What is the meaning of hot rolling and cold rolling of steel plate? What's the difference?

Both hot rolling and cold rolling are forming processes of steel plates or sections, which have a great influence on the structure and properties of steel. The rolling of steel is mainly hot rolling, and cold rolling is usually used to produce small section steel and sheet steel with precise size.

Hot rolled coil
The hot rolling coil is made of slab (mainly continuous casting slab) by roughing mill and finishing mill after heating. The hot steel strip from the finishing mill is cooled to the set temperature through laminar flow, then rolled into steel strip by coiler, and the cooled steel strip is rolled. According to the different needs of users, the products are processed by different finishing lines (leveling, straightening, cross cutting or longitudinal cutting, inspection, weighing, packaging and marking, etc.) and become steel plate, flat roll and longitudinal cutting steel strip products.

With the development of new technologies for controlling the size accuracy, shape and surface quality of hot rolling as well as the appearance of new products, hot rolling steel plate and strip products have been more and more widely used and become more and more competitive in the market.

Cold rolled coil
Cold rolling is a kind of steel plate produced by cold rolling process, which is based on the hot-rolled coil and rolled under the recrystallization temperature at room temperature. The thickness of cold-rolled sheet is generally between 0.1-8.0mm, and the thickness of cold-rolled sheet produced by most factories is less than 4.5mm. The thickness and width of cold-rolled sheet are determined according to the equipment capacity and market demand of each factory.

The difference between the hot rolled and cold rolled
Cold rolled steel sheet does not produce oxide scale because it is rolled at normal temperature. Therefore, the surface quality of cold rolled steel sheet is good, the dimension accuracy is high, and the mechanical and technological properties are superior to those of hot-rolled steel sheet. In many fields, especially in the field of home appliance manufacturing, it has gradually replaced hot-rolled steel sheet.