Editorial Feature

Galvanized Steel - Galvanic Corrosion of Galvanized Steel

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Although hot-dip galvanized coatings offer envelope protection for steel, zinc contained in the coating will also safeguard the steel cathodically in case the coating is destroyed and the bare steel exposed.

Preventing Corrosion in Galvanized Steel

The galvanized coating’s rate of consumption will be dependent on the cathode’s size (the bare steel) and the anode’s size (the galvanized coating). It is vital to reduce the exposure of galvanized coatings to cathodic metals and materials to avoid faster corrosion of the galvanized coating.

The table below lists metals in order of their relative reactivity with each other. When considering materials and coatings for highest durability, care must be taken to ensure there is no contact between dissimilar metals where there is a possibility of electrolyte forming moisture to occur.

ANODIC
more reactive

Magnesium
Zinc
Cadmium
Steel
Lead
Tin
Brass
Bronze
Copper
Nickel-Copper Alloys
Stainless Steel
Silver
Gold
Platinum
CATHODIC
less reactive

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