Galvanized steel coil is a thin steel plate with a layer of zinc adhered to the surface by immersing a thin steel plate in a molten zinc bath. It is mainly produced by continuous galvanizing process, that is, the 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 manufactured by hot dip method, but immediately after being out of the tank, it is heated to about 500 ℃ to form an alloy coating of zinc and iron. This galvanized steel coil has good paint adhesion and weldability.