What is the difference between hot-dip galvanized steel coil and cold-rolled steel coil?Hot-dip galvanized steel coil is made of slab (mainly continuous casting billet) as raw material. After heating, it is made into strip steel by rough rolling mill and finishing mill. The hot steel strip from the last rolling mill of finishing rolling is cooled to a set temperature by laminar flow, and then coiled into a steel coil by a coiler.