1、 Cold rolling
It refers to the cold drawing, cold bending, cold drawing and other cold processing processes of processing steel plate or steel strip into various types of steel at room temperature.
Advantages: fast forming speed, high yield, no damage to the coating, and can be made into various cross-section forms.
Disadvantages:
1. Although there is no thermoplastic compression in 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. Cold rolled sections are usually open sections, which makes the free torsional stiffness of the section low.
3. The wall thickness of cold-rolled section steel is small, and it is not thickened at the corner of the connecting plate, so the ability to bear local concentrated load is weak.
Second, hot rolling
The invention has the advantages that it can destroy the casting structure of the steel ingot, refine the grain of the steel, eliminate the microstructure defects, compact the steel structure and improve the mechanical properties.
Disadvantages:
1. After hot rolling, the non-metallic inclusions (mainly sulfide, oxide and silicate) in the steel are pressed into thin plates, resulting in delamination (interlayer).
2. Residual stress caused by uneven cooling.
3、 The main differences between cold rolling and hot rolling are:
1. Cold rolled section steel allows local buckling of the section, so as to make full use of the post buckling bearing capacity of the member. However, local buckling of hot rolled sections is not allowed.
2. The causes of residual stress in hot rolled steel and cold rolled steel are different, so the distribution on the section is also very different.
