Stainless steel screws are made of metal, and there are four main methods for metal corrosion protection, namely the nature of the material itself, the environment in which it is used, the interface between the material and the environment, and the design of improving the metal structure. If a complete corrosion-resistant alloy is used to manufacture stainless steel screws Unless there is a special requirement, it is not realistic in terms of economic concept, or the appearance of the screw is completely isolated from the environmental elements that will cause corrosion, which may not be feasible in practice, and it may be very difficult. Improved metal structure design can improve the impact of special circumstances under certain conditions, but the design of most stainless steel screws cannot be fully modified, and its maintenance function is not permanent. Therefore, this method cannot basically deal with the problem, as long as the interface is Anti-corrosion, that is, surface anti...