1.How can we reduce the generation of zinc dross at its source?
Beveling: Before welding, use an angle grinder to thoroughly grind away the zinc layer within about 15-20mm on both sides of the weld area to expose the natural metal. This is the most common and effective method.
2.How to select appropriate welding processes and materials?
MAG welding (gas metal arc welding): Typically uses specialized welding wire containing a zinc stripping agent (such as ER70S-6 wire with high silicon and manganese content), which helps zinc dross float to the weld surface, facilitating subsequent cleaning.
MIG welding: Uses a mixture of argon and a small amount of oxygen or carbon dioxide, which also helps control zinc dross.
Reducing welding heat input: Using lower current and faster welding speeds reduces overheating damage to the zinc layer, thereby reducing the generation of zinc vapor and dross.
3.How to operate and use a wire brush/stainless steel wire brush?
Tools: Handheld wire brush (suitable for small areas and fillet welds) or a bowl/disc wire brush mounted on an angle grinder.
Operation: Brush while the weld area is still warm after welding for better results. Be sure to brush along the direction of the weld to avoid scratching the base material laterally.
Advantages: Flexible, low cost, and high efficiency.
Note: Always use a stainless steel wire brush. Scrap from ordinary wire brushes may remain on the surface and cause future rusting.
4.How to operate and use an angle grinder?
Tools: Use louvered blades with a grit size of 40#-80#.
Operation: Grinding the weld and heat-affected zone effectively removes firmly adhering zinc slag and oxide layer, and smooths the weld.
Advantages: Thorough cleaning and improves weld appearance.
Caution: Control the force applied to avoid over-grinding, damaging the base material, or expanding the damaged area of the galvanized layer.
5.How to perform deep cleaning?
Phosphating: Wipe or spray the weld area with a phosphating solution. The phosphating solution reacts with the metal to form a phosphating film, which not only further enhances corrosion resistance but also serves as an excellent base coat for paint.
Special Metal Cleaners/Converters: Commercially available specialized products that neutralize and convert zinc salts on the surface.