Both hot rolling and cold rolling are processes for forming steel plates or profiles, and they have a great influence on the structure and properties of steel.
The rolling of steel is mainly based on hot rolling, and cold rolling is usually only used to produce steel with precise dimensions such as section steel and sheet.
The termination temperature of hot rolling is generally 800~900℃, and then it is generally cooled in air, so the hot rolling state is equivalent to normalizing treatment.
Most steels are rolled by the hot rolling method. Due to the high temperature, the steel delivered in the hot-rolled state has a layer of iron oxide scale on the surface, so it has certain corrosion resistance and can be stored in the open air.
However, this layer of iron oxide scale also makes the surface of the hot-rolled steel rough and the size fluctuates greatly. Therefore, the steel with smooth surface, accurate size and good mechanical properties is required, and hot-rolled semi-finished products or finished products are used as raw materials for cold rolling production.
advantage:
The forming speed is fast, the output is high, and the coating is not damaged, and it can be made into a variety of cross-sectional forms to meet the needs of use conditions; cold rolling can cause a large plastic deformation of the steel, thereby increasing the yield point of the steel.
shortcoming:
1. Although there is no hot plastic compression during the forming process, there is still residual stress in the section, which will inevitably affect the overall and local buckling characteristics of the steel;
2. The style of cold-rolled section steel is generally an open section, which makes the free torsional stiffness of the section low. It is prone to torsion when under bending, prone to bending-torsional buckling under compression, and has poor torsional performance;
3. The wall thickness of cold-rolled forming steel is small, and it is not thickened at the corners where the plates are connected, and the ability to withstand local concentrated loads is weak.
Post time: Aug-24-2022