In modernization, rolling technology is divided into cold rolling and hot rolling, so what is the difference between these two technologies? Let's find out together next.

Hot-rolled steel: It is made of slab (mainly continuous casting) as raw material. After heating, it is made into strip steel by rough rolling unit and finishing rolling unit. Compared with cold-rolled steel plate, the manufacturing process is simpler and the cost is lower. Experience believes that the hot rolling method is only suitable for the manufacture of steel plates with a thickness of more than 1.6 mm, and it is uneconomical for thinner steel plates. The surface quality and dimensional accuracy of hot-rolled steel plates are not as good as those of cold-rolled steel plates. In addition to longitudinal beams, cross beams and various brackets, it also punches wheel rims, wheel discs, etc. that require a certain strength, as well as shell covers that are not stressed and surface requirements are not too high. The former is a steel plate with a thickness of 3-5 mm, and the latter is used for both medium and thin plates. The amount of hot-rolled plates used in automobiles is mostly thick plates.

Cold-rolled steel: Using hot-rolled steel coil as raw material, after pickling to remove oxide scale, cold rolling is carried out. The finished product is hard-rolled coil. Cold work hardening caused by continuous cold deformation increases the strength, hardness and The toughness-plastic index decreases, so the stamping performance will deteriorate, and it can only be used for parts with simple deformation.

The difference between cold rolling and hot rolling:

1. Processing technology In terms of processing technology, hot rolling is hot working, and cold rolling is cold working. Hot rolling is rolling above the crystallization temperature, and cold rolling is rolling below the crystallization temperature.

2. Scope of application:

Hot rolling is mainly used in the production of steel structures, bridges, ships, vehicles, and various mechanical parts, etc., while cold rolling is mainly used in home appliances such as automobiles, refrigerators, and washing machines, as well as industrial equipment and various building materials.

3. Appearance performance：

（1）Cold-rolled section steel allows local buckling of the section, so that the bearing capacity of the member after buckling can be fully utilized; while hot-rolled section steel does not allow local buckling of the section.

（2）The reasons for the residual stress of hot-rolled steel and cold-rolled steel are different, so the distribution on the cross-section is also very different. The residual stress distribution on the section of cold-formed thin-walled steel is curved, while the residual stress distribution on the cross-section of hot-rolled or welded steel is thin-film.

（3）The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsion resistance of hot-rolled steel is better than that of cold-rolled steel.