工业纯钛TA2在含硫化物深海水环境中的应力腐蚀行为

深海水环境具有静水压力大、溶氧量低、侵蚀性离子复杂等特点,使得深海水环境具有较强的腐蚀性。目前,钛及钛合金在深海环境下的腐蚀及应力腐蚀行为机理尚不清楚,这对钛合金在深海环境中的应用造成较大的威胁。文中采用电化学方法及U型弯试验研究了工业纯钛TA2在模拟深海环境下的电化学行为及应力腐蚀行为。结果表明,静水压力对TA2均匀腐蚀及阴极析氢反应均有所促进,随着静水压力增大,TA2腐蚀电流密度及析氢电流密度均增加。硫化物的加入一定程度上降低了TA2钝化膜稳定性,并对阴极析氢反应有较为明显的促进。应力腐蚀试验表明深海硫化物作用下TA2具有一定的应力腐蚀敏感性。TA2在深海条件下,虽然SCC以氢致开裂为主,但是由于氧含量与浅海等环境的不同,阳极溶解机制也是TA2在深海条件下SCC开裂的原因。     

钛合金深海应力腐蚀研究进展

基于对钛合金应用及研究报道的梳理,综述了钛合金深海应力腐蚀产生原因及机理,探讨了静水压力、溶解氧含量、pH值和温度等深海环境因素对应力腐蚀开裂的影响,以期为今后钛合金深海应力腐蚀开裂等局部腐蚀行为及机制的深入研究提供参考,为优化钛合金组织性能,建立深海先进钛合金材料体系提供支撑。     

飞机上钛合金的特殊腐蚀形式

航空航天领域工作环境相当苛刻,随着钛合金在飞机和发动机上用量的增加,一些特殊的失效形式,如氢脆、应力腐蚀开裂、腐蚀疲劳等在钛合金结构件上时有发生,必须引起我们足够的重视.本文介绍了飞机上钛合金的这些腐蚀形式,并介绍了这些腐蚀类型的区别.     

模拟深海环境中阴极极化电位对钛合金应力腐蚀敏感性的影响

通过电化学试验和慢应变速率试验研究了阴极极化电位对钛合金Ti80、Ti75和Ti31在模拟深海环境中应力腐蚀敏感性的影响。结果表明：随着阴极极化电位的负移,3种钛合金的应力腐蚀敏感性均呈现上升趋势,在模拟深海环境中,Ti80、Ti75和Ti31无明显应力腐蚀倾向的最负阴极极化电位(相对于Ag/AgCl电极)分别为-0.77 V、-0.73 V和-0.73 V。     

不锈钢的腐蚀破坏与防蚀技术：（五） 腐蚀疲劳

1 基本概念材料在重复的交变应力(也称周期应力或循环应力)和腐蚀介质的联合作用下所发生的早期腐蚀开裂现象,称为腐蚀疲劳.在腐蚀介质中发生的腐蚀疲劳比在单纯空气中发生的机械疲劳要严重得多.通常,采用损伤比来表示腐蚀对疲劳强度的影响,即损伤比=材料的腐蚀疲劳强度/材料在空气中的疲劳强度不同的材料或同一种材料在不同的腐蚀介质中,其损伤比是不同的,对不锈钢而言,在以盐水为腐蚀介质的环境中,其损伤比约为0.5.腐蚀疲劳的S-N曲线与一般机械疲劳的S-N曲线有所不同,腐蚀疲劳曲线的位置较低,尤其是在低应力、高循环次数下,曲线的位置更低.而且,在腐     

304 不锈钢在模拟深海和浅海环境中的应力腐蚀行为

目的研究304不锈钢在模拟深海和浅海中的应力腐蚀开裂(SCC)行为。方法通过控制不同环境因素模拟南海某海域环境,利用动电位扫描、交流阻抗谱、慢应变速率拉伸(SSRT)及SEM表面分析等手段进行研究。结果 304不锈钢在模拟海水溶液中呈现钝化状态,出现应力腐蚀敏感性,且裂纹扩展方式为穿晶开裂。在深海中的SCC机制为氢致开裂,浅海中的SCC机制主要为阳极溶解。结论 304不锈钢在深海与浅海中的SCC机制不同,但两者的SCC敏感性相近且相对较低,在模拟海水环境中的应用不受海水深度限制。     

深海装备微生物腐蚀研究现状及发展趋势

主要介绍了深海装备微生物腐蚀机制，回顾了深海装备微生物腐蚀现状，分析并概述了微生物腐蚀的研究趋势，并对这一研究领域的影响因素进行了讨论。目前深海微生物腐蚀研究不多，且深海微生物环境模拟方法和技术也存在很多不足和不确定因素，应加强以应用为目的的深海装备微生物腐蚀性能研究，探索其在深海极端环境中的腐蚀规律和防护方法，并建立深海微生物腐蚀数据库，为今后深海装备的设计应用、防腐等性能的提高提供强有力的支持和保障。     

深海环境下金属及合金材料腐蚀研究进展

综述了深海环境下溶解氧含量、温度、pH、溶解CO2含量、含盐度、静压力、流速以及生物环境等各项因素对金属及合金材料腐蚀的影响,认为溶解氧含量通常为金属及合金材料腐蚀的最主要因素;重点介绍了实海暴露方法和室内模拟加速腐蚀方法在深海环境下的研究进展及具体应用,指出最好将室内模拟加速腐蚀试验和实海暴露方法相结合,同时体现二者的优势以研究金属及合金材料的腐蚀行为;总结了深海环境下金属及合金材料的腐蚀状况,对其防护手段-阴极保护及涂层保护进行了概述.     

含缺口TC21钛合金腐蚀疲劳性能分析

研究了TC21钛合金缺口试样在两种腐蚀环境（油箱积水、3.5%NaCl水溶液）与室温空气环境下的疲劳性能与断裂机理。并与光滑试样在室温空气环境下疲劳性能进行对比。结果表明,室温空气环境下,当两种试样疲劳寿命均达到5×105次循环时,缺口试样的循环应力值较光滑试样下降了52.7%;相同环境下随着应力水平降低,试样疲劳寿命增加;相同应力条件下,3.5% NaCl水溶液环境下试样疲劳寿命最低,油箱积水环境下次之,室温空气中TC21钛合金试样疲劳寿命最高;当应力较低时,差异更为显著。在腐蚀环境下,溶液中离子与金属原子发生电化学反应,加速了裂纹的萌生与扩展,3.5% NaCl水溶液中离子浓度较大,电化学反应更为剧烈     

7050铝合金晶界偏析与应力腐蚀,腐蚀疲劳行为的研究

研究了不同时效状态的７０５０铝合金晶界偏析与应力腐蚀开裂及湿空气环境下疲劳裂纹扩展的关系，并采用修正的化学方法计算了晶界偏析对断裂应力的影响。结果表明：随着时效程度的增加，晶界上Ｍｇ偏析浓度减小，捕获Ｈ的能力减弱，晶界断裂应力的百分数随之下降，因而合金的抗应力腐蚀和腐蚀疲劳性能提高。     

Environmental behavior of beta titanium alloys

Stemming from their unique combination of elevated strength, low density, and good overall corrosion resistance, beta titanium alloys have become attractive candidate materials for critical, high-stress components in corrosive services. An overview of the comparative corrosion resistance of beta alloys to conventional alpha and alpha/beta titanium alloys in common industrial and aerospace service environments generally reveals attractive behavior depending on the environment and alloy composition and, in some cases, alloy condition. Expanded performance windows are especially noted for the molybdenum-rich beta alloys, particularly with regard to resisting reducing acids, stress corrosion, and high-temperature localized chloride attack, along with hydrogen and oxidation resistance. Where applicable, implications of this enhanced corrosion performance on current and perspective beta alloy applications are also noted.     

Al-Cu-Li合金在盐溶液中的腐蚀行为以及腐蚀机理研究进展

Al-Cu-Li合金是航天航空工业中重要的轻质结构材料，已成为国产大飞机结构件的关键材料之一。飞行器在海洋等潮湿环境服役时，易受到具有腐蚀性的卤化物阴离子的侵蚀，尤其是在Cl^-离子侵蚀作用下，Al-Cu-Li合金构件表面易出现点蚀、晶间腐蚀和剥落腐蚀现象。Al-Cu-Li合金的局部腐蚀主要归因于合金相与合金基体间存在电势差，进而导致在腐蚀介质中形成微型腐蚀原电池。综述了Al-Cu-Li合金在NaCl溶液中的腐蚀行为以及热处理工艺对合金耐腐蚀性能的影响，重点分析了粗大第二相颗粒和时效析出相对Al-Cu-Li合金腐蚀性能的影响，研究了典型第3代Al-Cu-Li（2A97-T3、2A97-T6、2060-T8和2099-T83）合金以及航空用常规高强铝合金2024-T4在3种不同浓度NaCl溶液中的侵蚀行为以及在质量分数3.5%NaCl溶液中的电化学行为。综合分析各试样的微观腐蚀形貌、腐蚀电化学参数以及腐蚀程度，最终得出各试样的耐腐蚀性能由强至弱为：2A97-T3>2A97-T6>2024-T4>2060-T8>2099-T83。最后揭示了Al-Cu-Li合金在腐蚀介质中的腐蚀机理，总结了在海洋环境下铝合金的防腐措施。本文为后续Al-Cu-Li合金防腐性能的发展和飞机耐腐蚀性能的提升提供了参考。     

Electrochemical Performance of Passive Film Formed on Ti-Al-Nb-Zr Alloy in Simulated Deep Sea Environments

Titanium alloy Ti-Al-Nb-Zr has high specific strength and becomes a promising structural material used in the deep sea.The excellent corrosion resistance of the alloy is derived from the protective passive film formed on its surface.By now,full agreement on interpretation of the anti-corrosion performance of the film in marine environment,especially in the deep sea,has not been reached.In this work,the electrochemical performance of two-surface-state Ti-Al-Nb-Zr alloys which are treated by mechanical polishing and anodizing pre-passivation in the simulated shallow sea,1000 m and 3000 m deep sea environments,is investigated.By interpreting the electrochemical kinetic parameters,it is found that the dominant cathodic process becomes hydrogen evolution in simulated deep sea environments,but the reduction rate is restrained by high hydrostatic pressure,which arrests the passivation of the alloy.Assisted by X-ray photoelectron spectroscopy analysis,it is found that the passive film mainly consists of titanium oxides.There are intermediate oxides with non-stoichiometric ratio involved in the film formation due to the low dissolved oxygen concentration and low temperature.The results of Mott-Schottky and electrochemical impedance show that the film has n-type semiconducting property with oxygen vacancies as the main point defects.The anti-corrosion performance in simulated deep sea environments is one order of magnitude lower than that in the simulated shallow sea environment.However,from 1000 to 3000 m,the corrosion resistance is reduced very slightly.In the inner layers of the passive film and the passive film formed in simulated deep sea environments,the proportion of lowvalence titanium oxides is relatively high.The doping of low-valence titanium(Ti(Ⅱ) or Ti(Ⅲ)) results in a porous structure and ion permeability of the passive film,as well as relatively low corro sion resistance.     

The “C” family of Ni-Cr-Mo alloys' partnership with the chemical process industry: The last 70 years

The “C” family of alloys, the original being Hastelloy® alloy C (1930's) was an innovative optimization of NiCr alloys having good resistance to oxidizing corrosive media and NiMo alloys with superior resistance to reducing corrosive media. This combination resulted in the most versatile corrosion resistant alloy in the “NiCrMo” alloy family, with exceptional corrosion resistance in a wide variety of severe corrosive environments typically encountered in CPI and other industries. The alloy also exhibited excellent resistance to pitting and crevice corrosion attack in low pH, high chloride oxidizing environments and had virtual immunity to chloride stress corrosion cracking. These properties allowed this alloy to serve the industrial needs for many years, although it had some limitations. The decades of the 1960's (alloy C-276), 1970's (alloy C-4), 1980's (alloy C-22 and 622) and 1990's (alloy 59, alloy 686 and alloy C-2000) saw newer alloy developments with improvements in corrosion resistance, which not only overcame the limitations of alloy C, but further expanded the horizons of applications as the needs of the CPI became more critical, severe and demanding. Today the originally alloy “C” of the 1930's is practically obsolete except for some usage in form of castings. This paper presents a chronology of the various corrosion resistant alloy developments during this century, with special emphasis on the last 70 years evolution in the “C” family of NiCrMo alloys and their applications.     

Studying and modeling surface gas nitriding for titanium alloys

In this article, experimental studies for the nitriding of four titanium alloys at different temperatures and for different periods of time are summarized. The studies focused on microstructural changes in relation to the alloy composition and processing parameters; microindentation hardness testing on the nitrided titanium alloys to analyze their hardness evolution; and the corrosion behavior of titanium alloys before and after gas nitriding in response to the corrosive condition. In addition, models were developed to simulate and monitor the evolution of surface layers during the gas nitriding of titanium alloys.     

Custom age 625® plus alloy—A higher strength alternative to alloy 625

Highly corrosion- resistant, age- hardenable alloys are needed in severely corrosive environments such as those encountered in deep sour- gas wells. Age hardenability is important because high strength levels of 827 MPa (120 ksi) minimum 0.2% yield strength are required in large section sizes. Custom Age 625 PLUS was developed to provide higher strength levels than those attainable with alloy 625 along with similar corrosion resistance (more corrosion resistant than alloy 718). The development and metallurgy of Custom Age 625 PLUS are reviewed. The mechanical properties and corrosion resistance of 625 PLUS, 625, and 718 alloys are compared.     

高温海洋环境下过渡金属基合金的腐蚀与防护研究进展

综述了高温海洋腐蚀环境的类型,以及各类合金在不同环境下的腐蚀失效机理。重点考察了Fe、Ti、Ni基合金内部的主要元素在高温下的扩散行为,及其与侵蚀性离子之间的交互作用。从盐雾腐蚀以及熔融热腐蚀2个角度,讨论了化学/电化学反应发生的可能性。基于氧化腐蚀过程中复合氧化膜的形成过程,总结了氧化膜与侵蚀性离子以及杂质气体的再作用机理,明确了保护性氧化膜和非保护性氧化膜的类型。从合金化的角度,揭示了Cr、Al等元素对防腐性能提升的关键作用,指出了材料计算在高温海洋环境的潜在应用价值。最后归纳了高温海洋环境下的涂层防护手段和材料体系,其中结构稳定性和界面反应问题是涂层材料研究的重点。在未来研究方向上,指出应该重点关注腐蚀过程中活性元素的交互作用以及钝化膜的形成机理,筛选有效防护元素。利用氧化、盐雾等多种腐蚀条件,依托构效关系进行涂层优化,形成系统的海洋高温涂层防护方案。高熵合金涂层作为新兴体系在高温防护上的应用具有研究价值。     

油气开采用钛合金石油管材料耐腐蚀性能研究

选取5种油气开发常用钛合金材料(Ti-6Al-4V、Ti-6Al-4V-0.1Ru、Ti-6Al-2Sn-4Zr-6Mo、Ti-3Al-8V-6Cr-4Zr-4Mo和Ti-5.5Al-4.5V-2Zr-1Mo)为研究对象,使用高温高压釜模拟国内典型严酷服役工况环境,研究了不同钛合金材料耐均匀腐蚀、局部腐蚀、点蚀、应力腐蚀开裂(SCC)及缝隙腐蚀的性能,通过使用扫描电镜和能谱分析等手段对腐蚀形貌和腐蚀产物进行了分析,并使用电化学方法对不同合金的耐腐蚀机理进行了研究。结果显示,在所测试工况条件下,所有钛合金材料腐蚀反应均为阳极控制过程,均匀腐蚀速率均低于0.001mm/a,并且对应力腐蚀开裂均有良好的抗力。Ti-6Al-4V和Ti-5.5Al-4.5V-2Zr-1Mo合金出现明显的点蚀和缝隙腐蚀问题。对腐蚀机理研究表明,在工况条件温度下,随着pH值的降低,所有钛合金均发生自腐蚀电位降低,极化电阻减小,腐蚀电流增大,耐腐蚀性能下降,其中Ti-6Al-4V耐腐蚀性能下降的最为明显,研究结果为油气开发工况下钛合金石油管的选材和缝隙腐蚀问题防治提供理论基础。     

我国钛及钛合金研发与进展

我国材料工作者对不同领域使用的钛合金进行了卓有成效的研究工作。经过近50年的发展,我国的钛工业在科技和生产上都取得了长足进步。概述了我国自主研发的各种钛及钛合材料,包括高温钛合金、高强钛合金、低温钛合金、耐蚀钛合金、船用钛合金、医用钛合金等。最后对我国钛工业进行了简要的展望。