For galvanized coils, the sheet steel is immersed in a molten zinc bath to make a sheet of zinc coated on its surface. It is mainly produced by continuous galvanizing process, that is, the rolled steel plate is continuously immersed in a plating tank with molten zinc to make galvanized steel plate; alloyed galvanized steel plate. This kind of steel plate is also produced by hot dip method, but immediately after it is out of the tank, it is heated to about 500 ℃ to form an alloy film of zinc and iron. This galvanized coil has good paint adhesion and welding ability.