Coil Galvalume or cool language Galvalume Steel Sheet In Coil is a carbon steel sheet coated with aluminium zinc alloy by a continuous hot dip process. The nominal coating composition is 55% aluminum and 45% zinc.
A small but significant amount of silicone is added to the coating alloy.
It is not added to improve corrosion performance, but to provide good coating adhesion to the steel substrate when the product is rolled, stretched or bent during manufacturing.
Galvanized steel sheet combines the excellent corrosion protection of aluminum with the protection of galvanized steel.
The result is a durable coating, one that provides state-of-the-art protection along sheared edges and, therefore, one that provides excellent protection for steel sheets.
Although there are some exceptions, for most applications in most types of environments, when long-term atmospheric corrosion resistance is required, galvanized steel is the product of choice.
It is more durable than an equivalent thickness of galvanized coating and offers state-of-the-art protection not found in aluminum-coated panels.
This advanced protection means less rust, scratches and other imperfections in the finish on shaved edges. Additionally, because this coating is highly resistant to corrosion, it maintains a very bright surface appearance when exposed to most atmospheres.
These properties make Galvalume steel sheet the material of choice for roofing. The excellent corrosion resistance of galvanized steel sheets is achieved by the presence of zinc- and aluminum-rich microscopic domains within the coating.
Aluminum-rich regions that corrode very slowly provide long-term durability, while zinc-rich regions that corrode preferentially provide galvanic protection.