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Comparison between hot dip galvanized sheet and electro galvanized sheet
1. The thickness of zinc coating of hot dip galvanized sheet and electro galvanized sheet is different
The galvanizing amount of hot galvanizing cannot be too small, generally the minimum is 50~60g/m2 for both sides, and the maximum is 600g/m2. The zinc coating of the galvanized sheet can be very thin, the minimum is 15g/m2, and the maximum is about 100g/m2. In addition, galvanization can be carried out on one side or both sides. Hot galvanizing must be carried out on both sides.
2. There are fundamental differences between hot-dip galvanized sheet and electrogalvanized sheet in coating structure
There is a slightly brittle compound layer between the pure zinc coating of hot-dip galvanized sheet and the steel strip substrate. When the pure zinc coating crystallizes, zinc flakes are mostly formed, and the coating is uniform without pores. The zinc atoms of the galvanized layer are only deposited on the surface of the steel strip, and they are attached to the surface of the steel strip by physical action. There are many holes to air, which is easy to cause pitting corrosion due to corrosive media. Therefore, the hot-dip galvanized sheet is more resistant to corrosion than the galvanized sheet.
3. The heat treatment processes of hot-dip galvanized and electro galvanized sheets are different
Hot dip galvanized sheet is generally made of cold hard plate, which is continuously annealed and hot-dip galvanized on the galvanizing line. The steel strip is heated in a short time and then cooled again, so the strength and plasticity are affected to some extent. Electrogalvanized sheet takes cold rolled sheet as raw material, which basically ensures the same processing performance of cold rolled sheet, but its complex process also increases the production cost.
4. Hot dip galvanized sheet is characterized by thick zinc layer, good corrosion resistance and low production cost compared with electrogalvanized sheet
In the process of hot galvanizing, when the steel plate passes through the zinc pot, the zinc liquid is attached to the surface of the steel plate, and the air knife blows off the excess zinc liquid, so it is easy to produce thick coated steel plate. In recent years, in order to reduce production costs and meet the requirements of environmental protection, domestic automobile and household appliance enterprises have gradually used hot-dip galvanized steel instead of galvanized steel.
The surface quality of galvanized sheet is better, the coating is evenly distributed, and its weldability, painting ability and stamping formability are better than those of hot-dip galvanized sheet; Single side, double side or differential thickness coatings can be easily switched during production. However, in the process of galvanization, the zinc ions in the electroplating solution are sent to the steel plate by the current. The thicker the coating is, the more electric energy is consumed and the cost is higher.
The production cost of hot-dip galvanized sheet is lower, and its application scope is wider. It is the main variety of galvanized sheet market.