1. Hot-dip galvanizing: also called hot-dip galvanizing and hot-dip galvanizing is an effective way to prevent metal corrosion. It melts the zinc ingot at high temperature, puts in some auxiliary materials, and then immerses the metal structure in the galvanizing tank to make a layer of zinc adhere to the metal component, thereby achieving the purpose of corrosion protection. The advantage of hot-dip galvanizing is that it has strong anti-corrosion ability, and the adhesion and hardness of the galvanized layer are good, thus achieving the purpose of corrosion protection.

Cold galvanizing: It is electrogalvanizing, with a small amount of zinc, only 10-50g/m2, which is a process of using electrolysis to make a metal film adhere to the surface of metal or other material parts. The process of forming a uniform, dense, and well-bonded metal layer can prevent corrosion, improve wear resistance, conductivity, reflectivity, and enhance beauty.

2. Different reaction methods
Hot-dip galvanizing is a chemical treatment that belongs to an electrochemical reaction. Hot-dip galvanizing pipes react molten metal with the iron matrix to produce an alloy layer, thereby combining the matrix and the coating.

Cold galvanizing is a physical treatment, which is just brushing a layer of zinc on the surface, so the zinc layer is easy to fall off. Hot-dip galvanizing is mostly used in construction.

3. Different processes
Hot-dip galvanizing involves degreasing, pickling, soaking, dry the workpiece, immersing it in the dissolved zinc liquid for a certain period, and then taking it out.

Cold galvanizing is to use electrolytic equipment to put the workpiece into a solution composed of zinc salt after degreasing and pickling, and connect it to the negative electrode of the electrolytic equipment; place a zinc plate opposite the workpiece and connect it to the positive electrode of the electrolytic equipment, turn on the power supply, and use the directional movement of the current from the positive electrode to the negative electrode to deposit a layer of zinc on the workpiece.

Hot-dip galvanized square tubes emit fewer pollutants, mainly waste acid from pickling workpieces.

The pollutants of cold galvanizing mainly include waste acid from pickling workpieces, electroplating waste liquid, waste passivation liquid, etc. The types and quantities of emissions are much greater than hot-dip galvanizing.

1. galvalume steel sheet is designed to extend the service life of the steel sheet by covering its surface with a layer of zinc and aluminum to prevent corrosion. This thin steel sheet that has been galvalume is called galvalume steel sheet.
The key to the production of galvalume steel sheet lies in the zinc-aluminum coating on its surface. This process effectively prevents the oxidation of the steel surface. Galvalumed steel sheet usually has the characteristics of small zinc flowers, and its surface presents a white tone.

2. Stainless steel is known for its excellent corrosion resistance and can resist erosion by air, steam, water and various chemically corrosive media. The production of stainless steel depends on other metal elements added to the steel. Through the changes in the internal structure of these elements, the product has excellent rust resistance. For example, chromium stainless steel, chromium-nickel stainless steel, and chromium-manganese-nitrogen stainless steel are all common types of stainless steel. The surface of stainless steel is relatively smooth, without any decorations, showing its unique metallic texture.

The service life of thick-walled steel pipes is related to the surface decarburization of precision tubes. If the surface is decarburized, the strength and wear resistance of the spiral tube will be reduced, which will directly affect the service life of the spiral tube. If the decarburized layer on the spiral tube is not cleaned, the surface hardness and wear resistance of the spiral tube will be reduced accordingly, and during the quenching process, the change in the volume of the inner and outer layers will cause cracks to form on the surface of the workpiece.

To solve the problem of surface decarburization, it is mainly necessary to deal with the heat treatment process. Because decarburization and oxidation of the spiral tube are carried out at the same time, during the heat treatment process, the thick-walled steel pipe should be kept away from air as much as possible, which can improve the decarburization phenomenon. The media that cause decarburization on the surface of thick-walled steel pipes are mainly oxidizing gases such as oxygen, water vapor and carbon dioxide. When these gases come into contact with the heated spiral tube, they will cause oxidation and decarburization of the spiral tube. Therefore, it is also very important to control the ratio of carbon dioxide and carbon monoxide in the furnace. In fact, adding protective gas nitrogen into the thick-walled steel pipe forging furnace is also very effective. Nitrogen can disperse certain oxidizing gases and reduce the decarburization of the spiral tube.