Cold-rolled steel is one of the most popular types of rolled metal products. For the manufacture of such steel, the method of cold rolling is used. This method involves the processing of plastic metal using pressure. In some cases, a method such as dressing is used, that is, cold rolling combined with compression. The width of the rolls or sheets of steel that are made this way can be 50 cm or more, thickness – 0.5-5 mm. Finished metal may have an uncut edge.
Range of application of cold-rolled steel
Cold Rolled Sheet is used in various industries and areas of activity: construction, automotive, shipbuilding, instrument making, manufacturing of flexible and stamped products, etc. However, most often this type of metal is used as a blank for the manufacture of steel sheets, for example, corrugated board for construction work. Cold rolled steel sheets can be perforated, wall, roofing, coated with a polymer, painted, etc. for these purposes.
Technological schemes for the production of cold-rolled steel
There are two methods for the production of cold-rolled sheets: sheet and roll. A significant feature of the sheet rolling method is that initially steel is produced in coils that are cut into sheets after cold rolling, and further processing (annealing, dressing, dressing, etc.) is leafed.
In modern cold rolling shops, the roll method of production was adopted. In this case, all operations for the production of cold-rolled steel are in rolls. Before sorting (manual or automatic) the roll is cut into sheets. Mandatory operations for the production of cold-rolled steel are cleaning the surface of hot-rolled strips from the scale, rolling on continuous or reversing mills, heat treatment, training and finishing (cutting, editing, etc.).
The flow chart for cold-rolled strips and sheets of carbon and alloy steels is as follows. The initial billet is hot rolled metal in coils produced on continuous or semi-continuous mills. For some low- alloyed steels, the first operation is softening annealing of the rolled stock. For carbon steels, such annealing is usually not carried out. The next operation in the production of cold-rolled sheets is to clean the surface from the scale by etching, shot blasting or a combined method (shot blasting and subsequent etching). In the pickling line, butt welding of hot-rolled coils is carried out for their coarsening, trimming of the longitudinal edges and oiling.
Cold rolling of hot rolled strips is carried out on continuous or reversible mills. In the roll production of sheets, the following operations are annealing in rolls, training, cutting rolls into sheets on the cross-cutting units with simultaneous dressing and oiling, sorting, packing and shipping sheets. In the production of cold-rolled alloyed steels, the technological process includes a series of heat treatment operations.
Thus, in the production of cold-rolled strips and sheets of high-alloyed steel, the flow chart may be as follows. The first operation is the tempering of hot rolled strips or sheets. Hardening, in this case, allows increasing the ductility of steel. After quenching, etching of hot-rolled strips or sheets stripping of surface defects and cold rolling follows. After cold rolling, quenching of cold-rolled sheets or strips is performed that is followed by pickling, training, sorting, cleaning surface defects, packing, and shipping.