Modern steel sheet: past and present
Once people learned how to melt metal andto make products from it, we could appreciate the useful properties of steel (strength, durability, wear resistance). Creating their first masterpieces, smiths felt the need for a thin sheet iron. With hammers and sledgehammers, they flattened the metal blanks, turning their tin, this was the first sheet steel. The process was long and time consuming.
Progress did not stand still, but because of thiniron was required more and more, appropriate equipment was created on which the sheets were forged first, and later they were rolled on rolling mills. The first rolled sheets had a minimum thickness of 0.8 mm and dimensions of 710 mm by 1420 mm, it was extremely difficult to work with them because of their large thickness and small dimensions. Therefore, we gradually switched to rolling sheets of 1000 mm by 2000 mm and thickness of 0.6 mm, and later - 1250 mm by 2500 mm and thicknesses up to 0.5 mm, modern machines allow rolling a sheet from 0.25 mm in thickness and unlimited length.
And everything would be fine, but metal, as is known, is subject to oxidation (rust), at first could not think of anything, it was simply painted, but gradually people learned to cover the metal with zinc.
At first, steel sheet is cleaned, while from itScaling is removed by means of acid etching. Then, the hot-rolled strip is subjected to annealing to give it certain properties, physical and chemical. So it can be processed not only sheet steel, it can be applied to steel products: pipes, strips and so on. Its process can be performed using various methods, they depend on the type of product. There are methods of hot galvanizing, electrolytic galvanizing and thermal diffusion.
With the method of hot galvanizing sheet steelimmersed in molten zinc, where the thickness of the coating is fixed, as a result, galvanized sheet steel is obtained. The thermodiffusion method is used for products having a complex shape, for threaded ones as well. When applying zinc coating, zinc repeats the contours of the product. In the electrolytic galvanizing process, a layer is applied by means of conductive rollers. Some users call this a cathode method. With it, the steel part is loaded into the bath in which the saline solution is located, then an electric current is passed through it. With this application of zinc, a layer is formed whose thickness is 0.5-10 μm.
Such work in modern metal rolling is very in demand, it is difficult to overestimate, after its implementation the surface becomes protected from any impacts.
Otsinovka gives corrosion resistance to steelproducts, after that they can be used to solve the critical tasks of production. It is used for the automotive, construction, oil and gas industry. With the use of zinc steel sheet weight changes slightly, but it acquires the properties of protection from corrosion processes for a fairly long period, it can be up to 50 years.
The quality of the surface of the treated sheets should be in accordance with GOST 16523-89, the width of the sheet is from 710 mm to 1800 mm, its thickness can be from 0.5 mm and reach up to 5 mm.
Steel sheet is divided into 3 classes, this depends on the thickness of zinc on the sheets:
- Class "P" has a thickness of coatings from 40 microns and up to 60;
- Class "1" - from 18 microns and up to 40;
- Class "2" - from 10 microns and up to 18 microns.
