1.What are the basic remedial principles?
During welding, high temperature will destroy the original anti-rust layer of the parent material, and the weld and heat-affected zone are prone to form oxide scale and stress concentration. If not handled in time, water, oxygen and pollutants will quickly cause rust. Remediation should follow:
Thorough rust removal: avoid residual rust from becoming a "corrosion source";
Targeted protection: select anti-rust coating according to the material and use environment;
Eliminate hidden dangers: deal with welding defects and avoid crevice corrosion.
2.How to deal with slight floating rust (only yellow/brown rust powder on the surface, no pitting)?
Use sandpaper (80-120 mesh) or a wire brush to remove loose rust;
If the rust is thin, spray it with a rust remover (chemical rust remover containing phosphoric acid or organic acid), let it sit for 5-10 minutes, then wipe it clean with a rag, and then rinse the remaining agent with clean water (to prevent the agent from corroding the base material).
3.How to deal with local rust (thick rust layer, small pits but no holes)?
First, use an angle grinder with a wire wheel or sandpaper disc to remove the thick rust layer and expose the original color of the metal (be careful to avoid excessive grinding to damage the thickness of the base material);
For small pits or depressions after grinding, epoxy putty can be used to fill (suitable for non-load-bearing parts), and after drying, use sandpaper to smooth it to ensure a flat surface (to facilitate the subsequent coating adhesion).
4.How to deal with deep rust (with obvious pits or perforations)?
If the perforation area is small (diameter < 5mm), you can first grind and remove rust, then use repair welding (use welding rods that match the parent material, such as J422 welding rods for carbon steel) to fill the hole, and grind it flat again after welding;
If the perforation area is large or the parent material is severely thinned, you need to cut and replace the damaged part, re-weld it, and then remove rust.
5.Subsequent maintenance: How to extend the protection life?
Regular inspection: Check the repaired parts every 6-12 months. If the coating is peeling or bulging, clean it in time and re-apply it.
Environmental protection: For welded parts in outdoor or humid environments, additional anti-rust grease (short-term protection) or silicone sealant (seal gaps and prevent water accumulation) can be applied.
Avoid pollutants: Clean the accumulated water, oil and salt in the welding parts in time (such as washing after use at the seaside or in the snow).