Corrosion behaviour of aluminium in fresh waters with special reference to pipelines

Abstract

This review is largely concerned with work carried out on the long-term behaviour of aluminium in fresh waters and the methods developed for predicting service behaviour. The corrosion behaviour of aluminium in waters is discussed and it is shown that aluminium corrodes by pitting. The effect of pitting on tensile properties, on the bursting strength of pipes, and on the hydraulic efficiency of pipes is described. It is shown that the most important consideration is that of preventing of perforation by pitting. The mechanism of pit initiation and pit growth and its practical Implications are described. The methods used by these Laboratories for determining the corrosivities of waters are given. The alloys in general use.in fresh waters are given together with their chemical compositions. The types of all aplicationS are briefly mentioned, and a specific application, that of water pipelines, is then dealt With in detail. Finally, the methods usedfor preventing perforation are summarised.     

Bootstrapping with Noise: An Effective Regularization Technique

Bootstrap samples with noise are shown to be an effective smoothness and capacity control technique for training feedforward networks and for other statistical methods such as generalized additive models. It is shown that noisy bootstrap performs best in conjunction with weight-decay regularization and ensemble averaging. The two-spiral problem, a highly non-linear, noise-free data, is used to demonstrate these findings. The combination of noisy bootstrap and ensemble averaging is also shown useful for generalized additive modelling, and is also demonstrated on the well-known Cleveland heart data.     

Validity of using high-energy fluxes for the metallographic revelation of the structure

The possibility of applying high-energy effects for metallographic etching is considered. It is shown that the methods of affecting the metal surface carrying the thermal component can alter the sample structure or reveal effects which can complicate the perception and analysis of the structure. It is noted that the application of nonthermal effect methods such as a magnetic field, cold plasma, and glow-discharge plasma can substantially alter the material structure and properties. It is shown that scanning electron microscopy cannot be considered an adequate analysis tool when studying the microstructure of metallographic cross sections. Thus, the effects of physical fields cannot be used as the means of metallographic sample preparation by virtue of its not always expected influence on the structure and properties of metals and alloys.     

真空密封铸型强度测试方法

详细地介绍了真空密封铸型抗压强度、抗剪强度、拉伸强度等的测试方法及用这种方法测得的结果。实际应用表明，这些方法有操作简便、测试结果复现性好等优点     

酸雨对材料的腐蚀/冲刷研究现状

阐述了全球和我国酸性降雨分布、酸雨给人类带来的 危害及损失、酸雨对无机材料、有机涂层、金属材料的腐蚀/冲刷影响的研究现状，总结了 酸雨对材料腐蚀行为的研究方法.     

Determination of parameters of porous structure of carbon adsorbent during analysis of vapor adsorption isotherms in region of polymolecular adsorption

The methods for determining the parameters of the porous structure for adsorbents based on considering the polymolecular adsorption range are analyzed. Advantages of the δ method are shown compared to the methods of normalization of the adsorption isotherms, as it does not require knowing standard adsorption isotherms. The determination of the parameters of the porous structure can be performed based on the analysis of the adsorption isotherms for different adsorptives used directly in the sorption processes, which considerably extends the possibilities and importance of adsorption research methods. The analysis of extensive experimental materials on the sorption of different substances on nonporous and microporous carbon adsorbents is evidence of the reliability of results of the δ methods for determining the overall surfaces of mesopores and macropores and the external surface of adsorbent, as well as the volume of the macropores.     

集输泵站工艺管道腐蚀及控制

对十六座泵站工艺管道腐蚀情况进行了调查研究，分析了腐蚀产生的原因；采取污水处理、密闭隔氧和除砂等工艺措施，对管道采用阴极保护、外涂及包覆层等防护，并提出了油田腐蚀控制技术发展的方向。     

A generic statistical methodology to predict the maximum pit depth of a localized corrosion process

This paper outlines a new methodology to predict accurately the maximum pit depth related to a localized corrosion process. It combines two statistical methods: the Generalized Lambda Distribution (GLD), to determine a model of distribution fitting with the experimental frequency distribution of depths, and the Computer Based Bootstrap Method (CBBM), to generate simulated distributions equivalent to the experimental one. In comparison with conventionally established statistical methods that are restricted to the use of inferred distributions constrained by specific mathematical assumptions, the major advantage of the methodology presented in this paper is that both the GLD and the CBBM enable a statistical treatment of the experimental data without making any preconceived choice neither on the unknown theoretical parent underlying distribution of pit depth which characterizes the global corrosion phenomenon nor on the unknown associated theoretical extreme value distribution which characterizes the deepest pits.Considering an experimental distribution of depths of pits produced on an aluminium sample, estimations of maximum pit depth using a GLD model are compared to similar estimations based on usual Gumbel and Generalized Extreme Value (GEV) methods proposed in the corrosion engineering literature. The GLD approach is shown having smaller bias and dispersion in the estimation of the maximum pit depth than the Gumbel approach both for its realization and mean. This leads to comparing the GLD approach to the GEV one. The former is shown to be relevant and its advantages are discussed compared to previous methods.     

Improving the efficiency of electrospark treatment of metallic surfaces by combining the method with other methods

One of the methods of increasing the efficiency of the electrospark treatment (EST) of metallic surfaces is investigated. On the basis of the experimental results, it is shown that combining the EST with other methods produces the surface layers on components with new, improved high-quality and strength characteristics and widens the range of application of the EST.     

Development of the combined flashing method in welding of rails

It is shown that to produce seamless tracks, rails are joined together by welding. The special feature of this method is that the rail steel belongs in the group of low weldability of materials and the requirements on these materials are very stringent because of the need to ensure safe movement of trains. At present, there are several methods of welding rails but all these methods have shortcomings. To increase the mechanical properties and improve the structure of the metal in the weld zone, it is proposed to use a combination of two methods of resistance flash butt welding – pulsed and continuous.     

混料方法对Ti(C,N)基金属陶瓷性能的影响

研究了不同球磨混料方式和不同研磨体对烧结体的机械性能和密度的影响。结果表明，采用湿混，用硬质含金作研磨体效果较好。并从微观的角度分析了其原因。     

环境腐蚀科学研究中的模式识别方法

本文论证了引入模式识别技术的可能性和必要性.简单介绍了模式识别技术,重点叙述了非线性映照,主要量分析,Fisher判别,聚类分析等方法的数学原理和应用特点.根据实际应用的经验,讨论了数据预处理,训练集选择,特征参数和关键参数,以及方法效果验证方法等一系列基础问题,并介绍了模式识别技术在环境腐蚀科学中的部分应用实例.     

Methods for Analyzing Deformation and Fracture Processes of Thin-Walled Parts from Low-Strength Alloys

The presented complex methods for analyzing the processes of deformation and fracture, including the evaluation of process ductility and measurement of crack resistance characteristics, are based on joint analysis of loading diagrams, acoustic emission signals, and fractures of articles fabricated from low-strength alloys. The possibilities of the methods in evaluation of fracture resistance of thin-walled parts from zirconium alloys are shown. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 43 – 50, April, 2005.     

冷凝器不锈钢薄壁管的兰姆波检测

小直径不锈钢薄壁管广泛应用于电站机组的冷凝器中,常规涡流检测方法难以发现纵向贯通的条状缺陷。在Ф25mm×1mm和Ф38mm×2mm不锈钢管壁上,沿轴向和周向加工深度分别为0．1mm、0．2mm和0．5mm的人工切槽,并进行检测试验研究,确定了兰姆波检测技术对小直径不锈钢薄壁管上人工缺陷的可检性,探讨了对不锈钢薄壁管材进行兰姆波检测的有效性和可靠性,提出以兰姆波检测技术对小直径不锈钢薄壁管进行检测的建议。     

碳钢Ni-P化学镀耐碱性溶液腐蚀性能的研究

为了研究碳钢材料在碱性介质中的腐蚀以及防护方法,采用静态浸泡法以及电化学的方法,对普碳钢以及进行化学镀后的耐碱液腐蚀性能进行了研究.结果表明:普碳钢在室温碱性溶液中放置1h后,表面即发生了严重的腐蚀.在碱性溶液中浸泡24h后,出现了基体局部剥离的现象.普碳钢在碱性溶液中发生了严重的腐蚀.在施加了化学镀层后,普碳钢在碱性溶液中浸泡24h后,表面光洁完整,与未施加化学镀层相比,有很小的腐蚀电流.在碳钢表面施加化学镀层后在碱性介质中具有良好的耐腐蚀性.     

前处理对固态防腐耐磨剂的作用

通过比较三种前处理方法对所研制的固态防腐耐磨剂耐蚀性的影响,发现磷化前处理不仅能提高涂层与基体材料的结合力,而且也增强了涂层的耐蚀性,同时研究了磷化参数对涂层耐蚀性的影响。     

Optimization of the process of deposition of wear-resisting Stellite coatings on steel by laser radiation

Methods for the optimization of parameters of laser powder deposition of Stellite 6 on the surface of AISI 4340 steel are investigated. The methods are used in particular for depositing coatings on shafts of power engineering systems produced from this steel. Optimization was carried out using two methods: experimental–selective; processing of the experimental results by statistical models. It is shown that the experimental–selective method can be used to select several optimum conditions ensuring the highest wear resistance. Processing the experimental results using the statistical models determines the dependence of the geometrical parameters of the bead on the surfacing conditions.     

铝合金稀土转化膜处理对LC4合金耐SCC性能的影响

利用慢应变速率试验(SSRT)等方法研究了P5和SRE稀土转化膜处理对LC4铝合金在3.5%NaCl溶液中的应力腐蚀行为的影响。P5和SRE工艺对LC4合金的应力腐蚀有一定抑制作用,SRE处理液对SCC有缓蚀效果。     

Some Impressions of Electroplating in U.S.A.

The development of electrochemical machining methods is described and it is shown how the original process was improved by the introduction of automatic methods of controlling the inter-electrode distance and by pressure-feeding the electrolyte. Factors of importance in governing the rate of metal removal and controlling the shape of the workpiece are detailed and illustrated by reference to electrode design, electrolyte composition and filtration methods.     

Der Einfluß von Neutralsalzen auf das Korrosionsverhalten unlegierter Eisen-Werkstoffe in gut gepufferten Trinkwässern

The influence of increased neutral salt content on the corrosion behaviour of non-alloyed steel in well buffered drinking waters The influence of higher neutral salt contents in well buffered drinking water on the corrosion behaviour of unalloyed steel pipes is described in this paper. The tests were mainly performed by differential methods to measure corrosion rate and iron uptake rate. It could be shown, that higher contents in chloride and sulphate increase corrosion and even more iron uptake rate. Nitrates have no measurable effect. Additionally, it could be shown, that an increase in neutral salts leads to increased local corrosion. Further research in this field by using drinking waters with low buffer capacity will be performed and reported later on.