Production Process of Large Spangle Galvanized Steel Coil
Uncoiling & Precise Butt Joint
Taking high-quality cold-rolled steel coil as raw material, the steel coil is unfolded by uncoiler, and the steel strip is continuously and stably conveyed through welding and tension adjustment, laying a foundation for subsequent assembly line
processing.
Surface Pre-treatment (Degreasing + Water Washing + Drying)
The steel strip passes through the alkaline degreasing tank in turn to completely remove oil and impurities on the surface, then is washed by multi-stage clean water and dried at high temperature, ensuring the surface of the steel strip is clean
and dry, and improving the adhesion of zinc coating.
Annealing & Reduction Treatment
The clean steel strip is sent into a high-temperature annealing furnace, and protective hydrogen is injected into the furnace to create a reducing atmosphere, eliminate internal stress of the steel strip, activate the steel surface, and avoid missing
coating and peeling during galvanizing.
Hot-dip Galvanizing (Core Process of Large Spangle)
The annealed steel strip is accurately immersed in molten zinc liquid, forming a dense zinc coating through iron-zinc molecular reaction. By precisely controlling the composition, temperature and cooling rate of zinc liquid, the crystallization
speed of zinc liquid is delayed, promoting full growth of zinc grains, forming uniform and full large spangle texture.
Air Knife Zinc Coating Control
After the steel strip exits the zinc pot, a high-precision air knife device is used to accurately control the thickness of the zinc coating with high-pressure air flow, ensuring the zinc coating is uniform and flat, removing excess zinc liquid, and
maintaining the integrity of large spangle texture.
Large Spangle Crystallization & Cooling
Adopting gradient slow cooling process, the zinc coating is naturally crystallized and formed, precisely controlling the size and uniformity of zinc spangles, forming a beautiful and regular large spangle appearance, and enhancing the density
and corrosion resistance of the zinc coating.
Surface Finishing & Passivation Treatment
The cooled steel strip is leveled by a finishing machine to optimize surface flatness, and then passivated to form a protective film, further improving the product's rust resistance and prolonging its service life.
Coiling & Quality Inspection & Packaging
Finally, the finished steel strip is coiled by a coiler. After comprehensive quality inspection including thickness, zinc coating, zinc spangle and corrosion resistance, qualified products are packaged with moisture and dust prevention, then stored
in warehouse for delivery.
