Standard System and Quality Control of Aluminum-Zinc Coated Steel Sheets
Key aluminum-zinc coated steel sheet standards include ASTM A792 (USA), JIS G3321 (Japan), and GB/T 14978 (China), all of which impose strict requirements on coating composition, thickness, and performance. Quality control measures include: first, online coating thickness inspection (using X-ray fluorescence spectrometers with accuracy ±1μm); second, testing coating adhesion (via grid marking or bending tests); third, evaluating corrosion resistance (salt spray test, cyclic corrosion test). A steel mill has increased coating defect recognition rate from 90% to 99.5% by introducing an AI vision inspection system, achieving a first-pass pass rate of over 98%. Additionally, third-party certifications (such as SGS, TÜV) serve as a pass for aluminum-zinc coated steel sheets to enter the international market, with fewer than 50 manufacturers currently certified, indicating a high market concentration.