Corrosion has been a subject of keen scientific research for the past 150 years. It has a great impact on the safety and reliability in wide range of applications and also on the economy. Corrosion plays a crucial role in determining the lifecycle performance, safety, and cost of engineered products. Further, with the increasing demand for materials with multiple performance capability, advanced surface processing, surface coatings, joining, and welding techniques are being employed. As these

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... terials and methods will be utilized in technologies for high-end applications (e.g., aerospace and nuclear engineering), investigation of corrosion of advanced surfaced materials becomes essential. Metal joining is a controlled process that is widely employed to fuse similar/dissimilar metals. Among the several metal joining techniques, welding is one of the most widely used for a variety of applications. Metallurgical, physical, and chemical changes caused by welding processes severely affect the corrosion resistance of welds [1, 2] . Some of the recent and advanced welding processes include use of electron beam and laser beam for welding, and they have the advantage of narrow heat affected zone [3] . Even with the use of such advanced welding techniques, materials are still prone to corrosion, invariably due to (i) variation in composition, (ii) accumulation of residual stress, and (iii) modification in microstructure in the weld zone [1] . Similarly, solder joints undergo corrosion depending upon the local environmental conditions. Solder joints are severely prone to galvanic corrosion as they are comprised of dissimilar metals or alloy components that are in contact with each other. In particular, the phenomenon of electromigration is prevalent in solder joints, wherein corrosion causes buildup of by-product material between the two metal structures of different electrical potentials, resulting in a short-circuit [4] . Another major corrosion phenomenon which is accelerated by the presence of stress is stress corrosion cracking (SCC). In SCC, the imposition of mechanical loads (in particular tensile stress) on the structure causes increased sensitivity to corrosion. The required tensile stress for SCC crack growth may be in the form of directly applied stress (i.e., external stress) or in the form of residual stress (internal) [5] . SCC causes catastrophic failure in weldments. Recently, nanocrystalline (NC) materials (i.e., average grain sizes < 100 nm) are under intense research for their surface properties. In particular, nanocrystalline Ni-coatings are preferred as corrosion resistant coatings for metallic substrates [6] . The small grain size and the high volume fraction of grain boundaries would result in corrosion behavior different from that of polycrystalline materials. However, the effect of nanocrystallinity on the corrosion behavior is reported to vary among metal systems and corrosion environments. This makes it difficult to predict the electrochemical behavior of nanocrystalline coatings from that of their coarse-grained counterparts [7] .