A study of the galvanic corrosion behavior of inconel 718 after electron beam welding (EBW)

In this paper, the galvanic corrosion behavior of as-received, solution- and precipitation-pretreated Inconel 718 sheets welded by using electron-beam welding (EBW) was studied in 3.5wt% NaCl solution at 30°C. Meanwhile, an easy and reliable specimen-preparation method of a weld for electrochemical testing was proposed. The difference in corrosion potentials among fusion zone, heat-affected zone and base metal in an Inconel 718 weld is the key factor for galvanic corrosion. Owing to having active corrosion potential and very small exposing area compared to those of its adjacent heat-affected zone together with base metal, severe attack of the fusion zone could be observed in as-received and solution-pretreated welds when the welds were anodically polarized in 2.0 V for a few seconds. However, the galvanic corrosion of solution-pretreated weld can be prevented through post precipitation treatment, by which only a little difference in corrosion potentials between fusion zone, heat-affected zone and base metal could be achieved.