Galvanized steel

Galvanized steel is a common practice to protect steel parts that are going to be exposed to adverse environmental conditions for a long time. Hot-dip galvanizing is an industrial process intended to protect a wide variety of iron or steel products against corrosion.This process is achieved through the immersion of the materials in a bath of molten zinc at 450°C. Hot-dip galvanizing allows a zinc coating, which is not only deposited on the surface, but also forms a zinc – iron alloy that is highly resistant to the different corrosion agents in the atmosphere , water or soil .


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  • 1 Conditions relating to the surface condition of the steel
  • 2 Importance
  • 3 Good reasons to galvanize
  • 4 Operation
  • 5 sources

Conditions relating to the surface state of the steel

For the proper result of the galvanizing process, both the chemical composition of the steel with which the pieces are made, and the state of their surface are of great importance. A metallurgically clean steel surface is the indispensable starting point for correct galvanizing.
The surface preparation treatment that is carried out as part of the galvanizing process, pickling in diluted hydrochloric acid, completely eliminates the corrosion products, but not some of the contaminating substances ( fats and oils , soaps , dust, other layers of paint and residues of products used in operationsmechanical or welding ).


The choice of steels to be used is of special importance.
Suitable base materials for hot-dip galvanizing are carbon steels, high-strength low-alloy steels, cast steels, and gray, malleable, and nodular cast irons.
Steels with high carbon, silicon or phosphorous contents can give rise to coatings with a rough surface and a dark gray appearance, which are usually thicker than normal and are made up entirely of layers of zinc-iron alloy.

Good reasons to galvanize

Longer useful life of products
A hot-dip galvanized product has a useful life that varies from 30 to 40 years, depending on the degree of exposure.
No maintenance cost
Once galvanized, it is not necessary to paint or carry out any type of maintenance.
Low initial cost
The cost of galvanizing is low compared to other protection methods.
The immersion process allows galvanizing a wide range of sizes and shapes of materials.
Greater layer thickness and resistance
The alloy that is achieved gives great resistance to knocks and scratches derived from movements or installations
Coating guarantee
Dip galvanizing ensures a coating of the entire piece inside and out.
Triple Protection

  1. Physical barrier: The coating has greater hardness and resistance than any other type of coating.
  2. Electrochemical protection: Over time, a thin layer of zinc oxide forms that acts as an insulator for the galvanized.
  3. Self-curing: In the event of superficial scratches, a plugging is produced by chemical reaction of the damaged surface.

Systems used to prevent corrosion of iron and steel are essential to the economic use of these metals as building materials.


  • Iron and steel rust rapidly when exposed to the action of the atmosphere and the product of oxidation, which is essentially a hydrated iron oxide, and which does not protect the base metal, for which reason it continues to be attacked and reaches be totally destroyed.
  • One way to prevent rust or corrosion is to cover the surface with a waterproof barrier to prevent moisture or air from reaching the metal. Coats of paint do this to some extent, but they are not forever impervious to moisture and, in any case, will deteriorate over time and then allow moisture to pass through. Once this happens, the metal begins to oxidize and deteriorates rapidly.
  • The coating consists of a progression of zinc-iron alloy layers metallurgically bonded to the base steel. As a barrier protection, galvanizing provides a tough, metallurgically bonded zinc coating that completely covers the surface of the steel with a layer of zinc-iron alloy which is harder than the base steel. This provides a flexible outer layer with stronger adhesion and exceptional abrasion resistance.
    An additional feature of Hot Dip Galvanizing is that the zinc-iron layer grows perpendicular to the surface of the steel.
  •  The effect this has on the corners and edges of materials is that the coating there is generally thicker than the surrounding coating. This is in stark contrast to other types of protective coatings which tend to thin at the corners and edges of the materials.
  • The Galvanized coating is for this reason more resistant to physical deterioration than a layer of paint. Apart from the fact that the entire surface of the pieces is covered both inside and outside. The same happens with the narrow cracks, the corners and the hidden parts of the pieces, which are not well protected by other types of coatings.
  • It is even interesting to note that if there are small areas on the coating that are exposed (such as scratches) due to mishandling, these are still protected against oxidation. This is due to the difference in electrochemical potential between zinc and iron, so that the former is consumed in preference to the latter and thus provides “sacrificial or cathodic protection”. This type of protection is one of the main virtues of coatings obtained hot, being one of the great advantages it offers over the protection provided by paint-based treatments or plastic coatings.


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