Key Performance Indicators of Prepainted Galvanized Steel Coil

The key performance indicators (KPIs) of prepainted galvanized steel coil mainly revolve around four core dimensions: corrosion resistance, processability, appearance, and weather resistance, detailed as follows:
1. Corrosion Resistance Indicators
– Zinc coating weight: Common specifications range from Z80 to Z275 (g/㎡, double-sided). A higher value indicates stronger corrosion resistance. Corrosion resistance is also evaluated by the duration of salt spray testing; the PVDF coating system can withstand over 1000 hours of salt spray testing.
– Coating adhesion: Tested by cross-cut test, with a standard of Grade 0 (no coating peeling), ensuring the coating does not flake during processing and application.
2. Processability Indicators
– Bending performance: Capable of 180° cold bending (bending radius R = 0–3T, where T is the base metal thickness) without coating cracking or peeling, meeting the requirements of roll forming and stamping.
– Tensile strength & yield strength: These are mechanical properties of the base metal, determining the load-bearing capacity and deformation resistance of the product to suit structural needs in different construction and home appliance scenarios.
3. Appearance Indicators
– Color difference & glossiness: The color difference ΔE of products in the same batch should be ≤ 1.5. Glossiness can be customized on demand (high gloss ≥ 70%, medium gloss 30%–70%, matte ＜ 30%).
– Surface defects: Free from defects such as missed coating, blisters, pinholes, and scratches, with a flat and wave-free surface.
4. Weather Resistance Indicators
– UV aging resistance: After accelerated aging testing, the coating should show no chalking, discoloration, or cracking. Different coating systems have varying weather resistance lifespans (PE coating: 5–8 years; PVDF coating: over 20 years).
– Acid-alkali resistance: Resistant to mild acid and alkali corrosion, suitable for special environments such as chemical workshops and coastal areas.