Cold rolling refers to a rolling method that uses the pressure of a roller to squeeze the steel to change the shape of the steel at room temperature. Although the processing process also heats up the steel plate, it is still called cold rolling. Specifically, hot-rolled steel coils for cold rolling are used as raw materials, which are subjected to pressure processing after pickling to remove oxide scale, and the finished products are hard-rolled coils.
Generally, cold-rolled steels such as galvanized and color steel plates must be annealed, so they have better plasticity and elongation, and are widely used in industries such as automobiles, home appliances, and hardware. The surface of the cold-rolled plate has a certain degree of smoothness and is relatively smooth to the touch, mainly due to pickling. The change of cold rolling to the shape of the steel belongs to continuous cold deformation. The cold work hardening caused by this process increases the strength and hardness of the rolled hard coil, and the ductility index decreases.
Cold rolling can destroy the casting structure of the steel ingot, refine the grain of the steel, and eliminate the defects of the microstructure, so that the steel structure is dense and the mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; the bubbles, cracks and looseness formed during casting can also be welded under the action of high temperature and pressure.
