Subject
Galvanic corrosion occurs between any two metals that are electrically dissimilar, and the rate of corrosion is proportional to their electrical dissimilarity. The electrical property responsible is electronegativity and refers to their nobility.
If the nobility of two base metals are similar, e.g. they are both carbon steels or aluminium alloys, one should also consider the relative nobility of the alloying elements as their anodic/cathodic potential may lead to galvanic 'pitting' corrosion.
Whilst this phenomenon is a serious potential problem when connecting any two metals that may come into contact via an electrolyte, it can also be used to protect one metal from wetted corrosion; e.g. the cathodic protection of ships, pipelines and structures immersed in seawater.
You select any two metals and the galvanic corrosion calculator will provide their relative nobility and therefore, consequent likelihood of galvanic corrosion if immersed in an electrolyte.
The subject metals in this calculator are listed in anodic/cathodic order and the results are in order of corrosion strength ranging from 'None' to 'Aggressive'.
A list of atomic elements and their electronegativities is also provided, in order that you can check the corrosion potential of alloying elements. Pick an element and the yellow line will position itself relative to Caesium (lowest electronegativity and least noble) and Fluorine (highest electronegativity and most noble).
For help using this calculator see Technical Help
Galvanic Corrosion Calculator - Options
Nobility
Nobility can be used in one of two modes:
Either
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The galvanic corrosion strength rating
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Or
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You enter: |
and the galvanic corrosion calculator will provide: |
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The electronegativity of the element relative to Fluorine and Caesium
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