Cr、V合金化弹簧钢腐蚀产物的相组成与转化

采用中性盐雾腐蚀实验对不同Cr与V含量的合金弹簧钢进行了24~288 h的腐蚀实验，用光学显微镜(OM) 观察腐蚀样品的表面宏观形貌，通过扫描电镜 (SEM) 观察腐蚀产物 (简称锈层) 截面情况，用能谱仪(EDS) 分析确定了腐蚀产物中Cr、V和Cl含量与分布情况，用X射线衍射 (XRD) 和Rietveld分析确定了腐蚀产物各锈层相的相对含量。结果表明：当腐蚀时间达到288 h时，钢表面逐渐形成内层 (30~50 μm) 和外层 (100~180 μm) 的两层结构锈层。其中外层主要是由γ-FeOOH组成，很容易剥落；而内层包含α-FeOOH和Fe₃O₄，结构较致密，与基体结合比较牢固。Cr和V在内层锈层中明显富集，而没有Cl^-，说明在内层锈层区域Cl^-侵入受到阻止；而外层锈层中Cr和V基本没有富集，且含有一定量的Cl^-；通过XRD分析腐蚀的不同阶段和不同部位的锈层成分图谱及相对含量关系，分析了γ-FeOOH形成和γ-FeOOH转化为α-FeOOH的过程。基于上述分析构建了不同相的转化模型。     

Influence of carbon content and microstructure on corrosion behaviour of low alloy steels in a Cl containing environment

Corrosion behaviour of low alloy steels (A and B) with different carbon content was studied by a salt fog test and an outdoor test. A commercial weathering steel 09CuPCrNi was used for comparison. The corrosion resistance of steels A and B with homogeneous microstructures was better than that of the commercial weathering steel 09CuPCrNi in the salt fog test. Steel A with an ultra-low-carbon content had far less weathering resistance than the other steels in the outdoor test. Selective corrosion of large pearlite produces stress in initial corrosion product films. Uniform corrosion product films with few cracks tend to form on homogeneous microstructures such as ferrite and bainite, and this is advantageous for the formation of a compact rust layer in the initial stage of atmospheric corrosion. However, uniform microstructures will result in over even interfaces between rust layers and bases, which will lead to frequent peeling of rust layers from bases because stress is induced by large temperature fluctuations and wet-dry alternations. Protection of the rust layer on a low alloy steel is dependent on the rust density and the bonding performance of the rust-base rather than the proportion of the rust phase in the initial stage of atmospheric corrosion. These results indicate that homogenous microstructures, proper amounts of carbon content and fine carbon-rich phases that are produced by appropriate processes are beneficial for the corrosion resistance of steels.     

Effect of nickel on ion-selective property of rust formed on low-alloying weathering steel

The effect of nickel on the ion-selective property of the rust layers formed on the low alloy weathering steels under marine atmosphere was investigated by an alternate wet-dry accelerated corrosion test.Four types of low-alloying steels with different Ni contents were prepared for the corrosion test.The rust formed at various stages of corrosion was characterized by electrochemical impedance spectra(EIS),electron microprobe analysis(EMPA) and scanning electron microscopy(SEM).Afterwards,the corrosion resistance property of the rust was studied in the light of the experimental results.It is shown that increasing Ni content has significantly improved the corrosion resistance of the low-alloying steels under marine atmosphere.Furthermore,it is noted that an evident cation-selective property emerges in the rust layers with the Ni content of the rust layers up to 1.82%.However,when the Ni content of steel the matrix is below 1.5%,it has little effect on the cation-selective property.The ratio of Ni content in between the rust layer and the steel substrate decreases with the increase of Ni content in the steel substrate and varies little as the corrosion proceeds.     

10CrMoAI热轧薄板不同周期盐雾腐蚀的对比分析

目的揭示10CrMoAl钢的耐腐的蚀原因及机理。方法通过对10CrMoAl钢进行盐雾试验(72、168、240 h)来模拟其海水腐蚀,并对试验后的试样进行了腐蚀速率、SEM、能谱、XRD及电化学分析及研究。结果 72、168、240 h盐雾腐蚀周期下,试样的腐蚀速率分别为2.352、1.915、2.218 mm/a。72 h盐雾腐蚀试验后,Cr和Mo主要在靠近基体一侧富集;168 h盐雾腐蚀试验后,Cr主要在靠近外表面的锈层处偏聚严重;240 h盐雾腐蚀试验后,在靠近锈层的基体一侧又出现了Cr和Mo的明显偏聚,并同时出现"白亮层"。随着腐蚀时间的延长,锈层中Fe Cr2O_4和γ-Fe_2O_3含量的变化趋势是一致的,即先不断上升,然后趋于稳定。结论随着腐蚀时间的延长,腐蚀速率先降低后升高再降低,最后趋于稳定。腐蚀过程是一个周而复始的循环过程:Cr和Mo在锈层与基体交界处不断富集—形成耐腐蚀层—腐蚀脱落—Cr和Mo在锈层与基体交界处富集。这种富集规律对防腐蚀有一定的作用。此外,Fe Cr2O_4在锈层中含量较多时,具有显著的防腐功能。     

Cu,P,Cr 和 Ni 对低碳钢耐蚀性的影响简

选择Cu-P-Cr-Ni钢、Cu-P-Cr钢和Q235碳钢,在0.01 mol/L的NaHSO3溶液中进行周期浸润、阻抗谱和极化曲线实验,研究了Cu-P-Cr-Ni系合金钢相比Q235碳钢在模拟工业大气(SO2)环境下的耐腐蚀性能;利用SEM,EPMA面扫描和XRD分析腐蚀锈层的形貌、组成及Cu,Cr和Ni的元素分布情况。结果表明:Cu-P-Cr-Ni系钢的腐蚀诱发敏感性最低,其次为Cu-P-Cr钢,腐蚀速率分别为Q235碳钢的59.5%和52.8%;锈层分为内、外两层,致密的内锈层明显发生Cu的颗粒状、Cr的团聚状富集,外锈层主要有Cr的富集,Ni富集不明显。Cu和Cr等的富集可形成致密的内锈层,提高低碳钢的耐蚀性。     

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 通过周期性浸润腐蚀试验,研究了组织结构对贝氏体高强钢的耐腐蚀性能的影响。贝氏体高强钢和其退火试样的失重数据表明,贝氏体组织的耐腐蚀性能略优于铁素体和珠光体组织。运用扫描电镜和X射线衍射仪等分析测试手段对耐蚀机制进行了研究,发现两种试样均存在较致密的内锈层和疏松外锈层。两种试样的锈层成分主要是稳定的α-FeOOH和少量的γ-FeOOH组成。贝氏体组织的高强钢的锈层晶体更细小,均匀的组织结构有利于增强钢的耐腐蚀性能。     

Effects of rare earth elements on corrosion behaviors of low-carbon steels and weathering steels

The effects of rare earth elements on the corrosion properties of low-carbon steel and weathering steel were investigated. To elucidate the roles of rare earth elements (Ce and La) and the corrosion behavior of steels, salt spray tests, electrochemical techniques, X-ray diffractometer, scanning electron microscopy, Electron Probe Micro Analysis (EPMA), and Auger Electron Spectroscopy (AES) were conducted. The results showed that the addition of rare earth elements enhances the corrosion resistance of both low-carbon steels and weathering steels, indicated by lower corrosion current density and salt spray corrosion rate after rare earth alloying. On the one hand, rare earth elements modify the morphology of inclusions and thus slow down the micro-area electrochemical corrosion, which improves the electrochemical corrosion resistance of these two steels. On the other hand, rare earth atoms tend to segregate toward the interface between the rust layer and the matrix. Hence, salt spray corrosion resistance is improved due to the enhancement of adhesion and compactness of the rust by the addition of rare earth elements.     

电弧喷涂锌基防腐涂层在洞室环境中的耐蚀性研究

采用高速电弧喷涂技术在16MnR钢上制备了Zn和Zn-Al涂层,通过盐雾加速实验考核涂层在5％NaCl溶液中的腐蚀性能,并对涂层腐蚀前后的组织结构进行分析.结果表明,两种Zn基涂层致密,在盐雾实验40 d后未出现红锈,表现出优异的耐腐蚀性能.喷涂纯Zn涂层,其腐蚀产物疏松,对基体主要起到牺牲阳极的保护作用;喷涂Zn-Al涂层,其腐蚀产物致密,起到牺牲阳极和隔离的双重保护作用.     

Atmospheric corrosion of ASTM A-242 and ASTM A-588 weathering steels in different types of atmosphere

The work analyses the atmospheric corrosion resistance of two widely used weathering steels: ASTM A-242 and ASTM A-588. The steels were exposed for up to 5 years in different types of atmosphere: rural, urban, industrial and marine. The atmospheric corrosion resistance of the steels was evaluated and the rust layers formed on them were characterised by X-ray diffraction, optical microscopy and scanning electron microscopy. The most relevant conclusions reached include the following: (a) the visual appearance (colouring) of the rust, rust texture, nature of the corrosion products and compactness of the rust layers formed are similar in both types of weathering steel. (b) No great differences are observed in the corrosion resistance. Slight differences occur in the industrial atmosphere, where ASTM A-242 presents 10–13% less corrosion than ASTM A-588. (c) In the C2-C3 ISO corrosivity atmosphere both types of weathering steels are adequate for unpainted use. However are not suitable in higher ISO corrosivity atmosphere.     

晶粒尺寸对桥梁钢的耐腐蚀性能影响

通过周期性浸润腐蚀试验,研究了晶粒尺寸对桥梁钢Q345的耐腐蚀性能的影响。不同晶粒尺寸的Q345钢的失重数据表明,大晶粒尺寸的铁素体和珠光体组织的耐腐蚀性能略优。扫描电镜和X射线衍射仪对加速腐蚀产物-锈层进行了分析。结果表明,两种试样均存在较致密的内锈层和疏松外锈层,大晶粒尺寸试样的内锈层与钢基的结合更紧密。两种试样的锈层成分主要是Fe3O4和少量的各种FeOOH,内锈层FeOOH的含量更多。     

节镍型不锈钢的耐腐蚀性能比较

通过3.5%NaCl溶液中动电位极化曲线测定和中性盐雾试验,对200系列奥氏体不锈钢和400系列铁素体不锈钢两类节镍型不锈钢与304不锈钢的耐腐蚀性能进行了对比研究。结果显示,400系列铁素体不锈钢的耐点蚀性能优于200系列奥氏体不锈钢,两种节镍型不锈钢的耐点蚀性能均不如304不锈钢好;200系列奥氏体不锈钢的耐均匀腐蚀性能最差,443不锈钢耐均匀腐蚀性能与304不锈钢相当,439不锈钢比304不锈钢耐均匀腐蚀性能稍差。201、202、304、439和443不锈钢在3.5%NaCl溶液中的点蚀电位分别为(vs.SCE)-32 mV、-22 mV、312mV、165 mV和227 mV,腐蚀速率分别为0.0071 mm/a、0.0062 mm/a、0.0026 mm/a、0.0038 mm/a和0.0024mm/a。     

核级316NG控氮奥氏体不锈钢的局部腐蚀行为

采用电化学测试法、点腐蚀试验法、盐雾腐蚀试验法和慢应变速率测试法,分别对比研究了核级316NG控氮奥氏体不锈钢和321奥氏体不锈钢的局部腐蚀行为,并利用扫描电子显微镜、光学显微镜等分别观察腐蚀后不锈钢的表面形貌。结果表明:316NG和321不锈钢晶间腐蚀再活化率分别为3.83%和4.47%,点腐蚀速率分别为10.74g/(m2·h)和45.97g/(m2·h),盐雾腐蚀速率分别为2.14×10-2 g/(m2·h)和12.32×10-2 g/(m2·h),应力腐蚀开裂敏感指数分别为0.078和0.10;316NG不锈钢中N和Mo元素提高了其耐局部腐蚀性能,因此其耐局部腐蚀性能均优于核电站结构材料321不锈钢的。     

Ni对耐候钢在模拟海洋大气环境下耐蚀性的影响

通过周期浸润加速腐蚀实验,研究了不同Ni含量的耐候钢在模拟海洋大气环境下的腐蚀规律.采用失重法评价耐候钢的耐蚀性,并利用扫描电镜 (SEM),X射线衍射(XRD) 和电化学方法对耐候钢表面生成的锈层进行了分析.结果表明,随着Ni含量的增加实验钢的耐蚀性逐渐增加,当Ni含量超过3%(质量分数) 其耐蚀性较对比钢提高了两倍;Ni的存在能够提高实验钢的自腐蚀电位,并促进保护性腐蚀产物α-FeOOH的形成;电化学阻抗测试结果表明,实验钢中Ni含量越多,实验钢的电阻越大,锈层的保护性越好.     

周期干湿浸条件下P265GH钢和Q235钢的大气腐蚀行为简

以NaCl+NaHSO3为腐蚀介质,通过浸渍干湿复合循环实验及腐蚀失重分析,并利用SEM,XRD和FTIR技术,研究了Q235碳钢和P265GH低合金钢的大气腐蚀行为。结果表明,两种钢的腐蚀遵从相同的动力学规律,腐蚀产物中均存在大量致密的α-FeOOH和非晶态δ-FeOOH,锈层具有很好的保护性,使得腐蚀速率降低。实验开始阶段两种钢的腐蚀量基本相同,但随着腐蚀的进行两者差距增大,P265GH低合金钢较Q235碳钢的失重小、锈层致密、耐腐蚀性好。     

含铜低合金耐磨钢在盐雾环境中的腐蚀行为

对含铜和不含铜实验钢在中性盐雾试验箱中连续喷雾120、240、480和720 h,研究了在盐雾环境下Cu对低合金耐磨钢耐腐蚀性能的影响规律,通过失重法计算腐蚀速率,并利用XRD和SEM对腐蚀产物进行表征,利用动电位扫描、电化学阻抗谱 (EIS) 对比分析Cu在低合金耐磨钢腐蚀过程中起到的作用。结果表明：低合金耐磨钢的腐蚀产物主要包括γ-FeOOH、α-FeOOH、Fe₃O₄、γ-Fe₂O₃,前期腐蚀产物疏松多孔,后期产物致密难剥落,腐蚀速率先升高后下降,含铜实验钢的腐蚀速率明显低于不含铜实验钢,添加Cu后,实验钢的自腐蚀电位上升,阻抗谱容抗弧增大,电荷转移难度增加,说明Cu能有效降低实验钢腐蚀速率,增强其耐腐蚀性能。     

中性介质中Q420qD高强桥梁钢的腐蚀行为

通过中性盐雾腐蚀试验、电化学测试等手段研究了Q420qD超低碳贝氏体高强桥梁钢和其对比材料F500L-Z普钢在中性介质中的腐蚀行为.结果表明:Q420qD超低碳贝氏体高强桥梁钢的耐腐蚀性优于F500L-Z普钢;其电化学阻抗值随金属材料浸泡时间的延长而增大,说明随着浸泡时间的延长,金属材料表面锈层不断加厚,逐渐增加了阻挡电解液对金属材料的侵蚀及金属材料表面金属原子失去电子向溶液中迁移的过程.     

热带雨林碳钢、低合金钢的大气腐蚀

在西双版纳热带雨林地区进行了4年的大气暴露试验，结果表明：材料的腐蚀符合指数函数规律，即W=Atn，随着试验时间的增加，腐蚀率有逐渐降低的趋势.碳钢的锈层疏松，易脱落，腐蚀较重；低合金钢的锈层比较致密，表现出较好的耐腐蚀性能.     

海水飞溅区Ni-Cu-P钢的锈层和耐点蚀性能研究

在海水飞溅区对实验室冶炼的Ni-Cu-P钢、含Cu低合金钢和碳钢进行660 d的挂片实验,评价Ni-Cu-P钢的耐蚀性能;采用Fourier变换红外(FTIR)光谱、电感耦合等离子体原子发射光谱(ICP-AES)、电子探针(EPMA)、SEM和EDAX等技术,分析3种钢表面的锈层特征.结果表明,Ni-Cu-P钢表现出比...     

耐候钢锈层稳定化处理技术及其评价方法

概述了国内外有关加速耐候钢稳定化锈层形成过程的表面处理技术及其评价方法,着重阐述了耐候钢锈层稳定化处理技术的有机-无机复合膜技术,并展望了这一方面国内外的发展趋势。     

Effect of Co and W on the corrosion behaviour of 1% Cr steel in flowing synthetic seawater

The aqueous corrosion characteristics of 1% Cr‐steel alloyed with small amounts of Co and W in synthetic seawater was studied by using immersion weight‐loss tests, electrochemical corrosion tests (potentiodynamic tests and electrochemical impedance spectroscopy (EIS) measurements) and analytical techniques. 1% Cr steels containing Co or W from 0.2 to 0.4 wt.% showed higher corrosion resistance than the 1% Cr steel in the immersion and potentiodynamic tests. EIS measurements showed that the Nyquist plot presented one time constant. Furthermore, the Co‐ and W‐bearing steels present higher R_p values than the 1% Cr steel through all the test period. The better corrosion resistance of the Co‐and W‐bearing steels is attributed to the protectiveness of the surface layer. The corrosion products were examined using electron probe microanalysis (EPMA) and X‐ray photoelectron spectroscopy (XPS). The results of EPMA indicated that Cr was concentrated in the inner region of the rust layer, while Co and W were distributed all over the rust layer. XPS results showed that Co existed as a trivalent oxide in the rust layer and W in the rust appeared in the form of a WO₄ compound. These compounds act as a factor for corrosion resistance in aqueous solutions.