1. Pre-Treatment Process

During the pre-treatment stage, residual rolling oils, surface contaminants, and impurities on cold-rolled steel sheets are thoroughly removed. The sheets are passed through an alkaline cleaning solution under an electrically charged condition, generating an electrochemical reaction that ensures a clean and highly active surface for subsequent coating processes.

2. Annealing

The annealing process modifies and enhances the mechanical properties of pre-treated steel sheets through controlled recrystallization. This process improves material strength, ductility, and formability, providing the optimal metallurgical structure required for high-quality galvanized steel production.

3. Hot-Dip Galvanizing

After annealing, steel sheets pass through a molten zinc bath where a uniform zinc coating is applied to the surface. The coating thickness and weight are precisely controlled by removing excess zinc with a high-pressure air knife before solidification, ensuring consistent coating performance and excellent corrosion resistance.

4. Galvannealing

Following hot-dip galvanizing, the coated steel sheet undergoes a controlled reheating process to promote the diffusion of zinc atoms into the iron substrate. This forms a zinc-iron (Zn-Fe) alloy coating with enhanced weldability, paintability, and corrosion resistance, making it particularly suitable for demanding applications such as automotive manufacturing.

5. Skin Pass Mill (SPM) & Chemical Treatment

To achieve superior flatness, surface quality, and an attractive finish, galvanized steel sheets undergo skin pass rolling. A chrome-free chemical treatment is then applied to the surface to prevent white rust formation on activated zinc coatings while further improving corrosion resistance and long-term durability.

6. Inspection & Coiling

After surface treatment, galvanized steel sheets undergo comprehensive quality inspection to ensure compliance with strict requirements for surface appearance, coating uniformity, mechanical properties, and dimensional accuracy. Qualified products are then carefully coiled and prepared for shipment to customers.

1. Input and Strip Joining Process

The entry section of the electro galvanizing line is equipped with advanced production units, including a pay-off reel, shear machine, welding machine, looper, and tension leveler. Steel coils, including cold-rolled materials, are continuously fed into the line, accurately cut, and joined through automatic welding to ensure stable and uninterrupted production.

2. Pre-Treatment Process

Before electro galvanizing, steel sheets undergo a comprehensive electrolytic cleaning process consisting of electrolytic cleaning tanks, acid pickling sections, and rinsing systems. This process effectively removes surface contaminants, residual oils, and oxide films, creating a clean and activated surface to ensure excellent coating adhesion and uniform plating quality.

3. Electro Galvanizing Process

SHOUYUAN applies advanced electro galvanizing technologies, including the CAROSEL plating method, in which zinc coating is deposited onto the steel surface through controlled electrochemical reactions using conductor rolls. This process enables the production of single-sided, double-sided, and differential-coated steel sheets with precise coating control.

In addition, horizontal electro galvanizing technology allows simultaneous plating on both sides of the steel sheet, ensuring uniform coating distribution and meeting diverse customer requirements.

4. Phosphate Thin-Film Coating

A phosphate conversion coating is applied to the zinc surface through chemical or electrochemical treatment. This thin protective film provides temporary corrosion protection while improving paint adhesion and creating an ideal surface for subsequent coating and painting processes.

5. Anti-Fingerprint Treatment

To further enhance surface performance, an organic, inorganic, or organic-inorganic hybrid coating is applied to the galvanized steel surface. This treatment improves corrosion resistance, fingerprint resistance, surface appearance, and processing performance, making the products suitable for applications requiring high-quality surface finishes.

6. Output and Packaging Process

At the exit section of the production line, finished galvanized coils pass through an output looper, tension reel, and automated packaging system. These processes ensure stable coil formation, product protection, and safe handling before delivery to customers.