Galvanized sheet metal is metal which has been coated in a protective layer of zinc to prevent rusting and to protect the metal from the elements. Galvanization is typically performed on iron or steel, and steel is often galvanized while in sheets. However, there are several types of galvanized sheet metal; while all types are made of steel, they differ in their physical properties and the way in which they were galvanized.
Commercial Galvanized Steel
The term "commercial steel" refers to basic galvanized sheet steel, such as that pictured above, which can be cut and shaped at the location where it will be used or installed. It can be shaped using simple bending and drawing methods, and can be bent in any direction until flat on itself without requiring any application of heat. Commercial steel is used for countless manufacturing applications, and is particularly popular in the automobile industry.
Galvanized Forming Steel
Forming steel is a type of galvanized steel that is more ductile than commercial steel and has a higher tensile strength as well. This means that forming steel is more easily able to be shaped or drawn (stretched), and still retains its strength without growing brittle. Forming steel draws into more consistent sheets as well; however, it is more expensive than plain commercial steel.
Hot-Dipped Galvanized Steel
Hot-dipped galvanized steel is a form of sheet steel which has been unrolled and run through a galvanizing line. This is a manufacturing process which passes the long strips of steel through a vat of molten zinc or zinc-iron alloy. This process ensures that an even layer of zinc or zinc alloy covers the steel, and allows for the creation of different grades of zinc coating, as the zinc or alloy can be applied in a thick layer for heavy-duty galvanization.
Electrolytic galvanized steel, also called electrogalvanized steel, undergoes a different process for galvanization. During the galvanization process, electrolytic deposition is used to apply a thin coating of zinc on the surface of the sheet steel, in a similar manner to the process used during powder coating. Electrolytic galvanization does not create as thick or heavy of a protective zinc layer as hot-dipping, and is therefore usually reserved for steel which will not see extensive outdoor exposure.