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The difference between electrolytic galvanized steel and cold rolled steel commonly used in all steel test benches

Aug 10, 2020


1. Galvanized steel sheet: Galvanized steel sheet refers to a steel sheet coated with a layer of zinc on the surface. Galvanizing is an economical and effective anti-rust method that is often used to prevent corrosion on the surface of the steel plate and extend its service life.


Classification:


① Hot dip galvanized steel sheet. The thin steel plate is immersed in the molten zinc bath, so that a thin steel plate with a layer of zinc is adhered to the surface. At present, the continuous galvanizing process is mainly used for production, that is, the rolled steel sheet is continuously immersed in a galvanized bath with molten zinc to make galvanized steel sheet.


Hot-dip galvanized steel has an advantage over electro-galvanized steel. Electro-galvanized steel is very easy to rust in bending and section. Hot-dip galvanized steel has much better rust resistance under the same conditions. High-quality cabinets usually use electrolytic or hot-dip galvanized steel plates. The cabinet steel plates using this material are bright in color and have metallic luster. The advantage of this steel plate is its good corrosion resistance.


Hot-dip galvanized steel is more corrosion resistant than cold-rolled steel. The characteristics of hot-dip galvanized steel sheet are strong corrosion resistance, good surface quality, good for deep processing, economical and practical. The drawing performance of hot-dip galvanized steel is not as reliable as cold-rolled steel. Hot-dip galvanized steel is not as easy to weld as cold-rolled steel, and the zinc layer is destroyed during welding.


②Alloyed galvanized steel sheet. This kind of steel plate is also manufactured by hot dipping method, but immediately after being discharged from the tank, it is heated to about 500°C to form an alloy film of zinc and iron. This galvanized sheet has good coating adhesion and weldability.


③Electro-galvanized steel sheet. The galvanized steel sheet produced by the electroplating method has good workability. However, the coating is thinner, and the corrosion resistance is not as good as the hot-dip galvanized sheet (a commonly used test bench cabinet). Mainly used in home appliances, computer case shells and some door panels and panels.


④Single-sided and double-sided differential galvanized steel sheet. Single-sided galvanized steel sheet is a product that is galvanized on only one side. In welding, painting, anti-rust treatment, processing, etc., it has better adaptability than double-sided galvanized sheet. In order to overcome the shortcomings of uncoated zinc on one side, there is another galvanized sheet coated with a thin layer of zinc on the other side, that is, double-sided differential galvanized sheet.


⑤Alloy and composite galvanized steel sheet. It is made of zinc and other metals such as aluminum, lead, zinc, etc. to make alloys and even composite steel plates. This kind of steel plate not only has excellent anti-rust performance, but also has good coating performance.


In addition to the above five types, there are color galvanized steel sheets, printed coated galvanized steel sheets, polyvinyl chloride laminated galvanized steel sheets, etc. But the most commonly used is still hot-dip galvanized sheet.


Cold rolled steel:


Cold rolled steel is steel produced by cold rolling. Cold rolling is a steel sheet that is further thinned to a target thickness under room temperature conditions. Compared with hot-rolled steel plates, cold-rolled steel plates are more accurate in thickness, and have a smooth and beautiful surface. At the same time, they have various superior mechanical properties, especially in terms of processing properties. Because cold-rolled raw coils are relatively brittle and hard, and not suitable for processing, cold-rolled steel sheets usually need to be annealed, pickled, phosphated and surface smoothed.


The difference between cold-rolled steel and hot-rolled steel is not in the smelting process, but in the rolling temperature, or the end temperature of the rolling. The final rolling temperature is lower than the recrystallization temperature of the steel to become cold rolled steel. Hot-rolled steel is easy to roll, and the rolling efficiency is high, but under hot-rolling conditions, the steel is oxidized and the surface of the product is dark and gray. Cold-rolled steel requires high rolling mill power and low rolling efficiency. In order to eliminate work hardening during the rolling process, intermediate annealing is required, so the cost is also high. However, cold-rolled steel has a bright surface and good quality and can be directly used for processing. Finished products, so cold rolled steel sheets are widely used.


Cold-rolled plates are products obtained by cold-pressing hot-rolled sheets. After multiple passes of cold rolling, its surface quality is better than that of hot-rolled sheet, and after heat treatment, good mechanical properties can be obtained.


Summary: In terms of anti-corrosion performance under the same conditions, galvanized steel sheet has better performance than cold-rolled steel sheet. The coating of galvanized steel sheet is mainly to prevent oxidation corrosion. The corrosion resistance of cold-rolled steel sheets is slightly poor, and the steel sheets will oxidize and rust when exposed to air.


The thickness accuracy and strength of cold-rolled sheets are relatively high. In addition, the corrosion resistance of zinc alloys and stainless steels is extremely strong, and their prices far exceed galvanized sheets.


The base material of galvanized steel sheet is cold rolled sheet or hot rolled sheet, and the drawing performance of galvanized steel sheet is not as reliable as cold rolled sheet. Galvanized steel is not as easy to weld as cold rolled steel, and the zinc layer is destroyed during welding.