Cu-P-RE耐候钢的耐蚀性能

通过干湿周浸加速腐蚀实验研究了不同稀土含量的耐候钢和对比普碳钢的腐蚀行为及其耐蚀性能.采用失重法测得了各试样的腐蚀率;结果发现,稀土耐候钢的腐蚀率远远低于普碳钢的,不同稀土含量的耐候钢的耐腐蚀性不尽相同.采用电化学交流阻抗技术对带锈钢样的表面锈层结构及电化学反应过程进行了研究,提出在本实验条件下钢电化学腐蚀的等效电路模型,计算出锈层电阻、极化阻抗等表征锈层性能的电化学元件参数值.稀土耐候钢锈层中存在半无限扩散和有限厚度扩散两种过程,有限厚度扩散极化阻抗反映了耐候钢内锈层的保护性能.     

Corrosion behaviors of cold rolling automotive sheets coated with anti- rust oil

To investigate the corrosion performance of commercial automotive cold rolling sheets under severe atmospheric environment, electrochemical impedance spectroscopy was used to detect the electrochemical behaviors of three types of cold rolling sheets and a humid- temper test was carried out to explore the corrosion behavior under shipping and storage environments. Meanwhile, the effects of surface status and micro- structure of the sheets on the corrosion behaviors were analyzed based upon the results of profile measurements, contact angle tests and metallographic analysis.The results show that with the same load of anti- rust oil, 590DP steel presents the largest electric resistance of oil film and charge transfer resistance, and the longest incubation period of rust under storage environment. All these good properties could be assigned to the surface profile of the steel. However, the generation rate rust turns to be faster later on, which can be attributed to its dual- phase microstructure. In sum, the surface wetting status of different types of sheets are almost the same, which has no significant effect on the corrosion performance of the steels. Comparatively, surface profile of the steels plays an important role during the initial stage of corrosion, and the difference in microstructure has a more remarkable influence on the development stage of corrosion.     

In-Situ Electrochemical Monitoring and Ex-Situ Chemical Analysis of Epoxy Coated Steels in Sodium Chloride Environment Using Various Spectroscopic Techniques

The effect of immersion time and chloride ion concentration on the early stage of corrosion behavior of scratched epoxy-coated carbon (SM) and chromium containing low-alloy steel (H5) samples were investigated in an in situ manner using localized electrochemical impedance spectroscopy. The results revealed that, the H5 samples had significantly higher impedance values than the SM, which indicated higher corrosion resistance of H5 samples. The drop in impedance magnitude was observed for higher Cl^? ion concentration, which indicated that breakdown of passive film had been initiated by Cl^? ion resulting in localized corrosion attack of the surface. The morphological and elemental studies showed the formation of green rust and a very stable hydroxide (Cr_xFe_1?x(OH)₂) on SM and H5 surface respectively as a corrosion product. Hence, the H5 could be a hopeful material with extremely high corrosion resistance for the use as steel structures.     

海洋工程用钢的大气腐蚀与耐候钢的发展

综述了海洋工程用钢的大气腐蚀行为与耐候钢发展方面的研究,特别是近十余年来国内外的相关成果。首先介绍了钢大气腐蚀的电化学模型,并从耐候钢特殊的锈层结构与合金元素作用两方面论述了耐候钢的锈层保护机制;然后分析了环境因素,包括相对湿度与污染物、光照、锈层损伤等,对耐候钢大气腐蚀行为的影响;最后总结了耐候钢的发展历程以及晶粒尺寸与显微组织等非合金因素在耐候钢发展中的作用,可为新型耐候钢的设计与应用提供指导。     

海洋工程用钢的大气腐蚀与耐候钢的发展

综述了海洋工程用钢的大气腐蚀行为与耐候钢发展方面的研究,特别是近十余年来国内外的相关成果。首先介绍了钢大气腐蚀的电化学模型,并从耐候钢特殊的锈层结构与合金元素作用两方面论述了耐候钢的锈层保护机制;然后分析了环境因素,包括相对湿度与污染物、光照、锈层损伤等,对耐候钢大气腐蚀行为的影响;最后总结了耐候钢的发展历程以及晶粒尺寸与显微组织等非合金因素在耐候钢发展中的作用,可为新型耐候钢的设计与应用提供指导。     

大气腐蚀在低合金钢显微组织中的发生与发展

采用光学金相技术结合交流阻抗测量,分析了三种低合金钢在模拟的沿海大气环境中的初期腐蚀行为.实验发现,显微组织直接决定钢的初期腐蚀行为并间接影响长期腐蚀行为.在腐蚀初期,铁素体钢中的大角晶界易于被择优腐蚀,而贝氏体内的小角晶界的择优腐蚀趋势较弱,铁素体+珠光体钢的择优腐蚀集中于珠光体及其边界.铁素体裸钢有较强的耐腐蚀性,但其锈层电阻随腐蚀时间增加产生的增量较小;贝氏体与铁素体+珠光体裸钢的耐腐蚀性较差,但其锈层电阻随腐蚀时间增加产生的增量较大,长期腐蚀性能更优.这些结果表明,在适当合金化后,贝氏体作为新型低成本高强度耐候钢的基本组织极具应用潜力.     

表面状态对核级316LN不锈钢电化学腐蚀行为的影响

表征了打磨态和机械抛光态316LN不锈钢表面的粗糙度、表面残余应变和表面电子功函数的分布,并研究了打磨态和机械抛光态样品在硼酸盐溶液中电化学腐蚀行为的差异.与机械抛光态316LN不锈钢相比,打磨处理后样品表面较为粗糙,且表面的微观残余应变较大,近表面产生约50μm的加工硬化层.表面粗糙度和微观应变的增加引起打磨态表面电化学活性的增大,从而促进316LN不锈钢在硼酸盐溶液中腐蚀.机械抛光处理降低了表面钝化膜的载流子密度(供体和受体),并增大了钝化膜的阻抗,提高了钝化膜的致密性和保护性,能够有效抑制金属的进一步腐蚀.     

300M超高强钢在中性盐雾环境中的腐蚀行为及机制

为了研究300M超高强钢在中性盐雾环境中的腐蚀行为及腐蚀机制,采用失重法,宏观、微观腐蚀形貌分析,三维表面轮廓分析及电化学分析的研究方法,来表征腐蚀实验现象并进行分析。结果表明:300M超高强钢在中性盐雾环境中的腐蚀产物为FeOOH、Fe₂O₃、Fe(OH)₃和Fe₃O₄;腐蚀速率随着腐蚀时间逐渐降低,腐蚀后期(72 h)腐蚀速率降低50%;腐蚀初期以点蚀为主,点蚀坑通过横向扩展,逐渐发展为后期的均匀腐蚀,腐蚀表面形貌呈沟壑状;外腐蚀层对基体的保护能力很弱,Cr元素在锈层靠近基体的一侧偏聚使内腐蚀层具有一定的抗腐蚀性。     

集装箱钢板在湿热海洋大气环境中的腐蚀行为

研究了集装箱钢板在西沙海洋大气环境中暴露不同阶段的腐蚀行为。采用SEM（EDS）、XRD研究了锈层形貌及成分,采用极化曲线研究了暴露不同阶段的腐蚀电化学行为。通过腐蚀深度测试,建立了腐蚀速率与暴露时间的幂指数关系,结合腐蚀形貌和产物分析,主要的锈蚀产物为γ FeOOH、β FeOOH。Cr和Cu合金元素也参与了锈层的形成,有助于提高锈层的致密性。电化学测试结果表明,耐候钢暴露不同阶段的腐蚀电流,3个月时值最低,6个月随后暴露时间增加,锈层不断增厚,起到对Cl 的阻碍作用,降低腐蚀速率;之后随着曝露时间的增加,锈层出现脱落,腐蚀速率随之增加。     

含钼耐候钢的腐蚀性能

通过显微组织观察、周浸加速腐蚀实验、锈层微观分析、锈层交流阻抗特征分析等方法,研究了合金元素钼含量对耐候钢腐蚀性能的影响.合金元素钼可以促进钢中贝氏体组织的形成,促使锈层更加致密,对钢基体具有更好的保护性,有利于提高钢的耐腐蚀性能.随着钢中钼含量的增加,实验钢锈层的腐蚀电位正移,自腐蚀电流密度减小,锈层的阳极溶解反应受到明显阻碍,锈层具有更好的保护性.     

RE重轨钢在模拟工业大气环境下的腐蚀行为

采用周期浸润腐蚀实验结合电化学方法研究了模拟工业大气环境下RE重轨钢的腐蚀行为.结果表明,RE重轨钢的耐腐蚀性能优于不含RE的重轨钢.RE重轨钢中,RE合金元素在基体的局部富集促进了锈层中保护性好的α-FeOOH相的快速生成和含量的增加,提高了锈层阻止侵蚀性介质穿透的能力,改善了重轨钢在工业大气环境下的耐腐蚀性能.     

在混凝土模拟孔隙液中癸二酸二异辛酯的缓蚀特性研究

采用动电位极化曲线和电化学阻抗谱研究了癸二酸二异辛酯在模拟混凝土孔隙液中对钢筋的保护作用.癸二酸二异辛酯的加入导致混凝土钢筋的腐蚀电位正移,对钢筋的阳极电化学过程有抑制作用.其缓蚀效果随癸二酸二异辛酯浓度增加而增加,当癸二酸二异辛酯的浓度为2%时,对含有400mg/L Cl^-的混凝土模拟液中钢筋电极的缓蚀效率为78.5%.氯离子含量是影响钢筋腐蚀性能和癸二酸二异辛酯阻锈剂作用的重要因素.癸二酸二异辛酯能够在钢筋表面形成沉淀性保护膜.     

Cr-Ni-Cu系低合金铸钢在海洋大气环境中的腐蚀行为

为满足桥梁支座用铸钢在海洋大气环境下的耐蚀性要求,设计了2种成分的Cr-Ni-Cu系耐腐蚀低合金铸钢。采用周浸加速腐蚀试验、实地大气暴露试验考察试验钢在海洋大气环境中的腐蚀行为,并结合扫描电镜、XRD、电化学手段分析了合金元素对锈层和电化学行为的影响。结果表明,2种成分的Cr-Ni-Cu系低合金铸钢的耐蚀性均较好,随着时间延长,耐蚀铸钢腐蚀率下降并达到稳定,而对比钢种20MnSi腐蚀率保持下降趋势,未达到稳定状态。周浸腐蚀316h后耐蚀铸钢与20MnSi腐蚀率差距变小;Cr元素在内锈层中呈条带状富集,有效阻碍了Cl-的扩散,Ni的加入提高钢的自腐蚀电位,促进γ-FeOOH向α-FeOOH的转化,增加锈层稳定性;Cr、Ni、Cu的复合加入增大了铸钢的电荷传递电阻,提高了耐蚀性。     

Effect of pH on Semiconducting Property of Passive Film Formed on Ultra-High-Strength Corrosion-Resistant Steel in Sulfuric Acid Solution

Because Cr9Ni5MoCo14 is a new ultra-high-strength corrosion-resistant steel, it is important to study its corrosion behavior in sulfuric acid solution, which is used to simulate the aggressive environment. The effect of pH on the electrochemical and semiconducting properties of passive films formed on ultra-high-strength corrosion-resistant steel in sulfuric acid solution was investigated by means of the potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and X-ray photoelectron spectroscopy (XPS). The results indicated that Cr9Ni5MoCo14 steel showed a passive state in acid solutions. The corrosion behavior of this Cr9Ni5MoCo14 alloy was influenced by the passive film formed on the surface, including thickness, stability, and partitioning of elements of the passive film. The passive current density decreases with increasing pH, and the corrosion resistance was enhanced by the increasing thickness and depletion of the defects within the passive film. Moreover, an enrichment of chromium (primarily the oxides of Cr) and depletion of iron in the passive film led to improved corrosion resistance. These results can provide a theoretical basis for use of this alloy and further development of ultra-high-strength corrosion-resistant steel in today’s society.     

Corrosion behavior of coating with plasma sprayed 8YSZ on the surface of carbon steel

The corrosion behavior of plasma sprayed 8YSZ(ZrO2 stabilized by 8 wt.%Y2O3)coating on the surface of carbon steel in seawater was investigated.The electrochemical impedance spectroscopy was used as a non-destructive evaluation technique to monitor the protection properties of the coating when it was immersed in seawater,and corrosion products were characterized by scanning electron microscopy,energy dispersive spectrometry and X-ray photoelectron spectroscopy.The results indicated that three time constants were obtained during the initial immersion period,and then a new time constant appeared due to the formation of rust layer,which was corresponding to the corrosion process.Corrosion products were formed on the coating surface as well as inside the coating,and the crystalline composition of the rust layer mainly consisted of γ-FeOOH.     

Corrosion Behavior of Rusted 550 MPa Grade Offshore Platform Steel

 The corrosion behavior of a rusted 550 MPa grade offshore platform steel in Cl- containing environment was investigated. The results revealed that the corrosion process can be divided into initial stage in which corrosion rate increased with accumulation of corrosion products and later stage in which homogeneous and compact rust layer started to protect steel substrate out of corrosion mediums. On the contrary, structural analysis of rust layers by X-ray diffraction showed that α-FeOOH increased from 1. 3% to 3. 6% and the Fe3O4 increased from 1. 0% to 1. 5% while γ-FeOOH reduced slightly according to corrosion time increased from 30 cycles to 73 cycles. The results of electron probe microanalysis indicated that Cr concentrated mainly in the inner region of the rust, inner/outer interface especially, whereas Ni and Cu were uniformly distributed all over the rust after 73 corrosion cycles. According to electrochemical measurements, it was found that the corrosion rate of rusted steel reduced from 0. 61 mm/a after 45 cycles to 0. 34 mm/a after 85 cycles, 44. 3% reduction approximately, and Rrust values increased with increment of corrosion time. Therefore, formation of compact inner rust layer and enrichment of Cr are important to improve corrosion resistance of offshore platform steel.     

Q235钢在青霉菌作用下的腐蚀行为和电化学特性

采用表面分析技术、失重法及电化学测试方法研究了Q235钢在青霉菌(Penicillium)作用下的腐蚀行为和电化学特性.青霉菌在Q235钢表面形成致密的生物膜和腐蚀产物沉积膜层.青霉菌促进Q235钢的腐蚀,腐蚀类型为点蚀坑.青霉菌体系中试样表面膜经历由游离态变为固着态,由单层逐渐变为多层的过程;生物膜作用与细菌活性有关,当活性降低时微生物腐蚀促进作用也大幅降低.     

耐候钢和碳钢在竖直方向上的腐蚀行为

为研究耐候钢和碳钢在竖直方向上的腐蚀行为,利用干湿循环腐蚀试验,模拟研究了耐候钢和碳钢在表面受到雨水反复冲刷的条件下,竖直方向上不同位置的腐蚀行为特征以及锈层的形成和演变。结果表明,耐候钢试样和碳钢试样在干湿循环一定周期后,上部腐蚀程度较轻,底部腐蚀程度较重,而中部的腐蚀程度则随竖直方向位置的下移而明显加重;碳钢试样底部的腐蚀程度随腐蚀时间的延长而加重,但耐候钢试样底部的腐蚀至一定程度后几乎不再继续;碳钢试样锈层形貌随竖直方向位置的下移而逐渐粗化,锈层形态和致密度变化较小,耐候钢试样的锈层形貌则随竖直方向位置的下移而逐渐细化,锈层形态由球状变为块状,致密度明显增加,这也导致了耐候钢的锈层电阻明显高于碳钢的锈层电阻;在干湿循环过程中,湿润时间会影响腐蚀产物的类型,湿润时间较短时,腐蚀产物以β-FeOOH为主,随着湿润时间的延长,腐蚀产物逐渐向γ-FeOOH转变。     

经济耐候钢的研究

系统研究了Mn、Cu含量及腐蚀环境体系对协同作用的影响,并利用电化学测试、扫描电镜、XRD等材料分析技术对带锈电极的腐蚀行为、锈层组成、结构和性质进行了深入分析,阐述了Mn-Cu合金化协同作用的机制;利用Mn-Cu合金化的协同作用,成功开发出Mn-Cu型经济耐候钢和实现工业化试生产。实验表明：热轧Mn-Cu钢具有良好的耐候性,其耐候性略优于传统的09CuPTiRE和SPA-H耐候钢。     

Effect of solution pH,Cl~- concentration and temperature on electrochemical behavior of PH13-8Mo steel in acidic environments

The effect of solution pH,Cl~- concentration and temperature on the electrochemical corrosion behavior of PH13-8Mo steel in acidic solution was investigated by using the electrochemical tests,scanning electron microscopy and X-ray photoelectron spectroscopy.The PH13-8Mo martensitic precipitation hardened stainless steel is in the passivity state when the pH value is above 3.0,below which the anodic polarization curves of the steel are actively dissolved.The corrosion current density gradually decreases with increasing the solution pH and decreasing Cl~- concentration and solution temperature.Pits are initiated on the sample surface in the presence of the Cl~- and gradually developed into uniform corrosion with increasing the Cl~- concentrations.Moreover,the corrosion is more serious with an increase in solution temperature.