White Al-Zn coated sheet steel

Substrate: The base material is typically ordinary cold-rolled low-carbon steel strip. The core coating consists of an aluminum-zinc alloy—comprising 55% aluminum, 43.4% zinc, and 1.6% silicon—applied to the steel substrate via a coating process. In the case of white pre-painted Al-Zn coated sheets, a coating process is applied over the base Al-Zn sheet. Paint: The base Al-Zn sheet offers excellent paint adhesion, allowing for direct painting without the need for prior pretreatment. White finished products generally utilize a polyester white topcoat, though fluorocarbon white topcoats are used in select specialized applications; the latter offer superior weather and corrosion resistance, making them suitable for long-term outdoor use. Uncoiling and Pre-treatment: The steel coils are uncoiled and welded together, degreased and cleaned to remove impurities, dried, and then fed into the entry looper for buffering. Continuous Hot-Dip Coating: After annealing, the steel strip is immersed in a molten Al-Zn coating bath; the coating thickness is controlled by air knives, followed by air cooling and water quenching to set the coating. Post-treatment and Coiling: The strip undergoes skin passing and tension leveling, passivation, inspection, and oiling, followed by coiling and slitting to produce the finished Al-Zn coated coil.