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Types and Production Process of Galvanized Steel Sheets

1. Main Types of Galvanized Steel Sheets

2. Core Production Process of Galvanized Steel Sheets

1. Substrate Pre-treatment
   • Uncoiling & Leveling: Uncoil and level cold-rolled/hot-rolled steel coils to ensure flatness;
   • Degreasing & Cleaning: Remove oil and scale via alkaline washing and pickling, then rinse with clean water.
2. Annealing & Reduction
   
   
   The cleaned substrate is heated in a continuous annealing furnace at 800-900℃ in a reducing atmosphere (N₂+H₂) to eliminate cold-rolling stress and reduce residual iron oxide on the surface to pure iron (enhances zinc layer adhesion).
3. Galvanizing Treatment
   • Hot-Dip Galvanizing: The annealed substrate is immersed in 450℃ molten zinc, forming a double-layer structure (zinc-iron alloy layer + pure zinc layer);
   • Zinc Layer Control: High-pressure air from an air knife adjusts the zinc layer thickness; then cool with air to solidify the zinc layer.
4. Post-Treatment & Finished Product
   • Passivation/Fingerprint-Resistant Treatment (Optional): Form a passivation film on the zinc layer to improve corrosion resistance and processability;
   • Slitting & Coiling: Slit to customer specifications, coil into rolls, and package for storage after quality inspection.