Both cold rolling and hot rolling are processes for forming steel or steel plates, and they have a great influence on the structure and properties of steel.
The rolling is mainly based on hot rolling, and cold rolling is only used for the production of small sections and sheets.
The hot-rolled steel coil is used as the raw material for cold-rolling. After pickling to remove the oxide scale, the cold rolling is carried out. The index drops, so the stamping performance will deteriorate, and it can only be used for parts with simple deformation. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants, because hot-dip galvanizing units are equipped with annealing lines. The weight of the rolled hard coil is generally 6~13.5 tons, and the hot-rolled pickled coil is continuously rolled at room temperature. The inner diameter is 610mm. It is to process steel plates or steel strips into various types of steel through cold working such as cold drawing, cold bending, and cold drawing at room temperature.
Advantages: fast forming speed, high output, and no damage to the coating, can be made into a variety of cross-sectional forms to suit the use
The needs of the conditions; cold rolling can cause a large plastic deformation of the steel, thereby increasing the yield point of the steel.
Disadvantages: 1. Although there is no hot plastic compression during the forming process, there is still residual stress in the section, which has a negative impact on the overall steel.
and the characteristics of local buckling will inevitably have an impact; 2. The style of cold-rolled steel is generally an open section, which makes the free torsion of the section
Stiffness is low. It is prone to torsion during bending, and bending-torsional buckling is prone to occur under compression, and the torsional resistance is poor; 3. Cold rolled
The wall thickness of the section steel is small, and the corners where the plates are connected are not thickened, so the ability to withstand local concentrated loads is weak.
Because it has not been annealed, its hardness is very high (HRB is greater than 90), and its machinability is extremely poor. Only simple directional bending of less than 90 degrees (perpendicular to the coiling direction) can be performed. In simple terms, cold-rolled steel is processed and rolled on the basis of hot-rolled coils. Generally speaking, it is a process of hot rolling → pickling → cold rolling.
Cold rolling is processed from hot-rolled sheets at room temperature. Although the temperature of the steel sheet will be heated up during the processing, it is still called cold rolling. Cold-rolled coils formed by continuous cold deformation of hot-rolling have poor mechanical properties and high hardness. They must be annealed to restore their mechanical properties. Those without annealing are called hard-rolled coils. Hard-rolled coils are generally used to make products that do not need to be bent or stretched, and are bent on both sides or four sides with a thickness of 1.0 or less.
Post time: Aug-30-2022