摘要
钛合金因具有高强度、低密度和良好的耐腐蚀性等优点,被广泛应用于化工、航空航天、船舶等领域.然而,钛合金所具有的钝化特性使其在某些特定腐蚀环境中,尤其是在卤化物条件下,易发生局部腐蚀.局部腐蚀通常难以察觉,但却具有较强的穿透性,引发材料部件发生穿孔或断裂,导致泄露甚至更严重的事故发生.然而,现有公开文献鲜有系统介绍针对局部腐蚀的防护措施.本文简要介绍了钛合金局部腐蚀的主要形式及相应的腐蚀机制,包括点蚀、电偶腐蚀、缝隙腐蚀、应力腐蚀开裂和氢致开裂.讨论了钛合金化学成分、腐蚀介质中离子的种类与浓度以及服役环境中的温度和压力对钛合金局部腐蚀的影响规律.此外,概述了针对钛合金局部腐蚀导致失效的多种防护措施,包括合金化、表面改性技术以及热处理工艺等方法.最后,列举现有防护措施中的不足,并展望了未来针对钛合金局部腐蚀机制及防护方法的研究方向.
Abstract
Titanium alloys are widely used in fields such as chemical,aerospace,and maritime industries due to their advantages of high strength,low density,and excellent corrosion resistance.However,the passivation char-acteristics of titanium alloys make them susceptible to localized corrosion in certain corrosive environments,es-pecially those containing halide ions.Localized corrosion is often difficult to detect but can have strong penetra-tive effects,leading to perforation or fracture of material components,resulting in leaks or even more severe ac-cidents.However,there is a lack of systematic introduction to protective measures against different types of lo-calized corrosion in existing literature.This article provides a detailed description of the main forms of localized corrosion in titanium alloys and their corresponding corrosion mechanisms,including pitting corrosion,galvanic corrosion,crevice corrosion,stress corrosion cracking,and hydrogen-induced cracking.The influence of titanium alloy composition,concentration and types of ions in the corrosive medium,as well as temperature and pressure in the service environment,on the localized corrosion of titanium alloys,is discussed.In addition,various pro-tective measures against failure caused by localized corrosion in titanium alloys are outlined,including alloying,surface modification techniques,and heat treatment processes.Furthermore,shortcomings in existing protective measures are identified,and future research directions for understanding the mechanisms of localized corrosion in titanium alloys and developing protective methods are discussed.
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