Generally, cold rolled steel, such as galvanized steel and color steel plate, must be annealed, so it has good plasticity and elongation, and is widely used in automobile, household appliances, hardware and other industries. The surface of the cold-rolled sheet has a certain degree of finish, which is smooth to the touch, mainly due to pickling. Generally, the surface finish of the hot rolled plate cannot meet the requirements, so the hot rolled steel strip needs to be cold rolled. The thickness of the hot rolled steel strip is generally 1.0mm, and the cold rolled steel strip can reach 0.1mm. Hot rolling is rolling above the crystallization temperature point, and cold rolling is rolling below the crystallization temperature point.
The change of steel shape caused by cold rolling belongs to continuous cold deformation. The cold work hardening caused by this process makes the strength and hardness of rolled hard coil increase and the toughness and plasticity index decrease.
