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You may have seen galvanized steel coils: smooth surface, silvery and bright with zinc layer, commonly used in construction, home appliances, automobiles and other industries. But have you ever thought about how this seemingly ordinary material is processed step by step? Today's article will use popular language to take you through the production process of galvanized steel coils.
Everything starts with hot-rolled steel coils, which is what we often call "black coils". This kind of steel coil has oxide scale and impurities on the surface and cannot be directly used for galvanizing. It must be cleaned first.
This step is called pickling. The rust and oxide on the surface are removed by acidic solution, with the aim of making the subsequent galvanizing stronger.
After cleaning, it is also cold rolled, that is, the thick steel coil is further thinned and the surface flatness is improved. At this time, it becomes a "cold-rolled substrate".
After cold rolling, the structure of the steel plate becomes harder and brittle, which is not conducive to subsequent processing. So it needs to be sent to the continuous annealing furnace, heated and softened in a controlled atmosphere, so that it can restore a certain plasticity and toughness.
After annealing, the steel strip is both soft and tough, suitable for the next step of galvanizing.
The next protagonist is "galvanizing". The most common one is hot-dip galvanizing, which means that the treated steel strip is directly sent into a pot of molten zinc liquid.
There are several details in this step:
- Immersed in zinc pot: The steel strip passes through the zinc liquid quickly at a certain angle, and a uniform layer of zinc is coated on the surface.
- Air knife controls thickness: After the steel strip comes out of the zinc pot, it will pass through a high-pressure air knife to blow off the excess zinc liquid and control the final zinc layer thickness.
- Cooling and shaping: Then cool quickly to allow the zinc layer to adhere firmly.
Why use zinc? Because zinc can block water and air, and even when the steel is scratched, zinc can "sacrifice" itself to protect the steel from rusting. This is the principle of sacrificial anode protection.
In order to make the steel coils last longer, anti-fingerprint or meet the requirements of subsequent coating, sometimes a slight surface treatment process is added, such as:
- Passivation treatment: reduce the formation of white rust
- Oil coating or anti-fingerprint coating: avoid surface scratches or oxidation
- Paint pre-coating (special for color-coated steel coils)
The last process is leveling and winding, which uses equipment to level the surface of the steel strip, and at the same time cuts it into a fixed length according to user needs, or rolls it into a steel coil with a specified inner diameter and packs it for shipment.
Galvanized steel coils for different purposes have different requirements for zinc layer thickness and surface quality. If you are a user, pay attention to the specifications when purchasing, such as zinc layer thickness, corrosion resistance, surface treatment method, etc., in order to choose the most suitable material for yourself.
For manufacturers, each process is directly related to product quality, and details determine success or failure, which is especially true in the galvanizing industry.
We are looking forward to your buy Galvanized Steel Coil from our company made in China - Yintu. Our factory is a Galvanized Steel Coil manufacturer and supplier in China. You are welcome to buy our high quality products.Visit our website at www.yintuppgi.com to learn more about our products. For inquiries, you can reach us at sam@yintuppgi.com.
