Galvanized sheet metal is widely used in construction, equipment manufacturing, body construction, and decorative structures. The zinc coating provides reliable anti-corrosion protection, extends the service life of products and reduces maintenance costs.

However, when working with galvanized metal, especially when welding and soldering, specific difficulties arise. Zinc coating behaves differently than regular steel: it melts at low temperatures, emits toxic fumes, and affects the quality of the connection.

Company ArtMetal (art-metal.com.ua), which has experience working with metal structures and rolled metal products, has prepared a detailed guide on welding and soldering galvanized sheets.

Peculiarities of working with galvanized metal

Galvanized steel is coated with a zinc layer 10–25 µm thick. This layer serves a protective function, but when heated above 420°C, the zinc melts and vaporizes, creating a number of problems:

Burnout of the zinc layer
When welding, the area around the seam loses its protective coating, making the metal vulnerable to corrosion.
Release of toxic fumes
When heated, zinc releases vapors that are hazardous if inhaled and require ventilation and respiratory protection.
Difficulties in seam formation
Melting zinc impairs wetting and adhesion of metals, increasing the risk of porosity and cracks.

Therefore, standard methods of welding or brazing steel are not always suitable for galvanized sheets.

Welding of galvanized sheets

There are several basic methods for welding galvanized materials. The choice of method depends on the sheet thickness, the intended purpose of the structure, and the weld strength requirements.

1. Arc welding (MIG/MAG, MMA)

MIG/MAG (semi-automatic welding) And MMA (manual arc) used on thin and medium sheets.

Peculiarities:

adjustment of current parameters is required to minimize zinc overheating;
Preliminary cleaning of the zinc layer at the weld site is possible;
It is necessary to use a protective gas atmosphere (for MIG/MAG) and adequate ventilation;
After welding, it is advisable to cover the seam with an anti-corrosion compound.

Pros: high strength, versatility.
Cons: release of toxic fumes, partial destruction of the coating.

2. Spot welding

It is used primarily for thin sheet metal, such as in the production of car bodies and decorative panels.

Operating principle:
The sheets are clamped between electrodes and a short current is passed through the contact point, heating the metal and forming a weld.

Pros:

minimal damage to the coating around the seam;
high connection speed;
Suitable for mass production.

Cons:

sheet thickness limitation;
requires precise equipment.

3. Laser and plasma welding

Modern methods that allow you to obtain a neat seam with minimal zinc fading.

Pros:

high accuracy;
minimum thermal zone;
reduced formation of zinc vapor.

Cons:

high cost of equipment;
requires qualified personnel.

4. Gas welding

It's rarely used, mostly for repair work. Due to zinc's low melting point, the weld requires additional protection.

Pros: simplicity of equipment.
Cons: labor-intensive, large heat-affected zone, risk of porosity.

Soldering of galvanized sheets

For thin sheets and decorative items it is often used soldering, as it allows metal to be joined at low temperatures without significant destruction of the zinc layer.

1. Soft soldering (tin-lead solder)

solder melting temperature: 180–250 °C;
minimal heating of the sheet allows to preserve most of the zinc coating;
used for sealing, manufacturing decorative products.

Pros: simplicity, preservation of anti-corrosion protection.
Cons: low connection strength, not suitable for high load structures.

2. Hard soldering (copper-phosphorus or silver)

melting point: 600–800 °C;
provides a stronger seam;
used for critical connections, pipelines, plumbing.

Pros: high strength, durability.
Cons: requires qualification and temperature control, partial destruction of the zinc layer.

Recommendations for welding and soldering galvanized sheets

Cleaning the seam and the area around it
Removing zinc and contaminants reduces porosity and improves bond strength.
Providing ventilation and protective equipment
The use of a fume hood, respirators and safety glasses is mandatory when welding.
Selecting the right technology
For thin decorative items, it is better to use soft soldering; for structural elements, spot or arc welding with minimal thermal impact is recommended.
Anti-corrosion treatment after welding/soldering
The seam area is covered with primer, paint or anti-corrosion varnish.
Connection quality control
Visual inspection, ultrasonic testing of the seam or other methods are recommended to exclude defects.

Conclusion

Working with galvanized sheets requires attention and a professional approach. Welding and soldering have their own characteristics due to the zinc coating, which melts at low temperatures and releases toxic fumes.

Company ArtMetal applies an integrated approach:

choice of technology depending on the thickness and purpose of the sheet;
compliance with safety regulations.
seam quality control;
restoration of anti-corrosion coating after treatment.

Compliance with these rules ensures strong, durable and safe connections, while maintaining corrosion protection and the aesthetic appearance of the products.