Introduction And Difference Between Hot Rolled Steel And Cold Rolled Steel

DALIAN, China - Nov. 13, 2022 - PRLog -- Hot-Rolling

By definition, ingots or billets are difficult to deform and process at room temperature. Generally, they are heated to 1100~1250 ℃ for rolling. This rolling process is called hot rolling.

The end 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 steel is rolled by hot rolling. The steel delivered in hot rolling state has a layer of oxide scale on its surface due to high temperature, 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 hot rolled steel rough and the size fluctuates greatly. Therefore, steel with smooth surface, accurate size and good mechanical properties should be produced by cold rolling with hot rolled semi-finished products or finished products as raw materials.

Advantage:

With fast molding speed, high output, and no damage to the coating, it can be made into a variety of cross section forms to meet the needs of the use conditions; Cold rolling can make steel produce great plastic deformation, thus improving the yield point of steel.

Disadvantages:

1. Although there is no thermal plastic 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 section steel is generally open section, which makes the free torsional stiffness of the section low. Torsion is easy to occur in bending, and flexural torsional buckling is easy to occur in compression, with poor torsional resistance.
3. The wall thickness of cold-rolled formed steel is small, and there is no thickening at the corner of the plate connection, so the ability to bear local concentrated load is weak.

Cold Rolling

Cold rolling refers to the rolling method of extruding steel and changing the shape of steel with the pressure of rolls at room temperature. Although the processing process will also make the steel plate warm, it is still called cold rolling. Specifically, the hot rolled steel coil used for cold rolling is used as the raw material, and the pressure processing is carried out after the scale is removed by pickling, and the finished product is the rolled and hardened coil.

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