The galvalume coating is an alloy consisting of approximately 55% aluminum, 43.4% zinc and 1.5% silicon by weight, which is applied to steel by the continuous hot dip process. Galvalume steel sheet offers the best qualities of aluminum coated (aluminized) and zinc coated steel sheet (galvanized). The aluminum/zinc coating has barrier corrosion resistance and heat resistance similar to aluminum coated steel. It also has good bare edge galvanic protection and forming qualities similar to continuously annealed commercial quality galvanized. The appearance of Galvalume coating is quite distinctive. Its smooth, flat and fine spangle and a silvery metallic appearance make it attractive in unpainted applications.

Galvalume Specifications ASTM A792 / A792M 
Designation 
Commercial Steel

CS Type AAllows application of very low carbon grades (up to maximum of 0.10% carbon), including vacuum degassed & interstitial-free steels.
CS Type BSpecified to avoid carbon levels below 0.02%. Carbon range is 0.02 to 0.15%. This describes the typical ASTMCQ of the past.
CS Type CAllows application of very low carbon grades (up to a maximum of 0.08% carbon). Also allows higher phosphorus (0.10 max) levels.
Forming SteelFS
Drawing SteelDS
High Temperature SteelHTS
Structural SteelSS