Advantages of hot rolled coil:

Advantages: Hot rolled steel coil can destroy the casting structure of the ingot, refine the grain of the steel, eliminate the microstructure defects, make the steel structure dense, improve the mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; The bubbles, cracks and looseness formed during the casting of hot rolled steel coils can also be welded under high temperature and pressure.

Cold rolled coil disadvantages:

1.After hot rolling, the non-metallic inclusions (mainly sulfides and oxides, and silicates) inside the steel are pressed into sheets, so that the lamination (sandwich) occurs inside the hot rolled steel coil. Delamination makes the tensile properties of steel greatly deteriorated in the thickness direction, and interlayer tearing may occur when the weld seam of hot-rolled steel coil shrinks. The local strain caused by weld contraction is often several times of the strain at yield point, which is much larger than the strain caused by load.

2, hot rolled steel coil into the cooling caused by uneven residual stress. Residual stress is the internal self-equilibrium stress without external force. Hot rolled steel coils of various sections, hot rolled section steel, and formed steel undergoing hot rolling process all have such residual stress. Generally, the larger the section size of hot-rolled steel coil, the greater the residual stress. Although the residual stress is self-equilibrium, it still has a certain effect on the properties of the steel components of hot-rolled steel coils under the action of external forces. For example, it may adversely affect deformation, stability and fatigue resistance.

Advantages of cold rolled coil:

Advantages of cold rolled steel coil: fast forming speed, high output, cold rolled steel coil does not damage the coating, can be made into a variety of cross section forms, to meet the needs of use conditions; The cold rolled steel coil can produce large plastic deformation of the steel coil, so as to increase the yield strength of the steel point.

Cold rolled coil disadvantages:

1, although there is no hot plastic compression during the molding process, the section of cold-rolled steel coil still has residual stress, which is bound to affect the overall and local buckling characteristics of the steel;

2, the cold-rolled steel coil is generally an open section, so the free torsional stiffness of the section is low. Easy to twist when bending, easy to bend and buckle under pressure, poor torsion resistance;

3, cold rolled steel coil wall thickness is small, plate joint corner is not thickened, the ability to withstand local concentrated load is weak.