium widely available in natural ocean environments may be employed as a green and sustainable inhibitor in the marine industry. Based on electrochemical measurements, surface analyses and microbe experiments, a combined inhibition mechanism is proposed in the paper to interpret the interesting corrosion behavior of Mg.

关键词： Magnesium Corrosion inhibition marine environment Biofilm Bacterium

Sensitivity analysis of the deterioration of concrete strength in marine environment to multiple corrosive ions

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Frontiers of Structural and Civil Engineering 2022年第2期16卷 175-190页

作者： Jinwei YAO Jiankang CHEN Zhejiang Business Technology Institute Ningbo315012China Key Laboratory of Impact and Safety Engineering Ministry of EducationSchool of Mechanical Engineering and MechanicsNingbo UniversityNingbo315211China

The corrosion degradation behavior of concrete materials plays a crucial role in the change of its mechanical properties under multi-ion interaction in the marine *** this study,the variation in the macrophysical and mechanical properties of concrete with corrosion time is investigated,and the source of micro-corrosion products under different salt solutions in seawater are *** of the continuous hydration effect of concrete,the damage effects of various corrosive ions(Cl^(−),SO_(4)^(2−),and Mg^(2+),etc.)on the tensile and compressive strength of concrete are discussed based on measurement in different salt *** sensitivity analysis method for concrete strength is used to quantitatively analyze the sensitivity of concrete strength to the effects of each ion in a multi-salt solution without considering the influence of continued *** quantitative results indicate that the addition of Cl−can weaken the corrosion effect of SO_(4)^(2−) by about 20%,while the addition of Mg^(2+)or Mg^(2+)and Cl^(−)can strengthen it by 10%–20%during a 600-d corrosion process.

关键词： sensitivity analysis concrete strength corrosion deterioration multi-ion interaction marine environment

Predict the evolution of mechanical property of Al-Li alloys in a marine environment

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Defence Technology（防务技术） 2024年第1期31卷 557-566页

作者： Wei Li Lin Xiang Guang Wu Hongli Si Jinyan Chen Yiming Jin Yan Su Jianquan Tao Chunyang Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100036China Chongqing Innovation Center Beijing Institute of TechnologyChongqing400044China First Research Institute of the Ministry of Public Security for PR China Beijing100036China Southwest Technology and Engineering Research Institute Chongqing400039China

The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of marine equipment and *** study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine *** obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through marine exposure *** obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural ***,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li *** main conclusions are as follows:*** variation law of mechanical properties of2297-T8 in the marine atmosphere is *** the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.*** prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.*** study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of marine exposure *** results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.

关键词： marine environment Al-Li alloy Machine learning Corrosion

Modeling Boundary and Edge Effect of Chloride Diffusion for Durability Design of Concrete Structures Exposed in marine environment

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Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1112-1117页

作者： ZHOU Xingang LI Kefei CHEN Zhaoyuan Department of Civil Engineering Tsinghua University School of Civil Engineering Yantai University

According to the Fick＇s second law of diffusion, six analytical solutions of chloride profile in concrete were studied and discussed with regard to different boundary and initial conditions. In those analytical solutions, the most prevailing error-function solution which is based on semi-infinite assumption is the simple one, but may under-estimate the chloride content in concrete and over-rate the life time prediction of concrete structures. The experimental results show that compared with other solutions, the chloride content in concrete predicted by error-function model is the minimum, and the calculation difference produced by different analytical models should not be ignored. The influence of models on chloride content prediction is more than other environment and material coefficients in some time. In order to get a more realistic prediction model, modification to error-function model is suggested based on analysis and calculation examples concerning the boundary and edge effect.

关键词： durability of concrete marine environment durability design and life prediction error-function model model modification

Corrosion behavior of HVOF Inconel 625 coating in the simulated marine environment

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China Welding 2024年第1期33卷 46-51页

作者：彭超钟丰平袁梦谢世杰王学斌 National Quality Inspection and Testing Center of Special Metal Structural Materials Zhejiang Academy of Special Equipment ScienceHangzhou 310020China Key Laboratory of Special Equipment Safety Testing Technology of Zhejiang Province Hangzhou 310020China Zhejiang-Ukraine Joint Laboratory for Materials and Welding Testing Technology Hangzhou 310020China

High velocity oxygen fuel(HVOF)spraying process is commonly used to produce superalloy *** 625 coating was prepared on Q235B low carbon steel by HVOF.A series of experiments were conducted to examine the surface and corrosion resistance properties of Inconel 625 HVOF *** this paper,potentiodynamic polarization tests and electrochemical impedance spectroscopy(EIS)tests were carried out to evaluate the corrosion resistance of Inconel 625 coating under simulated marine *** experiment-al results showed that Inconel 625 coating revealed low porosity and desired coating *** in the corrosion potential(E_(corr))to-wards the noble direction combined with much low corrosion current density(i_(corr))indicating a significant improvement of HVOF Inconel 625 coating compared with the substrate.

关键词： high velocity oxygen fuel(HVOF) Inconel 625 coating marine environment corrosion