How to determine coating adhesion?
A: Perform a bending test (fold 180°). If the coating does not peel or flake, it is considered合格 (qualified).
What are some common surface defects? How to avoid them?
A: Defects include zinc particles, scratches, and incomplete plating. Specify the surface grade when purchasing, and protect the product with a protective film and corner protectors during transportation.
What if the mechanical properties are unqualified?
A: Contact the supplier for return or exchange based on the steel mill's quality certificate and test report.
How to test coating thickness?
A: Use a coating thickness gauge (magnetic induction method), randomly select 5-10 points, and take the average value.
What precautions should be taken during storage?
A: Store in a dry, well-ventilated indoor environment, avoiding rain and moisture; store coils vertically, and sheet metal flat with raised supports to prevent moisture; avoid contact with acidic or alkaline substances.
What to do if white rust appears on the surface after use?
A: Minor white rust can be wiped away and then coated with anti-rust oil. Severe white rust requires sanding and repainting, or replacement of the sheet metal.