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Galvanized Steel

Last updated: September 12, 2019

What Does Galvanized Steel Mean?

Galvanized steel is a type of steel that has been galvanized by the application of a zinc coating throughout its body so that it can be protected from corroding or rusting. Galvanized steel has a longer life and durability compared to non-galvanized steel. The application process of zinc on a steel structure is called "galvanization." This process was first invented and developed in France and England in 1837, in which a sheet of steel was dipped in a molten zinc bath (a method called "hot dip galvanization").


Corrosionpedia Explains Galvanized Steel

When steel is brought into contact with molten zinc, a chemical reaction takes place, which bonds zinc on the surface of steel. Thus, a zinc layer over steel acts as a layer that protects it from being corroded. The most common method of applying a zinc coating over steel is hot dip galvanization; however, there are various other processes that are also used for galvanizing steel, such as:

  • Hot dip galvanization – In this method, a steel sheet is dipped in a bath of molten zinc kept at a temperature of 860°F (460°C). When the steel comes into contact with this molten zinc, an iron zinc alloy is formed and when the steel sheet is taken out in a normal atmosphere, zinc oxide is formed, which prevents corrosion.
  • Zinc electroplating – In this method, a steel sheet is dipped into the zinc ion solution and an electric current is passed through it, which uniformly spreads zinc ion solution on the metal sheet.
  • Mechanical plating – In this method, zinc powder, along with glass beads and a special reducing agent, are coated on the steel sheet, which bonds zinc particles on the surface of the sheet.
  • Sherardizing – In this method, a steel sheet is heated up to a temperature of 752°F (400°C) and passed through zinc powder. At this high temperature, diffusion between zinc and steel molecules occurs.
  • Continuous strip galvanizing and galvanized wire – In this method, a steel strip or steel wire is passed through a solution of molten zinc at a high speed of 590 feet (180 meters) per minute in a controlled air pumping. This applies a zinc coat on the metal sheet.
  • Zinc metal spray – In this method, a steel sheet is cleaned to Class III level and then zinc powder is sprayed on top of it with the help of plasma flame gun.

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