From the standpoint of corrosion protection of iron and steel, metallic coatings can be classified into two types: noble coatings and sacrificial coatings. This article focuses on hotdipped zinc, aluminum, zinc-aluminum alloy and aluminum-zinc alloy coatings. It discusses the Sendzimir process and the Cook-Norteman process, which are the two commercial processes that are used for almost all hot-dip galvanized sheet steel in the United States. The article provides a discussion on the aqueous corrosion and atmospheric corrosion of galvanized steel and aluminized steel, as well as the intergranular corrosion of galvanized steel.

Steel sheet is often coated in coil form prior to fabrication to save time, reduce production costs, and streamline operations. This article examines the most common precoating methods and provides a metallurgical understanding of how they impact the manufacturability, performance, and service life of the host material. The article covers metallic coatings, including zinc, aluminum, zinc-aluminum alloys, tin, and terne; pretreatment or phosphate coatings; and preprimed and painted finishes based on organic coatings.