Among various coating methods for protecting steel substrate, Hot-dip Galvanizing is a very good one. It is when the zinc is in a liquid state and undergoes quite complex physical and chemical actions, not only a thicker pure zinc layer is plated on the steel, but also a zinc-iron alloy layer is formed. This plating method not only has the corrosion resistance of electro-galvanized steel, but also has a zinc-iron alloy layer. It also has strong corrosion resistance unmatched by electro-galvanizing. Therefore, this plating method is particularly suitable for various strong acid, alkali mist and other strong corrosive environments.