Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around 450 °C (842 °F). When exposed to the atmosphere, the pure zinc (Zn) reacts with oxygen (O2) to form zinc oxide (ZnO), which further reacts with carbon dioxide (CO2) to form zinc carbonate (ZnCO3), a usually dull grey, fairly strong material that protects the steel underneath from further corrosion in many circumstances.
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").
Steel strip can be hot-dip galvanized in a continuous line. Hot-dip galvanized steel strip (also sometimes loosely referred to as galvanized iron) is extensively used for applications requiring the strength of steel combined with the resistance to corrosion of zinc, such as roofing and walling, safety barriers, handrails, consumer appliances and automotive body parts. One common use is in metal pails. Galvanised steel is also used in most heating and cooling duct systems in buildings
Galvanized steel is one of the most popular steels because it is rust-resistant and more affordable than most treated steels. And, it doesn't require any maintenance or refinishing. Since the zinc coating protects it from the elements, the steel can last for 50 years in temperate environments. Even with severe weather exposure, galvanized steel can last for over 20 years.
As well as very good coating adhesion and outstanding corrosion resistance, hot-dip galvanized strip offers good forming properties, which are greatly influenced by the thickness of the zinc coating.
Its uses are many and varied: from gutter brackets and profiles with low coating weights and good formability, to roller shutter doors, building hardware, pipe brackets and barrel hoops with normal corrosion resistance and straightforward forming, to lightning conductors and earthing strips with increased corrosion protection and low formability requirements.
