Galvalume steel, a combination of aluminum and zinc, is formed by the alloying of 55% aluminum, 43.4% zinc, and 1.6% silicon at high temperatures of 600°C. The resulting structure is a dense four-element crystalline compound made up of aluminum, iron, silicon, and zinc. This composition gives Galvalume its superior corrosion resistance, which is three times higher than that of galvanized steel. Over time, if the zinc coating on Galvalume is worn down, aluminum forms a dense aluminum oxide layer, further protecting the material from corrosion and extending its lifespan. However, one downside of Galvalume steel is its relatively poor weldability.

Galvalume steel’s corrosion resistance stems from the protective functions of both aluminum’s passivation layer and zinc’s sacrificial protection. When the zinc coating is scratched or damaged, aluminum forms an insoluble oxide layer on the steel surface, providing a protective barrier against further corrosion. Galvalume is widely used in various industries, with its performance proven in extended atmospheric exposure tests in regions such as rural, industrial, coastal, and harsh marine areas. In fact, Galvalume has been shown to exhibit 2-6 times higher corrosion resistance than galvanized steel with the same coating thickness.

Key Differences Between Galvanized and Galvalume Steel

1. Composition and Structure
   Galvanized steel consists of a single layer of zinc, while Galvalume steel is made from an alloy of 55% aluminum and 43.4% zinc, with 1.6% silicon added for strength. The alloy structure of Galvalume provides enhanced corrosion resistance due to the dual protective properties of aluminum and zinc.
2. Corrosion Resistance
   Galvalume steel is more resistant to corrosion than galvanized steel. The aluminum oxide layer formed on the surface of Galvalume steel offers superior protection against rust, extending the material’s lifespan, particularly in harsh environments.
3. Appearance
   Galvanized steel is often recognized by its shiny, uniform surface with a distinct “zinc flower” pattern, while Galvalume steel tends to have a smoother, metallic finish. Galvalume’s appearance is typically more visually appealing due to the absence of the prominent zinc flower.
4. Durability
   Galvalume’s combination of aluminum and zinc makes it significantly more durable, offering better performance in terms of corrosion resistance, especially in outdoor and coastal environments. In comparison, galvanized steel, while still effective at preventing corrosion, does not offer the same level of long-term protection as Galvalume.
5. Cost
   While Galvalume steel offers superior durability and corrosion resistance, it tends to be more expensive than galvanized steel. However, market conditions and demand for Galvalume have influenced price fluctuations, with some markets seeing lower stock levels of galvanized steel as production capacity for Galvalume increases.

Conclusion

Both galvanized and Galvalume steels are essential materials in industries where corrosion resistance is critical. Galvalume steel, with its higher corrosion resistance, is particularly suitable for applications in aggressive environments such as coastal areas and industrial settings. Although Galvalume is typically more expensive, its enhanced durability often justifies the higher cost. Businesses should consider the specific environmental conditions and requirements of their projects when choosing between galvanized and Galvalume steel.