Galvanic Series of some commercial Metals and Alloys in Seawater

The Table is based on potential measurements and galvanic corrosion tests performed by The International Nickel Company at Harbour Island, North Carolina, in unpolluted seawater.

The relative placements of metals, rather than their potentials, are provided due to variances between the tests. Similar series should be conducted for metals and alloys in all conditions and at all temperatures, but this would necessitate nearly endless testing.

Stainless steels occupy a more noble position when they are in a passive state as opposed to a less noble position when they are in an active state. Inconel, which can be thought of as a stainless nickel, exhibits behaviour similar to that of nickel. The brackets in Table 3-2 are another intriguing aspect of the galvanic series. The alloys included in these brackets have a base composition that is somewhat similar, such as copper and copper alloys. The bracket shows that when metals in a certain bracket are linked or in contact with one another, there is typically a low risk of galvanic corrosion. This is due to the series’ close proximity of these components and the low potential of the couples they produce. The potential created increases with the series distance.

In simple terms, we observe an increase in nobility or cathodicity of the materials as we ascend the galvanic series table, relative to those that are located lower, which are characterized by higher activity or anodicity. Take, for instance, Nickel and Lead in a scenario where they are in contact under humid conditions. Due to Lead’s elevated activity, it would be susceptible to preferential corrosion by means of the galvanic corrosion mechanism. It’s important to note that the facilitation of galvanic corrosion requires the presence of both a potential difference between the materials and an electrolytic medium.