Post-weld metal cleaning refers to the set of processes carried out to remove slag, oxide layers, discoloration (heat affected zone), and dirt that form on the weld seam. This cleaning is critical for both aesthetic appearance and for corrosion resistance and coating quality.
1. Slag and Scale Removal
Occurs particularly in shielded metal arc (MMA) and flux-cored arc welding.
- Slag is broken off with a chipping hammer
- Surface is cleaned with a wire brush
- Grinding is performed if necessary
Purpose: to make the weld seam visible and clean
2. Grinding Process
Used to achieve a smoother surface.
- Performed with an angle grinder
- Corrects excess weld metal
- Reduces surface roughness
Caution: excessive grinding can lead to metal weakening
3. Chemical Cleaning
Used to remove post-weld oxide and discoloration.
- Passivation solutions (especially for stainless steel)
- Acidic cleaners
- Gel or spray form products
Purpose: to restore corrosion resistance
4. Passivation (Especially for Stainless Steel)
One of the most critical post-weld processes.
- Removes free iron particles
- Forms a protective chromium oxide layer on the surface
- Increases corrosion resistance
5. Mechanical Cleaning Methods
- Wire brush (manual or attached to a grinder)
- Shot blasting / sand blasting
- Sanding
More effective on large surfaces
6. Surface Degreasing and Final Cleaning
- Solvent-based metal cleaners
- Alkaline washing systems
- Fast-evaporating cleaners
Purpose: complete surface preparation before painting or coating
7. Protective Application
The metal should not be left exposed after cleaning.
- Anti-rust spray or oil
- Primer application
- Galvanizing or coating processes
8. Occupational Safety Measures
- Weld slag can be hot, posing a burn risk
- Goggles and face shields must be used during grinding
- Gloves and masks are mandatory for chemical cleaning
- Good ventilation must be ensured
You can contact us for technical support regarding solutions suitable for your operations.
