Localized Depth of Galvanic Corrosion at Dissimilar Metal Welding A508/Inconel 182/316L

Abstract

Recently, efforts have been made to develop the use of dissimilar metal welding in industrial components. Pressurized water reactors (PWR) in nuclear power plants frequently use dissimilar metal welding (DMW) in their primary water systems (NPP). The selection of the combination of stainless steel and low alloy steel is adjusted to the working conditions of work in high-temperature environments. Nickel-based Inconel 82/182 alloy is used as a weld filler in the GTAW method of joining to produce A508/Inconel-182/316L dissimilar welds with variations in the immersion time of the material at high temperatures. The depth of galvanic corrosion related to morphology using an optical microscope and SEM, changes in potential and current density using a potentiodynamic polarization test, and depth of galvanic corrosion using surface profiler (α -step) were thoroughly investigated. The results showed that low alloy steel A508 generally suffered from corrosion attacks. Still, the most severe corrosion attack was in the weld joint interface area of low alloy steel A508/Inconel 182 due to the influence of galvanic corrosion. These symptoms will not be seen if observed on the outside of the surface only, but severe symptoms occur on the inside of the weld joint A508/Inconel 182. Finally, there has been a change in the shape of the gap and concave (depth of galvanic corrosion effect) of the welded joint interface between Inconel 182 and low alloy steel A508 because the effects of galvanic corrosion with changes in potential, current density, and immersion time of dissimilar welded materials.