There are various thicknesses of galvalume sheet metal. The galvalume coating thickness is expressed by AZ+number. According to ASTM A792 Standard, AZ50 galvalume means 0.50 ounces of aluminum zinc coating per square foot (double sides); AZ150 indicates the Al-Zn coating weight of 1.5 ounces per square foot double sides. Wanzhi Steel offers AZ30 to AZ150 galvalume finish.

Generally, the higher the number, the thicker the Al-Zn coating. Coating thickness greatly affects the protective effect to the substrate. That is, the thicker the coating, the better the durability. Therefore, AZ150 will be more durable and more expensive than AZ50.

Due to the different densities of zinc and aluzinc coatings, AZ50 is not the same as G50. The thickness of G50 galvanized steel is 10.6 μm per side. While the Al-Zn layer thickness of AZ50 is about 20 μm per side. That’s why AZ50 will be more long-lasting and expensive than G50. Below is a picture for your reference.

What Is Galvalume Steel?

Galvalume steel is similar to galvanized steel. It uses cold-rolled steel sheet as a substrate and then is coated with 55% aluminum, 43.4% zinc, and 1.6% silicon at 600 °C. While galvalume coating aims to protect steel from oxidation. Due to the protection of aluminum, it is better able to resist rusting and corrosion. If the coating thicknesses of GL steel and GI steel are equal, the GL one will be more long-lasting to use in the same environment. The common manufacturing process is known as the hot-dipping process. Let’s review step by step.

1. Pre-treatment

Through the pre-treatment system, the contaminants on the surface of the base metal will be removed. It often includes degreasing, rinsing, pickling, etc.

Which Is Better Galvanized or Galvalume Steel?

As for corrosion resistance, galvalume is better than galvanized steel. GI and GL steel are very similar. Both of them are coated to protect the base metal from rust. The coating allows metal panels to last decades longer than non-coated metal. Essentially, GL steel is 55% aluminum to 43.4% zinc, and 1.6% silicon alloy coated sheet steel. While GI is coated with a zinc layer. Al-Zn coating combines the toughness of zinc with the rust resistance of aluminum and provides barrier protection on the metal surface. It performs better in fighting corrosion than zinc coating. However, if the zinc coating is scratched, it can continue to corrode. So the service life of GL steel will be longer than that of GI steel. Also, GL steel has better heat resistance so that it is more suitable for home appliances.

However, in terms of the price, the galvalume sheet price will be higher than that of galvanized sheet.