Cold rolled steel (cold-rolled) is one of the most popular types of modern metal rolling. In the total number of steel produced, the volume of sheet steel is continuously increasing. It is made, as the name implies, by cold rolling. Plastic metal is treated by a special method without preheating. Available in two types - cold rolled sheet and in rolls. Finished products can be of different lengths and sizes, with a trimmed edge, with compression.
Cold rolled steel characteristic
The growing demand for cold-rolled steel is explained by higher quality characteristics than hot-rolled products. In addition, the production of sheet metal with a thickness of 1 mm or less is economically feasible only by the cold method. Cold rolling is carried out on ordinary carbon, high-quality carbon, alloyed and high alloy steels, corrosion-resistant, heat-resistant and heat-resistant alloys. The chemical composition of the processed steel determines the properties of the resulting metal and, to a certain extent, its scope. So, for complex stamped products, low-carbon cold-rolled sheet steel is used, GOST 19904-90. The microstructure of the metal after rolling largely determines its ductility, all other things being equal.
Cold rolled steel is produced with a thickness of 0.25–5.0 mm and is supplied in sheets of various sizes - from 510x710 mm to 1250x2500 mm. 0.25–2 mm thick steel can be supplied galvanized. Cold-rolled transformer sheet steel is produced with a thickness of 0.28–0.5 mm, sheet sizes of 750-1000 mm. Important requirements are put forward for transformer steel, namely, the magnitude of the magnetic induction and the size of the watt losses. They produce sheet and rolled cold-rolled steel from structural steels, alloyed with high-quality structural steels for special purposes, electrical low-carbon and silicon steels. Cold-rolled spring, tool tape for magnetic cores is produced.
Features of cold rolled sheet
General-purpose cold-rolled sheet is made of steel grades, the chemical composition of which determines GOST 1050-88: 08ps, 08kp, 10kp, 10ps, 15ps, 15kp, 20ps, 20kp, 25, 30, 35, 40, 45. For cold stamping, high-quality rolling is performed steel grades 08yu, 08kp and 08ps. The surface of cold rolled steel is smoother, and the geometric shapes are more accurate.
Contrary to its name, cold rolled steel does not avoid heat treatment. Any cold-rolled metal is produced from hot-rolled billets.
Cold rolled steel production
Cold-rolled sheet is made in two ways: sheet or roll. In the sheet method, the hot-rolled steel produced in a roll after cold rolling is cut into sheets, which are separately sent for further processing (annealing, dressing, etc.).
In modern production, preference is given to the roll method. In this case, all stages of the production of cold-rolled steel are carried out in rolls and the finished products are manually or automatically cut into sheets. The roll method makes it possible to automate the bulk of technological operations, increases the yield of finished products, improves the properties and shape of the metal due to the stability of the production process. With this method, an increase in finished goods production is possible in the same areas. In some cases, cold rolled steel is supplied in rolls. Depending on the technological process of some engineering enterprises, this reduces the amount of waste. In the production of cold rolled steel, mandatory operations are the cleaning of hot rolled strips from scale, rolling on mills (reversible or continuous), heat treatment, cutting, dressing.
Distinctive features of hot-rolled and cold-rolled steel
Hot rolled metal is easier to process. For products manufactured by hot rolling, low-grade, lower-cost steel is more often used. Finished products are often covered with scale and require additional processing. Since it is impossible to calculate the limits of metal deformation during cooling, the geometry of hot-rolled metal does not differ in rigor (uneven thickness, unevenness at the edges and corners).
The cold-rolled method of rolling makes it possible to more accurately withstand the required dimensions of the products. The surface of such rolled products is smoother, the thickness is uniform, so the final processing of products is minimized, and sometimes not even required. Due to its homogeneous structure, cold-rolled metal is more durable and has better tensile, bending, and tensile characteristics. High-grade steel is used for production.
Cold rolled steel application
Cold rolled metal products are used in many industries: in the automotive industry for bodywork, for machine cases, manufacturing devices, machine parts, in construction, the processing industry, and the production of household appliances.
Cold rolled steel 3 is one of the most expensive in value. The minimum oxygen content helps to increase the uniformity of the structure, ductility and corrosion resistance. It is used for rigid metal structures and load-bearing elements, shaped sections, pipe fittings. Cold rolled steel is used in the manufacture of parts subjected to thermal and chemical effects.