1. Measures to Strengthen the Native Anti-Rust Film (For Long-Term Outdoor Use)
Accelerate artificial passivation: After manufacturing/processing, apply a weathering steel-specific passivation solution (e.g., phosphate-based or chromium-free eco-friendly passivators) to the plate surface. Let it react for 10–15 minutes, then rinse with clean water and dry. This shortens the natural oxide film formation time from 3–6 months to 1–2 weeks, forming a dense protective layer faster.
Controlled natural weathering: If conditions allow, place the plates in a well-ventilated outdoor area with alternating wet and dry cycles (e.g., misting with clean water 1–2 times a week) for 1–2 months. Avoid prolonged soaking in rain or standing water-this helps form a uniform, adherent oxide film instead of loose, flaky rust.
2. Isolation Protection (For Harsh Environments or Aesthetic Needs)
Apply weather-resistant coatings: For structural parts (e.g., outdoor frames, equipment casings), use a "primer + topcoat" system:
Primer: Inorganic zinc-rich primer (zinc content ≥ 85%)-it provides cathodic protection and strong adhesion to the steel surface.
Topcoat: Polyurethane weather-resistant paint or fluorocarbon paint-resists UV radiation, moisture, and salt spray, extending anti-rust life to 8–10 years.
Transparent clear coat for decoration: For decorative Q235NH panels (e.g., architectural facades), apply a transparent fluorocarbon clear coat after the oxide film stabilizes. This preserves the steel's natural "rusty patina" while preventing further corrosion from rain or dust.
3. Temporary Anti-Rust Measures (For Storage & Transportation)
Rust-preventive oil/wax: Wipe a thin layer of neutral mineral oil-based rust-preventive oil or apply anti-rust wax to the plate surface. This forms a physical barrier to isolate moisture and air. Before installation, clean the oil/wax with ethanol or a dedicated solvent.
VCI packaging: Wrap the plates in VCI (Volatile Corrosion Inhibitor) film or VCI paper. VCI molecules slowly volatilize and attach to the metal surface, forming an invisible corrosion-inhibiting layer-effective even in sealed, high-humidity containers.
Storage environment control: Store plates in a dry, well-ventilated warehouse (relative humidity ≤ 60%). Stack them with wooden spacers (5–10 cm apart) to avoid direct contact between plates and allow air circulation; keep them 10–15 cm above the ground to prevent dampness from the floor.
4. Post-Processing & Maintenance Measures
Optimize cutting/welding processes: When cutting (flame, plasma, laser), trim the oxidized edge with a grinder immediately (the high-temperature cut edge is prone to rust). After welding, grind the weld area and re-passivate or touch up with anti-rust paint to restore protection.
Regular inspection & touch-up: For outdoor-used plates, inspect the surface every 6–12 months. If minor rust spots or coating peeling appear:
Remove rust locally with sandpaper or a wire brush.
Wipe with ethanol to clean the area.
Touch up with matching paint or passivation solution to prevent rust spread.
