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Influence of Conductivity on Corrosion Behavior of 304 Stainless Steel in High Temperature Aqueous Environment

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Journal of Materials Science & Technology 2016年第4期32卷 333-340页

作者： Jiazhen wang jianqiu wang En-Hou Han Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences

The influence of conductivity on corrosion behavior of 304 stainless steel （SS） in high temperature water was investigated by using in-situ potentiodynamic polarization curves, electrochemical impedance spectra （EIS） at 300 ℃, and ex-situ scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and X-ray pho- toelectron spectroscopy （XPS）. The structures of oxide films formed on 304 SS change with different conductivities at 300 ℃. With the increase in conductivity, the passive current density increases while the resistances of oxide films decrease. But the resistances do not decrease lineally with the increase in conductivity. A modified double-layer model for oxide structure was proposed to explain the influence mechanism of conductivity on the oxide films on 304 SS in high temperature water. Improving the 10B enrichment level can reduce the conductivity of primary water and increase the corrosion resistance of 304 SS.

关键词： Stainless steelPolarizationElectrochemical impedance spectraHigh temperature corrosion

Effects of Forging and Heat Treatments on the Microstructure and Oxidation Behavior of 316LN Stainless Steel in High Temperature Water

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Journal of Materials Science & Technology 2015年第4期31卷 403-412页

作者： Yueling Guo En-Hou Han jianqiu wang National Center for Materials Service Safety University of Science and Technology Beijing Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Science

Microstructure of 316 LN stainless steel(ss),including the as-received material and samples processed by solution anneal treatment and stress relief treatment after forging,was characterized by Vickers hardness(HV) testing and electron back scattering diffraction(EBSD).The oxide film formed on samples after immersion in borated and lithiated water at 583.15 K was investigated by scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS).Results showed that the grain size of samples was largely reduced after *** fraction of coincidence site lattice(CSL) boundaries and lower residual strain were observed in samples with either solution anneal treatment or stress relief *** proportion of CSL boundaries was largely enhanced by solution anneal treatment after forging,due to the recrystallization occurring during solution anneal *** oxide film grown on 316 LNss with solution anneal treatment after forging exhibited more strong protectiveness,as compared to the oxide film grown on samples with stress relief treatment after forging and the oxide film grown on asreceived samples without *** mechanisms of oxidation were then discussed.

关键词： Stainless steel Forging Corrosion Residual strain

Repassivation behavior of alloy 690TT in simulated primary water at different temperatures

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Journal of Materials Science & Technology 2021年第9期68卷 227-235页

作者： Ji Liu jianqiu wang Zhiming Zhang Hui Zheng Key Laboratory of Nuclear Materials and Safety Assessment Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China State Nuclear Power Plant Service Company Shanghai200233China

The repassivation behavior of Alloy 690 T T in simulated primary water at different temperatures was investigated by the rapid scratching electrode technique together with electrochemical *** results showed that the repassivation process had three stages: the initial stage conformed to the place exchange model, the final stage conformed to the high field ion conduction model and in between there was a transition stage. At the initial stage, when the repassivation process of alloys was controlled by the place exchange model, anodic dissolution of substrate was dominated;after the film coverage rate was more than 0.99, the repassivation process of alloys was controlled by high field ion conduction model. Increasing the temperature resulted in a reduction of the repassivation rate and protectiveness of the passive film. The correlations among several mechanisms describing the repassivation behavior of alloys were discussed.

关键词： Repassivation Electrochemistry High temperature corrosion Alloy 690TT Electrochemical impedance spectroscopy

Corrosion Behavior of X52 Anti-H_2S Pipeline Steel Exposed to High H_2S Concentration Solutions at 90℃

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Journal of Materials Science & Technology 2014年第5期30卷 504-510页

作者： Meng Liu jianqiu wang Wei Ke En-Hou Han State Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of Sciences

Initial corrosion kinetics of X52 anti-H2S pipeline steel exposed to 90 ℃/1.61 MPa H2S solutions was investigated through high temperature and high pressure immersion tests. Corrosion rates were obtained based on weight loss calculation. The corrosion products were analyzed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and electron probe micro-analysis （EPMA）. The initial corrosion kinetics was found to obey the exponential law. With increasing immersion time, the main corrosion products changed from iron-rich mackinawite to sulfur-rich pyrrhotite. The corrosion films had two layers： an inner fine-grained layer rich in iron and an outer columnar-grained layer rich in sulfur. The corrosion film formed through the combination of outward diffusion of Fe2＋ ions and inward diffusion of HS^- ions. The variation of the corrosion products and compaction of the corrosion layer resulted in a decrease in the diffusion coefficient with increasing immersion time. The double-layered corrosion film formed after long time immersion acted as an effective barrier against diffusion.

关键词： H2S corrosion X52 anti-H2S pipeline steel High temperature Iron sulfide

Analysis of Surface Oxide Films Formed in Hydrogenated Primary Water on Alloy 690TT Samples With Different Surface States

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Journal of Materials Science & Technology 2014年第12期30卷 1181-1192页

作者： Zhiming Zhang jianqiu wang En-Hou Han Wei Ke Key Laboratory of Nuclear Materials and Safety Assessment Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials Institute of Metal Research Chinese Academy of Sciences

Oxidation of Alloy 690 TT samples either manually ground to 400 and 1500 grit, mechanically polished, or electropolished was performed in a solution of 1500 10 6B and 2.3 10 6Li with 2.5 10 6dissolved H2, at 325℃ and 15.6 MPa for 60 days. The oxide films grown on samples with different surface states were analyzed using various techniques. Results show that a triple-layered structure was formed after immersion： an outermost layer with large scattered oxide particles rich in Fe and Ni, an intermediate layer with small compact oxide particles rich in Cr and Fe for the ground surfaces and loose needle-like oxides rich in Ni for the polished surfaces, and an inner layer with continuous Cr-rich oxides. The surface state was found to affect not only the surface morphology, but also the corrosion rate. Grinding accelerated the growth of protective oxide films such that the ground samples showed a lower oxidation rate than the polished *** of ground Alloy 690 TT showed superior resistance to intergranular attack（IGA）.

关键词： Alloy 690TT Oxidation Surface states High pressure and high temperature

Characterization of Different Surface States and Its Effects on the Oxidation Behaviours of Alloy 690TT

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Journal of Materials Science & Technology 2012年第4期28卷 353-361页

作者： Zhiming Zhang jianqiu wang En-Hou Han Wei Ke _TState Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Alloy 690TT samples with four kinds of surface states were prepared： 1） ground to 400 grit; 2） ground to 1500 grit; 3） mechanically polished （MP） and 4） electro-polished （EP）. The surface morphologies and the surface skin layers＇ microstructures of these samples were characterized systematically using various methods and the effects of surface states on the oxidation behaviours of Alloy 690TT were also discussed. The results showed that surface roughness and micro-hardness decreased gradually from the ground to EP surfaces. The grains in the near-surface layers of the ground and MP surfaces had been refined and the residual strains were also very high. The dislocations on the ground surfaces were mainly parallel dislocation lines. The thickness of the superficial cold-worked layers decreased gradually from the ground surfaces to polished surfaces. The oxide morphologies and oxidation rate depended greatly on the surface states of samples. Cold-working by grinding treatments could benefit the outward diffusion of metallic atoms and the nucleation of surface oxides and then accelerate the growth of surface oxide films.

关键词： Alloy 690TT Surface states Cold-worked layer Microstrain Grain refinement

Effect of temperature on corrosion behavior of alloy 690 in high temperature hydrogenated water

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Journal of Materials Science & Technology 2018年第8期34卷 1419-1427页

作者： Jiazhen wang jianqiu wang Hongliang Ming Zhiming Zhang En-Hou Han Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Reactor Engineering Research Sub-lnstitute Nuclear Power Institute of ChinaChengdu 610213China

The influence of temperature on the corrosion behavior of Alloy 690 is evaluated using potentiodynamic polarization curves, electrochemical impedance spectra （EIS）, scanning electron microscopy （SEM）, X- ray photoelectron spectroscopy （XPS） and transmission electron microscopy （TEM）. The corrosion rate of Alloy 690 reaches a local maximum at 250℃. The kinetic control step of the growth of oxide film changes from the diffusion process of aqueous-phase ions to the growth of Cr-rich barrier layer in the temperature range of 200-300 ℃. A modified double-layer model is proposed to describe the effect of temperature on the structure and composition of the oxide film.

关键词： Alloy Polarization EIS SEMTEM High temperature corrosion

Effects of cutting parameter on microstructure and corrosion behavior of 304 stainless steel in simulated primary water

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Journal of Materials Science & Technology 2022年第27期122卷 219-230页

作者： Honglin Yan jianqiu wang Zhiming Zhang Bright O.Okonkwo Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China

The influence of surface conditions on the corrosion behavior of engineering structures has been paid more ***,there is still a lack of systematic research on the effect of cutting parameters on material’s microstructure and performance in *** this paper,the effect of cutting parameters on microstructure and corrosion behaviors of 304 stainless steel in simulated primary water is well *** results show that different cutting parameters can cause the superficial layer a gradient microstructure with nanocrystalized layer on top and deformation band structures *** the similar surface roughness,the deformation microstructure can be very different due to the different cutting *** effect degree on the depth of deformation zone is feed rate>cutting depth>cutting *** larger feed rate,lower cutting depth,lower cutting rate may induce a deeper deformation *** the increasing depth away from the machined surface,the localized corrosion rate is decreased,and at the same depth the localized corrosion rate along the deformation bands is higher than that along the grain boundaries(GBs).The nanocrystalized surface has a smallest general corrosion rate due to the quick formation of Cr rich oxide ***,once the corrosion penetrates through this nanocrystalized layer,subsequent preferential corrosion at deformation bands and GBs will dominate and may lead to the significant increase of corrosion rate of the component in high temperature pressurized water.

关键词： Stainless steel Transmission electron microscopy(TEM) High temperature corrosion Cutting parameter

Effects of Surface State and Applied Stress on Stress Corrosion Cracking of Alloy 690TT in Lead-containing Caustic Solution

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Journal of Materials Science & Technology 2012年第9期28卷 785-792页

作者： Zhiming Zhang jianqiu wang En-Hou Han Wei Ke State Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The effects of surface state and applied stress on the stress corrosion cracking （SCC） behaviors of thermally treated （TT） Alloy 690 in 10 wt% NaOH solution with 100 mg/L litharge at 330 ℃ were investigated using C-ring samples with four kinds of surface states and two different stress levels. Sample outer surfaces of the first three kinds were ground to 400 grit （ground）, shot-peened （SP） and electro-polished （EP） and the last one was used as the as-received state. Two samples of every kind were stressed to 100% and 200% yield stress of Alloy 690TT, respectively. The results showed that the oxide film consisted of three layers whereas continuous layer rich in Cr was not found. The poor adhesive ability indicated that the oxide film could not protect the matrix from further corrosion. Lead was found in the oxide film and the oxides at the crack paths and accelerated the dissolution of thermodynamically unstable Cr in these locations and also in the matrix. The crack initiation and propagation on Alloy 690TT were effectively retarded by SP and EP treatments but were enhanced by grinding treatment, compared with the cracks on the as-received surface. The cracking severity was also enhanced by increasing the externally applied stress. The accelerated dissolution of Cr and the local tensile stress concentration in the near-surface layer caused by cold-working and higher applied stress reduced the SCC-resistance of Alloy 690TT in the studied solution.

关键词： Alloy 690TT Surface state Applied stress Stress corrosion cracking