Q:From the perspective of process optimization, how to improve the welding performance of galvanized steel sheets?
A:Increase heat input: Use a larger welding current (10%-15% higher than galvanized steel) or reduce the welding speed to ensure that the coating (including aluminum) is fully melted and discharged to reduce weld porosity.
Control thermal cycle: Avoid high temperature residence time for too long (aluminum is easy to oxidize). Pulse welding (such as pulse MIG welding) can be used to reduce the formation of oxide film through intermittent heating.
Q:What are the key measures to improve the welding performance of galvanized steel sheets?
A:Pretreatment of coating
Mechanical grinding: Before welding, use a wire brush or sandpaper to remove 5-10mm of coating (aluminum-zinc layer) on both sides of the weld to expose the steel layer of the substrate and reduce the entry of aluminum into the molten pool (care should be taken to avoid rusting of the substrate).
Chemical cleaning: Use a weak acid solution (such as 5% dilute hydrochloric acid) to clean the coating surface, remove the oxide film (Al₂O₃), and improve welding wettability.
Q:How to improve the welding performance of galvanized steel sheets by selecting welding materials?
A:Welding wire selection: Welding wire containing silicon (Si) or magnesium (Mg) (such as ER50-6 silicon-manganese welding wire) is preferred. Silicon can inhibit the oxidation of aluminum, and magnesium can refine the weld grain and improve toughness.
Flux/shielding gas: Use active gas (such as 80% Ar+20% CO₂) instead of pure argon to enhance arc stability; or use flux pads (such as fluoride flux) to absorb aluminum oxide.
Q:Will welding operation affect welding performance?
A:Angle and path: The welding gun is tilted back 10-15° to promote welding (not drag welding), promote gas escape, and reduce pores.
Arc initiation and arc termination: Use an arc initiation plate or reserve a slope at the end of the weld to avoid the lack of fusion caused by the burning of the coating at the arc initiation.
Multi-pass welding management: When welding thick plates, use narrow welds, multiple layers and multiple passes, and control the interlayer temperature below 150°C to prevent repeated thermal degradation of the coating.
Q:What to do after welding?
A:Spatter and residue cleaning: Use a copper brush or special scraper to remove spatter from the weld surface to avoid corrosion caused by residual zinc and aluminum oxides.
Anti-corrosion repair: Apply zinc-rich paint (zinc content ≥ 85%) or cold-spray zinc on the welding area to restore the anti-corrosion performance.
Passivation treatment: Spray chromate or inorganic silane passivation liquid to delay the oxidation of the coating around the weld.