How are steel coils galvanized?

The main purpose of galvanizing steel coils is to protect the steel substrate through the zinc layer to prevent corrosion.

The process flow of galvanizing steel coils mainly includes the following steps:

1. Pretreatment: First, the steel coil needs to be pickled to remove surface oxides and impurities to ensure that the metal surface is clean and pollution-free.

2. Degreasing and cleaning: Through multi-stage cleaning processes (such as alkali spraying, alkali brushing, electrolytic cleaning, etc.), the rolling oil and iron powder on the surface of the strip are thoroughly removed to ensure the adhesion and surface quality of the coating.

3. Annealing: The cleaned strip is sent to the continuous annealing furnace for recrystallization annealing to obtain good mechanical properties and coating properties. The annealing furnace usually includes several stages such as preheating, heating, soaking and cooling.

4. Hot-dip galvanizing: The annealed strip enters the galvanizing tank and is immersed in the molten zinc liquid to form a uniform galvanized layer on the surface through physical and chemical reactions. This process requires strict control of the zinc liquid temperature and immersion time to ensure the quality and thickness uniformity of the coating.

‌5. Post-treatment‌: The galvanized strip needs to be treated with air knife blowing, flattening machine and tension straightening machine to improve its performance and flatness. It is then passivated or fingerprint-resistant, oiled and sheared, and finally coiled and stored.