Galvanic series

A ranking of metals and alloys by their measured corrosion potentials in a specified electrolyte. It helps predict which material will corrode when electrically connected to another.

Galvanic corrosion: Accelerated corrosion of one electrically connected material caused by electrochemical coupling to another in an electrolyte. The series predicts which coupled material becomes the anode and corrodes.
Seawater corrosion: Corrosion caused or influenced by seawater’s salts, dissolved gases, organisms, and flow. Seawater-specific galvanic rankings guide material pairing in marine structures.
Electrode potential: The electrical potential difference between an electrode and a reference electrode in an electrochemical system. Corrosion potentials are electrode potentials measured under active corrosion conditions.
Standard electrode potential: The potential of a redox couple measured relative to the standard hydrogen electrode under standard conditions. It is a controlled thermodynamic value, not a corrosion potential measured for an alloy in service electrolyte.
Corrosion potential: The electrode potential of a material undergoing corrosion in a particular environment. Measured corrosion potentials determine a material’s position in the series.
Sacrificial anode: A more reactive metal electrically connected to a structure so it corrodes preferentially and protects that structure. The series helps select an anode that will dissolve instead of the protected metal.
Electrolyte: A substance that conducts electricity through the movement of ions when molten or dissolved. The electrolyte changes measured potentials, so the ranking is environment-specific.
Pourbaix diagram: A potential–pH diagram showing the thermodynamically favored forms of an element in aqueous conditions. It maps stability across potential and pH rather than ranking alloys by measured corrosion potential.
Galvanic cell: An electrochemical cell that converts chemical energy into electrical energy through coupled oxidation and reduction reactions. Galvanic corrosion is an unintended galvanic cell formed by joined materials and an electrolyte.
Marine corrosion: Material degradation caused by marine environments, including seawater, marine atmospheres, and seabed conditions. Galvanic-series data are especially useful when selecting metals for marine exposure.

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Reactivity seriesCompared with: Unlike a general reactivity series, it ranks practical corrosion behavior in a specified medium.