Type of surface galvanizing of steel plate

Cold galvanizing
Cold galvanizing, also known as electro galvanizing, is the use of electrolytic equipment to remove oil, pickling, and then put the pipe into a zinc salt solution, and connect the negative electrode of the electrolytic equipment, place a zinc plate on the opposite side of the pipe, connect the positive electrode of the electrolytic equipment to connect the power supply, use the current from the positive to the negative directional movement will deposit a layer of zinc on the pipe fittings, cold plated pipe fittings are processed before galvanizing.
Mechanical galvanizing
In the rotating barrel with plating piece, glass ball, zinc powder, water and accelerant, the glass ball as impact medium rotates with the barrel, friction and hammering with the surface of plating piece produce mechanical physical energy. Under the action of chemical accelerant, the coated zinc powder is "cold welded" to the surface of plating piece, forming a smooth, uniform and meticulous coating with a certain thickness.

American ASTM b695-2000 and military c-81562 mechanical zinc plating technical standards are adopted.


Hot dip galvanizing
At present, the main method of galvanizing steel plate is hot galvanizing.
Hot dip galvanizing is developed from the older hot dip galvanizing method. It has a history of 170 years since France applied hot dip galvanizing to industry in 1836. However, with the rapid development of cold rolled strip in recent 30 years, the hot-dip galvanizing industry has been developed on a large scale.
The production process of hot-dip galvanized sheet mainly includes: preparation of original sheet → pretreatment before plating → hot-dip → post-treatment after plating → inspection of finished product, etc. According to the custom, the hot-dip galvanizing process can be divided into two categories: off-line annealing and in-line annealing, i.e. wet process (single sheet hot galvanizing), off-line annealing (single sheet hot galvanizing), wheeling process (continuous hot-dip galvanizing), Sendzimir process (protective gas process) The improved senjimir method, the American steel union method (the same as Kawasaki method in Japan), the selas method and the Sharon method.
Off line annealing
That is, before hot-rolled or cold-rolled steel plates enter the hot-dip galvanizing line, they are first recrystallized and annealed in the bottom drawing annealing furnace or bell type annealing furnace, so there is no annealing process in the galvanizing line. Before hot-dip galvanizing, the steel plate must keep a clean pure iron active surface free of oxides and other dirt. In this method, the annealed surface oxide scale is removed by pickling first, and then coated with a layer of zinc chloride or a mixture of ammonium chloride and zinc chloride for protection, so as to prevent the steel plate from being oxidized again.