Hot Dipped Galvanized / Galvannealed
Hot Dipped Galvanized – sheet or strip steel bathed in a molten solution containing not less than 98% pure zinc to uniformly coat for corrosion resistance. The coating is not intended to withstand outdoor exposure without chemical treatment or painting. Sheets are produced as commercial quality, drawing quality, drawing quality special killed, structural, physical quality, and are available in regular spangle, minimized spangle, and zinc-iron alloy. Galvannealed A-40, A-60 – Galvannealed is a form of hot-dipped galvanized sheet consisting of an iron-zinc alloy coating on both sides which is passed continuously through a pot of molten zinc. The coating amount applied to the surface is controlled by wiping, rollers and/or air jets. When coil exits the zinc bath, the molten zinc is subjected to inline annealing that forms the zinc-iron alloy layer. The coating is denoted by an “A” designation, i.e., A-60 (referred to as coating weight) which is the amount of zinc usually represented in ounces per square foot. For example, its designation may be A-60, constituting .60 oz/ft2. Galvannealed has a uniform light-medium gray color and a semi-porous finish and is suitable for painting. Compared to regular hot-dipped Galvanized, it has similar corrosion resistance and a harder coating that is more resistant to scratching. Galvannealed is primarily used in panels, components, studs, metal framing, decks and roof components. Galvanized / Galvannealed ASTM A-653 This specification covers steel sheet, zinc-coated (galvanized) or zinc-iron alloy-coated (galvannealed) by the hot-dip process in coils and cut lengths. The material is available in several designations as follows: commercial steel, forming steel, deep drawing steel, extra deep drawing steel, structural steel, high strength low alloy steel, high strength low alloy steel with improved formability, solution hardened steel, and bake hardenable steel. Structural steel, high strength low alloy steel, solution hardened steel, and bake hardenable steel are available in several grades based on mechanical properties. Yield strength, elongation, and bending properties of the steel shall be determined. A bend test shall be done to the coated sheets. For detail specification, please refer to www.astm.com