Key production process stages
The production of aluminum-zinc coated light sheet involves multiple precise processes. Firstly, cold-rolled steel plates must undergo degreasing and acid washing to remove surface oil and iron oxide scale, ensuring the adhesion of the coating. Then, they enter an annealing furnace for recrystallization annealing to eliminate work hardening and enhance the plasticity of the sheet. The hot-dipping phase is the core step: the steel plate is preheated and dipped into molten aluminum-zinc alloy (approx. 600℃), where the dipping time, speed, and alloy composition are controlled to form a uniform coating. The addition of silicon at this stage is crucial as it reduces the surface tension of the alloy liquid, preventing "leakage coating." After coating, the cooling must be rapid and even to avoid brittleness of the coating. Some products also undergo a finishing process, adjusting surface roughness through roller pressure to improve flatness and paint adhesion. The entire process requires high standards of temperature, speed, and environmental cleanliness, as fluctuations can affect coating quality.