- Different Zinc Coating Weights
There is a big difference in zinc coating weight between hot-dip galvanized sheet and electro-galvanized sheet. The zinc coating of hot-dip galvanizing cannot be very small. Generally, the minimum is 50-60g/m2 on both sides, and the maximum can reach 600g/m2. The galvanized layer of electro-galvanized sheet can be very thin, the minimum is 15g/m2.
- Different Structural
There is a slightly brittle compound layer between the pure zinc coating of the hot-dip galvanized sheet and the steel strip substrate. When the pure zinc coating is crystallized, most of the spangle are formed, and the coating is uniform and free of pores. The zinc atoms of the electro-galvanized layer are only deposited and precipitated on the surface of the steel strip, and are attached to the surface of the steel strip by physical action. There are many pores, so pitting corrosion is easily caused by corrosive media. Therefore, hot-dip galvanized sheet is more corrosion-resistant than electro-galvanized sheet.
- Different Processing Techniques
Hot-dip galvanized sheet is generally made of chilled sheet as raw material, which is continuously annealed and hot-dip galvanized on the production line. The steel strip is heated and then cooled in a short time, so its strength and workability are affected to some extent. Electrogalvanized sheet uses cold-rolled sheet as raw material, which basically guarantees the same processing performance of cold-rolled sheet, but its complicated process also increases production costs. In short, the production cost of hot-dip galvanized sheet is lower, and the application range is wider, and it has also become the main variety in the galvanized sheet market.