ZAM Zinc-Aluminum-Magnesium Coated Steel

Zinc-Aluminum-Magnesium coated steel, also known as ZAM-coated steel, is an innovative steel finish with superior corrosion resistance. Initially, pure zinc alloys were primarily used to enhance the corrosion resistance of metal surfaces. With continuous innovation in steel manufacturing technology, corrosion-resistant coated steels like zinc-aluminum alloys and ZAM alloys continue to emerge in the market, significantly improving the corrosion resistance of steel surfaces.

Zinc-Aluminum-Magnesium (ZAM) steel is a type of coated steel that offers enhanced corrosion resistance compared to traditional galvanized steel. The coating composition typically includes:

Zinc (Zn): The primary component, usually comprising around 90-96% of the coating. Zinc provides the primary corrosion protection.

Aluminum (Al): Generally makes up about 1-8% of the coating. Aluminum helps to improve the adhesion of the coating and enhances corrosion resistance.

Magnesium (Mg): Typically present in the range of 1-4%. Magnesium further enhances corrosion resistance, especially in harsh environments.

These elements work synergistically to provide a durable, long-lasting protective layer that is more effective than traditional zinc coatings alone. The exact composition can vary depending on the specific requirements and manufacturer formulations.

ZAM's corrosion resistance mechanism is due to its coating layer of aluminum and magnesium. The blend of Mg and Al creates an enduring protective film on its zinc base, giving protection against corrosion.

Compared to hot-dip galvanized coating layers, ZAM offers a finer and tighter adhesive property on the substrate. ZAM's coating surfaces block the corrosive action over a long period of exposure to harsh environments.

In a salt spray test that lasted for four hours on both ZAM and hot-dip galvanized steel, ZAM formed a protective film on the coating surface. Take a glimpse at the figure below:

The cut-edge parts of the ZAM steel have superior corrosion resistance. The ends are covered with a fine base that contains a protective film comprising aluminum and magnesium leaching on its coating layer.

The corrosion resistance on the cut edge was based on a test on the steel substrate. The initial exposure period took several weeks, during which there was an initial rust on the exposed cut edge. The rust formed due to oxidation from condensation and rain.

The intermediate exposure period took several weeks to years. During this period, the cut edge resists corrosion due to the fine zinc-based protective film, which has a leaching of zinc, aluminum, and magnesium coating layers. The substrate turns darker to gray-black over the years of exposure to the elements.

The coating layer of ZAM steel affects its weldability performance due to its zinc base. Zinc has a low melting point, which is not ideal for arc welding. This application leads to weak joints and deformation compared to cold- and hot-rolled steel sheets.

ZAM is prone to splashing, hole formation, and cracking. ZAM performs better if you weld it into joints, provided the structure has adequate strength and is under proper conditions.

Experts recommend conducting tests when welding ZAM steel to achieve greater strength and maximum welding parameters. The weld quality depends on the type of welding machine and the shape of the joints.

Defective joints are avoidable if you follow the right conditions when welding ZAM steel. The joints should have enough welding strength and adequate internal sectional structure before welding the steel.

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EN 10346: Specifies the technical delivery conditions for continuously hot-dip coated steel flat products, including zinc-aluminum-magnesium coatings.

JIS G 3323: Specifies the requirements for hot-dip zinc-aluminum-magnesium alloy-coated steel sheets and coils.

ASTM A1046/A1046M: This specification covers the requirements for steel sheet, zinc-aluminum-magnesium alloy-coated by the hot-dip process.

ZAM coil and sheet Widely used in building roofs, walls, window frames, metal façades, car bodies, chassis, motor housings, brackets, agricultural storage facilities, solar racks, parapet façades, cable bridges, noise barriers, and other applications, with a corrosion resistance of more than 25 years.

Construction Industry: Coastal building roofs/walls, steel bridges.

Automotive: Chassis guards, inner door panels.

Appliances & Energy: Solar racks, air conditioning units.

Agriculture and Transportation: Greenhouse skeleton, highway soundproof screen.

1.How is the coating applied to the steel?
Through hot-dip coating or continuous coating processes.

2.Can Al-Zn-Mg steel be used for food storage or equipment?
Yes, as long as it meets local food safety standards and proper finishing is applied.

3.Is Galvalume steel costlier than regular galvanized steel?
Yes, slightly higher due to improved corrosion protection.

4.Can Galvalume steel be used in high-temperature applications?
Yes, coating stability allows use up to 315°C for short periods.

5.Is maintenance required for Al-Zn-Mg steel structures?
Minimal; periodic inspection is usually sufficient to ensure longevity.