The substrate of power coated steel sheet is made of zinc-aluminum-magnesium (ZM) alloy coating. On the basis of the traditional galvanizing technology, a certain proportion of aluminum and magnesium are added to form a zinc-aluminum-magnesium alloy coating. A eutectic structure containing aluminum and magnesium is formed in the coating, which effectively improves the corrosion resistance and weather resistance of the coating. It has a certain automatic self-healing function for cuts, scratches and damages generated during steel sheet processing, transportation and installation. Experiments show that after salt spray corrosion, corrosion products containing magnesium and aluminum also appear at the cut of the steel plate. The low conductivity and dense nature of these corrosion products isolate the cut from ambient water and oxygen, forming an effective protective layer. Therefore, even if the resin coating is damaged, the zinc-aluminum-magnesium alloy layer still has excellent corrosion resistance and weather resistance. To a certain extent, this avoids the corrosion hazards caused by scratches, shearing, and punching that are prone to occur during the installation of the steel sheet.
