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. The cooled steel coil undergoes different finishing operations according to the different needs of users. Wire (flattening, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) into steel plates, flat coils and slitting steel strip products, and then galvanized to make galvanized steel coils. Its strength is not very high, but its plasticity and weldability are good, its appearance is bright in color, and its corrosion resistance is strong.
Cold-rolled steel coil is made of hot-rolled steel coil as raw material. After pickling to remove the oxide scale, it is cold-rolled. The finished product is hard-rolled coil. The strength and hardness of the hard-rolled coil are increased due to cold work hardening caused by continuous cold deformation. , Tough plastic index declines, so the stamping performance will deteriorate, can only be used for simple deformed parts. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants, because the hot-dip galvanizing units are equipped with annealing lines, and the steel coils are continuously rolled for hot-rolled pickled coils at room temperature. Its strength is very high, but its toughness and weldability are slightly worse, its surface is bright, and it is not easy to corrode. In order to prevent rust, the surface is coated with a protective oil when it leaves the factory (not hot-rolled).