The chemical composition of galvalume layer in hot-dip galvalume steel products isn’t a specific point or area on phase diagram. It’s a composition with better performance chose according to the need.
1. The choice of aluminum content
Aluminum content of aluminum products is optimized based on the experiment. When the aluminum content exceeds 45%, with the increase of aluminum content, corrosion resistance basically unchanged. On the other hand, as the aluminum content increases, the protective properties of coated products on the fracture gradually decrease.
Based on the two factors, CAMELSTEEL generally selects the ingredient contains 55% aluminum as the ingredient of the stereotyped products. This can not only achieve better corrosion resistance, but also has better fracture protection value.
2. The choice of silicon content
In the production process of galvanized products, aluminum is more lively than zinc. The main role of aluminum is to inhibit the reaction between the zinc and iron. Reducing the thickness of the compound layer in the coating and reducing the amount of dross in the plating solution.
In the production of aluminum products, there must be more lively elements to inhibit the reaction between aluminum and iron. Reducing the thickness of the compound layer in the coating and reducing the amount of slag in the plating solution.
Because when pure aluminum is plated, there generally added silicon to inhibit the reaction between the aluminum and iron, so the silicon must be added when plating aluminum-zinc plate. When pure aluminum is plated, 3% silicon is generally added, and it is more suitable to add 1.6% silicon to the galvanized 55% aluminum alloy coating according to the ratio.
3.The choice of rare earth content
Entering rare earth in the production of galvalume layer production is our country’s characteristics. It is the innovation and development according to the needs and the development of China’s national conditions after the technology into our country. Rare earth elements can be added to reduce the liquid surface tension of the coating alloy to improve the non-wetting properties of the strip, and also refine the grain and reduce the impact of loose coating organization.