残余应力对金属材料局部腐蚀行为的影响

Effect of residual stress on localized corrosion behavior of metallic materials

  • 摘要: 基于残余应力测试新方法与先进电化学测试技术的进展, 围绕残余应力类型和大小对金属材料点蚀以及应力腐蚀行为的作用机理进行了总结和归纳. 研究发现, 尽管残余压应力对腐蚀行为的抑制作用得到了大量实验的证实, 但是在不同条件下其作用方式以及机理不尽相同, 并且与材料的结构特点以及腐蚀产物等密切相关. 同时, 残余拉应力的作用尚不明确, 受到材料类型和其他因素耦合的严重影响. 另外, 在某些环境下, 影响腐蚀行为的关键是残余应力梯度或残余应力的某个临界值. 但是对有色金属的研究表明残余拉应力和压应力均会导致基体中位错和微应变等结构缺陷增加, 进而促进点蚀敏感性, 降低材料服役性能. 最后, 对目前研究存在的局限进行了讨论和展望.

     

    Abstract: It has been generally recognized that the synergistic action of aggressive media and residual stress that arises during metals fabrication, processing, and service can affect the behavior of corrosion electrochemistry. However, due to the limitation of testing techniques, studies on the influence of residual stress and its synergistic effects with other factors on corrosion initiation and propagation are relatively rare and confined to macro levels. With the developments of residual stress measurements and local electrochemical methods, especially the application of localized electrochemical probe techniques, the effect of residual stress on corrosion electrochemical behavior in the micro-domain has been studied by many researchers in recent years. Based on new testing methods of residual stress and advanced electrochemical measurements, this paper mainly summarized the contents and progress of recent research on metallic materials pitting and stress corrosion behavior under different types and levels of residual stresses. For iron and steel materials, the inhibition of compressive residual stress on corrosion has been supported by many experiments, but it shows different roles and mechanisms in different conditions, closely correlating with material structure and corrosion product. In addition, research has demonstrated that tensile residual stress has different impacts on corrosion resistance in alkaline and acidic conditions and that the influence of tensile residual stress on corrosion, strongly influenced by material types and other coupling factors, is still uncertain. Moreover, some experimental results have also shown that residual stress gradient or its critical value is a significant contributor to corrosion behavior, and only when they are greater than a certain value can pitting or micro-cracks be significantly initiated. However, studies on nonferrous metals suggest that both tensile and compressive residual stresses reduce corrosion resistance because they can increase dislocation density and microstrain, and these structural defects increase the occurrence of active sites for pitting corrosion, thereby degrading performance. Finally, the limitations and prospect of current research were also presented in this paper.

     

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