Galvanization or galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing(Galvanizing of galvanized steel coils is a hot dip galvanizing method), in which the parts are submerged in a bath of molten zinc.
Galvanizing protects the underlying steel coil in the following main ways:
● The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
● The zinc protects iron by corroding first. For better results, application of chromates over zinc is also seen as an industrial trend.
● In the event the underlying metal becomes exposed, protection can continue as long as there is zinc close enough to be electrically coupled. After all of the zinc in the immediate area is consumed, localized corrosion of the base metal can occur.
What is galvanizing?
Hot dip galvanizing
Hot Dip Galvanizing is a unique process. When clean steel is immersed into molten zinc, a series of zinc-iron alloy layers are formed by a metallurgical reaction between the iron and zinc, providing a robust coating which is an integral part of the steel.
When the reaction between iron and zinc has virtually ceased and the article is taken out of the galvanizing bath complete with its outer coating of free zinc, the process is complete. In reality there is no demarcation between steel and zinc but a gradual transition through the series of alloy layers which provide the metallurgical bond.
History of galvanizing
In 1836, Sorel in France took out the first of numerous patents for a process of coating steel by dipping it in molten zinc after first cleaning it. He provided the process with its name ‘galvanizing.
Hot-dip galvanizing is the process of immersing steel coil in a bath of molten zinc to produce a corrosion resistant, multi-layered coating of zinc-iron alloy and zinc metal. While the steel is immersed in the zinc, a metallurgical reaction occurs between the iron in the steel and the molten zinc. This reaction is a diffusion process, so the coating forms perpendicular to all surfaces creating a uniform thickness throughout the part.
How galvanizing protects steel coil
Galvanizing provides a barrier protection between all internal and external steel surfaces and their environment. Galvanizing is a term often wrongly used to describe zinc coatings in general. The life expectancy of a zinc coating is largely determined by its thickness. Thicker coatings give longer life. Hot dip galvanizing provides fabricated iron or steel products with maximum protection through a continuous, tough, metallurgically bonded coating of much greater thickness.
Why galvanize in steel coil
Galvanizing is durable
Quite simply, galvanizing a metal gives it anti-corrosion properties. Without the protective zinc coating, the metal would remain exposed to the elements and potentially oxidize and corrode much faster.
A key benefit of using Hot Dip Galvanizing is its durability. Data shows that galvanizing can provide between 34 to 170 years of protection for steel. One of the main atmospheric pollutants that affect the performance of hot dip galvanizing is Sulphur Dioxide.
Galvanizing is sustainable
Galvanizing’s long-term durability is achieved at relatively low environmental burden in terms of energy and other globally relevant impacts.
Galvanized steel is all around us and plays a vital role in our everyday lives. It is used in construction, transport, agriculture, power transmission and everywhere that good corrosion protection and long life are essential.A large proportion of galvanized steel is used in construction.
How Does Galvanization Protect the Base Steel Coil?
1. The zinc coating prevents corrosive substances like acid (acid rain for example) from reaching the metal underneath.
2. Galvanization protects from rusting. When the coating is scratched, zinc will still “sacrifice its anode” easier than the base metal does – which protects it from rusting.
3. The zinc protects the metal by corroding faster than the base metal. Sometimes a special ingredient called a “chromate” is added to the galvanized metal, this makes it corrode even faster. It may sound like that is not what you want to happen, but remember the zinc corroding before the metal is what protects the metal underneath from rusting.
3 benefits of choosing galvanized roofing sheet
If you’re looking to buy steel coil for your roofing sheet, consider opting for galvanized steel coil. Galvanized steel touts numerous measurable benefits, including the following:
1. Economical: Choosing galvanized steel initially may seem more expensive, but it’s a great investment in the long run. Moreover, galvanizing is actually cheaper than many other protective steel coatings.
2. Low-maintenance: Steel that lacks a protective coating requires more maintenance to upkeep the appearance and structural safety of the product.
3. Long Lasting: Galvanized steel coatings can have a life expectancy of up to 50 years and can withstand urban and coastal exposure.