Localized Corrosion Characteristics of Nickel Alloys:A Review

There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase.Nickel alloys are generally designed for and used in highly aggressive environments,for example,those where stainless steels may experience pitting corrosion or environmentally assisted cracking.While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments,they may be prone to crevice corrosion attack.Addition of chromium,molybdenum and tungsten increases the localized corrosion resistance of nickel alloys.This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations,in the chemical process industry and in seawater service.     

上海石化海水用材的回顾与思考

介绍了上海石化海水凝汽器与冷却器及泵等的腐蚀与防护情况，并对铜合金，钛与不锈钢等用材及防腐蚀措施作了探讨与评述。     

Zur Korrosion metallischer Werkstoffe in Tetrachlorkohlenstoff

Corrosion of metals in carbon tetrachloride Nickel, nickel alloys, titanium, the titanium-palladium alloy, carbon steel, stainless steel, zinc, aluminium und lead were immersed in the following boiling media: carbon tetrachloride dried and saturated with water and two phase mixtures of carbon tetrachloride and water. Titanium, the titanium alloy and nickel alloys of type C-4, G and 825 are high-corrosion-resistant, the alloy B-2 were only slightly corroded. Nickel, alloy 600, zinc and lead were corroded in the boiling two phase mixture. The weight loss of the stainless steel is very low, but the sensitivity of these steel grades to pitting and/or stress corrosion cracking have to be taken into account. Carbon steel and aluminium corroded heavily in contact with the boiling mixture. The composition of the gaseous phase corrosion products shows different corrosion mechanism.     

CVD-Silizium als Korrosionsschutz für die Beschaufelung von stationären Gasturbinen

Chemical Vapor Deposited silicon as a corrosion protection for the blades of stationary gas turbines In order to improve the corrosion resistance of heat resistant nickel alloys used as the blade materials for stationary gas turbines these materials were given a silicon coating by a chemical vapour deposition process. With the aid of microprobe and X-ray investigations the silicides formed were investigated. Coated specimens were exposed to a series of tests specifically oriented toward the intended use in stationary gas turbines. It turned out, that the silicide coatings on nickel base alloys are exceptionally stable to high temperature corrosion, so that a considerable increase of the useful life of silicided gas turbine blades may be expected.     

Capability of thermodynamic calculation in the development of alloys for deposition of corrosion‐protection coatings via thermal spraying

The capability of thermodynamic calculations for the development of materials for corrosion protection of steels via thermal spraying is illustrated in several practical examples. Although the thermodynamic calculations are usually performed for the equilibrium state, they can yield important information even about fast chemical reactions that are far from the equilibrium conditions. The relevance and reliability of thermodynamic calculations can be improved significantly if their results are complemented by chemical and microstructural analyses. In this contribution, details on the melting and alloying processes in technically relevant nickel‐based alloys were obtained from the combination of the thermodynamic calculations, differential thermal analysis, local chemical analysis using scanning electron microscopy with energy dispersive spectroscopy of characteristic X‐rays and X‐ray diffraction analysis. Furthermore, the results of the thermodynamic calculations performed on nickel‐based alloys clarified the role of individual chemical elements dissolved in the alloys for the corrosion resistance of the alloys and thus they contributed to the improvement of the chemical stability of these alloys during the chemical reaction with gaseous substances containing chlorine.     

钛合金表面激光熔覆的研究进展

钛合金具有优异的物理化学性能,其在航空航天行业中被广泛应用.但钛合金的低硬度和低耐磨性能使它的应用受到了限制.激光熔覆因其熔覆层与基体结合力强,无污染等优点成为钛合金表面改性研究热点之一.钛合金表面熔覆具有不同特性的熔覆材料来提高钛合金表面的相应性能.介绍国内外钛合金激光熔覆的研究现状和发展趋势.     

Boron and phosphorus saturation of nickel coatings on titanium alloys

The use of titanium alloys for parts that operate under contact friction conditions is possible if the alloy's tribological characteristics are substantially improved. This paper concerns the investigation of technological, high-temperature, diffusion saturation with boron and phosphorus coatings on titanium alloy surfaces by the chemical precipitation of nickel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 13 – 15, February, 1995.     

Korrosionsschutz durch Auftragschweißen mit den reaktiven Metallen Titan,Tantal und Zirkonium

Corrosion protection using surface-welded titanium, tantalum and zirconium claddings Very stringent demands are imposed on the corrosion resistance properties of components, apparatus, and plants of the chemical industry as well as in apparatus and machine construction. For technical and economic reasons, composite-layer materials which withstand the mechanical and corrosive conditions are employed. The special-purpose metals, titanium, tantalum, and zirconium exhibit high resistance to corrosion by many aggressive media, even at high pressure and temperature; these properties are not achieved by any of the conventional corrosion-resistant materials under the same conditions. The object of the research work was to develop a basis for producing claddings of titanium, tantalum, and zirconium by weld surfacing on a base metal of different composition with the application of the PHS method. Within the scope of the present project, single-layer claddings were applied by PHS weld surfacing with the use of titanium, tantalum, and zirconium of high purity as cladding materials on intermediate layers of nickel and copper, or alloys of these plasma hot wire weld surfacing, titanium, tantalum, zirconium, dilution, intermetallic phases, bonding, ductility elements. Boiler plate HI1 was employed as substrate for the three-layer composite materials. The titanium claddings thus applied have been thoroughly examined by metallographic techniques, layer analysis, and corrosion chemistry. The results indicate the possibility of producing corrosion-resistant claddings of titanium by the PHS method, provided that the welding process is shielded against contamination by atmospheric gases, and the formation of undesirable reaction products in the bonding zone between the base metal and filler material is minimized by means of an intermediate layer. The corrosion resistance of the surface-welded titanium claddings on an intermediate nickel layer coincides extensively with that of the reference material. On the basis of the corrosion analyses, the surface-welded titanium cladding on an intermediate copper layer is not resistant to corrosion. The results of weld surfacing with titanium have been applied to heterogeneous PHS weld surfacing with the special purpose metals tantalum and zirconium. In principle, metallographic examinations verify the possibility of producing a flawless bond between a cladding of zirconium and an intermediate nickel layer. In comparison with the filler material, Zr 702, however, the zirconium claddings applied by PHS weld surfacing exhibit a considerably greater hardness and low ductility. Because of the large difference between the melting points of tantalum and the substrate material, claddings of this kind cannot be reproducibly manufactured with sufficient quality by the PHS method, since the necessary parameters are at the extreme limit of the feasible range as far as the heat transfer is concerned.     

Anticipated Degradation Modes of Metallic Engineered Barriers for High-Level Nuclear Waste Repositories

Metallic engineered barriers must provide a period of absolute containment to high-level radioactive waste in geological repositories. Candidate materials include copper alloys, carbon steels, stainless steels, nickel alloys, and titanium alloys. The national programs of nuclear waste management have to identify and assess the anticipated degradation modes of the selected materials in the corresponding repository environment, which evolves in time. Commonly assessed degradation modes include general corrosion, localized corrosion, stress-corrosion cracking, hydrogen-assisted cracking, and microbiologically influenced corrosion. Laboratory testing and modeling in metallurgical and environmental conditions of similar and higher aggressiveness than those expected in service conditions are used to evaluate the corrosion resistance of the materials. This review focuses on the anticipated degradation modes of the selected or reference materials as corrosion-resistant barriers in nuclear repositories. These degradation modes depend not only on the selected alloy but also on the near-field environment. The evolution of the near-field environment varies for saturated and unsaturated repositories considering backfilled and unbackfilled conditions. In saturated repositories, localized corrosion and stress-corrosion cracking may occur in the initial aerobic stage, while general corrosion and hydrogen-assisted cracking are the main degradation modes in the anaerobic stage. Unsaturated repositories would provide an oxidizing environment during the entire repository lifetime. Microbiologically influenced corrosion may be avoided or minimized by selecting an appropriate backfill material. Radiation effects are negligible provided that a thick-walled container or an inner shielding container is used.     

Einfluß von Eisen auf die Korrosionsbeständigkeit von Nickelbasislegierungen als mögliche Werkstoffe für SCWO-Reaktoren

Effect of iron on the corrosion behaviour of nickel based alloys for SCWO plants An experimental set up to study corrosion at high temperatures and high pressures and able to simulate the conditions of supercritical water oxidation is described. On the basis of the alloys AC 66, 45 TM, G-3 and 601 H the influence of iron on the corrosion behaviour of nickel base alloys in aqueous solution under high pressures containing oxygen and chloride is shown and discussed. The corrosion resistance of the nickel base alloys is decreased with increasing iron concentration in the whole temperature range (100 °C–420 °C). The corrosion started at lower temperatures and the weight loss increased rapidly with increasing iron content. The corrosion morphology changed from uniform corrosion for alloys with less iron content to deep pits for alloys with high iron concentrations.     

钛镍及其合金的激光热处理现状

本文综述了近期国内Ti－Ni及其合金的激光热处理研究现状,试验证明激光热处理可以改善Ti－Ni及其合合的耐磨性、抗蚀性、高温抗氧化性和热稳定性。     

316不锈钢和825镍基合金在超临界水氧化毒死蜱介质中的腐蚀

在连续式超临界水氧化试验装置中，测量了316不锈 钢和825镍基合金在150℃～450℃分解杀虫剂毒死蜱过程中的腐蚀速度.两种合金的均匀腐蚀 速度随温度升高而增加，825镍基合金的腐蚀速度比316不锈钢的腐蚀速度小，450℃下316不 锈钢和825镍基合金的均匀腐蚀速度分别达143 μm/h和125 μm/h；200℃以上发生孔蚀 ，在较高分解温度下，由于孔蚀和均匀腐蚀的同时进行，形成相互贯穿的敞口蚀坑腐蚀形貌 .热力学分析表明，Fe-Cr-Ni合金在高温氧化性介质中是不稳定的，并且低熔点金属氯化物 的产生也可能是合金在超临界条件下出现高腐蚀速度的原因之一.     

The corrosion of nickel–aluminium bronze in seawater

Nickel–aluminium bronze (NAB) alloys show good corrosion resistance under marine conditions. The corrosion behaviour of cast and wrought NAB alloys is illustrated in this work through a range of electrochemical techniques including open-circuit potentiometry with time, oxygen reduction voltammetry, NAB dissolution voltammetry, potential step (or flow step) current transients and linear polarisation resistance. The galvanic coupling of NAB to stainless steel or copper is examined by zero resistance ammetery. The importance of using controlled flow working electrodes is illustrated by the use of a rotating disc electrode, a rotating cylinder electrode and a bimetallic (NAB/copper–nickel) rotating cylinder electrode. In addition to controlling the hydrodynamics, such electrodes allow charge transfer data to separate from those of mass transport control under mixed kinetic control. Longer term seawater immersion trials on planar coupons coupled to titanium or cupronickel are also reported. The relative contributions of erosion and corrosion attack are considered using a wall-jet electrode and the corrosion characteristics of NAB are compared to those of copper and copper–nickel in chloride media.     

Corrosion in flue gas desulfurization plants and other low temperature equipment

A literature study of corrosion problems in flue gas desulfurization (FGD) plants and other low-temperature equipment has been made. The study in question has been limited to coal- and waste-fired plants. The results of the study shall contribute to selection of better materials and an optimization of the flue gas processing in such a way that the corrosion risk will be diminished leading to less costs of operation and maintenance. Before the selection of materials for FGD plants experiences from similar plants, pilot plant data, laboratory results and general recommendations for material selection must be carefully studied. Material recommendations from manufacturers are of great value, especially when selecting organic or inorganic coatings alternatively linings. The choice of an alloy is strongly dependent on the process chemistry, above all the pH and the chloride concentration. In several cases high-alloyed steels, nickel base or titanium alloys are recommended, e.g. nickel base alloys or titanium can be installed either as solid plates, clad plates or attached liners. Properly selected protective linings or coatings of non-metallics applied in a qualified manner and maintained well will, however, perform cost-effectively. Different ways to minimize the corrosiveness of the process environment have also been discussed, e.g. the use of inhibitors but considerable interest has also been devoted to corrosion monitoring.     

Behaviour of Cu-Ni alloys in natural sea water and NaCl solution

A series of Cu-Ni alloys, ranging from 30 to 90% copper was studied by electrochemical methods in 3.5% sodium chloride solution and in sea water. The composition of the corrosion layer and of the solution after various immersion times was determined by chemical methods and X-ray diffraction. The results are consistent with a corrosion process involving dissolution of copper and nickel enrichment at the surface. The corrosion resistance of all the alloys is better in NaCl solution than in sea water.     

Corrosion behaviour of reactor coolant system materials in nuclear power plants

The materials used for the pressure‐retaining parts of reactor coolant system components in light water reactor nuclear power plants have to meet special requirements in terms of their mechanical properties, workability and in‐service performance. Corrosion issues play an important role in connection with plant operating conditions. While giving consideration to the specific service environment of the reactor whether a pressurized or boiling water reactor – the materials used for the individual components and the water chemistries employed in the various systems are selected such that metal loss due to general corrosion will remain very low. Thus the materials used in light water reactor plants exhibit a high general resistance to corrosion for their specified service conditions, material conditions and mechanical loads. However, under certain operating conditions other corrosion mechanisms may be found to induce damage. This paper uses data from the literature, published results of national and international research programs, information on damage which has actually occurred world‐wide and experience gained by Framatome ANP GmbH (former Siemens/KWU) in this field as a basis for discussing these mostly localised corrosion phenomena in terms of “classical” corrosion systems. Aspects associated with irradiation and its effects are not considered. Suitable remedial actions are, however, addressed wherever these are of relevance. The materials considered comprise unalloyed and low‐alloy steels, austenitic chromium‐nickel steels as well as high‐nickel steels and nickel‐base alloys which are exposed to the reactor coolant environment of boiling water reactor or pressurized water reactor plants, including materials investigated in corresponding water environments simulated in the laboratory.     

Comparison of the kinetics and morphologic properties of titanium,Ti-1.5Ni and Ti-2.5Cu during oxidation in pure oxygen between 600 and 820°C

The kinetics and morphologic oxidation properties of titanium, Ti-1.5Ni and Ti-2.5Cu were compared. Titanium and Ti-1.5Ni have a similar behavior, concerning the kinetics and the oxide micro structure. Copper additions decrease the oxidation rate of titanium. The oxide scales formed on Ti-Cu are thinner and less cracked than those obtained on Ti or Ti-1.5Ni. Copper is found in the oxide scale of Ti-Cu, whereas nickel is not found in the oxide scale of Ti-Ni. The oxidation of titanium and its alloys is controlled chiefly by diffusional phenomena in the oxide scale. Thus the alterations of the oxide scale structure and the slower oxidation rate of Ti-2.5Cu can be attributed to the copper which diffuses towards the gas-oxide interface.     

Werkstoff- und Korrosionsprobleme in wäßrigen Lösungen bei hohen Temperaturen und Drücken

Materials and corrosion problems in aqueous solutions at high temperatures and pressures The present report, based on papers and discussions of an international conference on electrochemistry at high temperatures and pressures forms a survey of materials and corrosion problems at high temperatures and pressures. Among the topics of the conference there were, among others, corrosion problems in power stations with particular emphasis on high alloy chromium nickel steels and nickel base alloys which are preferentially used in nuclear power stations. Unalloyed and low alloy steels were lower on the scale of interests. A matter of particular interest, however, were investigations and findings on corrosion cracking failures, which may occur on chromium nickel steels and nickel chromium iron alloys under rather different conditions of heat treatment of the materials (solution annealed or sensitized) and of the corrosive medium. With reference to pertaining literature data a summary is presented of the present state of knowledge concerning the various type of cracking corrosion which may occur on the materials of interest, i. e. chromium nickel steels of the 18 8 type, Incoloy 800 und nickel base alloys of the Inconel 600 type.     

Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

The paper is focused on selection of a proper material for construction elements of water electrolysers, which make use of a 85% phosphoric acid as an electrolyte at temperature of 150 °C and which might be loaded with anodic polarization up to 2.5 V versus a saturated Ag/AgCl electrode (SSCE). Several grades of stainless steels were tested as well as tantalum, niobium, titanium, nickel alloys and silicon carbide. The corrosion rate was evaluated by means of mass loss at free corrosion potential as well as under various levels of polarization. The only corrosion resistant material in 85% phosphoric acid at 150 °C and at polarization of 2.5 V/SSCE is tantalum. In that case, even a gentle cathodic polarization is harmful in such an acidic environment. Hydrogen reduction leads to tantalum hydride formation, to loss of mechanical properties and to complete disintegration of the metal. Contrary to tantalum, titanium is free of any corrosion resistance in hot phosphoric acid. Its corrosion rate ranges from tens of millimetres to metres per year depending on temperature of the acid. Alloy bonded tantalum coating was recognized as an effective corrosion protection for both titanium and stainless steel. Its serviceability might be limited by slow dissolution of tantalum that is in order of units of mm/year.     

Untersuchungen über das Korrosionsverhalten von Zirkoniumlegierungen. III. Untersuchungen an Zirkonium-Titan-Legierungen

Investigations into the corrosion behaviour of zirconium alloys III. Investigations on zirconium titanium alloys Investigations on zirconium alloys containing up to 4OO% titanium and, eventually, up to 10% Nb or Mo and small amounts of Fe, Ni and Cr (together 1.5% maximum) have revealed that titanium increases the dissolution power of zirconium for other alloying elements without tending to form two-phase structures. As to corrosion behaviour the better alloys are somewhat superior to other alloys. While titanium impairs the corrosion resistance of pure zirconium with respect to boiling mineral acids (20% HCl, sulphuric or nitric acids) titanium additions up to 10% of improve the corrosion behaviour of ZrNb and ZrMo alloys; alloys of the type Zr10Nb10Ti or Zr10Ti10Ta are comparable, with respect to the corrosion resistance, to pure zirconium. The scaling resistance of zirconium passes through a minimum at a five to ten percent Ti and arrives at its maximum value with 40% Ti. Further improvements may be obtained by addition of 10% Nb.