Production and specifications of galvanized coils

Aluminum-zinc coated steel coils begin with hot-rolled or cold-rolled steel strip substrates. These undergo rigorous surface treatment through a multi-stage pretreatment system—including degreasing, rinsing, and pickling—to thoroughly remove impurities and ensure optimal coating adhesion. The treated steel strip then enters a continuous hot-dip galvanizing line, passing through an annealing furnace before immersion into molten zinc baths maintained at approximately 600°C. Upon exiting the furnace, high-pressure air knives precisely control the final coating thickness to the specified weight (typically AZ50 to AZ275 grams per square meter), removing excess coating. The coated strip is cooled, inspected, and finally coiled into master coils weighing 3 to 15 metric tons, ready for direct distribution or further processing.

Aluminum-zinc coated steel sheets demonstrate significant performance advantages over traditional galvanized products. Comparative studies indicate that under equivalent environmental conditions—particularly in highly corrosive marine, industrial, and high-humidity settings—aluminum-zinc coatings last 2 to 4 times longer than conventional galvanized coatings. Additionally, as an excellent substrate for subsequent coating applications, the pre-painted aluminum-zinc steel sheet (PPGL) version offers a wide range of colors and surface treatments, making it widely applicable in the construction sector.

The dimensional range of galvanized steel coils is comprehensive, with thicknesses typically spanning from 0.12 mm (suitable for lightweight applications like household appliances and small components) to 4.0 mm (for structural and heavy industrial uses). Common commercial specifications include 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, and 2.0 mm, with these readily available in stock. Width options range from 600mm to 2000mm, with 914mm, 1000mm, 1200mm, 1219mm, and 1250mm being the most commonly used standard widths to maximize material utilization in downstream processing. Coil inner diameters are standardized at 508mm or 610mm to accommodate most processing equipment; Weights range from 3 tons to 15 tons, supporting efficient long-run production cycles and minimizing equipment downtime. Coating weights are designated by AZ (Aluminum-Zinc) grades, ranging from AZ50 for light indoor environments to AZ275 for harsh conditions. Each grade undergoes precise control during the hot-dip galvanizing process to ensure uniform protective layer coverage.