Electro-galvanizing, commonly known as cold galvanizing, uses an electrochemical method. Zinc ingots are used as anodes. Zinc atoms lose electrons and become ions and dissolve into the electrolyte. Steel strips serve as cathodes. Zinc ions gain electrons on the steel strips and are reduced to Zinc atoms are deposited onto the surface of the steel strip to form a coating.

There is a big difference in the amount of galvanizing between hot-dip galvanized sheets and electro-galvanized sheets. The galvanizing amount of hot-dip galvanizing cannot be too small. Generally, the minimum is 50~60g/m2 on both sides and the maximum is 600g/m2. The galvanized layer of electro-galvanized sheets can be very thin, with a minimum of 15g/m2. However, if the coating is required to be thicker, the production line speed will be very slow, which is not suitable for the process characteristics of modern units. Generally, the maximum is about 100g/m2. Because of this, the production of electro-galvanized sheets is greatly restricted.

There are fundamental differences in the coating structure between hot-dip galvanized sheets and electro-galvanized sheets. There is a slightly brittle compound layer between the pure zinc coating of the hot-dip galvanized sheet and the steel strip matrix. When the pure zinc coating crystallizes, most of the zinc flowers are formed, and the coating is uniform and has no pores. The zinc atoms in the electroplated zinc layer are only precipitated on the surface of the steel strip, and are physically attached to the surface of the steel strip. There are many holes for drying, and it is very easy to cause pitting corrosion due to corrosive media. Therefore, hot-dip galvanized panels are more durable than electro-galvanized panels. More resistant to corrosion.

The heat treatment processes of hot-dip galvanized and electro-galvanized sheets are also completely different. Hot-dip galvanized sheets generally use cold hard plates as raw materials, and are continuously annealed and hot-dip galvanized on the galvanizing line. The steel strip is heated and then cooled in a short period of time. Therefore, the strength and plasticity are affected to a certain extent, and its stamping performance is worse than the same cold-rolled plate after degreasing and annealing in a professional production line. Electro-galvanized sheets use cold-rolled sheets as raw materials, which basically guarantees the same processing performance of cold-rolled sheets, but its complex process also increases production costs. In short, hot-dip galvanized sheets have lower production costs and wider application range, and have become the main variety in the galvanized sheet market.