1.How to pre-treat before cutting?
Keep the cutting environment dry: Before cutting, make sure that there is no moisture, oil or dust on the galvanized steel surface and the cutting area. You can wipe the surface with a clean cloth first to prevent moisture from penetrating into the incision during the cutting process.
Choose the right cutting tool: cold cutting tools are preferred to reduce oxidation or burning of the galvanized layer caused by high temperature during the cutting process. If hot cutting is used, the temperature must be controlled and the oxidized slag at the incision must be removed in time after cutting.
2.How to perform immediate rust prevention after cutting?
The cut must be treated within 24 hours after cutting to avoid long-term exposure of bare steel to the air.
Clean the cut surface, select targeted anti-rust materials, and expand the treatment range
3.How to choose anti-rust materials?
Short-term rust prevention
Apply galvanized repair paint: directly cover the cut to form a coating with high zinc content, using the "sacrificial anode" principle to protect the exposed steel, and have good compatibility with the original galvanized layer.
Use anti-rust oil/grease: suitable for parts stored indoors or used for a short period of time. After application, an oil film is formed to isolate water and oxygen. The disadvantage is that it needs to be removed later, and it is not suitable for decorative parts.
Mid-term rust prevention
Apply zinc-based anticorrosive primer: high zinc powder content, strong adhesion, better corrosion resistance than cold-spray zinc paint, can be used alone or as a primer, and can be matched with topcoat to enhance protection.
Use zinc alloy spray: a thin layer of zinc alloy is formed by spraying, which is closely combined with the cut metal, and the anti-rust effect is close to the original galvanized layer, which is suitable for small area repairs.
Long-term rust prevention
Local re-plating: For important parts, local electroplating can be used to restore the zinc coating of the cut, which has the best protection effect, but the cost is relatively high, and it is suitable for batch or high-precision parts.
Multi-layer protection system: First apply zinc-based primer, and then apply intermediate paint and topcoat after drying to form a composite protective layer, which greatly improves corrosion resistance.
4.What are the precautions for subsequent maintenance and long-term protection?
Regular inspection: Check the anti-rust layer of the cut every 3-6 months to see if there is any damage, peeling or rust, and repair it in time (such as sanding the rusted area and then applying anti-rust paint).
Suitable use environment
High humidity/rainy areas: Prefer waterproof coatings (such as polyurethane topcoat) to avoid water infiltration.
Coastal/high salt fog areas: Increase the coating thickness, or choose anti-rust materials with higher zinc content (such as zinc-nickel alloy plating) to resist Cl⁻ erosion.
Outdoor exposure environment: Choose UV-resistant topcoat (such as acrylic topcoat) to prevent coating aging and cracking.
5.What should be paid attention to when cutting galvanized steel for rust prevention?
Avoid using cleaning agents containing strong acids or alkalis to treat the incisions to prevent corrosion of the surrounding intact galvanized layer.
If the incision needs to be welded, anti-rust treatment should be carried out after welding (the high temperature of welding will destroy the anti-rust layer). After welding, the welding slag needs to be removed and the surface needs to be re-grinded and coated with anti-rust material.
For parts with high decorative requirements (such as furniture and exposed building parts), you can choose anti-rust paint that is close to the color of the galvanized layer (such as silver-gray cold-sprayed zinc) to achieve both protection and aesthetics.