1.What are the basic principles of rust prevention?
The core of rust prevention of cutting section is to block the contact between "water + oxygen + pollutants" and metal, and enhance protection according to the characteristics of the material:
Carbon steel/low alloy steel: the section has no natural protective layer and needs to be actively covered with an anti-rust layer;
Galvanized steel: the section destroys the zinc layer and needs to be supplemented with zinc-based protection (using the sacrificial anode effect of zinc);
Stainless steel: although the section has passivation ability, the high temperature of cutting may destroy the passivation film and the passivation layer needs to be repaired.
2.How to prevent rust on the cut section of carbon steel/low alloy steel?
Apply anti-rust oil/grease:
Choose a thin layer of anti-rust oil (such as solvent-based anti-rust oil), directly brush or spray it on the cross section to form an oil film to isolate air and moisture;
Advantages: simple operation, low cost, and can be directly wiped off if processing is required later;
Note: Not suitable for humid or dusty environments (the oil film easily absorbs impurities and becomes ineffective).
Wrap with anti-rust paper/tape:
Wrap the cross section with vapor phase anti-rust paper containing corrosion inhibitor, or paste anti-rust tape (with the adhesive surface in contact with the cross section), suitable for small-sized cross sections (such as steel pipe cuts, plate edges);
Advantages: Good isolation effect, suitable for temporary protection during storage or transportation.
3.How to prevent rust on the cut section of galvanized steel?
The rust prevention of galvanized steel depends on the surface zinc layer. The exposed steel base of the cut section needs to be protected by a "zinc sacrificial anode" to prevent the steel base from corroding first:
First choice: cold spray zinc / spray with zinc content ≥95%:
Spray the section directly to form a zinc layer of the same quality as the original zinc layer. The zinc will be corroded first to protect the steel base;
After the operation, it can form a continuous protection with the original galvanized layer to prevent the section from becoming a corrosion "breakthrough".
Second choice: zinc-rich paint + topcoat:
First apply zinc-rich primer (zinc content ≥80%), then apply topcoat of the same color as the original galvanized layer surface (such as zinc-specific passivation paint), taking into account both protection and beauty.
4.What are the operating precautions?
Pretreatment: Before rust prevention, the burrs, iron filings, and oil stains on the cross section must be cleaned (wipe with alcohol or degreaser), otherwise it will affect the adhesion of the protective layer;
Timeliness: The rust prevention treatment should be completed within 2 hours after cutting (especially in humid environments) to avoid rusting the cross section before treatment (rust will reduce the effectiveness of the protective layer);
Regular maintenance: In outdoor or highly corrosive environments, check once every 6-12 months. If the protective layer is found to be damaged (such as coating peeling, zinc layer powdering), it needs to be cleaned and repainted.
5.How to prevent rust on aluminum alloy cutting sections?
After aluminum alloy cutting, the surface oxide film (Al₂O₃) is destroyed. Although a new oxide film will form naturally, it is slow and not dense, and is prone to "white spot" rust:
Anodizing (increasing oxide film thickness):
Partial anodizing of the cross section to form a dense oxide film of 5-20μm to enhance corrosion resistance (suitable for outdoor or humid environments).
Apply aluminum special primer + topcoat:
Use zinc yellow primer (containing chromate to enhance adhesion) as a primer, and then apply fluorocarbon paint or acrylic paint. It is suitable for scenes with requirements for appearance (such as door and window profile cutting).