Ni-Cu-P钢在海水中的耐点蚀性能分析

研究了Ni-Cu-P钢、含铜量相对低的合金钢和普通碳钢在海水中的腐蚀行为。结果表明,铜元素能够减缓合金的腐蚀速率,所以Ni-Cu-P钢的耐腐蚀性能最好。Ni-Cu-P钢的组织更为密实,这是因为其蚀坑中有铜元素的富集。     

蒸汽发生器管690TT合金的点蚀性能

通过化学浸泡试验、动电位极化曲线的测量并结合扫描电镜(SEM)对经特殊热处理的690合金(690TT)点蚀形貌的观察,研究探讨了两种国产690TT合金在室温下的点蚀性能;并根据ASTM G48A与ASTM G61两种标准对690TT合金抗点蚀性能评估进行了比较。结果表明:两种国产690TT合金中,合金B的抗点蚀性能显著优于合金A的。ASTM G48A对690TT合金进行点蚀试验的最佳试验参数为50℃/3h,所得相应数据结果可靠;由于缝隙腐蚀等原因使ASTM G61对690TT合金管的点蚀电位测量稳定性不佳,可重复性较差。     

Corrosion Resistance of a High-Silicon Alloy in Metal-Dusting Environments

A Si-containing, high-temperature alloy (Fe–17Cr–9Ni–8Mn–4Si) was exposed to high-carbon activity and low-oxygen partial pressure environments (CO–H₂) over a temperature range from 650 to 950 °C. No metal dusting corrosion was observed in this alloy. The structure and composition of the surface films formed were characterized in detail at the nanometer level. At a temperature of 650 °C, the surface-oxide films formed are made up of an inner, continuous, amorphous-silica (SiO₂) layer and an outer crystalline manganese chromate (MnCr₂O₄) spinel layer with manganese oxide (MnO) crystals on the surface. By contrast, at a higher temperature of 950 °C, a more-complex layered structure is developed, comprising inner, continuous, amorphous SiO₂ and crystalline manganese-silicate (Mn₂SiO₄) layers and an outer crystalline Cr₂O₃/MnCr₂O₄ duplex layer with MnO crystals having variable textures on the surface.     

Pitting and Stress Corrosion Cracking Susceptibility of Nanostructured Al-Mg Alloys in Natural and Artificial Environments

The stress corrosion cracking (SCC) behavior of two developmental nanocrystalline 5083 alloys with varied composition and processing conditions was studied. The results were compared to a commercial aluminum AA 5083 (H111) alloy. The pitting densities, size and depths, and residual tensile strengths were measured after alternate immersion in artificial seawater and atmospheric exposure under different loading conditions. Optical and scanning electron microscopy (SEM) with EDX was used to analyze the fracture surfaces of failed specimen after removal at selected intervals and tensile testing. One of the nanostructured Al-Mg alloys exhibited significantly superior pitting resistance when compared to conventional microstructured AA 5083. Under conditions where pitting corrosion showed up as local tunnels toward phase inclusions, transgranular cracking was observed, whereas under conditions when pitting corrosion evolved along grain boundaries, intergranular cracking inside the pit was observed. Pit initiation resistance of the nano alloys appears to be better than that of the conventional alloys. However, long-term pit propagation is a concern and warrants further study. The objective of this investigation was to obtain information regarding the role that ultra-fine microstructures play in their degradation in marine environments and to provide insight into the corrosion mechanisms and damage processes of these alloys.     

Corrosion Resistance of Zinc-alloy Coated Steel in Construction Industry Environments

Considerable efforts are being made to improve the corrosion resistance of zinc coatings by alloying and application of compatible conversion coating treatments. These new systems have the potential for reliable and cost effective protective coatings on steel used in construction applications.

The present investigations have been concerned with: (i) development of a simple sensor that can be used to determine corrosion rates of zinc alloy coated steel in the macro/micro climates found in and around buildings and other structures.

(ii) determination of the compatibility and corrosion rates of zinc alloy coatings in contact with cementitious materials and preservative treated timber.

This paper describes the rationale for the investigations and the experimental techniques used, with a summary of the principle results and conclusions.     

Inconel 740H合金在模拟煤灰/烟气中的抗腐蚀性研究

针对用于超超临界锅炉过热器管的镍基高温合金Inconel 740H,在750 ℃及合成烟气的条件下,研究了涂刷合成煤灰试样和无涂刷试样累计3000 h的腐蚀情况。利用XRD、EDS和SEM对试样的表面和截面进行了分析。结果表明,涂刷合成煤灰试样的腐蚀分为两个阶段,开始在表面生成Cr₂O₃保护膜,随时间的延长氧化膜被硫酸盐溶解,腐蚀程度较重。无涂刷试样的腐蚀为一个阶段,即氧化和硫化腐蚀。     

医用镁合金的耐蚀性研究及其进展

从加工工艺、合金化、非晶化和表面改性等方面,阐述了医用可降解镁合金材料耐蚀性的研究状况和最新进展。分析了各种提高镁及镁合金耐蚀性的方法,并指出其存在的问题和今后的研究方向。     

高温高压CO_2腐蚀环境中含Cr低合金钢耐蚀机理的研究进展

阐述了含Cr低合金钢耐CO_2腐蚀的机理,并介绍了如何通过极化曲线来确定含Cr低合金钢是否耐蚀的方法,同时也列举了含Cr低合金钢腐蚀产物膜沉积机制的最新进展,并提出了含Cr低合金钢耐蚀机理研究中亟待解决的问题。     

Corrosion Behavior of IN-800 Superalloy in Waste-Incineration Environments: Hot Corrosion by Molten Chlorides

The corrosion resistance of the IN-800superalloy in contact with a molten mixture of (52-48)mol.% PbCl₂-KCl, similar to that found inwaste-incineration plants, has been studied. Thecorrosion kinetics have been analyzed using continuous-currentelectrochemical techniques and electrochemical-impedancespectroscopy (EIS). Studies were performed to determinethe influence of temperature and of the presence of carbon in the salt on the corrosion rate.Scanning electron microscopy (SEM) and electron probemicroanalysis (EPMA) were used as additional techniquesto analyze the corrosion products in order to elucidate the corrosion mechanism.     

Corrosion Behavior of 12CrMoV Steel in Waste Incineration Environments: Hot Corrosion by Molten Chlorides

The corrosion resistance of a 12CrMoV alloy incontact with a molten mixture of (52-48)mol.%PbCl₂-KCl, similar to that found inwaste incineration plants, has been studied. Thecorrosion kinetics have been analyzed using continuous-currentelectrochemical techniques and electrochemical impedancespectroscopy (EIS). Studies were performed to determinethe influence that temperature and the presence of carbon in the salt have on the corrosion rate.Scanning electron microscopy (SEM) and electron-probemicroanalysis (EPMA) were used as additional analyticaltechniques to analyze the corrosion products in order to elucidate the corrosionmechanism.     

Determination of the Life Cycle of Heat-Exchange Tubes of Vapor Condensers on the Basis of Statistical Analysis of Local Pitting Corrosion According to Data of Eddy Current Testing

Protection of Metals and Physical Chemistry of Surfaces - The possibility is shown of creating a chart of local corrosion damage in the walls of heat-exchange tubes on the basis of the data of...     

Pitting Corrosion Characterization of Wrought Stellite Alloys in Green Death Solution with Immersion Test and Extreme Value Analysis Model

This article presents a study of the corrosion behavior of two wrought Stellite alloys, Stellite 6B, and Stellite 6K, in Green Death solution, utilizing the extreme value analysis (EVA) model, which is a statistics tool developed based on the Gumbel distribution. Green Death solution a typical oxidized testing solution used in industry for assessing the corrosion resistance of materials. The data of maximum pit depths are obtained from the immersion tests on these alloys for various exposure periods. The top ten maximum pit depths in each specimen surface after the immersion test are measured using a surface texture and contour measuring instrument. These data are the input parameters of the EVA model and the outcomes of the model are the extreme values (minimum thickness) required for the alloys under a given service condition. It is shown that Stellite 6K, which contains higher carbon content but smaller-size carbides, exhibits better corrosion resistance in regard to the extreme value. The results and mechanisms of Stellite 6B and Stellite 6K in Green Death solution corrosion are discussed.     

建筑用E36钢焊接接头的耐蚀性分析

对E36海面建筑用耐蚀钢与耐蚀实心焊丝配套焊接及其耐腐蚀性能进行研究,分析焊接接头化学成分、微观组织与夹杂物对接头耐蚀性的影响。结果表明,焊接接头处各区的微观组织不同。焊接接头整体力学性能较好,各区域耐蚀性也能满足要求。其中,焊缝区耐蚀性最佳,热影响区由于受到夹杂物的影响耐蚀性最差。     

Corrosion Testing of Ni Alloy HVOF Coatings in High Temperature Environments for Biomass Applications

This paper reports the corrosion behavior of Ni alloy coatings deposited by high velocity oxyfuel spraying, and representative boiler substrate alloys in simulated high temperature biomass combustion conditions. Four commercially available oxidation resistant Ni alloy coating materials were selected: NiCrBSiFe, alloy 718, alloy 625, and alloy C-276. These were sprayed onto P91 substrates using a JP5000 spray system. The corrosion performance of the coatings varied when tested at ~525, 625, and 725 °C in K₂SO₄-KCl mixture and gaseous HCl-H₂O-O₂ containing environments. Alloy 625, NiCrBSiFe, and alloy 718 coatings performed better than alloy C-276 coating at 725 °C, which had very little corrosion resistance resulting in degradation similar to uncoated P91. Alloy 625 coatings provided good protection from corrosion at 725 °C, with the performance being comparable to wrought alloy 625, with significantly less attack of the substrate than uncoated P91. Alloy 625 performs best of these coating materials, with an overall ranking at 725 °C as follows: alloy 625 > NiCrBSiFe > alloy 718 ? alloy C-276. Although alloy C-276 coatings performed poorly in the corrosion test environment at 725 °C, at lower temperatures (i.e., below the eutectic temperature of the salt mixture) it outperformed the other coating types studied.     

基于计算机技术的镁合金轮毂耐蚀性预测分析

镁合金轮毂压铸件可能存在气孔、裂纹、变形、缩孔、缩松、冷隔、欠铸、流痕、飞边、塌陷和粘附共11类缺陷.对不同压铸缺陷的AM60B镁合金轮毂在酸雨环境和中性盐雾环境下的耐蚀性进行了测试,建立了4层结构的集成压铸缺陷的镁合金轮毂耐蚀性预测模型,并进行了预测分析.结果表明,经过L-M优化算法训练的预测模型具有较高的预测能力和精度;对镁合金轮毂耐蚀性影响最大的4类压铸缺陷依次是缩孔、缩松、气孔和裂纹.     

Case Study: Pitting and Stress Corrosion Cracking in Heat-Affected Zone of Welded Underground 304 Stainless Steel Pipe

A jacketed underground pipeline made of 304 stainless steel tubing to transport utility water in a petrochemical plant at ambient temperature was perforated after few months of operation. Perforation started preferentially at the outer bottom surface of the pipe in the weld heat-affected zones where the insulating coating was damaged. Detailed microstructural characterization was carried out to determine the cause of failure using optical metallography, x-ray diffraction, scanning electron microscopy combined with energy dispersive spectroscopy, and transmission electron microscopy. Experimental results indicated that the failure occurred by interaction between the outer bottom surface of the pipe and surrounding environment leading to pitting and stress corrosion cracking in the presence of chloride ions. This could have been aided by residual welding stresses and the characteristic low stacking fault energy of the material.     

核电厂水池覆面用不锈钢钢板在硼酸水溶液中的点蚀行为

采用电化学方法研究了温度、Cl~-以及SO_4~(2-)含量对不锈钢板S30403、S32101和S32205在硼酸溶液中点蚀行为的影响。结果表明:3种材料的点蚀电位(Eb)和再钝化电位(Er)均随Cl~-含量的升高而降低,S32205不锈钢的点蚀电位和再钝化电位普遍高于S32101和S30403不锈钢的;存在临界温度(约60℃),当温度高于临界温度,S32205不锈钢的点蚀电位大幅降低,再钝化电位的临界温度介于40~60℃;SO_4~(2-)含量对3种材料点蚀电位和再钝化电位的影响不明显。S32205不锈钢的耐点蚀性能优于S32101和S30403不锈钢的,而S32101和S30403不锈钢的耐点蚀性能相当。     

316L奥氏体不锈钢在海水中的耐蚀性研究及计算机辅助分析

研究了温度和海水浓缩度对316L不锈钢在海水中腐蚀性的影响,提出了延长试样寿命的方法。结果表明,温度和浓缩度的增大都使钢的耐腐蚀性能下降,但是温度的影响更大,所以可通过降低温度的方法延长试样的寿命。     

Q235钢/导电混凝土在3种典型土壤环境中腐蚀的灰色关联度分析

采用动电位扫描和电化学阻抗谱(EIS)技术,研究了Q235钢/导电混凝土在盐碱土、黄棕壤、红壤中的腐蚀行为,分析了土壤环境因素对腐蚀过程的影响规律,并基于灰色关联度理论计算了土壤中各离子对导电混凝土中Q235钢腐蚀过程的影响权重.结果 表明,加速腐蚀45 d后,Q235钢/导电混凝土表面出现孔洞、边缘出现细微裂纹.Q2...