Cold rolled steel is steel produced by cold rolling. Cold rolling is to further thin the No. 1 steel sheet to a target thickness under room temperature conditions. Compared with hot-rolled steel plates, cold-rolled steel plates are more accurate in thickness, and have smooth and beautiful surfaces. At the same time, they also have various superior mechanical properties, especially processing properties. Because cold-rolled raw coils are relatively brittle and hard, and not suitable for processing, cold-rolled steel sheets are usually required to be annealed, pickled and surface smoothed before being delivered to customers. The maximum thickness of cold-rolled is 0.1-8.0mm or less. For example, the thickness of cold-rolled steel plate in most factories is less than 4.5mm; the minimum thickness and width are determined according to the equipment capacity of each factory and market demand.
The difference between cold-rolled steel and hot-rolled steel is not in the smelting process, but in the rolling temperature, or the end temperature of the rolling. The final rolling temperature is lower than the recrystallization temperature of the steel to become cold rolled steel. Hot-rolled steel is easy to roll and has high rolling efficiency. However, under hot-rolled conditions, the steel is oxidized and the surface of the product is dark and gray. Cold rolled steel requires high rolling mill power and low rolling efficiency. In order to eliminate work hardening during the rolling process, intermediate annealing is required, so the cost is also high. However, cold rolled steel has a bright surface and good quality, which can be used directly for processing. Finished products, so cold rolled steel sheets are widely used.
Hot-rolled steel coils are used as raw materials, and after pickling to remove the oxide scale, they are cold rolled. The finished product is hard-rolled coils. Cold work hardening caused by continuous cold deformation increases the strength and hardness of the hard-rolled coils and decreases the toughness index. , So the stamping performance will deteriorate and can only be used for simple deformed parts. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants because all hot-dip galvanizing units are equipped with annealing lines. The weight of the rolled hard coil is generally 6 to 13.5 tons, and the steel coil is continuously rolled on the hot-rolled pickled coil at room temperature. The inner diameter is 610mm.
