The main methods of metal corrosion protection are: ① Change the internal structure of the metal. For example, adding chromium and nickel to ordinary steel to make stainless steel. ② Cover the metal surface with a protective layer. For example, painting, electroplating or chemically forming a dense and corrosion-resistant oxide film on a metal surface. The protective metal layer is plated on the surface of the steel ring, and the metal layer is still oxidized and damaged, which will still affect the corrosion of the steel ring and will not play the role of fundamental protection.