Galvanization

Not to be confused with Galvanism or Electrogalvanization.

Galvanization (also spelled galvanisation)[1] is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are coated by submerging them in a bath of hot, molten zinc.[2]

Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel, and is considered superior in terms of cost and life-cycle. It can be identified by the crystallization patterning on the surface (often called a "spangle").[3]

Galvanized steel can be welded; however, welding gives off toxic zinc fumes. Galvanized fumes are released when the galvanized metal reaches a certain temperature. This temperature varies by the galvanization process used. In long-term, continuous exposure, the recommended maximum temperature for hot-dip galvanized steel is 200 °C (392 °F), according to the American Galvanizers Association. The use of galvanized steel at temperatures above this will result in peeling of the zinc at the inter-metallic layer.[4]

Like other corrosion protection systems, galvanizing protects steel by acting as a barrier between steel and the atmosphere. However, zinc is a more electropositive (active) metal in comparison to steel. This is a unique characteristic for galvanizing, which means that when a galvanized coating is damaged and steel is exposed to the atmosphere, zinc can continue to protect steel through galvanic corrosion (often within an annulus of 5 mm, above which electron transfer rate decreases).

  1. ^ "Galvanize". Cambridge English Dictionary. Retrieved 10 November 2019.
  2. ^ "What is the HDG Process?". American Galvanizers Association. Retrieved 2025-03-12.
  3. ^ GalvInfo (August 2011). "GalvInfoNote / The Spangle on Hot-Dip Galvanized Steel Sheet" (PDF). GalvInfo. Archived from the original (PDF) on 2 March 2014. Retrieved 27 February 2014.
  4. ^ "Performance and Inspection of HDG Exposed to Extreme Temperatures". American Galvanizers Association. 2020-03-02. Retrieved 2025-06-08.
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