Effect of residual stress on localized corrosion behavior of metallic materials

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.