Cold rolling is made by rolling hot-rolled coil under the recrystallization temperature at normal temperature. Cold rolled steel plate is the steel plate produced by cold rolling process, referred to as cold plate. Hot rolling uses continuous casting slab or blooming slab as raw material, which is heated by a walking beam heating furnace, descaled by high-pressure water, and then enters the roughing mill. The roughing material enters the finishing mill after head cutting, tail cutting, and then enters the computer-controlled rolling. After the final rolling, it is cooled by laminar flow and coiled by a coiler to become a straight coil.
Cold rolled and hot rolled steel plates are mainly different in the following points:
(1) The essence of cold rolled steel plate: cold rolled steel is the steel produced by cold rolling. Cold rolling is the process of further rolling a steel plate to a target thickness at room temperature.
(2) The essence of hot rolled coiled steel plate: hot rolled steel is a kind of steel that is rolled above the recrystallization temperature.
(1) Characteristics of cold-rolled steel plate: the thickness of cold-rolled steel plate is more accurate, and the surface is smooth and beautiful. At the same time, it also has various excellent mechanical properties, especially in processing performance.
(2) Characteristics of hot rolled steel plate: during hot rolling, the metal plasticity is high and the deformation resistance is low, which greatly reduces the energy consumption of metal deformation. Hot rolling can improve the processing properties of metals and alloys, that is, the coarse grains in the casting state are broken, the cracks are significantly healed, the casting defects are reduced or eliminated, the as cast structure is transformed into the deformed structure, and the processing properties of alloys are improved.
(1) Processing requirements of cold rolled steel plate: cold rolled steel requires high rolling power and low rolling efficiency, and intermediate annealing is required to eliminate work hardening during rolling, so the cost is also high.
(2) Processing requirements of hot rolled steel plate: hot rolled steel is easy to roll and has high rolling efficiency. Hot rolling temperature includes start rolling temperature and finish rolling temperature. The start rolling temperature is mainly determined according to about 80% of the solidus temperature in the alloy phase diagram, while the finish rolling temperature is determined according to the alloy plasticity diagram. Generally, it is required to be controlled above the recrystallization temperature of the alloy.