G550 Galvanized Steel ZN275

Aluminum-zinc coated steel sheet is produced by continuously hot-dipping a cold-rolled steel substrate in an alloy bath containing 55% aluminum, 43.4% zinc, and 1.6% silicon. At high temperatures of 600°C, this structure forms a dense "aluminum-iron-silicon-zinc" quaternary crystalline barrier, fundamentally blocking the penetration of moisture, oxygen, and corrosive ions. This design makes it not only suitable for standard building roofing but also the preferred material for highly corrosive environments such as coastal regions, industrial zones, and livestock farms. Dual Protection Mechanism: Zinc undergoes an electrochemical reaction at cut edges and scratches, corroding preferentially (acting as a sacrificial anode) to protect the exposed steel substrate; Aluminum rapidly oxidizes to form an insoluble Al₂O₃ film, covering the damaged area and acting as a physical barrier. Self-Healing Capability: When the coating sustains minor scratches, the zinc reacts with the air to form basic zinc carbonate, which automatically fills the defect and prevents further corrosion. Empirical Service Life Data: Outdoor exposure tests have verified that the cut-edge protection performance of 55% aluminum-zinc coated steel sheets is superior to that of galvanized steel and 5% aluminum-zinc coated steel; In Neutral Salt Spray (NSS) tests, the zinc-aluminum-magnesium coating (an upgraded version) took more than four times longer to exhibit red rust compared to a pure zinc coating,