The cutting edges of Q500NH weathering steel generally require rust prevention treatment after cutting, despite its inherent corrosion resistance. Here's why and how to handle it:
1. Why Treat Cutting Edges?
Patina Disruption:
Cutting removes the protective oxidized layer (patina), exposing bare steel vulnerable to initial rust.
Galvanic Risk:
Untreated edges may corrode faster than the patinated surface, creating uneven degradation.
2. Recommended Treatments
Short-term: Apply weathering-resistant primer (e.g., zinc-rich paint) to edges until natural patina reforms (~6–12 months).
Long-term: Use patina-accelerating sprays (e.g., ammonium chloride solution) to speed up oxidation.
3. When Can You Skip Treatment?
If edges will be welded/covered (e.g., by plates or sealants).
In low-corrosion environments (dry inland climates).
Pro Tip: For critical structures (bridges, facades), always treat edges to ensure uniform corrosion resistance.
